Tall Fescue Climate Response And Growth Monitoring Research Based On Hyperspectral Remote Sensing Data

To ascertain the impacts of elevated CO2concentration on tall fescue physiological characteristics and drought resistance, and explore new methods to monitor and study tall fescue using hyper-spectral data. A pot control experiment under different moisture conditions (sufficient soil water supply, mild drought stress and severe drought stress) and different CO2concentrations (390μmol/mol and700μmol/mol) was conducted to study physiological and spectral changes of tall fescue. Statistical methods were used to analysis the correlation between characteristic parameters and physiological parameters of tall fescue, and the above finding were verified in the study area of Yanqing county in Beijing. The main conclusions are:(1) Elevated atmospheric CO2concentration is conductive to tall fescue growing enhancement, when combines with drought stress simultaneously, it can weaken the negative effects of drought stress on growth of tall fescue, and maintain high water use efficiency and photosynthetic assimilation by stomatal regulation, thus it can enhance the drought resistance of tall fescue.(2) High spectral reflectance curves can reflect tall fescue growing condition and level of it being stressed, when drought stress or CO2concentration elevating occur, spectral reflectance, spectrum fluctuation and red edge characteristics of tall fescue reflectance spectra will change. Among the selected spectral characteristic parameters in the experiment, Dλr, Dλ744, Sr, NDSI, Fd, and Dλr, Sr, NDSI, Fd, and NDSI, RSI, RVI, PRI have significant correlation with leaf water content, chlorophyll content and net photosynthetic rate respectively, so, they are effecitve parameters for simulating physiological characteristics listed above. Among these parameters, NDVI, Rch and Fd can distinct the extent of drought of tall fescue effectively, they are effective spectral parameters that can be used in tall fescue drought monitoring.(3) There has a significant positive correlation between the size of grassland area and precipitation in study area, and the festure also applies to tall fescue grass species.(4) Reflectance spectra of tall fescue has obvious fractal characteristics,and there has a strong negative correlation between fractal dimension and chlorophyll and leaf water content of tall fescue, it can be used in tall fescue remote sensing monitoring. The result provide theoretical guidance for the breeding of grass under the background of climate change, and technical support for the use of remote sensing methods in rapid detection of tall fescue growing in a large scale.