CN108663483B - Method and system for measuring aboveground biomass of grassland plant population - Google Patents
Method and system for measuring aboveground biomass of grassland plant population Download PDFInfo
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Abstract
The invention discloses a method and a system for measuring the aboveground biomass of grassland plant population. In practical application, the method and the system only need to measure the height and the coverage of the plant species, establish a regression equation between the total biomass on the actually measured sample site and the estimated total biomass on the sample site, and obtain the aboveground biomass of the plant population to be measured on the sample site to be measured through the relative value of the height coverage of the plant species and the corrected value of the total biomass on the sample site. The method and the system are simple, efficient and high in calculation accuracy, solve the problems that the biomass measurement on the plant population on the composite weed land is time-consuming and labor-consuming, low in efficiency and low in measurement accuracy, and are suitable for monitoring the biomass on the plant population on the grassland in a large range.
Description
Technical Field
The invention relates to the technical field of grassland plant community characteristic measurement, in particular to a method and a system for measuring the aboveground biomass of grassland plant populations.
Background
The alpine meadow in the Qinghai-Tibet plateau is one of the important natural pastures in China, and plays an important role in the aspects of biodiversity protection, water conservation, Tibetan animal husbandry development and the like. Aboveground biomass of a plant refers to the dry weight of a plant contained in a unit area above the ground surface, and is an important research content of the ecology of grassland vegetation. The method has the advantages that the aboveground biomass of the alpine meadow plant population and the growth dynamics of the alpine meadow plant population are monitored regularly, and the method has important practical significance for reasonable grazing and sustainable utilization of meadow resources.
At present, methods for measuring the overground biomass of grassland plants mainly comprise a ground actual measurement method and a remote sensing estimation method. The ground measuring method mainly adopts the traditional measuring method of 'a pair of scissors and a steelyard'. Although the method has the advantages of high measurement precision, reliable measurement result and the like, the method wastes time and labor in the measurement process, and is not suitable for monitoring the biomass on the grassland plant population in a large range. Meanwhile, the ground real-time measurement method cuts the plants in the sample prescription every time, so that the grassland is damaged to a certain extent, and continuous and long-term dynamic monitoring on the biomass on the grassland plant population can not be carried out. The remote sensing estimation method is based on a satellite remote sensing digital image or an aerial remote sensing image, based on strong absorption or strong reflection of plant leaf surfaces in visible light and infrared bands, by utilizing a remote sensing vegetation index and combining ground survey data and a remote sensing image processing system, an aboveground biomass statistical model is constructed, dynamic monitoring of aboveground total biomass is realized, and the method can be used for monitoring the total biomass of grasslands in a large range. However, the remote sensing estimation method cannot estimate the biomass on the grassland plant population, and the precision of measuring the total grassland biomass is low.
Disclosure of Invention
The invention aims to provide a method and a system for measuring the biomass on the grassland plant population, which can realize simple, efficient and high-precision measurement of the biomass on the alpine grassland plant population of the Qinghai-Tibet plateau and are simultaneously suitable for monitoring the total biomass of the grassland in a large range.
In order to achieve the purpose, the invention provides the following scheme:
a method of aboveground biomass measurement of a plant population of a grassy land, the method comprising:
acquiring a total sample above-ground biomass estimation value and a total sample above-ground biomass measured value of a sample side of a sample area to be measured;
establishing a biomass correction equation on the total sample ground according to the estimated value of the biomass on the total sample ground and the measured value of the biomass on the total sample ground;
determining a sample square total aboveground biomass correction value of the jth sample square according to the sample square total aboveground biomass correction equation;
obtaining a relative height coverage value of the ith plant in the jth sample prescription;
determining the aboveground biomass of the ith plant in the jth sample party according to the sample total aboveground biomass correction value of the jth sample party and the height coverage relative value of the ith plant in the jth sample party;
and determining the aboveground biomass of the ith plant on the sample to be measured according to the aboveground biomass of the ith plant in the jth sample.
Optionally, the establishing a correction equation of biomass on the total sample area according to the estimated value of biomass on the total sample area and the measured value of biomass on the total sample area specifically includes:
establishing a linear regression equation y ═ ax + b between the total aboveground biomass estimated value of the sample party and the actual aboveground biomass measured value of the sample party, wherein y represents the actual aboveground biomass measured value of the sample party, x represents the estimated aboveground biomass estimated value of the sample party, a is the slope of the equation y ═ ax + b, and b is the intercept of the equation y ═ ax + b;
substituting the estimated value of the total biomass on the sample side and the measured value of the total biomass on the sample side into the linear regression equation y ═ ax + b, and solving to obtain the values of the slope a and the intercept b;
establishing a biomass correction equation CB on the sample square total ground according to the slope a and the intercept bj＝axj+ b; wherein CBjTotal above-sample biomass correction, x, representing the jth samplejRepresents the total aboveground biomass estimate for the jth sample.
Optionally, the obtaining of the relative height coverage value of the ith plant in the jth sample comprises:
obtaining the height H of the ith plant in the jth sampleji；
Obtaining the coverage C of the ith plant in the jth sampleji；
According to the formula
Calculating the height coverage relative value of the ith plant in the jth sample; wherein R isjiRepresenting the relative height coverage, n, of the ith plant in the jth samplejIs the total number of plants in the jth sample.
Optionally, the determining the above-ground biomass of the ith plant in the jth sample party according to the corrected value of the total above-ground biomass of the sample party of the jth sample party and the relative value of the height coverage of the ith plant in the jth sample party specifically includes:
according to formula Bji＝CBj×RjiDetermining aboveground biomass B of the ith plant in the jth plotji。
Optionally, the determining the aboveground biomass of the ith plant on the sample to be measured according to the aboveground biomass of the ith plant in the jth sample prescription specifically includes:
according to the formula
Determining aboveground biomass B of the i-th plant on the sample to be measuredi(ii) a Where m is the total number of samples on the sample plot to be measured.
The invention also discloses a system for measuring the biomass on the grass land plant population ground, which comprises:
the system comprises an estimation value and actual measurement value acquisition module, a data acquisition module and a data acquisition module, wherein the estimation value and the actual measurement value are used for acquiring a total aboveground biomass estimation value and a total aboveground biomass actual measurement value of a sample party to be measured;
the correction value equation establishing module is used for establishing a correction equation of the biomass on the total sample space according to the estimated value of the biomass on the total sample space and the measured value of the biomass on the total sample space;
the correction value determining module is used for determining the biomass correction value on the sample side total of the jth sample side according to the sample side total above biomass correction equation;
the height coverage relative value acquisition module is used for acquiring the height coverage relative value of the ith plant in the jth sample;
the sample above-ground biomass determining module is used for determining the above-ground biomass of the ith plant in the jth sample according to the sample total above-ground biomass correction value of the jth sample and the height coverage relative value of the ith plant in the jth sample;
and the aboveground biomass determining module is used for determining the aboveground biomass of the ith plant on the sample to be measured according to the aboveground biomass of the ith plant in the jth sample.
Optionally, the correction value equation establishing module specifically includes:
a linear regression equation establishing unit, configured to establish a linear regression equation y ═ ax + b between the total terrestrial biomass estimated value of the sample and the actual terrestrial biomass measured value of the sample, where y represents the total terrestrial biomass measured value of the sample, x represents the total terrestrial biomass estimated value of the sample, a is a slope of the equation y ═ ax + b, and b is an intercept of the equation y ═ ax + b;
the slope and intercept calculation unit is used for substituting the estimated value of the biomass on the total sample area and the measured value of the biomass on the total sample area into the linear regression equation y ═ ax + b, and solving to obtain the values of the slope a and the intercept b;
a correction value equation establishing unit for establishing a correction value equation according to the slope a and the interceptb, establishing a biomass correction equation CB on the total sample spacej＝axj+ b; wherein CBjTotal above-sample biomass correction, x, representing the jth samplejRepresents the total aboveground biomass estimate for the jth sample.
Optionally, the height coverage relative value obtaining module specifically includes:
a plant height obtaining unit for obtaining the height H of the ith plant in the jth sampleji；
A plant coverage obtaining unit for obtaining coverage C of the ith plant in the jth sampleji；
A relative value calculating unit for height coverage according to a formula
Calculating the height coverage relative value of the ith plant in the jth sample; wherein R isjiRepresenting the relative height coverage, n, of the ith plant in the jth samplejIs the total number of plants in the jth sample.
Optionally, the module for determining biomass on the sample site specifically includes:
a biomass determination unit on the sample side for determining the biomass according to formula Bji＝CBj×RjiDetermining aboveground biomass B of the ith plant in the jth plotji。
Optionally, the aboveground biomass determination module specifically includes:
aboveground biomass determination unit for determining biomass according to the formula
Determining aboveground biomass B of the i-th plant on the sample to be measuredi(ii) a Where m is the total number of samples on the sample plot to be measured.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a method and a system for measuring the aboveground biomass of grassland plant populations, wherein in practical application, the aboveground biomass of the plant populations to be measured on a sample plot can be obtained by only measuring the height and the coverage of the plant species, establishing a regression equation between the actual measurement and the estimated total biomass on the sample plot and correcting the relative value of the height coverage of the plant species and the total biomass on the sample plot, the method and the system are simple, easy, efficient and high in calculation precision, the problems that the measurement of the aboveground biomass of the grassland plant populations on grasslands with complex species composition wastes time and labor, the efficiency is low and the measurement precision is low are solved, and the method and the system are suitable for monitoring the aboveground biomass of the grassland plant.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a method for measuring biomass on grass land plant population ground according to the present invention;
FIG. 2 is a schematic diagram of a measured regression equation obtained by measuring the aboveground population biomass of plot 1;
FIG. 3 is a schematic diagram of a measured regression equation obtained by measuring the aboveground population biomass of plot 2;
FIG. 4 is a schematic structural diagram of a system for measuring biomass on a plant population of a grassland according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a method and a system for measuring the aboveground biomass of grassland plant populations, aiming at the characteristics of high species abundance and complex species composition of grassland, particularly alpine grassland communities on Qinghai-Tibet plateau, so that the simple, efficient and high-precision measurement of the aboveground biomass of grassland plants can be realized, and the method and the system are simultaneously suitable for monitoring the total biomass of grasslands in a large range.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
FIG. 1 is a flow chart of a method for measuring biomass on grass land plant population ground provided by the invention. Referring to fig. 1, the method for measuring biomass on the grass land plant population ground provided by the invention specifically comprises the following steps:
step 101: and acquiring the estimated total sample side biomass value and the measured total sample side biomass value of the sample side to be measured. Specifically, the estimated value of the total biomass on the sample space of n sample spaces on the sample space to be measured and the measured value of the total biomass on the sample space of t sample spaces covering the variation range of the total biomass on the sample space to be measured are obtained.
Before the estimated value of the total aboveground biomass of the n samples on the sample plot to be measured and the measured value of the total aboveground biomass of the t samples covering the variation range of the total aboveground biomass of the sample plot to be measured are obtained, sample plots to be measured on the alpine meadow in Qinghai-Tibet plateau, which are required to measure the aboveground biomass of the plant population, are selected, and a certain number of survey sample plots are set according to the area size of the sample plots to be measured.
The setting method of the sample plot to be measured comprises the following steps: on the sample land to be measured, a plurality of sample squares of 50cm × 50cm are randomly arranged according to the sample land area size of the sample land to be measured, and preferably, 25 sample squares are arranged per hectare, thereby obtaining n sample squares on the sample land to be measured.
Then, estimating the total aboveground biomass dry weight of each sample in the n samples according to the experience of an investigator to obtain an estimated value x of the total aboveground biomass of the sample of the mth sample on the sample to be measuredmWhere m ∈ (1, n). Preferably, the height of the grass layer in the sample and the density of the vegetation can be selected according to the selectionSelecting the total aboveground biomass estimated value x of t samples covering the variation range of the total aboveground biomass to be measured from the n samples1～xtAnd calculating the slope a and the intercept b, wherein t epsilon (1, n) is preferably 5-7. Correspondingly, cutting all the plants in the t sample squares covering the variation range of the total biomass on the sample plot to be measured at the same place, drying the cut plants to constant weight by using an oven at a preset temperature, and weighing to obtain the measured value y of the total biomass on the sample plot of the t sample squaretSo as to obtain the total estimated biomass value x of the sample sides of t sample sides1～xtMeasured total aboveground biomass values y of corresponding t samples1～yt. Preferably, when the plants in the tth sample are dried, the preset temperature is 65 ℃.
Step 102: and establishing a sample square total aboveground biomass correction equation according to the sample square total aboveground biomass estimation value and the sample square total aboveground biomass measured value.
Establishing a linear regression equation between the estimated biomass value on the total sample area and the measured biomass value on the total sample area:
y＝ax+b (1)
wherein y represents the measured value of the total aboveground biomass of the sample, x represents the estimated value of the total aboveground biomass of the sample, a is the slope of the equation y ═ ax + b, and b is the intercept of the equation y ═ ax + b.
Substituting the estimated value of the total biomass on the sample side and the measured value of the total biomass on the sample side into the linear regression equation y ═ ax + b, and solving to obtain the values of the slope a and the intercept b, preferably:
acquiring total aboveground biomass estimation values x of t samples1～xtAnd t corresponding measured values y of biomass on the total sample space1～ytThe linear regression equation is established by establishing a regression equation y as ax + b in excel and solving the values a and b.
Establishing a biomass correction equation on the total sample space according to the slope a and the intercept b:
CBj＝axj+b (2)
wherein CBjTotal above-sample biomass correction, x, representing the jth samplejRepresents the total aboveground biomass estimate for the jth sample. Wherein the jth one of the n samples is one of the other samples except the t samples, i.e., j e (1, n-t).
Step 103: and determining a sample total aboveground biomass correction value of the jth sample according to the sample total aboveground biomass correction equation.
By using the established correction equation of the total biomass on the sample side and the estimated value of the total biomass on the sample side of other sample sides in the sample side to be measured, the correction value of the total biomass on the sample sides of other sample sides can be calculated, which specifically comprises the following steps:
estimating the total aboveground biomass dry weight of each of the n samples according to the experiential of the investigator, wherein the estimated total aboveground biomass value of the jth sample is represented by xj；
Correcting equation CB by utilizing total aboveground biomass of established samplej＝axj+ b and j sample Total aboveground Biomass estimate xjCalculating the total biomass correction value CB on the jth samplej。
Step 104: and acquiring a relative height coverage value of the ith plant in the jth sample.
In each of the n samples, the Height (Height, abbreviated as H) and Coverage (Coverage, abbreviated as C) of each plant species were investigated, specifically:
for each plant in each sample, measuring by using a measuring tape to obtain the height H of the ith plant in the mth samplemi；m∈(1,n)；
For each plant in each sample prescription, the coverage C of the ith plant in the mth sample prescription is obtained by measuring by adopting a visual method or a needle punching methodmi；
The relative height coverage of a certain plant species in a certain sample ═ 100% (height of the plant species in the sample x coverage)/(height of all plant species in the sample x sum of coverages)). According to said height HmiAnd the coverage CmiCalculate the said firstThe height coverage relative value of the ith plant in the m sample squares is calculated by the following formula:
wherein R ismiRepresenting the relative height coverage value of the ith plant in the mth sample; n ismIs the total number of plants in the mth sample, i.e. n in total in the mth samplemAnd (4) planting plants.
Step 105: according to the total biomass correction value CB on the sample side of the jth sample sidejAnd the relative value R of the height coverage of the ith plant in the jth samplejiAboveground biomass of the ith plant in the jth prototype was determined.
The corrected value of the total biomass on the sample side of a certain sample side or the product of the measured value of the total biomass on the sample side and the relative value of the height coverage of each plant species in the sample side is the aboveground biomass of each plant species in the sample side. Determining the aboveground biomass of the ith plant in the mth sample according to the corrected value of the total aboveground biomass of the jth sample, the measured value of the total aboveground biomass of the t sample and the corresponding relative value of the height coverage of the ith plant in the mth sample, specifically:
according to formula Bmi＝CBm×RmiDetermining aboveground biomass B of the ith plant in said mth sample plotmi。
Wherein, for the t samples covering the range of variation of total aboveground biomass of the samples to be measured, among the n samples, the CBmThe measured value y of biomass on the total area of the m-th sample among the t samplesm。
For other ones of the n samples except the t samples, the CBmThe total aboveground biomass correction value CB for the mth one of the other samplesjWhere j equals m and j ∈ (1, n-t). Biomass correction value CB on the sample room totalj＝axj+b。
That is to say that the first and second electrodes,
step 106: and determining the aboveground biomass of the ith plant on the sample to be measured according to the aboveground biomass of the ith plant in the jth sample.
And the average value of the aboveground biomass of a certain plant species on the sample to be measured in all sample directions is the aboveground biomass of the plant. The above-ground biomass of the i-th plant on the sample to be measured is calculated as follows:
wherein B isiRepresenting aboveground biomass of an ith plant on a sample to be measured; n is the total number of samples on the sample plot to be measured.
According to the formula (5), the aboveground biomass of all plant species on the sample to be measured can be calculated, and the aboveground biomass of the plant population can be measured efficiently and accurately.
Therefore, the method for measuring the biomass on the grass land plant population ground provided by the invention at least has the following advantages:
1. the height of the plant seeds is measured by adopting the measuring tape, the coverage of the plant seeds is measured by adopting an eye measuring method or an eye acupuncture method, the investigation method is simple and easy to implement, time and labor are saved, and the cost of a field test is reduced.
2. When the biomass on the plant species ground is measured each time, only t sample plants covering the total biomass range on the sample ground to be measured need to be cut, the grassland is low in destructiveness, and when the biomass on the plant species ground of the alpine meadow is monitored, long-term and continuous dynamic monitoring of the biomass on the plant species ground can be achieved.
3. In practical application, the overground biomass measurement method for grassland plant populations provided by the invention only needs to measure the height and the coverage of plant species, a regression equation is established between the actually measured and estimated total biomass on the sample plot, and the overground biomass of the plant populations can be obtained through the relative value of the height coverage of the plant species and the correction value of the total biomass on the sample plot, so that the overground biomass of the plant populations can be accurately and quickly investigated in the survey of the alpine meadow vegetation community characteristics with complex species composition.
4. When the sample parties used for calculating the values a and b in the linear regression equation are selected, t sample parties capable of covering the range of the total aboveground biomass of the sample sites to be measured are selected, and the estimated value of the total aboveground biomass of the sample parties of the t sample parties and the measured value of the total aboveground biomass of the sample parties can objectively reflect the aboveground biomass information of the grassland plant population.
The method for measuring biomass on grass plant population and the advantages thereof provided by the present invention are further illustrated by two specific examples.
Example one
(1) Selecting the following steps:
in the same way, 1: the method is located in alpine meadow summer pasture of grazing Tibetan livestock in the nima town of Maqu county of autonomous prefecture of Nakan province of Gansu province, geographic coordinates N33 degrees 44 '-34 degrees 10', E101 degrees 45 '-102 degrees 16', and altitude between 3400-4000 m, and belongs to an obvious plateau continental alpine humid region. Only the difference of cold and warm is that the annual average temperature is 2.3 ℃; rainwater is concentrated, and annual average precipitation is 510.5 mm; sufficient sunshine, annual sunshine hours 2583.9 h; no absolute frost period.
(2) Setting a sample prescription: on summer pastures (about 1.3 hectare) 27 50cm x 50cm squares were randomly placed.
(3) Height and coverage survey of plant species: investigating the height and coverage of all plant species in each sample according to the formula
The height coverage relative value for each plant species was calculated.
(4) Aboveground total biomass survey: selecting 5 samples covering the variation range of the total aboveground biomass of the sample to be measured 1, and estimating the dry weight x of the aboveground total biomass in each sample1～x5Simultaneously, the plants in the 5 sample squares are mown in the same place, dried to constant weight at 65 ℃, and weighed to obtain the measured value y of the aboveground biomass in the sample squares1～y5。
(5) Data processing: by the measured value y of the above-ground total biomass1～y5And corresponding estimated value x1～x5And obtaining a linear regression equation of which y is 0.58x +18 to obtain a total aboveground biomass correction equation CB of the samplej＝0.58xj+18, calculating equation and estimated value by the correction value to obtain total biological value CB on the sample side of other sample sidesj，j∈(1,22)。
(6) Aboveground biomass: the product of the total biomass in a certain sample square and the relative value of the height coverage of each plant species is the aboveground biomass of each plant species in the sample square according to the formula Bmi＝CBm×RmiDetermining aboveground biomass B of the ith plant in said mth sample plotmi. The average value of the biomass of a certain plant species in all the sample prescriptions is the estimated aboveground biomass of the plant species, and the biomass is calculated according to the formula
Estimation of aboveground biomass B of the ith plant on the sample to be measuredi。
By actually measuring the aboveground biomass of the grassland plant population, the accuracy of the aboveground biomass estimation of the population provided by the method for measuring the aboveground biomass of the grassland plant population can be verified. FIG. 2 is a schematic diagram of the regression equation obtained by actually measuring the aboveground population biomass of plot 1, wherein the regression equation of plot 1 obtained by actually measuring is 1.17x +1.29, and the determination coefficient of the regression equation for actually measuring and estimating the population biomass by the method of the present invention is R2The closer the coefficient of decision is to 1, which indicates the evaluation accuracy, 0.93The higher. Therefore, the method for measuring the overground biomass of the grassland plant population can accurately evaluate the overground biomass of the grassland plant population.
Example two
(1) Selecting the following steps:
in the same way, 2: on the alpine meadow winter pasture of many-year grazing yaks and zang sheep in the county of the Tianzhu Tibetan province, Gansu province, the geographic coordinates N37 degrees 11 '-37 degrees 14' and E102 degrees 40 '-102 degrees 47'. The mountain land is in the intersection zone of the Qinghai-Tibet plateau, the loess plateau and the inner Mongolia plateau, the terrain of the interior is northwest high, southeast low, and the altitude is 2960-4325 m. The annual average temperature is-0.1 ℃, the 1-month average temperature is-18.3 ℃, the 7-month average temperature is 12.7 ℃, and the accumulated temperature is 1380 ℃ when the temperature is higher than 0 ℃; the annual precipitation is 416mm, no absolute frost period exists, only two seasons of cold and hot are adopted, and the soil type is subalpine meadow soil.
(2) Setting a sample prescription: 25 50cm x 50cm squares were randomly placed on the pasture land in winter (about 1 hectare).
(3) Height and coverage survey of plant species: the height and the coverage of all the plant species in each sample were investigated, and the relative height coverage of each plant species was calculated, which is the relative height coverage of a certain plant species in the sample (height of the plant species in the sample x coverage)/(height of all the plant species in the sample x the sum of the coverage)) × 100%.
(4) Aboveground total biomass survey: estimating the dry weight of the overground total biomass in each sample square, simultaneously, cutting any 7 sample squares of plants covering the range of the overground total biomass of the sample squares in a same time, drying the cut plants to constant weight at 65 ℃, and weighing, wherein the value is the measured value of the overground total biomass in the sample squares.
(5) Data processing: and (3) solving a linear regression equation y of 1.51x +7.32 according to the measured value and the estimated value of the above-ground total biomass, so as to obtain a corrected value of the total biomass on the sample sides of other sample sides according to the regression equation and the estimated value of the total biomass on the sample sides.
(6) Aboveground biomass: and the product of the corrected value of the aboveground total biomass in a certain sample and the relative value of the height coverage of each plant species is the aboveground biomass of each plant species in the sample, and the average value of the aboveground biomass of a certain plant species in all the samples is the estimated aboveground biomass of the plant population.
By actually measuring the aboveground biomass of the grassland plant population in the same plot 2, the accuracy of estimating the aboveground biomass of the population by using the method for measuring the aboveground biomass of the grassland plant population provided by the present invention can be verified. FIG. 3 is a schematic diagram of the actually measured regression equation obtained by actually measuring the aboveground population biomass of the same plot 2, wherein the regression equation of the actually measured plot 2 is that y is 1.24x +0.99, and the determination coefficient of the actually measured regression equation and the linear regression equation for estimating the population biomass by the method of the present invention is R20.92. Since the closer the decision coefficient is to 1, the higher the evaluation accuracy is indicated, the coefficient R is decided by2The above-ground biomass measurement method for meadow plant populations provided by the invention can be used for accurately evaluating the above-ground biomass of plant populations of alpine meadows in Qinghai-Tibet plateau, which can be shown as 0.92.
The invention also provides a system for measuring the biomass on the grass land plant population ground. FIG. 4 is a schematic structural diagram of a system for measuring biomass on a plant population of a grassland according to the present invention. Referring to fig. 4, the above-ground biomass measurement system for a grass plant population includes:
an estimated value and actual value acquiring module 401, configured to acquire an estimated value of total biomass on a sample side of the sample to be measured and an actual value of total biomass on the sample side.
A correction value equation establishing module 402, configured to establish a correction equation of biomass in the total sample area according to the estimated biomass value in the total sample area and the measured biomass value in the total sample area.
And a correction value determining module 403, configured to determine a biomass correction value on the sample total of the jth sample according to the sample total above biomass correction equation.
And the height coverage relative value acquiring module 404 is configured to acquire a height coverage relative value of the ith plant in the jth sample square.
And a sample above-ground biomass determining module 405, configured to determine the above-ground biomass of the ith plant in the jth sample according to the sample total above-ground biomass correction value of the jth sample and the height coverage relative value of the ith plant in the jth sample.
An aboveground biomass determination module 406 for determining aboveground biomass of an ith plant of the sample to be measured from aboveground biomass of an ith plant of the jth sample.
The correction value equation establishing module 402 specifically includes:
a linear regression equation establishing unit, configured to establish a linear regression equation y ═ ax + b between the total terrestrial biomass estimated value of the sample and the actual terrestrial biomass measured value of the sample, where y represents the total terrestrial biomass measured value of the sample, x represents the total terrestrial biomass estimated value of the sample, a is a slope of the equation y ═ ax + b, and b is an intercept of the equation y ═ ax + b;
the slope and intercept calculation unit is used for substituting the estimated value of the biomass on the total sample area and the measured value of the biomass on the total sample area into the linear regression equation y ═ ax + b, and solving to obtain the values of the slope a and the intercept b;
a correction value equation establishing unit for establishing the biomass correction equation CB on the total sample space according to the slope a and the intercept bj＝axj+ b; wherein CBjTotal above-sample biomass correction, x, representing the jth samplejRepresents the total aboveground biomass estimate for the jth sample.
The height coverage relative value obtaining module 404 specifically includes:
a plant height obtaining unit for obtaining the height H of the ith plant in the jth sampleji；
A plant coverage obtaining unit for obtaining coverage C of the ith plant in the jth sampleji；
A relative value calculating unit for height coverage according to a formula
Calculating the height coverage relative value of the ith plant in the jth sample; wherein R isjiRepresenting the relative height coverage, n, of the ith plant in the jth samplejIs total planting in the jth sampleThe number of species.
The above-mentioned sample site biomass determination module 405 specifically includes:
a biomass determination unit on the sample side for determining the biomass according to formula Bji＝CBj×RjiDetermining aboveground biomass B of the ith plant in the jth plotji。
The aboveground biomass determination module 406 specifically includes:
aboveground biomass determination unit for determining biomass according to the formulaDetermining aboveground biomass B of the i-th plant on the sample to be measuredi(ii) a Where m is the total number of samples on the sample plot to be measured.
The grassland plant population aboveground biomass measurement system provided by the invention is simple and easy to operate, can be used for rapidly, accurately and nondestructively investigating the grassland plant population aboveground biomass, can be used for continuous and long-term dynamic monitoring of the grassland plant population aboveground biomass and grassland community succession evaluation, and solves the problem that the measurement of the grassland plant population aboveground biomass in a cold meadow with complex species composition takes time and labor.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (8)
1. A method for aboveground biomass measurement of a plant population of a grassy area, the method comprising:
acquiring a total sample above-ground biomass estimation value and a total sample above-ground biomass measured value of a sample side of a sample area to be measured;
establishing a biomass correction equation on the total sample ground according to the estimated value of the biomass on the total sample ground and the measured value of the biomass on the total sample ground; establishing a correction equation of the biomass on the total sample area according to the estimated value of the biomass on the total sample area and the measured value of the biomass on the total sample area, specifically comprising:
establishing a linear regression equation y ═ ax + b between the total aboveground biomass estimated value of the sample party and the actual aboveground biomass measured value of the sample party, wherein y represents the actual aboveground biomass measured value of the sample party, x represents the estimated aboveground biomass estimated value of the sample party, a is the slope of the equation y ═ ax + b, and b is the intercept of the equation y ═ ax + b;
substituting the estimated value of the total biomass on the sample side and the measured value of the total biomass on the sample side into the linear regression equation y ═ ax + b, and solving to obtain the values of the slope a and the intercept b;
establishing a biomass correction equation CB on the sample square total ground according to the slope a and the intercept bj＝axj+ b; wherein CBjTotal above-sample biomass correction, x, representing the jth samplejRepresenting the total aboveground biomass estimated value of the jth sample;
determining a sample square total aboveground biomass correction value of the jth sample square according to the sample square total aboveground biomass correction equation;
obtaining a relative height coverage value of the ith plant in the jth sample prescription;
determining the aboveground biomass of the ith plant in the jth sample party according to the sample total aboveground biomass correction value of the jth sample party and the height coverage relative value of the ith plant in the jth sample party;
and determining the aboveground biomass of the ith plant on the sample to be measured according to the aboveground biomass of the ith plant in the jth sample.
2. The method of claim 1, wherein the obtaining of the relative height coverage of the ith plant in the jth sample comprises:
obtaining the height H of the ith plant in the jth sampleji；
Obtaining the coverage C of the ith plant in the jth sampleji；
According to the formula
Calculating the height coverage relative value of the ith plant in the jth sample; wherein R isjiRepresenting the relative height coverage, n, of the ith plant in the jth samplejIs the total number of plants in the jth sample.
3. A method of measuring an above-ground biomass of a population of grassland plants according to claim 2, wherein said determining the above-ground biomass of the ith plant in the jth sample from the corrected value of the total above-ground biomass of the jth sample and the relative value of the height coverage of the ith plant in the jth sample comprises:
according to formula Bji＝CBj×RjiDetermining aboveground biomass B of the ith plant in the jth plotji。
4. A method of measuring aerial biomass of a population of grassland plants as claimed in claim 3, wherein said determining the aerial biomass of the ith plant of said sample to be measured from the aerial biomass of the ith plant of said jth sample comprises:
according to the formulaDetermining aboveground biomass B of the i-th plant on the sample to be measuredi(ii) a Where m is the total number of samples on the sample plot to be measured.
5. A system for aboveground biomass measurement of a plant population in a grassland, the system comprising:
the system comprises an estimation value and actual measurement value acquisition module, a data acquisition module and a data acquisition module, wherein the estimation value and the actual measurement value are used for acquiring a total aboveground biomass estimation value and a total aboveground biomass actual measurement value of a sample party to be measured;
the correction value equation establishing module is used for establishing a correction equation of the biomass on the total sample space according to the estimated value of the biomass on the total sample space and the measured value of the biomass on the total sample space; the correction value equation establishing module specifically includes:
a linear regression equation establishing unit, configured to establish a linear regression equation y ═ ax + b between the total terrestrial biomass estimated value of the sample and the actual terrestrial biomass measured value of the sample, where y represents the total terrestrial biomass measured value of the sample, x represents the total terrestrial biomass estimated value of the sample, a is a slope of the equation y ═ ax + b, and b is an intercept of the equation y ═ ax + b;
the slope and intercept calculation unit is used for substituting the estimated value of the biomass on the total sample area and the measured value of the biomass on the total sample area into the linear regression equation y ═ ax + b, and solving to obtain the values of the slope a and the intercept b;
a correction value equation establishing unit for establishing the biomass correction equation CB on the total sample space according to the slope a and the intercept bj＝axj+ b; wherein CBjTotal above-sample biomass correction, x, representing the jth samplejRepresenting the total aboveground biomass estimated value of the jth sample;
the correction value determining module is used for determining the biomass correction value on the sample side total of the jth sample side according to the sample side total above biomass correction equation;
the height coverage relative value acquisition module is used for acquiring the height coverage relative value of the ith plant in the jth sample;
the sample above-ground biomass determining module is used for determining the above-ground biomass of the ith plant in the jth sample according to the sample total above-ground biomass correction value of the jth sample and the height coverage relative value of the ith plant in the jth sample;
and the aboveground biomass determining module is used for determining the aboveground biomass of the ith plant on the sample to be measured according to the aboveground biomass of the ith plant in the jth sample.
6. The system for measuring biomass on a grass plant population as claimed in claim 5, wherein said relative height coverage value obtaining module comprises:
a plant height obtaining unit for obtaining the height H of the ith plant in the jth sampleji；
A plant coverage obtaining unit for obtaining coverage C of the ith plant in the jth sampleji；
A relative value calculating unit for height coverage according to a formula
Calculating the height coverage relative value of the ith plant in the jth sample; wherein R isjiRepresenting the relative height coverage, n, of the ith plant in the jth samplejIs the total number of plants in the jth sample.
7. The system of claim 6, wherein the on-sample biomass determination module comprises:
a biomass determination unit on the sample side for determining the biomass according to formula Bji＝CBj×RjiDetermining aboveground biomass B of the ith plant in the jth plotji。
8. The system of claim 7, wherein the above-ground biomass determination module comprises:
aboveground biomass determination unit for determining biomass according to the formula
Determining aboveground biomass B of the i-th plant on the sample to be measuredi(ii) a Where m is the total number of samples on the sample plot to be measured.
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