Research On Hyperspectrum Of Degraded Seriphidium Transiliense Desert Grassland Under Condition Of Enclosure

To monitor recovery condition of Seriphidium transiliense desert grassland, the vegetation, soil and spectrum were measured and analyzed in this study. The main results are as follows:(1) The community's and plant's spectrum has been studied, it showed that, with the increasing length of fencing time, importance value of S. transiliense increased and importance value of annual vegetation and ephemeral plant gradually decreased under the same degradation gradient. Meanwhile, community spectral absorbed feature decreased within growth period; community spectrum in vegetation maturity period has obvious absorption characteristics only under the condition of enclosure in 10 years. Through the characteristic spectra of vegetation can be found, different vegetation responses to fenced disturbance is inconsistent. With increase of length of fencing time, S. transiliense's red slope was significantly greater than whom outside the fence(P<0.05), Petrosimonia sibirica on the contrary(P<0.01) and Malcolmia africana had no significant difference between inside and outside the fenced(P>0.05) in May. Characteristic vegetation can be divided into three types:Avoidant type(M. africana); Drought tolerant type(P. sibirica); Sleep type(S. transiliense).By NDVI correlation analysis to height, coverage and biomass, has achieved good effect,adjust the R square was 0.17, 0.32 and 0.36, respectively.(2) The soil physical and chemical properties and the spectrum had measured on S.transiliense desert grassland. Generally, results show that soil moisture has a decrease trend in the growth period,soil moisture was increased with the length of fencing time in May and September, and modeled soil moisture by community spectrum, R2=0.63. Difference of soil organic matter within and outside the fence was increased with the length of fencing in May.With the increase of enclosed years, soil organic matter showed rise firstly, then reduce, andelevated finally. Difference of organic matter decreased linearly through growing period for enclosed 7 and 10 years. Model of soil organic matter has achieved good results by laboratory soil spectrum and naked spectrum in the wild field, adjust the R square was 0.64 and 0.38 respectively. Studies have showed that soil moisture and organic matter for grassland restoration is sensitive to health monitoring for S. transiliense desert grassland.(3) On the regression analysis of the quantitative indicators, NDVI of community and plants, it has founded that 3 indexes got maximum in 5 year, meanwhile, soil moisture and organic matter reached limit value in 10 years. Combined with the sensitive index of vegetation and soil, it concluded that enclosed grassland vegetation had recovery after enclosed 5 years, while soil recovery lag, can make the appropriate use in this time.