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Correction method for measuring leaf area index by use of plant canopy analyzer

A technology of leaf area index and correction method, which is applied in the field of forest ecology, can solve the problems of low accuracy of measuring leaf area index, and achieve the effects of true and reliable data, improved measurement accuracy, and easy realization

Active Publication Date: 2015-02-04
NORTHEAST FORESTRY UNIVERSITY
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AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to solve the limitations of the existing LAI-2000 plant canopy analyzer measurement method, and the problem of low accuracy in determining the leaf area index

Method used

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  • Correction method for measuring leaf area index by use of plant canopy analyzer
  • Correction method for measuring leaf area index by use of plant canopy analyzer

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Experimental program
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specific Embodiment approach 1

[0011] Specific embodiment one: a kind of correction method that utilizes LAI-2000 plant canopy analyzer to measure leaf area index, comprising:

[0012] Use the LAI-2000 plant canopy analyzer to measure the effective LAI value, denoted as L e , the method includes: when the LAI-2000 plant canopy analyzer is collecting data, make the induction probe 1.3m above the ground and keep it level, and use a 45° top cover to avoid the influence of the operator on the collected data; Before and after the data, use LAI-2000 to measure five sets of data in the open area not far from the sample site, that is, the sky blank value, to ensure the standardization of the measured values ​​of the sample site; the data used are processed by FV2200 software, and the zenith angle range is 1- Ring 3, in order to avoid the influence of direct light on the measured value, the data collection time is selected on cloudy days or around sunrise and sunset.

[0013] Obtain the correction coefficient, the ...

specific Embodiment approach 2

[0022] Embodiment 2: For coniferous forests and broad-leaved forests, the ratio α of the woody index to the total LAI can be determined by a direct method.

specific Embodiment approach 3

[0023] Specific embodiment three: for broad-leaved forest, obtain correction index α and can utilize following method, its step is 1, utilize DHP software to process hemispheric photographic image and obtain the total LAI that comprises xylem and blade, i.e. vegetation index, denoted as LAI total 2. Utilize the imitation stamp tool in the Photoshop software to replace the trunk in the image with its nearby non-trunks, then use the DHP software to process the image again to obtain the LAI produced by the green leaves, which is denoted as LAI green ; 3. According to the following formula, α=(LAI total -LAI green ) / LAI total .

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Abstract

The invention provides a correction method for measuring a leaf area index by use of a plant canopy analyzer, relates to a correction method for measuring the leaf area index and aims at solving the problem that the existing measuring method by use of the LAI-2000 plant canopy analyzer is limited and low in leaf area index estimation accuracy. The correction method is used for obtaining an LAI value by use of the LAI-2000 plant canopy analyzer; correction is based on a formula as shown in the description; in the formula, L represents the LAI numerical value after correction and Le represents the LAI numerical value before correction; alpha, omega E and gamma E in the formula are correction coefficients, wherein alpha is the proportion of a lignin index in the total LAI, and the values of alpha of an artificial Korean pine forest and a betula platyphylla secondary forest are 0.03 and 0.04, respectively; omega E is a crowding index, and the values of omega E of the artificial Korean pine forest and the betula platyphylla secondary forest are 0.95 and 0.87, respectively; gamma E is a needle-cluster ratio. The correction method for measuring the leaf area index by use of the plant canopy analyzer takes the influence of the crowding effect into account and is comprehensive in the range of consideration, and the obtained data are true and reliable.

Description

technical field [0001] The invention relates to a correction method for leaf area index, in particular to a correction method for measuring leaf area index by using LAI-2000 plant canopy analyzer, and belongs to the field of forest ecology. Background technique [0002] Leaf area index (LAI) refers to half of the total leaf surface area per unit surface area (Chen and Black, 1992). LAI affects the microclimate in the forest ecosystem canopy, determines radiative transfer, transpiration, water and carbon exchange between the canopy and the atmosphere, and is also an important component of biogeochemical cycles in simulated ecosystems. Meanwhile, LAI is closely related to stand productivity. Therefore, accurate determination of LAI is crucial for further understanding of many physiological and ecological processes. At present, the determination methods of LAI are mainly divided into direct method and indirect method. The direct method mainly includes the destructive samplin...

Claims

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Application Information

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IPC IPC(8): G01B11/28
Inventor 刘志理蔡慧颖王全波李明文金光泽
Owner NORTHEAST FORESTRY UNIVERSITY
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