CN115868377A - Method for recovering vegetation in hydropower development area of dry and warm valley of plateau - Google Patents

Abstract

The invention discloses a method for recovering vegetation in a hydropower development area of dry and warm valleys in plateau, which is used for providing artificial grassland planting and vegetation recovery through fruit forest planting based on the ecological conditions of multiple gravels and drought climate of the dry and warm valleys in southeast of the Tibetan province. The artificial grassland of the invention is planted by combining alfalfa and oat, the survival rate is high, and the coverage of the current situation reaches more than 90%; the walnuts are selected for planting through fruit forest planting, the survival rate is over 90 percent, the whole test area basically covers vegetation, the treatment effect is good, and the vegetation recovery of a hydropower station slag yard in an ecological fragile area can be accelerated.

Description

Method for recovering vegetation in hydropower development area of dry and warm valley of plateau

Technical Field

The invention belongs to the technical field of vegetation recovery in a hydropower station residue disposal field, and relates to a method for recovering vegetation in a hydropower development area of dry and warm valley of plateau.

Background

Since the three gorges hydropower station is built and operated, 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 technical research of low-altitude areas, dry and hot valley slag discarding areas and reservoir area hydro-fluctuation zones. The three gorges reservoir area is mainly researched for vegetation restoration and water and soil loss control 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 on vegetation restoration of the hydropower station spoil area in China mostly focuses on the technology of vegetation restoration of the spoil area of the dry-hot valley in the low-altitude area. 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 in China, zhang Xinbao and the like (1996) consider that serious water and soil loss of the rock-soil residue field, bare rock or thin soil lump are important limiting factors influencing the vegetation recovery of the rock-soil residue field, propose that the vegetation recovery mode of the rock-soil residue field should determine a recovery strategy according to the type of the rock-soil and combining conditions such as climate, soil, terrain and the like, and put the selection of suitable plant species to the top. Ruweili et al (2011) survey the waste disposal site of the Jinshajiang dry-hot valley hydropower station, and found that after 5 years of recovery, 49 plant species belong to 23 families and 45 genera, and plant communities are in the primary stage of secondary succession. Research on vegetation recovery technology of the waste disposal field of the dry and hot valley hydropower station of the Jinsha river by Mojun and the like (2010) shows that the water-retaining agent and the water-retaining slow-release fertilizer have certain application value in the vegetation recovery of the waste disposal field of the dry and hot valley hydropower station.

However, in the prior art, researches on vegetation restoration of a waste disposal site of a hydropower station in a plateau area are lacked, and particularly, a method for disturbing areas of dry and warm valley related engineering which is fragile in ecological environment and difficult in vegetation restoration is lacked.

Disclosure of Invention

The invention aims to provide a method for recovering vegetation in a hydropower development area of dry and warm valleys in plateau, which screens out proper plant species for recovering vegetation, provides recovery measures and accelerates the vegetation recovery of a hydropower station slag yard in an ecologically vulnerable area.

The invention is realized by the following technical scheme:

a method for recovering vegetation in a hydropower development area of dry and warm valley of plateau, which is to provide artificial grassland planting and vegetation recovery through fruit forest planting based on the ecological conditions of much gravel and drought climate of the dry and warm valley of the south of the Tibet;

the artificial grassland planting method comprises the following steps:

leveling a slag field, paving an agricultural film for anti-seepage treatment, covering a soil layer with the thickness of 20-30 cm, and adding cattle and sheep manure for improvement; carrying out furrow sowing by taking oat and/or alfalfa as grass seeds and in a manner of shallow seeds; the seeding rate of grass seeds is 10 to 13kg/mu;

irrigating after sowing; irrigating at three-leaf stage, five-six-leaf stage, late jointing stage to flowering stage and milk stage of oat; irrigating once in 5-8 months for 10 days;

the planting mode of the fruit bearing forest is as follows:

before planting, enclosing and leveling a slag field, digging a planting hole, paving an agricultural film at the bottom for seepage prevention, then covering soil with the thickness of 40-50 cm, adding cow dung to improve the soil, covering the soil with the thickness of 30-40 cm, and finally covering the soil with the film with the thickness of 0.05-0.07mm;

the planting period is selected in 2-3 months, and the tree seedling is selected to be a walnut seedling with the tree diameter of 3-4 cm; before the walnut seedlings are fixedly planted, the walnut tree roots are soaked in rooting powder solution or dipped in slurry, and the rooting powder is scattered on the roots during planting;

digging pits in the middle of the prepared pits for field planting of walnut seedlings, and compacting while returning soil during field planting; after covering soil, sowing alfalfa in the planting holes, and then mulching;

building a soil ridge which is 10-20cm higher than the ground level after planting; watering root fixing water of not less than 30kg per plant after planting, and watering once again seven days after planting; and field management till the walnut forest is built.

The artificial grassland planting method 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 soil;

4) Planting on an 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.

The fruit forest planting method 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 injured root and rotten root of seedling before planting, and applying 100mg/kg for root ^-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 pits in the middle of the prepared pits for field planting, and compacting while returning soil during field planting so as to straighten and stretch root systems;

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.

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

the slag yard in the dry and warm valley area of the plateau has poor site conditions, the piled slag body mainly comprises gravels, and in order to fully utilize the local hydrothermal conditions, the slag yard needs water and fertilizer retention measures to develop artificial grassland planting, improve the water and soil retention function and increase the forage grass supply capacity; the invention is used for paving a flat slag field by selecting a film of 0.05 to 0.07mm. The film is covered to be beneficial to keeping soil moisture and preventing the moisture from seeping and losing from slag stone gaps, and the film with the thickness of 0.05 to 0.07mm can be gradually degraded along with the change of time without polluting the environment. Adding 1000 to 1300kg of cattle and sheep manure per mu for soil improvement. The cattle and sheep manure belongs to organic fertilizers, can provide effective nutrients for plant growth while improving soil texture, and is beneficial to plant growth.

The invention adopts 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 increasing the income of local herdsmen. In view of the characteristics of severe spring drought, easy soil moisture leakage and difficult seedling preservation in the Tibetan region, the seedling preservation measure of deep planting and shallow emergence is adopted to ensure the rate of emergence.

In the planting of the fruit tree, an agricultural film with the thickness of 0.05mm is selected to prevent seepage at the bottom of a planting hole and cover 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; and (3) selecting a film with the thickness of 0.05 to 0.07mm for covering. The film is covered to be beneficial to keeping soil moisture and preventing the moisture from seeping and losing from slag stone gaps, and the film with the thickness of 0.05 to 0.07mm can be gradually degraded along with the change of time and does not pollute the environment.

The artificial grassland of the invention is planted by combining alfalfa and oat, the survival rate is high, and the coverage of the current situation reaches more than 90%; the walnuts are selected to be planted in the fruit forest, the survival rate is over 90 percent, the whole test area basically covers the vegetation, the treatment effect is good, and the vegetation recovery of the hydropower station slag field in the ecological fragile area can be accelerated. In addition, the transgression forest established by the invention can generate direct economic income by harvesting fruits. Through the implementation of fruit forests, the production and living conditions of part of the agricultural and herding people can be directly improved, the employment opportunity is increased, the transfer of abundant labor force of the agricultural and herding people to the second and third industries can be accelerated, the development of agricultural and herding areas is promoted, and certain economic benefit is generated.

Drawings

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

FIG. 2-1 is a diagram showing the results of above-ground biomass detection of artificial grasslands of different covering soil thicknesses;

FIG. 2-2 is a diagram showing the results of underground biomass detection of artificial grasslands with different casing thicknesses;

FIG. 3-1 shows the content of nutrient elements in the oat leaves with different casing thicknesses;

FIG. 3-2 shows the contents of nutrients in the leaves of alfalfa having different casing thicknesses;

FIG. 4 shows the biomass of the overground part of the artificial grassland combined by different grass seeds;

FIG. 5 is a schematic diagram of vegetation recovery of an artificial grassland;

FIG. 6 shows the survival rate of the walnut seedlings with different covering soil thickness and with or without anti-seepage measures;

FIG. 7 shows the volume water content of soil with different covering soil thickness and with or without anti-seepage measures.

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 method for recovering vegetation in hydropower development areas of dry and warm valley of plateau is explained by specifically using the vegetation recovery of the abandoned dreg site of the dry and warm valley hydropower station with the elevation of 2000-3000 m. The dry and warm valley slag field (velvet curved slag field) is a typical geological condition in the southeast Tibetan region, the ecological environment is fragile, the slag field area is mainly formed by stacking waste slag, the vertical ground condition of the slag field area is poor (most of gravel), the climate is drought, the vegetation recovery difficulty is high, and the vegetation recovery technology can be popularized to a relevant engineering disturbance area with the altitude of 2000-3000m.

3 sampling points (2 are positioned at two sides of a valley and 1 is positioned at the bottom of the valley) are respectively arranged at the elevations 2800m, 2900m and 3000m of the Mazhen upstream villus flexure, a small sample is adopted to collect soil samples, 27 parts of soil seed bank samples are counted, and the soil seed bank screening is carried out by adopting a seed germination method. Preliminary statistics show that the number of seed banks is 248 grains/m at the altitude of 2800m ² (ii) a At an altitude of 2900m, the number of seed banks is 416 grains/m ² (ii) a At an altitude of 3000m, the number of seed banks is 315 grains/m ² The seed pool is mostly gramineous plants. Seed bank of Jinshajiang river dry and hot valley (1341.7 grains/m) ² 17 species; zhang Jian Li et al, 2008), minjiang arid river valley (average 890.0 grains/m) ² 26 species; luyanjiao et al, 2015), overall, the soil seed pool was low and the number of species was low.

Therefore, according to the characteristics of local natural resources, artificial intervention is needed to recover the vegetation, and in the process of recovering the artificial vegetation, the technical means of fully applying a water retention mode, soaking roots with rooting powder and the like are considered.

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

1. Foundation improvement and seepage-proofing treatment

Soil improvement: because the slag field has a certain probability of gravel exposure, selecting gravel with the diameter of 10-40 cm for mixing, and paving a simulated slag field scene with the thickness of 30-40 cm;

adding 2 kg/m of cattle manure 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 thickness of the soil layer determines the water holding capacity of the soil, and the covering soil thickness is respectively 10cm, 20cm, 30cm and 40cm for screening;

and (3) seepage control treatment: an agricultural 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 degraded gradually with time without polluting environment.

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 position of 10cm deep in soil is lower, because the position of a velvet slag field belongs to a dry and warm valley, the air temperature is high, the sunlight is strong, and therefore, the water in the soil is evaporated quickly, and 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, 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 treatment with the impermeable layer (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 alkaline hydrolysis nitrogen and cation exchange capacity increase 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 increasing 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.

Further collecting the aboveground biomass and the underground biomass of the artificial grassland of the slag yard. After drying and weighing, the analysis is carried out. Wherein, FIG. 2-1 is a graph of the detection result of the aboveground biomass of the artificial grassland with different covering soil thicknesses; FIG. 2-2 is a graph showing the results of underground biomass detection of artificial grasslands with different covering soil thicknesses; FIG. 3-1 shows the content of nutrient elements in the oat leaves with different casing thicknesses; FIG. 3-2 shows the contents of nutrients in the leaves of alfalfa having different casing thicknesses;

specific data are shown in table 1.

TABLE 1 variation of soil nutrient elements for different covering thicknesses and with or without anti-seepage measures

Covering soil Thickness of

Whether or not to prevent Seepage measure

Recovery (Mode)

pH

Organic matter （g/kg）

Total nitrogen （g/ kg）

Available phosphorus （mg/kg）

Quick-acting potassium （mg/kg）

Alkaline hydrolysis of N （mg/ kg）

Cation exchange Volume (coml/kg)

10cm

Nature recovery Compound medicine

Nature of nature Recovery of

8.71 ± 0.52

14.38 ± 1.23c

1.1± 0.1b

14.15± 1.3c

77.69± 2.6d

14.7± 2.2c

5.44±2.3b

10cm

Artificial recovery Compound medicine

Artificial operation Recovery of

7.57 ± 0.23

22.22 ± 2.25b

1.2± 0.2b

21.13± 3.2b

83.24± 5.6d

13.48 ±1.3c

6.22±1.2b

20cm

Without seepage control Film

Artificial operation Recovery of

8.62 ± 0.12

23.71 ± 2.39b

1.5± 0.2a

26.82± 3.1b

110.9± 9.5c

36.75 ±4.2b

7.3±1.6b

20cm

With prevention of seepage Film

Artificial operation Recovery of

8.31 ± 0.35

29.95 ±4.2b

1.8± 0.1a

35.23± 2.6a

277.4± 10.6b

44.1± 6.8b

8.18±2.4b

30cm

Without seepage control Film

Artificial operation Recovery

8.65 ± 0.41

48.81 ± 3.26a

2.5± 0.2a

35.39± 3.5a

277.4± 11.3b

57.58 ±4.8a

13.28±3.2a

30cm

With prevention of seepage Film

Artificial operation Recovery of

8.34 ± 0.52

40.45 ± 1.56a

1.9± 0.1a

35.35± 4.2a

388.4± 15.6a

61.25 ±7.2a

11.32±2.6a

The results show that: after the soil is covered by 10cm, the vegetation can be naturally recovered. But the aboveground biomass is not as high as the artificial grassland 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 biomass is higher in 10cm of the covering soil, and the biomass of underground biomass has no obvious difference in treatment with and without anti-seepage measures at 20cm and 30cm of the covering soil. From the above results it can be seen that a casing of 10cm can also recover vegetation, but the biomass is lower and increasing casing thickness can increase the biomass.

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

2. Grass seed screening:

a plant diversity survey was conducted at the dry and warm valley (altitude 2000 to 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 artificial grassland for further screening: when 20g of seeds are sowed 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 is the smallest when the elymus is planted and the old awn is planted separately;

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

when the three plants are combined, the biomass of the overground part of the alfalfa, oat and old mango wheat combination is the largest, and the biomass of the overground part of the alfalfa, elymus serrulata and old mango 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 that of 1 or 2 plant combination.

The screening result is shown in figure 4, and the result shows that 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 blume can survive, but the biomass is small, so that the method is not suitable for being planted in the Maoqu dreg field, and the alfalfa and oat combination is more suitable for being planted in the artificial grassland of the Maoqu dreg field.

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, total carbon and total phosphorus of alfalfa leaves tend to increase 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 significantly higher than that of the oat leaves, because 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. And through analyzing the variation 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 20-30 cm, 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) paving an agricultural film with the thickness of 0.05-0.07 mm in the leveled slag field. The film is covered to be favorable for keeping soil moisture and preventing the 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 without polluting 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 20-30 cm can maintain the water content of the soil under the condition of large evaporation capacity of dry and warm 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 soil moisture leakage and difficult seedling preservation in southeast Tibetan areas, the seedling preservation measure of deep planting and shallow emergence is adopted. The improved soil is dug with the depth of 10-15 cm and the width of 10-15 cm. Selecting a mixed sowing ratio of oat and alfalfa seeds of 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 method prevents the oat from lodging due to excessive soil moisture.

According to the monitoring of the soil temperature from 11 months in 2015 to 11 months in 2016, the lowest soil temperature in a fuzzy slag field area of 0-15 cm is about 2.5 ℃, and meanwhile, the surface temperature of the soil is greatly changed due to strong sunshine in the daytime. The temperature is gradually increased along with the increase of the depth in winter, and the opposite trend is shown in spring, and generally, the condition that the temperature of the soil in the villus dreg field is below 0 ℃ does not exist, namely, the temperature can not cause large frostbite on plants in the whole winter. Therefore, during the vegetation recovery process of the fluff residue field, the vegetation may not need to be subjected to heat preservation overwintering treatment. Therefore, the possibility of planting via the fruit forest is provided, and in order to increase the economic benefit while recovering the vegetation, a recovery mode of planting via the fruit forest in a residue field with the best ecological and economic benefits is screened on the basis of the grassland recovery (the recovery condition is shown in figure 5).

In view of the ecological condition of the dry and warm valley, the walnuts are selected to be planted in a dreg field through a fruit forest, and screening of walnut planting mode through anti-seepage 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 cattle manure ^-2 Soil improvement is carried out in the holes; walnut with the diameter of 3cm to 4cm is selected for planting, and the walnut root is used in an amount of 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 6, and the volume water contents of the soil with different soil covering thicknesses and the anti-seepage measures are shown in figure 7; the result shows that the water content of the soil at the depth of 15cm is lower, because the position of the velvet slag field belongs to a dry and warm valley, the air temperature is high, the sunlight is strong, and therefore the water in the soil is quickly evaporated, and 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 position of 60cm and 80cm of the depth of the soil is similar to that of the soil at the position of 15cm of the depth of the soil in the treatment without the impermeable layer (60 cm-CK and 80 cm-CK), which is probably because the bottom is completely slag stone and has poor water retention, so the volume water content of the soil is lower, and the water content can change greatly 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, in the dry and warm valley climate, the irrigation in winter and spring is noticed, and the irrigation is carried out once per week, so that the survival of the trees through fruit trees is facilitated.

The following concrete measures for establishing the fruit forest for vegetation restoration are provided:

a soil preparation

Digging planting holes of 80cm multiplied by 80cm in a leveled slag field, and enabling the row spacing to be 3m multiplied by 3m.

B planting hole arrangement

Selecting an agricultural film with the thickness of 0.05mm to perform seepage prevention at the bottom of the planting hole, 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; selecting agricultural film of 0.05-0.07 mm for covering. 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.

Planting C channel fruit forest

The planting period is selected in 2-3 months (at the moment, the dry and warm valley plants start to grow).

The main root and the lateral root of the sapling are selected to be complete, no plant diseases and insect pests are generated, and the stress resistance is strong. Selecting walnut seedlings with the tree diameter of 3-4 cm for planting; before the seedlings are planted in a field, the damaged roots and rotten roots of the seedlings are cut off, the roots of the seedlings are soaked for 1 day by using a 100mg/kg rooting powder solution, or the roots are dipped in slurry to enable the roots to absorb enough water so as to be beneficial to survival, and the rooting powder is scattered on the roots during planting;

then, digging pits in the middle of the prepared pits for field planting, wherein the size of the pits is determined according to the planted seedlings; during planting, the seedlings are planted in soil and are compacted, so that the seedlings are straightened and root systems are unfolded. After covering soil, sowing alfalfa in the planting holes to prevent soil moisture evaporation and increase nitrogen fixation effect, and then covering a film and preserving water;

and then constructing a ridge which is about 20cm higher than the ground level. The soil ridges can collect rainwater. After planting, watering each plant with root fixing water of not less than 30kg, and watering once more seven days after planting.

D management of fertilization

The fruit trees have high requirements on fertilizer and water. The fertilizer is applied for four times before germination, after flower fall, in the fruit hard core period of 7 months and before land is frozen, which is favorable for germination, branching and flowering, promotes fruit hypertrophy, and plump seeds. Manure and green manure are used as main materials, compound fertilizer is applied in a matching way, and 100-200 kg of manure or green manure is needed for each adult tree.

Irrigation: because the dry and warm valley is dry in winter and spring, large in evaporation capacity and less in rainfall, irrigation is carried out in winter and spring, and irrigation is carried out once every two weeks.

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%; the walnuts are selected to be planted in the fruit forest, the survival rate is over 90 percent, the whole test area basically covers vegetation, and the treatment effect is good. In addition, the fruit bearing forest established by the invention can generate direct economic income by harvesting fruits.

The embodiments given above are preferred 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 (3)

1. A method for recovering vegetation in hydropower development areas of dry and warm valleys in plateaus is characterized in that artificial grassland planting and vegetation recovery through fruit forest planting are provided based on ecological conditions of multiple gravels and drought climate of the dry and warm valleys in the southeast of the Tibetan province;

the artificial grassland is established by the following steps:

leveling a slag field, paving an agricultural film for anti-seepage treatment, covering a soil layer with the thickness of 20-30 cm, and adding cattle and sheep manure for improvement; performing furrow sowing by taking oat and/or alfalfa as grass seeds and in a deep seed and shallow seed mode; the sowing quantity of the grass seeds is 10 to 13kg/mu;

irrigating after sowing; irrigating at three-leaf stage, five-six-leaf stage, late jointing stage to flowering stage and milk stage of oat; irrigating once in 5-8 months for 10 days;

the fruit bearing forest planting method comprises the following steps:

before planting, enclosing and leveling a slag field, digging a planting hole, paving an agricultural film at the bottom for seepage prevention, then covering soil with the thickness of 40-50 cm, adding cattle manure for soil improvement, covering the soil with the thickness of 30-40 cm, and finally covering with the film with the thickness of 0.05-0.07mm;

in the planting period, selecting 2-3 months, and selecting walnut seedlings with the tree diameter of 3-4 cm; before the walnut seedlings are fixedly planted, the walnut tree roots are soaked in rooting powder solution or dipped in slurry, and the rooting powder is scattered on the roots during planting;

digging pits in the middle of the prepared pits for field planting of walnut seedlings, and compacting while returning soil during field planting; after covering soil, sowing alfalfa in the planting holes, and then mulching;

building a soil ridge which is 10-20cm higher than the ground level after planting; watering not less than 30kg of root fixing water for each plant after planting, and watering once again seven days after planting; and (5) field management till the walnut forest is built.

2. The method for recovering vegetation in the hydropower development area of the dry and warm valleys in the plateau as claimed in claim 1, wherein the construction of the artificial grassland 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 on an artificial grassland: the deep-planting and shallow-planting 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 selecting oat and alfalfa to be mixed and sown, 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 at three-leaf stage, five-six-leaf stage, late jointing stage to flowering stage and milk stage.

3. The method for recovering vegetation in the plateau dry and warm valley hydropower development area as claimed in claim 1, wherein the planting through fruit forest specifically comprises the following operations:

1) Land preparation: digging planting holes of 80cm multiplied by 80cm in a leveled slag field, and enabling line spacing to be 3m multiplied by 3m;

2) Planting hole arrangement: paving 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 of cow dung into each hole for soil improvement, 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 injured root and rotten root of seedling before planting, and applying 100mg/kg for root ^-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 pits in the middle of the prepared pits for field planting, and compacting while returning soil during field planting so as to straighten and stretch root systems;

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) Managing and fertilizing: 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.

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