CN115720819A

CN115720819A - Vegetation recovery method for high-altitude hydropower development area

Info

Publication number: CN115720819A
Application number: CN202211399583.0A
Authority: CN
Inventors: 卢吉; 曹学兴; 迟福东; 陈凡; 王小丹; 李金洁; 秦鑫; 梅增荣; 洪江涛; 吴建波; 鄢燕; 孙荣; 孔维林; 周云; 胡存宝
Original assignee: Institute of Mountain Hazards and Environment IMHE of CAS; PowerChina Guiyang Engineering Corp Ltd; Huaneng Lancang River Hydropower Co Ltd
Current assignee: Institute of Mountain Hazards and Environment IMHE of CAS; PowerChina Guiyang Engineering Corp Ltd; Huaneng Lancang River Hydropower Co Ltd
Priority date: 2022-11-09
Filing date: 2022-11-09
Publication date: 2023-03-03

Abstract

The invention discloses a vegetation recovery method for a high-altitude hydropower development area, which provides a slag field artificial grassland and fruit forest planting technology, a subalpine soil farm grass-shrub-forest artificial vegetation recovery technology, a alpine region soil farm turf transplantation and artificial grassland planting technology based on the ecological conditions of much gravel and drought climate of dry valley of the southeast Tibetan region. The method disclosed by the invention finds out the current situation of natural environment elements, simulates construction situations, monitors the dynamic change characteristics of regional environment elements, develops the plateau high mountain canyon regional vegetation recovery research under the hydropower development disturbance, integrates monitoring and situation simulation, forms a targeted and scientific recovery technology and mode, and fills up the relevant blank in the field of high and cold regions.

Description

Vegetation recovery method for high-altitude hydropower development area

Technical Field

The invention belongs to the technical field of vegetation recovery in a hydropower station spoil area, and relates to a method for recovering vegetation in a high-altitude hydropower development area.

Background

Since the construction and operation of the three gorges hydropower station, the climax of hydropower construction is raised, but the research on the restoration of ecological problems caused by hydropower engineering is just started. The current ecological restoration technology of hydropower development areas mostly focuses on the ecological restoration technology research of low-altitude areas, dry and hot valley slag discarding areas and hydro-fluctuation zones of reservoir areas. The three gorges reservoir area is mainly researched for vegetation recovery and water and soil loss treatment of the hydro-fluctuation belt in the reservoir area, and more achievements are obtained. The method comprises the steps of establishing a 3S technology-based water-level-fluctuating zone ecological environment problem monitoring and early warning system in a water-level-fluctuating zone of a three gorges reservoir area, dividing a functional area, optimizing a land utilization policy, adjusting a rural industry reasonable utilization water-level-fluctuating zone area, adopting a concrete slope protection greening technology and a thick-layer substrate spraying vegetation slope protection technology to stabilize a side slope, recovering different vegetation types by adopting different elevations for vegetation recovery, adopting reasonable matching of arbor, shrub, grass and vine to recover vegetation, and simultaneously adopting the side slope greening technology to treat the problem of non-point source pollution.

The research of vegetation restoration of hydropower station abandoned residue fields in China mostly focuses on residue field vegetation restoration technology of dry and hot valley in low-altitude areas. Most hydropower stations are in low-altitude areas and have sufficient temperature, so that vegetation can be recovered to a certain extent through natural succession of plants. The scholars Zhang Xinbao and the like (1996) in China think that the serious water and soil loss of the rock-soil residue field and the bare rock or thin soil carbuncle are important limiting factors influencing the vegetation recovery of the rock-soil residue field, and propose that the vegetation recovery mode of the rock-soil residue field determines the recovery strategy according to the type of the rock-soil and combining the conditions of climate, soil, terrain and the like, and the selection of suitable plant species is put to the top. Luli and the like (2011) survey the waste residue field of the Jinshajiang river dry and hot valley hydropower station, and after 5 years of recovery, 49 plant species belong to 23 families and 45 families, and a plant community is in the primary stage of secondary succession. Mu Jun and the like (2010) show that the water-retaining agent and the water-retaining slow-release fertilizer have certain application value in the vegetation restoration of the waste disposal site of the dry and hot valley hydropower station of the Jinsha river.

In summary, most hydropower station projects in China are in low-altitude areas at present, the temperature is sufficient, and the project areas can be recovered to a certain extent through natural succession of vegetation after slight manual transformation. However, more ecological restoration technical problems exist for the hydropower development of high altitude and multi-altitude gradient, and further research and attack are needed.

Disclosure of Invention

The invention aims to provide a vegetation recovery method for a high-altitude hydropower development area, provides a slag field artificial grassland and a fruit forest planting technology, a sub-alpine soil yard grass-shrub-forest artificial vegetation recovery technology, a high and cold region soil yard turf transplantation and artificial grassland planting technology, and accelerates the vegetation recovery of a hydropower station slag field in an ecologically fragile area.

The invention is realized by the following technical scheme:

a vegetation recovery method for high-altitude hydropower development areas is characterized by comprising the steps of dry and warm valley vegetation recovery, subalpine vegetation recovery and alpine meadow recovery which are suitable for different elevation gradients in the southeast of the Tibetan province, and specifically comprises the following operations:

1) In the dry and warm valley with the altitude of 2000-3000 m, artificial grassland construction and fruit forest construction are adopted for vegetation recovery; wherein:

the artificial grassland construction comprises the following steps: leveling an area to be repaired, paving an agricultural film for anti-seepage treatment, then covering a soil layer with the thickness of 20-30cm, adding cattle and sheep manure for soil improvement, and performing furrow sowing by taking oat and/or alfalfa as grass seeds and in a deep seed and shallow seed manner; irrigating in time after sowing;

the construction of the fruit forest comprises the following steps: digging a planting hole, paving an agricultural film at the bottom for seepage prevention, then covering soil with the thickness of 40-50cm, adding cow dung to improve the soil, covering the soil with the thickness of 30-40 cm, and finally paving an agricultural plastic film; before planting, soaking the root of the tree seedling in rooting powder solution or dipping the root in slurry, and spreading rooting powder on the root during planting; digging a pit for planting the nursery stock in the middle of the prepared pit, compacting while returning soil during planting, sowing alfalfa in a planting hole after covering soil, and then coating a film; building a soil ridge which is 10-20cm higher than the ground level after planting; irrigating and performing field management after planting;

2) Carrying out vegetation recovery by adopting arbors, shrubs and subalpine meadows in a subalpine area with the altitude of 3400-4000 m; wherein, the subalpine meadow area needs to be covered with surface layer soil with the thickness of 30-50 cm, and the elymus nutans, the old awn wheat and/or the alfalfa grass seeds are selected for single-broadcasting or mixed-broadcasting; deep seed shallow sowing is adopted during sowing, and the sowing depth is 3-5 cm; compacting the seeds on the same day of sowing, covering a mulching film after sowing, covering gravels with the particle size of 5-10 cm, wherein the area proportion of the gravels accounts for 40% of the surface soil, uncovering the mulching film after seedling emergence, watering in time and keeping the gravels;

transplanting or planting arbors/bushes, keeping the root systems of shrub seedlings and arbors seedlings to be transplanted wet, dipping the root systems with slurry or a water-retaining agent, filling the root systems into a seedling planting barrel, injecting water soaked with the roots of the seedlings into the seedling planting barrel, lifting the barrel, planting the seedlings and cultivating; after planting, flattening the surface of the planting hole, and covering surface soil with the thickness of 20-25 cm; within one week after the cultivation, the nursery stock is held and stepped;

4) The alpine meadow is in the alpine region of elevation more than 4000m, adopts the mode of turf transplantation or planting to carry out vegetation restoration, wherein:

the turf transplantation realizes vegetation restoration through turf stripping, stocking maintenance and replanting;

the planting is implemented by taking old awn wheat and elymus as vegetation recovery grass seeds and adopting an artificial grassland planting mode to carry out vegetation recovery;

when the turf is transplanted, the longest edge of the cutting area of the original turf is not more than 50cm, the shortest edge is not less than 25cm, and a certain space is reserved when the turf is transported and stacked; when the turf is replanted, firstly backfilling an organic soil layer, placing gravels under 10cm, and ensuring smooth replanting so that the root of the turf is seamlessly connected with soil; after the turf is replanted, filling the grass gaps with humus soil tightly, and lightly compacting the turf; the original growing environment of the turf is recovered in time after the turf is replanted;

when the grassland is artificially built and planted, the surface soil is peeled off, the soil is prepared by adopting a block soil preparation mode, furrows are opened, the row spacing is kept between 15cm and 20cm, the grass seeds are sowed in a single way or in a mixed way, and deep seeds are shallow when the grass seeds are sowed in the furrows; compacting in time after sowing, and performing field management in time after sowing; the grass is covered after the grass leaves are withered and yellow.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention provides a slag field artificial grassland and fruit forest planting technology, a subalpine soil field grass-shrub-forest artificial vegetation recovery technology, a alpine region soil field turf transplantation and artificial grassland planting technology based on ecological conditions of multiple gravels in dry and warm river valleys in the southeast region and drought climate. The method disclosed by the invention finds out the current situation of natural environment elements, simulates construction situations, monitors the dynamic change characteristics of regional environment elements, develops the plateau high mountain canyon regional vegetation recovery research under hydropower development disturbance, integrates monitoring, a test platform and situation simulation, forms a targeted and scientific recovery technology and mode, and fills up the relevant blank in the field of high and cold regions.

According to the invention, the coverage of the film on the dry and warm valley is favorable for keeping soil moisture, so that the moisture is prevented from seeping and losing from slag stone gaps, the film can be gradually degraded along with the change of time, and the environment is not polluted; adopting nitrogen-fixing plants oat and alfalfa with large biomass as planting plants; the oat has high growth speed and large biomass, can be firm and is beneficial to increasing the income of local herdsmen; alfalfa is a leguminous plant, can fix nitrogen and improve soil, and has higher feeding value; the mixing of the two plants is beneficial to improving the vegetation recovery efficiency and improving the income of local herdsmen. The artificial grassland of the invention is planted by combining alfalfa and oat, the survival rate is higher, and the coverage of the current situation reaches more than 90%; walnut is selected to be planted by a fruit forest, and the survival rate is over 90 percent; the established fruit bearing forest can also generate direct economic income by harvesting fruits.

According to the method, the elymus nutans and the alfalfa are selected as the artificial grassland planting species in the subalpine area, or the elymus nutans and the old mango are selected as the unicast grass species, and the result shows that the artificial grassland is good in growth vigor, and the coverage degree reaches more than 80%; furthermore, placing gravels on the upper layer of the covered and modified surface soil is recommended to be beneficial to soil heat preservation, water preservation and fertilizer preservation, and further promote the growth of plant roots; the invention constructs a good vegetation recovery scheme by exploring artificial grass planting and proportion collocation thereof, a placement technology of gravel promoting plant growth, an optimal scheme of surface soil covering thickness, a tree and shrub transplanting and maintaining means, aweto turf transplanting and other technologies through continuous monitoring for 3 years: the survival rate of spruce tree species after two growing seasons is close to 100%, which shows that spruce has strong adaptability to environment as local soil species, and is an ideal tree for vegetation recovery in the future.

The alpine region soil material field turf transplanting and artificial turf planting method provided by the invention fully considers the particularity of the alpine region soil material field turf, pays attention to the relevance of the size and thickness of alpine meadow turf blocks during cutting and the viability, provides that the longest edge of a cutting area is not more than 50cm, the shortest edge is not less than 25cm, prevents the turf from withering due to the fact that plant root systems are cut due to too small blocks, and reduces the survival rate due to the fact that the turf is too large and not beneficial to carrying and influences the adhesion of the turf to the ground after being laid back; and the bottom of the turf needs to be in complete contact with soil during replanting and stacking, so that turf blocks can be completely turned green and survive through winter exercise; meanwhile, the stacking space meets the requirement that the turf blocks are not stacked in an overlapping mode, and the situation that the turf dies due to the fact that air is deficient between the turf blocks due to untimely watering is avoided. The method overcomes the technical bias in the turf transplanting process, ensures the overwintering of the turf transplanting in the soil farm in the alpine region, and realizes the survival of the turf in the severe environment.

Drawings

FIG. 1 shows the volume water content of soil with different covering soil thickness and with or without anti-seepage measures;

FIG. 2 shows the biomass of the overground part of different grass species of the artificial grassland;

FIG. 3 shows the survival rate of the walnut seedlings with different soil thickness and with or without anti-seepage measures;

FIG. 4 shows the volume water content of soil with different covering soil thickness and with or without anti-seepage measures;

FIGS. 5-1 and 5-2 are both views showing the growth of the root system "wrapped" with gravel;

FIG. 6-1 is a graph of the effect of gravel placement hierarchy on soil temperature;

FIG. 6-2 is a graph of the effect of gravel placement level on soil moisture;

FIGS. 7-1 to 7-3 show the effect of gravel placement on spring greening of Elymus nutans by gravel covering the surface layer, placing gravel in the middle layer, and placing gravel in the lower layer, respectively;

FIG. 8 is a schematic diagram of an alpine artificial grass seed screening test;

FIG. 9 is a graph of the effect of density and fertilization on first year biomass distribution of Dimoxysternia.

Detailed Description

The present invention will now be described in further detail with reference to the following examples, which are intended to be illustrative, but not limiting, of the invention.

A vegetation restoration method for a high-altitude hydropower development area specifically uses a vegetation restoration test field of a downy curve slag field, a Lawu 1# and a Lawushan soil field to explain a slag field artificial grassland and a fruit forest planting technology, a sub-high mountain soil field grass-shrub-forest artificial vegetation restoration technology and a high-cold area soil field turf transplantation and artificial grassland planting technology.

Lawushan test field: facilities such as fences, signboards, simple board houses and the like are arranged, tall fescue, purple fescue, ryegrass and bluegrass are selected as artificial grassland planting species, the growth vigor of various grass species is good, heat preservation is not needed in winter, the grass species can be turned green again in the year, and the coverage degree reaches more than 80%; and the transplanting area of the turf adopts single-layer transplanting, each turf survives, and the survival rate approaches 100 percent.

Lawu 1# test field: set up facilities such as rail, cistern, runoff field, signboard, simple and easy board house, homoenergetic normal operating at present, the species is built as artifical meadow to this test field screening elymus nutans and alfalfa, and the current situation is grown well, and the cover degree reaches more than 80%. In addition, the test field carries out a spruce planting test, the survival rate of spruce tree species is close to 100% after the spruce tree species are cured in two growing seasons, and the spruce still survives in the field at present.

Pile bending groove test field: facilities such as fences and signboards are arranged, and the storage is good at present. The artificial grassland is planted by combining alfalfa and oat, the survival rate is high, and the coverage of the current situation reaches more than 90%; in addition, according to local reality, apples, walnuts, peach trees and the like are selected to be planted through fruit forests, the survival rate is over 90 percent, the whole test area basically covers vegetation, and the treatment effect is good.

Example 1 restoration of vegetation in artificial grasslands on dry and warm valleys

Concretely, the vegetation recovery of the dry and warm valley slag field with the altitude of 2000-3000 m is explained. The dry and warm valley slag field (velvet curved slag field) is a typical geological condition of the southeast Tibetan, the ecological environment is fragile, the slag field area is mainly formed by stacking abandoned slag, the vertical conditions of the slag field area are poor (all gravels), the climate is dry, the vegetation recovery difficulty is large, and the vegetation recovery technology can be popularized to a related engineering disturbance area with the altitude of 2000-3000 m.

In order to screen the slag yard artificial grassland planting recovery mode with both ecological and economic benefits, the artificial grassland planting mode screening is carried out through slag yard soil improvement, anti-seepage treatment, covering soil thickness, grass seed combination treatment and recovery effect monitoring.

1. Improvement and anti-seepage treatment of foundation

Soil improvement: as the slag field has a certain probability of gravel exposure, gravel with the diameter of 10-40 cm is selected for mixing, and the situation of the simulated slag field with the laying thickness of 30-40 cm is laid;

2kg/m of cow dung is added into a leveled slag yard ² Soil improvement is carried out; the cattle and sheep manure belongs to organic fertilizers, can provide effective nutrients for plant growth while improving the soil texture, and is beneficial to plant growth.

Seepage-proofing treatment and soil covering thickness: the soil layer thickness determines the water holding capacity of the soil, and the soil covering thicknesses are respectively set to be 10cm, 20cm, 30cm and 40cm for screening;

and (3) seepage control treatment: a film with the thickness of 0.05-0.07 mm is selected for covering, the covering of the film is favorable for keeping soil moisture, and the moisture is prevented from seeping and losing from slag stone gaps; the film can be gradually degraded along with the change of time, and the environment is not polluted.

The soil moisture, temperature and plant growth conditions were monitored simultaneously after the above treatments.

The results of the volume water content of the soil with different covering soil thicknesses and with or without the anti-seepage measure are shown in figure 1; the results show that: the water content at the soil depth of 10cm is lower, because at the curved dreg site position of fine hair, belong to dry and warm river valley, the temperature is high, sunshine intensity, therefore soil moisture evaporates soon, leads to the surface soil volume water content to be lower.

The volume water content of the soil with the impermeable layer is greatly different from that of the soil without the impermeable layer, the volume water content of the soil at 15cm in the treatment without the impermeable layer (15 cm-CK,30 cm-CK) is higher, the volume water content of the soil at 30cm (30 cm-CK) is lowest, and probably because the bottom is all the slag stones and the water retention property is poor, the volume water content of the soil is lower; the greater water content at 15cm, which may be due to soil skinning, results in reduced water transpiration, while the water rises by capillary action, which may result in a higher volumetric water content at 15cm of soil. In the impermeable layer treatment (15 cm-FS,30 cm-FS), the water content of the soil at 15cm and 30cm in the soil has no great difference, which indicates that the water retention of the soil is maintained.

The contents of soil organic matter, total nitrogen, available phosphorus, quick-acting potassium alkaline hydrolysis nitrogen and cation exchange capacity increase along with the increase of the thickness of the covering soil, which indicates that the increase of the thickness of the covering soil is beneficial to the increase of the growth of plants. And when the soil is covered by 20cm, the contents of organic matters, total nitrogen, available phosphorus and quick-acting potassium can be increased by the impermeable layer, and when the soil is covered by 30cm, the impermeable layer has no obvious influence on soil nutrient elements.

After the soil is covered by 10cm, the vegetation can be naturally recovered. But the above-ground biomass is not as high as the artificial grass biomass. The aboveground biomass of 20cm and 30cm of the covering soil is higher than the aboveground biomass of 10cm of the covering soil. There was no significant difference in aboveground biomass between 20cm and 30cm of casing with and without the provision of a barrier. The biomass of underground is higher in 10cm of the covering soil, and the biomass of underground is not obviously different in the treatment with and without the anti-seepage measures of 20cm and 30cm of the covering soil. From the above results it can be seen that a casing of 10cm can also recover the vegetation, but the biomass is lower and increasing the casing thickness can increase the biomass.

Therefore, the soil layer thickness of 20-30cm is selected and the anti-seepage treatment is carried out, so that the water content of the soil can be maintained under the condition of large evaporation capacity of the dry and warm river valleys, and the survival of the plants is ensured.

2. Grass seed screening:

plant diversity studies were conducted in the dry and warm valley (altitude 2000-3000 m).

The method is characterized in that 4 species of elymus, old awn wheat, alfalfa and oat are initially taken as candidate grass species by adopting a survey method combining plant phylogeny and plant phylogeny.

Then establishing an artificial grassland for further screening: when 20g of seeds are sown in each square meter, the biomass of the overground part of the oat is the largest when a single plant is planted, and the biomass of the overground part of the elymus and old aweto which are planted separately is the smallest;

when the two plants are planted in a combined manner, the biomass of the alfalfa and the oat is the largest, and the biomass of the elymus and the old mango wheat is the smallest;

when the three plants are combined, the biomass of the overground part of the alfalfa, oat, old mango and wheat combination is the largest, and the biomass of the overground part of the alfalfa, elymus foenum-graecum and old mango and wheat combination is smaller;

when the four species are planted in combination, the biomass of the overground part of the 4 species is not higher than the biomass of 1 or 2 plant combinations.

The screening result is shown in fig. 2, which indicates that as the oat biomass is large and the growth speed is high, the alfalfa can fix nitrogen and increase soil nitrogen, and the old awn wheat and the elymus can survive, but the biomass is small and is not suitable for being planted in the field of the Maoqu dreg, so that the artificial grassland for planting the field of the Maoqu dreg is suitable for selecting the combination of the alfalfa and the oat.

And further, analyzing the content of nutrient elements in oat and alfalfa leaves with different covering soil thicknesses and with or without anti-seepage measures. The contents of nitrogen, carbon and phosphorus of the oat all tend to increase with the increase of the soil covering bottom, but no significant difference exists.

The contents of total nitrogen, carbon and phosphorus of alfalfa leaves are increased along with the increase of the thick bottom of the soil covering soil, but no significant difference exists. The total nitrogen content of the alfalfa leaves is obviously higher than that of the oat leaves, because the alfalfa is a nitrogen fixation plant, the total nitrogen content of the leaves is higher.

In conclusion, the artificial grassland in the field of the Daqu dregs can be planted by combining the oat and the alfalfa, and the vegetation can be recovered even if the soil covering is 10cm, but the biomass on the ground is low. By analyzing the change trend of the water content of the soil, the thickness of the covering soil of the artificial grassland in the slag field is recommended to be 20-30cm, the normal growth of herbaceous plants can be ensured, and the anti-seepage measure is adopted, so that the better growth of the plants can be ensured.

Specific recovery measures for the dry and warm valley grassland are given below

1) Planting on artificial grassland

A soil preparation

And (4) in the leveled slag field, selecting a film with the thickness of 0.05-0.07 mm for paving. The film is covered to be beneficial to keeping soil moisture and preventing moisture from seeping and losing from slag stone gaps, and the film with the thickness of 0.05-0.07 mm can be gradually degraded along with the change of time and does not pollute the environment.

B covering soil

The covering thickness of the soil layer is 20-30 cm. The soil layer thickness determines the water holding capacity of the soil, and the soil layer thickness of 20-30cm can maintain the water content of the soil under the condition of large evaporation capacity of dry and warm river valleys, so that the survival of plants is ensured.

C soil improvement

Adding 1000-1300 kg/mu of cattle and sheep manure for soil improvement. The cattle and sheep manure belongs to organic fertilizers, can provide effective nutrients for plant growth while improving the soil texture, and is beneficial to plant growth.

D Artificial grassland planting

The planted seeds meet the national seed grading standard, the purity and the purity are not lower than 95%, the germination rate is not lower than 90%, and the seeds cannot carry quarantine objects. The oat has high growth speed and large biomass, can be fruited and is beneficial to increasing the income of local herdsmen; the alfalfa is a leguminous plant, can fix nitrogen and improve soil, and has higher feeding value; the mixing of the two plants is beneficial to improving the vegetation recovery efficiency and improving the income of local herdsmen.

E depth of sowing

Aiming at the characteristics of severe spring drought, easy moisture leakage and difficult seedling preservation in the Tibet region, a seedling preservation measure of deep planting and shallow emergence is adopted. The improved soil is dug to a depth of 10-15 cm and a width of 10-15 cm. Selecting the mixed sowing ratio of the oat and the alfalfa seeds to be 0.8; furrow sowing is carried out at 10-13 kg/mu.

F field management

After sowing, leveling is performed, followed by irrigation.

Watering the oat in the trefoil stage, the five to six leaf stage (about 15 days after the trefoil stage), the late jointing stage to the flowering stage and the milk stage, which is the guarantee of high yield of the oat.

In the dry and warm river valley, the evaporation capacity is large in 5-8 months, the rainfall is low, the irrigation frequency is increased, and the irrigation is carried out once in 10 days. Meanwhile, the oat lodging caused by overlarge soil moisture is prevented.

Example 2 Vegetation restoration of Dry Warm valley Via fruit forest

In view of the ecological conditions of the dry and warm river valley, the walnuts are selected to simulate a slag field to be planted by fruit trees, and screening of walnut planting mode through simulating slag field scene, seepage-proofing treatment, covering soil thickness treatment and recovery effect monitoring is carried out:

paving gravels with the thickness of 30-40 cm and the diameter of 10-40 cm in the planting holes, mixing, and simulating the slag field situation; the thickness of the covering soil in the planting hole is respectively 50-60 cm, 70-80 cm and 90-100 cm, and the anti-seepage treatment is carried out; adding 4-5kg.m of cow dung ^-2 Soil improvement is carried out in the holes; walnut with the diameter of 3-4 cm is selected for planting, and the root of the walnut is 100mg ^-1 Soaking in rooting powder solution; 10 walnut seedlings were planted per treatment while monitoring soil moisture and plant survival rate.

The survival rates of the walnut seedlings with different soil covering thicknesses and the anti-seepage measures are shown in figure 3, and the volume water contents of the soil with different soil covering thicknesses and the anti-seepage measures are shown in figure 4; the result shows that the water content of the soil at the depth of 15cm is lower, because the soil belongs to a dry and warm valley at the position of the velvet curved slag field, the temperature is high, the sunlight is strong, and therefore the water in the soil is quickly evaporated, so that the volume water content of the surface soil is lower;

the volume water content of the soil with the impermeable layer is greatly different from that of the soil without the impermeable layer, and the volume water content of the soil at the soil depth of 60cm and 80cm in the treatment without the impermeable layer (60 cm-CK,80 cm-CK) is similar to that of the soil at the soil depth of 15cm, which is probably because the bottom is completely slag stone and the water retention is poor, so that the volume water content of the soil is lower, and the water content can be greatly changed along with the change of time;

in the treatment with the impermeable layer (60 cm-FS,80 cm-FS), the soil water content at the position of 60cm and 80cm in the soil depth has no great difference, which indicates that the water retention of the soil is maintained, and the difference of the volume water content of the soil with the impermeable measure and without the impermeable measure is not obvious compared with the position of 100cm in the soil depth.

In conclusion, according to the survival rate of walnut seedlings, the change of the volume and the water content of soil and the economic cost of the thickness of covering soil, the thickness of the covering soil is recommended to be 70-80 cm in the process of planting walnuts in a dreg site through fruit trees, and meanwhile, certain anti-seepage measures (planting holes are adopted for laying films for preventing seepage and the covering soil is 80cm in the process of planting the walnuts through the fruit trees) are adopted, so that the water and the nutrients of the soil can be kept. According to the monitoring of soil moisture, under the climate of dry and warm valley, the irrigation in winter and spring is noticed, and the irrigation is carried out once per week, which is beneficial to the survival of trees through fruit trees.

Example 3 sub-alpine vegetation restoration

The vegetation is recovered aiming at the characteristics of sensitivity, fragility and metamorphosis of the ecological environment in alpine/subalpine areas (Wushan No. 1 soil material field, belonging to the three-river concurrent flow area of the western part of a cross mountain). If the valley is deeply cut in the area of the dam site, the climate and ecological environment of the valley is different from that of the mountaintops of two banks, the local soil resources are scarce, and especially the arable land resources are precious.

The invention explores artificial grass planting and proportion collocation thereof, gravel placement technology for promoting plant growth, top soil covering thickness optimal scheme, arbor and shrub transplanting and maintaining means, awn bract transplanting and other technologies by simulating excavation, artificial grass planting, arbor and shrub transplanting, nutrient control, field monitoring and other test means, and the technologies are respectively explained below.

3.1 Screening Elymus nutans, amur rye and alfalfa as artificial grassland planting species

According to the biomass condition after the grass seeds are tried out shown in the table 1, the biomass current stock and the pastoral tolerance are analyzed, and the Lawushan No. 1 soil farm is recommended to select the elymus nutans and the old mango wheat as the unicast grass seeds.

TABLE 1 Biomass of sowing mode of different grass species

If the nitrogen fixation effect of leguminous plants at the later stage of ecological restoration needs to be comprehensively considered, the mixed sowing of the elymus nutans, the old aweto and the alfalfa is recommended to be more suitable; mixing Elymus nutans, amur aweto and alfalfaSowing, biomass is not easy to be separated and counted, and biomass on the existing ground is about 245g/m ² . When selecting from grass seeds, certain pasturage resistance is considered, and the matching pasturage resistance is strong.

3.2 Optimal solution for artificial grass growth at different topsoil coverage thicknesses

The covering thickness of the top soil is 30cm, which is a recovery mode with more favorable growth and higher benefit of the mixed sowing grass seeds, and the scheme can ensure that the canopy biomass, the root system of 0-25cm and the root system of 25-50cm respectively reach 111.47, 139.47 and 51.87g/m in 2015 ² (ii) a And reaches 86.67 g/m, 99.53 g/m and 27.07g/m in 2016 ² (shown in Table 2).

TABLE 2 screening of the Effect of topsoil thickness (including gravel ratio) on the Biomass of mixedly sown grass seeds

Note: different lower case letters represent significant difference (P = 0.05)

TABLE 3 screening of the Effect of topsoil thickness (gravel ratio) on alfalfa biomass

Note: different lower case letters represent significant difference (P = 0.05)

The cover soil thickness of 50cm is a favorable and efficient recovery mode for the growth of the alfalfa, and the scheme can enable the canopy biomass, the root system of 0-25cm and the root system of 25-50cm to respectively reach 16.53, 44.80 and 19.20g/m < 2 > in 2015 and respectively reach 61.33, 104.73 and 26.73g/m < 2 > in 2016 (shown in Table 3).

The surface soil covering thickness of 40cm is a recovery formula with more favorable growth and higher benefit of the elymus nutansThe scheme can ensure that the canopy biomass, the root system of 0-25cm and the root system of 25-50cm respectively reach 62.93 g/m, 125.33 g/m and 33.33g/m ² (as shown in table 3).

TABLE 3 Effect of unscreened topsoil thickness (gravel ratio) on Elymus nutans biomass

Note: different lower case letters represent significant difference (P = 0.05)

Generally, the surface soil is too thin, the gravel proportion is large, heat preservation is facilitated in winter, and water preservation is not facilitated; the surface soil is too thick and lacks the heat preservation effect of gravels, so the soil temperature is lower in winter, but the porosity of the soil layer is small, and the water preservation is facilitated.

The covering thickness of the soil layer has no obvious influence on the pH, organic matters and total nitrogen of the soil with the thickness of 0-10 cm. The thinner surface soil in the alfalfa seed plot covers (20-30 cm) the soil total phosphorus and the available phosphorus content is higher, and the highest value of the soil total phosphorus and the organic phosphorus for planting the mixed sowing grass seeds is positioned in the surface soil covering (40-50 cm) of the deep thickness. The maximum value of the available nitrogen is located in a sample plot covered by 20cm of surface soil for planting alfalfa and is probably related to certain nitrogen fixation capacity of leguminous plants. The total nitrogen, available phosphorus and available nitrogen contents of the lower soil (10-20 cm) are not obviously different under different species and surface soil thicknesses, and the highest value of the total phosphorus content is positioned in a sample plot covered by 30cm surface soil for planting alfalfa.

Low level of compound fertilizer (20 g/m) ² ) The nutrient content of the soil can be effectively improved.

3.3 Soil gravel placement technique for promoting plant root growth

In the Lawushan No. 1 subalpine area, gravels are placed on the surface layer (0-10 cm), the middle layer (20-30 cm) and the lower layer (40-50 cm) to remarkably promote the growth of the plant root system on the layer. The gravel placement surface promotes an increase in total biomass of 76-100% (2015) and 43-61% (2016) compared to gravel placement in the lower layer. Interestingly, the root system of the plant is characterized by the growth of the 'wrapped' gravel (as shown in figures 5-1 and 5-2), and because the local area has less precipitation and vigorous evaporation, the water in the soil is not easy to preserve. The gravels in the soil have certain pores and certain water absorption performance, so that the function of storing water is achieved, and the existence of the gravel layer is beneficial to the growth of plant roots. This promotion is more pronounced in the case of gravel placed in the surface and middle layers.

The gravel covering the surface layer of the soil is also beneficial to heat preservation in winter, and the average temperature can be increased by 4 ℃ (shown in figures 6-1 and 6-2). In addition, the gravel placement layer has obvious influence on the soil fertility, and the gravel covers the surface layer of the soil, so that the soil fertility is favorably maintained, and the fertilizer is prevented from being washed away and lost by rainwater.

Therefore, in the vegetation recovery test of the Lawushan No. 1 soil yard, a certain proportion of gravels, particularly gravels, are properly mixed in the reclaimed surface soil and placed on the surface layer of the soil, so that the growth of plant roots is facilitated. In addition, researches show that the gravel covering the surface layer can intercept snowfall, reduce the effect of soil evaporation (the snowfall is reduced, so the evaporation amount is small, the heat preservation is facilitated), and facilitate the spring germination and the green turning of plants (the temperature influence is more consistent with the temperature influence than the moisture influence of the herbs in the subalpine overwintering period, as shown in figure 7-1, figure 7-2 and figure 7-3).

3.4 Scheme for artificial grass growth under different surface soil coverage thicknesses of preferred slope

The top soil covering thickness of 30cm and 40cm is the recovery mode with the highest ecological benefit of the old mango wheat, and the scheme can enable the canopy biomass, the root biomass and the total biomass to reach the highest value. In consideration of the problem of the covering cost of the surface soil, the side slope is recommended to be covered with the surface soil with the thickness of 30cm.

3.5 Technique for transplanting and maintaining aweto turf

Through observation for one year, the germination of the Chinese silvergrass seeds is difficult, and the Chinese silvergrass can be judged to be propagated not in a seed mode but in a root tillering mode. The aweto is recommended to mainly protect the whole turf. The aweto grass turf protected in situ can basically survive. However, in the ex-situ protection, due to changes of environmental elements such as altitude, terrain, climate and the like, a small part of the death rate still exists after maintenance, and most of the turf can survive.

3.6 Allopatric planting of spruce

The survival rate is more than 90% through field tests, and the spruce is selected from the street trees from Mangkang county to Meizhen, so that the whole survival rate is high and the growth vigor is good;

the survival rate of spruce tree species after two growing seasons is close to 100%, which shows that spruce has strong adaptability to environment as local soil species, and is an ideal tree for vegetation recovery in the future.

Method and technology for transplanting sabina chinensis and quercus semicarpifolia

Transplanting in the lower soil (simulating soil sampling field) in the transplanting area, wherein the survival rates of the backfilled surface soil and the backfilled lower soil are lower. The observation of the juniper chinensis in two growing seasons is lower than 10 percent. The survival rate of the transplanted quercus acutissima is lower than 50 percent.

Example 4 sub-alpine vegetation restoration includes the following operations:

1) Artificial grassland planting

A soil preparation

Covering surface layer soil in a soil-free area before sowing in spring: if the artificial grassland is a mixed-sowing grass seed (the elymus nutans and the alfalfa are mixed according to the mass ratio of 1:1, or the old awn wheat and the alfalfa are mixed according to the weight ratio of 1:1), the thickness of the soil layer covered on the bottom surface of the grassland is 30cm; if the artificial grassland is the unicast elymus nutans, the thickness of the soil layer covered on the bottom surface of the grassland is 40cm; if the artificial grassland is the single-broadcast alfalfa, the thickness of the soil covering layer on the bottom surface of the grassland is 50cm; if the artificial grassland is a slope unicast old awn wheat, the thickness of the covering soil layer is 30cm;

after the covering soil layer is turned over, the soil layer is raked to be thin and dragged to be flat. After soil preparation, 30g/m of compound fertilizer is applied ² The proportion of nitrogen, phosphorus and potassium in the compound fertilizer is 1:0.5:1.5; and (3) fully mixing the soil and the fertilizer by using manpower or agricultural implements, and harrowing the fine soil.

Irrigation before sowing is the key of germination, growth and survival of the elymus nutans seeds. On the basis of turning the land in spring, making furrows and ridges for irrigation. Irrigation technology must be improved before sowing, irrigation quality is guaranteed, and water leakage and depression water accumulation are prevented so as to avoid influencing a sowing period.

Sowing (B)

The suitable sowing time is 5 months and 1 day to 5 months and 30 days. Ditching and drilling by using machinery or manpower and animal power, wherein the row spacing is as follows: 20-30cm, sowing uniformly by manpower, wherein the sowing amount is as follows: 300kg/hm ² 。

Aiming at the characteristics of severe spring drought, difficult soil moisture preservation, difficult seedling preservation and the like in dry and warm valley areas in Tibet, a seedling preservation measure of deep planting and shallow emergence is adopted, and the proper sowing depth is 3-5 cm.

After seeding, the soil is compacted in time, the same day of seeding is compacted to prevent soil moisture from running, and the transverse compression is preferably achieved along the seeding to improve the compacting effect. After sowing, mulching can play a role in heat preservation and water retention, and the periphery of the film is compacted by stones and soil, so that the film is prevented from being blown away by wind until seedlings emerge. After seedling emergence, the mulching film can be uncovered. After sowing, gravel with the grain diameter of 5-10 cm is covered, so that the function of heat preservation and water retention can be achieved until seedlings emerge. After emergence, gravel is retained.

C field management

The Elymus nutans grows slowly in the seedling stage, and the sowing is carried out in the same year, and the removal of impurities and the grazing are forbidden. Watering once a week within one month after seedling emergence to ensure the growth of the elymus nutans. The late stage irrigation can be performed according to the actual rainfall condition, irrigation needs to be performed for 1-2 times in time when a drought is found, and meanwhile, the situation that the elymus nutans falls down due to overlarge soil moisture is prevented.

2) Planting of spruce

A soil preparation

Soil preparation can be carried out in other seasons except for the freezing of the soil in winter (the soil preparation is carried out before the rainy season in places with less rainfall and drought in winter and spring). The soil preparation is carried out before the rain season of the previous year and in the autumn of the previous year at latest in spring cultivation. The method can be used for planting on deep and fertile ripe plowed land and new cut land which is moist in soil and low in weed coverage rate without preparing the land in advance.

The artificial hole-shaped and horizontal ditch land preparation is used for areas with much wind, less rainfall, broken terrain, thick soil layer and no water accumulation. The specification is width multiplied by depth multiplied by 50cm multiplied by 30cm, and the plant spacing is determined according to the cultivation density. The cultivation density is determined according to local conditions and orientation of business value, and is generally 3330 strains/hm ² About 5000 hm of strain ² 。

B cultivation

Keeping the root system moist, loading the nursery stock into a bucket after the nursery stock is transported to a cultivation site, and lifting the bucket to plant the nursery stock for cultivation.

During transportation, the people do not need to be pressed heavily and sunned, and pay attention to moisture preservation and sealing (triangular support is adopted to prevent heavy pressing, a non-woven fabric covering is arranged to prevent sun, and initial watering management is enhanced to pay attention to moisture preservation).

Temporary planting on the spot, putting into a planting bucket (injecting water soaked in the root of the seedling or dipping with water-retaining agent, the water-retaining agent is an Edson water-retaining agent) before planting, and carrying out bucket cultivation.

The planting time is preferably that the soil thawing depth reaches or exceeds the seedling root length by 20-25 cm, and is generally carried out at the end of 4 months and at the beginning of 5 months. When pruning injured root system, abnormal developing partial root, overlong main root and lateral root. The root system is dipped in thick slurry or water-retaining agent.

And (3) vertically slotting at a final singling point, and repeatedly pushing and pulling the insertion spade forwards and backwards, wherein the width of a slot is about 3-5 cm. Deep lifting, spreading root system (buried in foundation of 1-2 cm), and fixing seedling by foot. The spade is vertically arranged about 5cm away from the seedling, the seedling root is squeezed and compacted after pulling, the process is repeated once, and the spade gap is blocked by the last half spade. Leveling the acupoint surface, covering with 25cm of clay. And (3) within one week after the cultivation is finished, carrying out supporting treading on the nursery stocks, and carrying out Miao Mufu planting and supporting treading again after unfreezing in spring of the next year.

C management

Because the spruce grows slowly in the seedling stage, the impurity removal management is required to be performed periodically every year. Except for weeds which are about 5cm around the root system of the nursery stock, all the weeds are cut off, and the cut weeds and shrubs are cleaned to the outside of the forest land.

The invention constructs a good vegetation recovery scheme by exploring artificial grass planting and proportion collocation thereof, a placement technology of gravel promoting plant growth, an optimal scheme of surface soil covering thickness, a tree and shrub transplanting and maintaining means, aweto turf transplanting and other technologies and continuously monitoring for 3 years: the survival rate of the spruce tree species after the maintenance of the two growing seasons is close to 100 percent.

Example 5 recovery of alpine vegetation

The explanation is specifically given in the Lawushan; on the west side of Minkang county, the linear distance from Minkang county is about 7Km, and the longitude is as follows: 98.5234669 °, latitude: 29.7027983. The area has the characteristics of high altitude, large temperature difference, less rainfall and large evaporation capacity, and the vegetation recovery needs to overcome the problems of high altitude, low rainfall, large temperature difference and the like. In addition, the area belongs to an ecological fragile area, the structural stability of an ecological system is poor, the self-repairing capability is weak, and the ecological system is difficult to recover once the ecological system is degraded.

Since the ecological system is fragile and the self-recovery capability is low after the native vegetation is damaged in the plateau high altitude area with the altitude of about 4000m or more, the soil has no seed bank. Meanwhile, continuous observation shows that pioneer species rarely appear after the surface soil of the area is stripped, and only a few of artemisia plants and 1 poa annua appear in 3 years. Therefore, the ecological function is difficult to recover in a short time by a method of building a species frame by establishing pioneer species, so the vegetation recovery in the region needs manual intervention.

The vegetation re-planting mainly comprises the steps of peeling off the turf in the original area, transplanting shrubs, and transplanting the turf and the shrubs back to the original area after the area is used; and in the planting step, the vegetation species are purchased again to carry out vegetation recovery on the disturbed area. Replanting fully utilizes the tree and grass seed resources of the original area, but needs to consider the transplanting field, and the survival rate of multiple transplanting in a high and cold area is difficult to ensure; transplanting fields need not to be considered for planting, but the original vegetation is not protected enough, and other expenses such as vegetation purchase and transportation need to be considered for planting.

The vegetation recovery and mode of the Lawushan earth stock ground will be explained below.

5.1 Artificial grass land establishment and overwintering

After artificial grasslands are selected and planted for 1 year (as shown in figure 8), the artificial grasslands are subjected to winter exercise for nearly 6 months (for example, the artificial grasslands are not examined in winter, whether the artificial grasslands can survive or not in the second year is not clear, and the long-term effect can not be evaluated and recovered), the results show that alfalfa and awnless oat are not suitable in the area with the altitude of about 4200m, the growth vigor of the artificial grasslands is good in the first year, but the artificial grasslands cannot survive and turn green in the second year after one winter; the miscanthus-free oat belonging to annual grass is good in growth but not suitable for long-term recovery of a soil sampling field (annual is not suitable for long-term).

The elymus and old aweto are suitable for growing in the area with the altitude of about 4200m, belong to the genus of elymus, are pastures grown in drought, have wide adaptability, are particularly cold-resistant and drought-resistant, can safely overwinter in the area of minus 41 ℃ in winter, and can grow for 4 to 5 years in the growing period, so the elymus and old aweto can grow well in the area.

The mixed grass seeds of the tall fescue, the purple fescue, the ryegrass and the blue grass can not be revived and survive in the second year after being exercised in a winter. But a certain warm-keeping measure is adopted, namely a layer of straws is covered, and the grass plants can grow better in the next year.

Therefore, the species selected as suitable for the region are Elymus serpyllum and Amur aweto, and the classification is shown in Table 1.

TABLE 1 Vegetation recovery species suitable for Wula mountain

Species Chinese name	Miscanthus perenneus Linnaeus	All-grass of Manchurian Thalictrum
			Species Latin name	Elymus sibiricus Linn	Elymus nutans Griseb.
Boundary of China	Kingdom of plants	Kingdom of plants
			Door with a door panel	Angiosperm plant door	Angiosperm plant door
Line rope	Class Monocotyledonae	Class Monocotyledonae
			Eyes of a user	Order of Gramineae	Order of Gramineae
Medicine for curing cancer	Gramineae family	Gramineae family
			Subfamily of subfamily	Pooideae annuae	Pooideae annuae
Family of people	Wheat group	Wheat group
			Belong to	Genus Dinopalhyceae	Genus Dioscorea

5.2 Technique for peeling, maintaining and replanting turf layers

Soil improvement of the disturbance area: building garbage in a backfill area is cleaned before surface soil backfilling, a pit is filled and recessed for ground finishing, manual earth covering is generally adopted for a slope after finishing, the earth covering thickness is 10-20cm, mechanical earth covering is adopted for a flat land area, and the thickness is mostly 30cm.

Replanting the peeled turf part of the soil yard on the soil of the improved disturbed area (applying 2kg/m of organic fertilizer) ² ) Or chemical fertilizer (30 g/m) ² ) Or no treatment, part of the waste is still stacked in the stacking area.

After the turf is peeled and replanted 7 months from 2015, the turf is maintained for nearly 1 year, particularly after 6 months of winter (11-4 months) exercise, and the turf is observed to be basically revived and survive 6 months in 2016.

In the stripping and replanting processes, the relevance between the size and thickness of alpine meadow turf blocks and the survivability during cutting is noticed, the longest edge of a cutting area is not more than 50cm, the shortest edge is not less than 25cm, the withering of turf caused by cutting off plant root systems due to too small blocks is prevented, and the turf is not easy to carry and the survivability of turf is influenced due to too large blocks; therefore, the alpine meadow turf blocks should be carefully sized and thick when being cut,

the invention provides the following implementation modes for cutting the turf blocks: the side length of the turf blocks is controlled to be 30-50 cm, the blocks can be basically controlled according to the side length during excavation according to the result of repeated tests, a hoe can be manually adopted for blocking, and the blocks do not need to be of special specifications.

Meanwhile, the turf blocks are not overlapped to prevent the turf from dying due to untimely watering and air shortage between the turf blocks.

Care should be taken during replanting and stacking that the bottom is in full contact with the soil: carrying out soil preparation, finishing the terrain, leveling a soil covering field, and filling and compacting the grass gaps with humus; the turf is lightly compacted to prevent the corner raising and the bulge, and the measures can ensure that the bottom is completely contacted with the soil during the replanting and stacking. Thus, the turf blocks can be completely turned green and survive through winter exercise. The specific replanting adopts machinery, manual transportation and manual replanting, and funds come from water conservation approximate calculation to ensure the replanting work.

5.3 Artificial grass land establishment

The artificial grassland grass seeds are selected from alfalfa, awnless oat, elymus, old awn and mixed grass seeds of festuca arundinacea, ryegrass and bluegrass, are planted for 1 year, and are exercised in winter for nearly 6 months.

The result shows that the alfalfa and the awnless oat are not suitable in the area with the altitude of about 4200m, the growth vigor is good in the first year, but the alfalfa and the awnless oat cannot survive and turn green in the second year after one winter. The reason for this is probably that the optimum temperature for growing the alfalfa is 15-25 ℃, the growth of the alfalfa is slowed down or grazing occurs at the temperature higher than 30 ℃, the growth of the overground part is stagnated at the temperature lower than 5 ℃, and the overground part is dead at the temperature lower than-2.2 ℃. In the Lawushan area, the temperature is obviously lower than-2.2 ℃ in winter; in the last ten days from 12 months to 3 months, the temperature of the surface layer of the soil is between-0.05 and 2.53 ℃, and the water content is very low, which indicates that the soil is very arid. Therefore, even if certain heat preservation measures (straw covering) are adopted, the straw can not survive and grow.

Awnless oats belonging to annual grasses, although well grown, are not suitable for long-term recovery in a soil-taking facility. The elymus and old aweto are suitable for growing in the area with the altitude of about 4200 m. The reason for this is probably that the elymus and old aweto belong to the genus elymus, are dry and middle-growing pasture, have wide adaptability, are particularly cold-resistant and drought-resistant, can safely overwinter in the winter area at-41 ℃ and grow for 4-5 years, and can grow better in the local area.

The mixed grass seeds of the tall fescue, the purple fescue, the ryegrass and the blue grass can not be revived and survive in the second year after being exercised in a winter. But a certain heat preservation measure is adopted, namely a layer of straws is covered (the plants are withered in winter, the covering is mainly heat preservation, and the green returning can be ensured in the next year), and the grass can grow better in the next year.

From the observation and analysis of plant community succession in 1 year, the elevation of the Lawushan test field is about 4200m, and grass seeds such as elymus dahuricus, old mango wheat, alfalfa, awnless oat, tall fescue, red fescue, ryegrass and bluegrass mixed grass seeds are selected. The results show that the elymus and old mango wheat are suitable for being planted in the Lawushan area; alfalfa and awnless oats are less suitable; if the mixed grass seeds of tall fescue, purple fescue, ryegrass and bluegrass do not have overwintering measures in winter, the grass seeds can not turn green and survive in the next year.

After more than 1 year of growth, the growth vigor of the old aweto and the elymus dahurica in the Lawushan soil stock ground test area is good, and the plant height can reach about 80-90 cm; the height of the awnless oat plant sowed in the current year can reach 60-70cm, and the awnless oat plant is replanted in the second year after blooming; alfalfa is essentially non-viable.

Therefore, the artificial grassland of the Lawushan earth stock ground is preferably planted with the elymus and the awnless oat. However, if considered economically, the choice of elymus is recommended.

5.4 Effect of grass seed Density and fertilization on the Biomass of a Togaea Artificial lawn

Analysis of the density and fertilization and the interaction of the two shows that the density and fertilization have significant influence on the biomass. Performed at 30g/m ² 、40g/m ² And 50g/m ² Density test of (2), found 30g/m ² Aboveground biomass at planting density was significantly greater than aboveground biomass at other densities under any fertilizing conditions. The underground biomass has a density of 30g/m except when farmyard manure is added ² The underground biomass is obviously larger than that of other densities, and the underground biomass of other densities or other fertilization conditions has no obvious difference; the results are shown in FIG. 9.

The results do not agree with theoretical assumptions which generally hold that the theoretical seeding rate is the optimum density, i.e. at 40g/m ² High yield is achieved. However, the test results revealed that the density was low at 30g/m ² The above-ground biomass and the underground biomass (under the condition of farmyard manure) are highest and 40g/m ² And 50g/m ² There was no significant difference between aboveground biomass and underground biomass. This means that 40g/m ² The seeding rate is not the optimal density in the local area, but the seeding density is larger, so that the resource space occupied by each individual plant is small, the individual growth is hindered, and the expected high biomass cannot be obtained. Therefore, the present invention considers that 30g/m ² To the optimum seeding density

In the first year of fertilization, the aboveground biomass can be obviously increased after farmyard manure or compound fertilizer application, but the aboveground biomass can only be higher than the underground biomass when the farmyard manure is applied. The alkaline hydrolysis nitrogen is obviously higher than the condition of no fertilization after the farmyard manure and the compound fertilizer are applied, and the quick-acting phosphorus is obviously higher than the farmyard manure and the condition of no fertilization after the compound fertilizer is applied.

In the second year of fertilization, the compound fertilizer or the farmyard manure enables the elymus dahuricus biomass (including aboveground biomass, underground biomass, total biomass and root-cap ratio) to be obviously higher than that without fertilization, and the effect of the compound fertilizer on the biomass is obviously higher than that of the farmyard manure.

Example 6 alpine vegetation restoration includes the following operations:

6.1 Alpine meadow turf peeling, stacking and replanting

A turf Peel

The thickness of the original turf (with root system) needs about 15-30 cm, the thickness of the lower layer humus needs about 10-20cm, and stripping conditions are provided. The stripping needs to pay attention to the selection of seasons, namely, the seasons with rich rainfall and humid climate are selected as much as possible, generally, the seasons are between 6 months and 8 months every year, the alpine meadow is in the growth period, plants have strong vitality, and meanwhile, the climate is warm and humid, so that the plants are easy to survive.

The turf and the humus within the disturbance range are manually stripped by a machine, the stripped turf needs to be partitioned for convenient transportation and storage, the side length is controlled to be 30-50 cm, and the turf withered due to the fact that the plant root systems are cut off due to too small partitioning is prevented. After the turf is peeled off, the lower layer humus soil is very important for the replanting survival of the turf, and the turf is required to be piled up intensively so as to be used when the turf is replanted.

Temporary piling of sod

Laying and storing: if the stacking place is relatively wide, the storage can be performed by tiling. When the turf grass is stored, the humus soil is piled at the lower part, the piling thickness is 30-40 cm, the turf grass is flatly paved at the upper part in a single layer, 3-5 cm intervals are reserved among the turf grass, and the humus soil is covered among the intervals, so that the turf grass is convenient to grow and transplant at the later stage.

Stacking and storing: if the storage area is limited and the working time is short, the peeled sod can be stored in a stack without the storage time being too long (not more than 3 months). While the stacking and storage of turfs has a certain effect, if the management and protection are enhanced after the transplantation, the vegetation can be recovered in a short time after the replating. When storing the greensward in an overlapping way, the humus soil is stacked at the lower part, the greensward is stored on the surface (3-5 layers can be stacked) in an overlapping way, a certain cross space is required to be reserved during the overlapping and storing, so that the air permeability and the water seepage are facilitated, and the height of the greensward and the humus soil is 1.0-1.5 m. The turf storage area is kept by a meadow soil block retaining wall, the meadow soil block retaining wall is of a trapezoidal section, and meadow soil blocks are placed in an overlapping mode.

C turf temporary stacking maintenance

When the turf is temporarily stocked, the leeward surface and the flat terrain are selected as much as possible, if the turf is in a condition, the surface of the turf can be covered by a windproof and breathable dense mesh net, the moisture accumulation is prevented from being taken away by strong wind, and the survival of the turf is ensured. The surface soil pile surface is covered and sheltered by rain-proof cloth, so that wind power sand raising is avoided. And sprinkling water in the temporary turf storage area to keep the soil moist and ensure the water demand of the turf. Meanwhile, the temporary turf storage area is arranged at a higher place, if the temporary turf storage area is unconditional, a ditch is arranged around the temporary turf storage area, so that redundant rainfall in a heavy rain period can be timely drained away, and the situation that the temporary turf is submerged for a long time and is rotted and dead is avoided.

D turf reimplantation

Before the soil material is disturbed, the surface soil needs to be stripped, the organic soil comes from the surface soil stripped in the early stage, gravel is covered to prevent the soil from being 10cm below the surface soil, and gaps are backfilled by the soil. When the turf is replanted, firstly, an organic soil layer is backfilled, and the replanting is smooth, so that the root of the turf is seamlessly connected with the soil;

after the turf is replanted, the grass gaps are tightly filled with humus soil; the replanting and the gap filling are both manually operated, so that the turf can be lightly compacted to prevent corner warping and bulging.

Post E turf reculture maintenance

Fertilizing and watering the replanted turf at proper time according to the actual environmental conditions and the growth and development season of the replanted turf (fertilizing once a quarter on average, watering times are not fixed according to the current year, watering once a month on average, and fertilizing amount: the amount of compound fertilizer is 500kg/hm ² 20000kg/hm of organic fertilizer ² . The water consumption is 3m ³ /100m ² . ) To meet the nutrient and moisture requirements of the vegetation. The reinplanted turf is fragile and can be combined with the bottom soil only after a period of time, so that the artificial or external disturbance to the reinplanted turf area is reduced as much as possible within 10 days after the reinplanted turf is reinplanted, and the maintenance period of the poor turf area is prolonged correspondingly to enable the poor turf area to recover. After the turf is replanted, humus soil scattered on lower-layer native vegetation is removed in time, the original growth environment is restored, and the turf is promoted to turn green in time.

The overwintering adopts non-woven fabric tarpaulin cover for heat preservation.

6.2 Artificial grass land establishment

A soil preparation

After the surface soil is stripped, according to the terrain, the slope is formed, a block soil preparation method is adopted, the machine is used for plowing, the soil is loosened, and then the soil is leveled by a spike-tooth harrow. The rake is 4-10 cm deep, farmyard manure is applied, soil blocks are broken, the ground is leveled, and the manure is buried to be fused. Turning over the farmland, and applying farmyard manure (cow manure or sheep manure) 2kg/m ² And after being uniformly spread, soil preparation is carried out for 1 time, the ploughing depth is 18-20 cm, so that the soil and the fertilizer are fully mixed, and the fine soil is raked and raked.

B planting

Unicast or multicast. The Elymus nutans is selected as the main material, and can also be mixed with the seeds of Miscanthus sinensis and the like for sowing. Scientifically and reasonably collocating the mixed sowing proportion according to the actual situation (grass seeds are mixed according to 1:1 and are sowed after being mixed, and the seed consumption is 200-300 kg/hm ² ). The suitable sowing time is 5 late ten months to 6 early months. Sowing or drilling, mainly drilling, ditching by using machinery or manpower, uniformly sowing by manpower with the row spacing of 15-20 cm and the sowing quantity of 300kg/hm ² . And compacting in time after sowing. Aiming at the characteristics of more gravels on the ground and less soil in the research area, a seedling protection measure of deep planting and shallow planting (the proper planting depth is 3-5 cm) is adopted, and the proper planting depth is 3-5 cm. After sowing, irrigation is carried out in time, and water is thoroughly poured to ensure that the seeds are fully contacted with water, soil and fertilizer.

C field management

The elymus nutans is perennial pasture, the growth of the seedling stage is slow, and the grazing is forbidden in the current year of sowing.

The turf planted or replanted by the method has good growth vigor at present, the survival rate is over 90 percent, each turf basically survives, the planted elymus is good in growth vigor, and the plant height can reach about 80-90 cm.

The embodiments given above are preferable examples for implementing the present invention, and the present invention is not limited to the above-described embodiments. Any non-essential addition and replacement made by the technical characteristics of the technical scheme of the invention by a person skilled in the art belong to the protection scope of the invention.

Claims

1. A vegetation recovery method for high-altitude hydropower development areas is characterized by comprising the steps of dry and warm valley vegetation recovery, subalpine vegetation recovery and alpine meadow recovery which are suitable for different elevation gradients in the southeast of the Tibetan province, and specifically comprises the following operations:

1) Carrying out vegetation recovery on dry and warm valley with the altitude of 2000 to 3000m by adopting artificial grassland construction and fruit forest construction; wherein:

the artificial grassland construction comprises the following steps: leveling an area to be repaired, paving an agricultural film for anti-seepage treatment, then covering a soil layer with the thickness of 20-30cm, adding cattle and sheep manure for soil improvement, and performing furrow sowing in a deep-seed and shallow-seed mode by taking oat and/or alfalfa as grass seeds; irrigating in time after sowing;

the construction of the fruit forest comprises the following steps: digging a planting hole, paving an agricultural film at the bottom for seepage prevention, then covering soil with the thickness of 40-50cm, adding cow dung to improve the soil, covering the soil with the thickness of 30-40 cm, and finally paving an agricultural plastic film; before planting, soaking the root of the tree seedling in rooting powder solution or dipping the root in slurry, and spreading rooting powder on the root during planting; digging a pit for planting the nursery stock in the middle of the prepared pit, compacting while returning soil during planting, sowing alfalfa in a planting hole after covering soil, and then coating a film; building a soil ridge after planting, wherein the height of the soil ridge is 10-20cm higher than the ground level; irrigating and performing field management after planting;

2) Carrying out vegetation recovery by adopting arbor, bush and subalpine meadow in a subalpine area with the altitude of 3400-4000 m; wherein, the subalpine meadow area needs to cover surface covering soil with the thickness of 30 to 50cm, and the elymus nutans, the old awn wheat and/or the alfalfa grass are selected to be sown in a unicast mode or a mixed mode; deep seed shallow sowing is adopted during sowing, and the sowing depth is 3-5 cm; compacting the seeds on the same day of sowing, covering a mulching film after sowing, covering gravels with the particle size of 5-10 cm, wherein the area proportion of the gravels accounts for 40% of the surface soil, uncovering the mulching film after seedling emergence, watering in time and keeping the gravels;

transplanting or planting arbors/bushes, keeping the root systems of shrub seedlings and arbors seedlings to be transplanted wet, dipping the root systems with slurry or a water-retaining agent, filling the root systems into a seedling planting barrel, injecting water soaked with the roots of the seedlings into the seedling planting barrel, lifting the barrel, planting the seedlings and cultivating; after planting, flattening the surface of the planting hole, and covering the surface soil with the thickness of 20 to 25cm; within one week after the cultivation, the nursery stock is held and stepped;

3) The alpine meadow is in the alpine region of elevation more than 4000m, adopts the mode of turf transplantation or planting to carry out vegetation restoration, wherein:

when the turf is transplanted, the longest edge of the cutting area of the original turf is not more than 50cm, the shortest edge is not less than 25cm, and a certain space is reserved when the turf is transported and stacked; when the turf is replanted, firstly backfilling an organic soil layer, placing gravels under 10cm, and ensuring smooth replanting so that the root of the turf is seamlessly connected with soil; after the turf is replanted, filling and compacting the grass gaps with humus, and lightly compacting the turf; the original growing environment of the turf is recovered in time after the turf is replanted;

2. The method for recovering vegetation in a high-altitude hydropower development area as claimed in claim 1, wherein the construction of the artificial grassland in the dry and warm valley specifically comprises the following operations:

1) Land preparation: leveling the slag field, and paving an agricultural film with the thickness of 0.05-0.07 mm for anti-seepage treatment;

2) And (3) covering soil: covering soil on the film, wherein the covering thickness of the soil layer is 20-30 cm;

3) Soil improvement: adding cattle and sheep manure with the addition amount of 1000-1300 kg/mu to improve the soil;

4) Planting artificial grassland: the deep-planting and shallow-emergence furrow sowing mode is adopted, the seed purity and the purity are not lower than 95%, and the germination rate is not lower than 90%;

digging a ditch with the depth of 10-15 cm and the width of 10-15 cm during furrow sowing, and sowing oat and alfalfa in a mixed mode, wherein the mass ratio of the oat to the alfalfa is 0.8 to 1;

5) Leveling the land after sowing, and then irrigating;

irrigating water in the three-leaf stage, five-six-leaf stage, late jointing stage to flowering stage and milk stage of oat.

3. A vegetation recovery method in a high-altitude hydropower development area as claimed in claim 1, wherein the establishment of the dry and warm valley through fruit forests specifically comprises the following operations:

1) Land preparation: digging planting holes of 80cm multiplied by 80cm and row spacing of 3m multiplied by 3m in a leveled slag field;

2) Planting hole arrangement: laying an agricultural film with the thickness of 0.05mm at the bottom of the planting hole for seepage prevention, and covering soil with the thickness of 40-50 cm; adding 4-5 kg/hole of cow dung to improve soil, and covering 30-40 cm of soil; finally, a film with the thickness of 0.05-0.07 mm is used for covering;

3) Planting in a fruit forest: selecting walnut seedlings with the tree diameter of 3 cm-4 cm for planting in 2-3 months in the planting period; cutting out damaged and rotten root of seedling before field planting, and applying 100mg ^-1 Soaking ABT rooting powder solution for 1 day, or dipping the root with slurry; during planting, root-growing powder is scattered at the root;

then digging a pit in the middle of the prepared pit for field planting, and treading while returning soil during field planting to ensure that the seedlings are normal and root systems are stretched;

after covering soil, sowing alfalfa in the planting holes to prevent soil moisture from evaporating and increase nitrogen fixation effect, and then covering a film and preserving water;

then building a soil ridge which is 20cm higher than the ground level;

4) Management and fertilization: fertilizing four times before germination, after flower falling, in the hard core period of fruits in the last 7 months and before land freezing; mixing and applying animal manure and green manure with compound fertilizer, wherein 100-200 kg of animal manure or green manure is needed for each adult tree;

irrigation: irrigation is carried out in winter and spring, and irrigation is carried out once every two weeks.

4. The method for vegetation restoration in a high-altitude hydropower development area as claimed in claim 1, wherein the vegetation restoration in the subalpine meadow comprises the following operations:

a, soil preparation:

covering surface soil in a grassland planning area before sowing in spring, wherein the thickness is 30 to 50cm; after covering soil, turning over the soil, raking finely and dragging flatly; then applying compound fertilizer, fully mixing the soil and the fertilizer, and then raking, finely raking, ridging and ridging;

b, sowing:

the sowing period is 5 months and 1 day to 5 months and 30 days, ditching and drilling are carried out, and the row spacing is 20 to 30cm; unicasting or mixed sowing elymus nutans, old aweto and/or alfalfa seeds, wherein the sowing amount is 30 g/m; deep seed shallow sowing is adopted during sowing, and the sowing depth is 3-5 cm; compacting on the same day as sowing, covering a mulching film after sowing, and covering gravels with the particle size of 5-10 cm, wherein the area ratio of the gravels accounts for 40% of the surface soil; uncovering the mulching film after seedling emergence, and reserving gravels;

c, field management:

watering once a week within one month after seedling emergence; watering in the later period in combination with the actual rainfall condition.

5. The method for recovering vegetation in a high-altitude hydropower development area as claimed in claim 4, wherein if the artificial grassland is a mixed-seeded grass seed, the thickness of the soil covering layer on the bottom surface of the grassland is 30cm;

if the artificial grassland is the unicast elymus nutans, the thickness of the soil layer covered on the bottom surface of the grassland is 40cm;

if the artificial grassland is the single-broadcast alfalfa, the thickness of the soil covering layer on the bottom surface of the grassland is 50cm;

if the artificial grassland is a slope unicast old awn wheat, the thickness of the covering soil layer is 30cm.

6. The method for recovering vegetation in a high-altitude hydropower development area as claimed in claim 1, wherein the vegetation recovery of trees and shrubs in the sub-high mountain area comprises the following operations:

a, soil preparation:

preparing the soil before the premise of rainy season; the method is characterized in that the method is used for cultivating new cut lands with deep and fertile soil layers and wet soil and low weed coverage rate;

the cultivation density is 3330-5000 hm; the specification of the hole planting pits is 50cm multiplied by 30cm with the width multiplied by the depth, and the planting distance is determined according to the planting density;

b, cultivation:

keeping the root systems of shrub seedlings and arbor seedlings to be transplanted wet, and trimming injured root systems, abnormally developed partial roots, overlong main roots and lateral roots after the shrub seedlings and arbor seedlings are transported to a cultivation field; then dipping the root system with slurry or water-retaining agent, loading into a seedling planting barrel, injecting water soaked with the root into the seedling planting barrel, lifting the barrel, planting seedlings and cultivating;

the planting time is carried out at the end of 4 months and the beginning of 5 months, and the soil thawing depth reaches or exceeds the seedling root length by 20 cm-25 cm;

vertically slotting at a final singling point, repeatedly pushing and pulling an insertion spade, and enabling the width of a slot to be 3-5 cm; deep lifting and shallow lifting, stretching root systems, deeply burying the foundation at the diameter position of 1-2 cm, and treading for final singling; vertically lowering the spade 5cm away from the seedling, pulling and pushing the spade, compacting the seedling root, repeating the steps once, and finally blocking the spade seam by a half spade; leveling the cave surface, and covering the surface layer with the depth of 20-25 cm;

within one week after the cultivation, the seedlings are subjected to supporting treading, and after the seedlings are unfrozen in the spring of the next year, the seedlings are subjected to Miao Mufu planting and supporting treading again;

c, management:

and (4) carrying out impurity removal management every year at regular intervals, cutting off all the weeds except for keeping 5cm of weeds around the root system of the seedling, and cleaning the cut weeds to the outside of the forest land.

7. The method for recovering vegetation in the high-altitude hydropower development area as claimed in claim 1, wherein the vegetation recovery of the alpine meadow adopts turf replanting and comprises the following operations:

a, peeling off turf:

the stripping time is 6-8 months per year, and stripping conditions are met when the original turf thickness and root system grow to 15-30 cm and the lower layer humus thickness is 10-20cm;

the peeled turf is divided into blocks, and the side length is controlled to be between 30cm and 50cm; after the turf is peeled off, collecting and stacking the lower-layer humus soil;

b, stacking the turf:

laying and storing: when the turf is stored, the humus soil is piled at the lower part, the piling thickness is 30-40 cm, the turf is flatly paved at the upper part in a single layer, 3-5 cm intervals are reserved among the turf, and the collected humus soil is covered among the intervals;

stacking and storing: when the greensward is stacked and stored, humus soil is stacked at the lower part, the greensward is stacked and stored in a shape of Chinese character 'pin' by 3-5 layers, and the height of the greensward and the humus soil is 1.0-1.5 m; the turf storage area is kept and protected by a meadow soil block retaining wall, the meadow soil block retaining wall is of a trapezoid cross section, and meadow soil blocks are stacked and placed;

c, stacking and maintaining turf:

selecting a leeward, high-terrain and flat section when the turf is temporarily stocked;

the surface of the surface soil pile is covered and shielded completely by waterproof cloth; sprinkling water in the temporary turf storage area to keep the soil moist;

d, turf replanting:

when the turf is replanted, firstly, an organic soil layer is backfilled, and the replanting is smooth, so that the root of the turf is seamlessly connected with the soil; after the turf is replanted, the grass gaps are tightly filled with humus soil, the turf is lightly compacted, and the raised corners and bulges are prevented;

e, maintaining the grass after replanting:

artificial or external force disturbance to the replanted turf area is reduced as much as possible within 10 days after the turf is replanted, and the maintenance period of the poorly restored turf area is prolonged correspondingly to enable the poorly restored turf area to restore the growth;

after the turf is replanted, the humus soil scattered on the lower native vegetation is removed in time, the original growth environment is restored, and the turf is promoted to turn green in time.

8. A method of vegetation restoration in a high altitude hydroelectric development area as claimed in claim 7 wherein the longest edge of the turf cutting area is no more than 50cm and the shortest edge is no less than 25cm during replanting; during excavation, basically controlling the block division according to the side length, controlling the side length to be 30cm to 50cm, and manually adopting a hoe for block division;

the stacking space is required to meet the requirement that the turf blocks are not overlapped to be stacked, and a distance of 10cm to 20cm is reserved;

the bottom of the turf is in full contact with the soil during replanting: after the land is replanted and prepared, the terrain is trimmed, the earth covering field is flat, and the grass gaps are tightly filled with humus; the turf is lightly compacted to prevent the upwarp and bulge, and the bottom is ensured to be completely contacted with the soil during replanting and stacking.

9. The method for recovering vegetation in the high-altitude hydropower development area as claimed in claim 1, wherein the vegetation recovery in the alpine meadow area is artificially established and comprises the following operations:

a, soil preparation:

stripping surface soil, ploughing by using a machine in a block soil preparation mode, loosening the soil, and leveling the soil by using a rake; harrowing the soil 4-10 cm deep, applying farmyard manure, crushing soil blocks, leveling the ground, burying the manure to enable the soil manure to be melted;

ploughing twice, applying farmyard manure of 2kg/m, uniformly spreading and then carrying out land preparation for 1 time, wherein the ploughing depth is 18-20 cm, so that the soil and the manure are fully mixed, and raking and harrowing the fine soil;

b, planting:

the sowing period is 5 late months to 6 early months, and the grass seeds are sowed in a single way or in a mixed way;

the sowing mode is broadcast sowing or drill sowing, ditching is carried out mechanically or manually, the row spacing is 15-20 cm, manual uniform sowing is carried out, the sowing quantity is 200-300kg/hm, deep sowing is shallow, the sowing depth is 3-5 cm, and timely compaction is carried out after sowing;

irrigating in time after sowing, and watering thoroughly to make seeds fully contact with water, soil and fertilizer;

c, field management:

the elymus nutans is perennial pasture, and the grazing should be forbidden in the current year of sowing.