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CN-121980723-A - Estimation method for daily photosynthetic yield of forest and single tree

CN121980723ACN 121980723 ACN121980723 ACN 121980723ACN-121980723-A

Abstract

The invention discloses a method for estimating daily photosynthetic yield of forests and single trees. The method has the advantages that the method for estimating the daily photosynthetic yield of the forest and the single tree overcomes the defects of time resolution (daily) and single tree scale in the prior art, the efficiency and the precision of forest photosynthetic yield estimation are remarkably improved, meanwhile, the method combines environmental factor monitoring and a light Wen Xiangying curve, the difficulty of photosynthetic yield estimation under different environmental conditions is solved, and an important theoretical and practical basis is provided for accurate calculation and dynamic monitoring of the photosynthetic yield of a forest ecological system.

Inventors

  • XU ZHENZHAO
  • QIN LIHOU
  • ZHOU GUANG

Assignees

  • 德清县浙工大莫干山研究院

Dates

Publication Date
20260505
Application Date
20231228

Claims (5)

  1. 1. The method for estimating daily photosynthetic yield of forests and single trees is characterized by comprising the following steps of: Step S1, selecting a representative forest sample area in a target area, measuring and recording the area of the forest sample area, measuring each tree in the forest sample area in detail, and recording the tree species, the breast diameter, the tree height and the crown length of each tree; step S2, setting an environmental factor monitoring instrument in the forest sample plot, and continuously monitoring and recording photosynthetic effective radiation and temperature data of the forest sample plot; Step s3, obtaining the sun-leaf area indexes of the forest sample at different canopy heights, which specifically comprises the following steps: Step S31, setting up a plurality of sample trees for each arbor tree species in the forest sample plot, observing the leaf expanding object and the leaf falling object of the sample trees, setting up a regression model aiming at arbor tree species leaf object and sample plot temperature, and predicting daily dynamics of arbor tree leaves in a growing season; Step S32, based on tree species and breast diameter data measured by the forest plot, combining a different-speed growth equation L=aD b of arbor tree species, wherein L is leaf area, D is breast diameter, a and b are coefficients of a different-speed growth equation corresponding to the arbor tree species, obtaining leaf area of each tree, and combining daily dynamics of arbor tree leaves to obtain daily leaf area dynamics of arbor in a growing season; Step S33, dividing a forest canopy into a plurality of layers based on the tree height, crown length and daily leaf area dynamics of each tree in the forest sample area, obtaining daily leaf areas of each tree at different crown heights, adding the daily leaf areas of all the trees in the forest sample area at the crown heights, and dividing the sum by the area of the forest sample area to obtain the daily leaf area index of the forest sample area at the crown heights; Step S4, based on the sun-leaf area indexes of different canopy layers of the forest sample plot, obtaining photosynthetic effective radiation I i ＝I 0 e -k ×LAI i of the forest sample plot at the different canopy layers, wherein I i is the illumination intensity of the canopy layer height, I o is the illumination intensity above the canopy layer, e is a natural constant, k is an extinction coefficient, and LAI i is the leaf area index of the canopy layer height; S5, obtaining a light response curve of each arbor tree species leaf under different temperature conditions, wherein the light response curve of each arbor tree species leaf is obtained by measuring the photosynthetic effective radiation intensity of the leaf photosynthetic rate of arbor tree species in the forest sample area through a photosynthetic-fluorescence full-automatic measurement system, analyzing the relation between the photosynthetic rate of the arbor tree species leaf and illumination and temperature environmental factors, and establishing a dynamic photosynthetic rate estimation model of the arbor tree species leaf; S6, obtaining daily photosynthetic yield of the single tree, and according to a formula Obtaining daily photosynthetic yield of the single tree, wherein I is the I-th tree in a forest sample plot, j is the j-th canopy height, c is the canopy height degree divided by the forest canopy, k is the time period of recording photosynthetic effective radiation and temperature data in the kth day, T is the time resolution of the photosynthetic effective radiation and the temperature data, 86400/T is the number of the photosynthetic effective radiation and the temperature data which can be recorded in the day, A (I, T) is a photosynthetic rate dynamic estimation model of tree leaves of the tree, and LA is the tree leaf area of the tree single tree; s7, acquiring daily photosynthetic yield of the forest sample, and according to a formula And obtaining the daily photosynthetic yield of the forest sample land, wherein i is the individual tree of the ith arbor in the forest sample land, n is the number of the arbor trees in the forest sample land, and DLNPA is the daily photosynthetic yield of the individual tree.
  2. 2. The method for estimating daily photosynthetic yield of forests and individual trees according to claim 1, wherein the environmental factor monitoring instrument sets a timer in step S2 to automatically record photosynthetic effective radiation and temperature data at fixed time intervals.
  3. 3. The method for estimating daily photosynthetic yield of forests and individual trees of claim 1 wherein the time interval of photosynthetic active radiation and temperature data in step S2 is in the range of 1 to 60 minutes.
  4. 4. The method for estimating daily photosynthetic yield of forests and individual trees according to claim 1, wherein the scale of highly layering the canopy of the forest specimen in step S3 is set to 0.8-1.2m.
  5. 5. The method for estimating daily photosynthetic yield of forests and individual trees according to claim 1, wherein the temperature in step S5 is used as a correction adjustment factor for response curve of arbor species She Guang, and the calculation method of the temperature adjustment factor is as follows: Wherein T is the environmental temperature of the forest sample, and T min 、T max and T opt are the minimum temperature, the maximum temperature and the optimum temperature of photosynthesis of arbor species respectively.

Description

Estimation method for daily photosynthetic yield of forest and single tree Technical Field The invention belongs to the technical field of ecological research, and particularly relates to a method for estimating daily photosynthetic yield of forests and single trees. Background In the research of the forest ecological system, accurate estimation of photosynthetic yield is important for understanding carbon circulation, climate change and influence on the ecological system. Currently, the estimation method of photosynthetic yield mainly depends on remote sensing technology, model simulation and ground observation. These methods have made some progress in estimating photosynthetic yield throughout a forest or wide range of ecosystems. Existing estimation methods often lack high temporal resolution, especially on a daily scale, due to the complexity of the forest space and dynamic changes in time seasons. This limits the understanding of rapid changes in forest photosynthetic activity, especially when dealing with sudden environmental changes. Furthermore, most existing methods have limited application on the individual tree scale, often providing only an average value across a forest or a particular area. The method ignores the difference among the single trees, and cannot accurately evaluate the response of the single trees to environmental changes and the effect of the single trees in the whole forest system. Therefore, the development of the method capable of accurately estimating the photosynthetic yield of the single tree on a daily scale has important significance for improving the accuracy and the application value of forest photosynthetic yield estimation. Disclosure of Invention Aiming at the problems in the prior art, the invention provides a method for accurately estimating the photosynthetic yield of trees and forests on a daily scale and a single plant scale. The method can effectively make up the defect that the photosynthetic yield is difficult to measure on the time resolution and the single plant scale in the prior art, and aims to realize more accurate and higher-precision estimation of the photosynthetic yield of the single plant tree and the forest, thereby better supporting the research and management of a forest ecological system. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: The embodiment of the invention provides a method for estimating daily photosynthetic yield of forests and single trees, which comprises the following steps: selecting a representative forest sample area in a target area, measuring and recording the area of the forest sample area, measuring each tree in the forest sample area in detail, and recording the tree species, the breast diameter, the tree height and the crown length of each tree; Setting an environmental factor monitoring instrument in the forest sample, and continuously monitoring and recording photosynthetic effective radiation and temperature data of the forest sample; Setting up a plurality of sample trees for each arbor tree species in the forest sample plot, observing leaf expanding weathers and fallen weathers of the sample trees, establishing a model of arbor tree species leaf weathers and sample plot temperature, and predicting daily dynamics of arbor tree leaves in a growing season; Based on tree species and breast diameter data measured in the forest sample plot, combining a different-speed growth equation L=aD b of arbor tree species, wherein L is leaf area, D is breast diameter, a and b are coefficients of a different-speed growth equation corresponding to the arbor tree species, obtaining leaf area of each tree, and combining daily dynamics of arbor tree leaves to obtain daily leaf area dynamics of the arbor in a growing season; Dividing a forest canopy into a plurality of layers based on the tree height, crown length and daily leaf area dynamic of each tree in the forest-like plot, obtaining daily leaf area of each tree at different crown heights, adding the daily leaf areas of all trees in the forest-like plot at the crown heights, and dividing the sum by the area of the forest-like plot to obtain the daily leaf area index of the forest-like plot at the crown heights; Acquiring photosynthetic effective radiation I i＝I0e-k×LAIi of the forest sample at different canopy based on the daily leaf area indexes of different canopy of the forest sample, wherein I i is the illumination intensity of the canopy height, I 0 is the illumination intensity above the canopy, e is a natural constant, k is an extinction coefficient, and LAI i is the leaf area index of the canopy height; Acquiring a light response curve of each arbor tree species leaf under different temperature conditions, wherein the light response curve of each arbor tree species leaf is obtained by measuring the photosynthetic effective radiation intensity of the leaf photosynthetic rate of arbor tree species in the forest sample area th