Remote Sensing Spectral Characteristics And Physiological And Ecological Parameters Retrieval Of Quercus Mongolica And Stipa Krylovii

The condition of plant is an indicative factor of its response and adaption to environmental changes.Under the global environmental change pattern,it is particularly significant to study the effect of multiple environmental elements and interactions on plants.However,traditional technologies are difficult to monitor plants conveniently and quickly,and even cannot meet actual needs.Remote sensing,as an emerging convenient means to obtain plant physiological and ecological parameters,has been extensively employed in current research.In order to study the indicative impact of the spectral index on the plant growth affected by the environment,and to enhance the remote sensing supervising capacity of plant growth,and achieve faster,better and wider acquisition of vegetation information by remote sensing,this study took the dominant species of Quercus mongolica in Northeast China and the preponderant species of Stipa krylovii in Inner Mongolia grassland as the research objects,and analyzed the changes of physiological and ecological parameters of Quercus mongolica and Stipa krylovii under the synergistic effect of different environments and their relationship with the spectral indeices,and the development of remote sensing inversion models for plant physiological and ecological parameters.The environmental conditions in this study came from the artificial climate chamber and in-situ experiments.The environmental factors included photoperiod,nitrogen application,temperature,water content and their interactions.The physiological and ecological parameters selected leaf net photosynthetic rate,photosynthetically active radiation,chlorophyll content and vegetation coverage,and Normalized Difference Vegetation Index(NDVI),Normalized Chlorophyll Index(Chl NDI),Ratio Vegetation Index(RVI),Difference Vegetation Index(DVI),Soil Adjusted Vegetation Index(SAVI),Normalized Green Band Difference Vegetation Index(GNDVI)and other vegetation indices were used to invert the physiological and ecological parameters.The main results are as follows:(1)There was no significant difference in the chlorophyll content and growth status of Quercus mongolica under different photoperiods.The increase in temperature was conducive to the synthesis of Quercus mongolica chlorophyll.The nitrogen-applied Quercus mongolica also had higher chlorophyll content but poor growth.The interaction of increasing temperature and nitrogen application also achieved similar results,that is,promoting the synthesis of chlorophyll of Quercus mongolica but inhibiting its growth.The spectral information of Quercus mongolica can reflect the chlorophyll content and growth changes caused by environmental factors such as photoperiod,temperature,and nitrogen;(2)The vegetation indices can retrieve physiological and ecological parameters of Quercus mongolica.The binary linear regression model of Chl NDI and PRI can well retrieve SPAD of Quercus mongolica,and the adjusted R~2 reached 0.930.Both the net photosynthetic rate and photosynthetic active radiation of Quercus mongolica are helpful to evaluate its photosynthesis.These two parameters can be estimated by RVI and DVI respectively,but the model accuracy is low;(3)Analyzing the change trend of Stipa krylovii,it can be found that NDVI and the leaf net photosynthetic rate are the same.The change trends of SAVI and GNDVI were also similar,while the change trends of chlorophyll content are different.In terms of the impact of environmental factors on Stipa krylovii,the treatment of increasing the temperature by 3?and reducing the water by 100%not only inhibited the photosynthesis and chlorophyll synthesis of Stipa krylovii,but also showed small vegetation indices.Appropriate temperature increase can enhance the photosynthesis of Stipa krylovii and meanwhile show an increase in vegetation indices,but had no obvious effect on the synthesis of chlorophyll;(4)The net photosynthetic rate of Stipa krylovii leaves was the most sensitive to NDVI,showing a very good linear relationship.And the binary linear regression model of NDVI and GNDVI can better invert the net photosynthetic rate,and the particularity of the chlorophyll change trend indicated that the inversion result of chlorophyll content was poor,R~2 was only0.277,and there was a good linear relationship between the coverage of Stipa krylovii and the vegetation indices.