The Research On Healthy Evaluation Of Hill Meadow Steppe Bases On Remote Sensing Technology

Hilly meadow steppes which degraded obviously were selected as sample plots to carry out the research in West Ujimqin Banner of Xilin Gol League in order to search for a method to evaluate grassland healthy extensively, quickly and successively which combined the traditional steppe resource ground survey technique with EOS-MODIS remote sensing technique and ground hyper- spectral technique.the division of degradation degrees on sample plots was carried out based on classification standard of natural steppe degradation, desertification and salinity (GB19377-2003), using ground data from June to August in 2007. The result showed that it was easy to cause deterioration evaluation errors if based on the data of June and July; the sample plots could be divided into four grades: non-degraded(CK), light, moderate and heavy degraded based on the data of August.the regularity that 13 vegetation indexes and 42 soil indexes varied with that degradation degree deepened was compared and analyzed. Eight vegetation indexes(forage cover degree, bare ground cover degree, litter cover degree, total biomass, litter weight, dominant species dominance index, degradation indicator plant dominance, grass height etc.) and five soil indexes (soil density, soil water content, soil organic carbon content from 0 to 5cm, soil total P content from 0 to 5cm, soil K content from 0 to 5cm etc.) were selected which have strong indicative to grassland degradation degree and have same regulation with degradation gradient.5 principal components which could character grassland degradation were selected using principal component analysis method. Health Assessment Index of grassland (RHI) was constructed using vague mathematics. The referred health thresholds were determined: non-degraded from 1.00 to 0.82, light degraded from 0.65 to 0.52, moderate-degraded from 0.58 to 0.48, heavy-degraded from 0.46 to 0.39 when hilly meadow grasslands were evaluated using RHI.correlation analysis was carried between vegetation index and RHI, single band spectrum and RHI using MODIS-NDVI index and data of high spectrum reflectance. Remote sensing model and spectrum model were constructed to evaluate RHI of the grasslands. The optimal estimation model was determined by the test of reliability and accuracy.Estimation model of MODIS-NDVI index was as follows: y = 3.518x - 0.692 R~2 = 0.7046 Accuracy 90.66%; y = 33.67x~2 - 20.546x + 3.5414 R~2 = 0.7764 Accuracy 90.39%; y = 1.2257Ln(x) + 1.8351 R~2 = 0.682 Accuracy 90.38%; y = 4.4797x~2.0502 R~2 = 0.738 Accuracy 90.51%; y = 0.0658e5.8664x R~2 = 0.7578 Accuracy 90.82%。Estimation model of spectral vegetation index was as follows: NDVI: y = 0.2553e1.8456x R~2 = 0.6694 Accuracy 77.85% RVI: y = 0.2947x0.6795 R~2 = 0.6328 Accuracy 82.23% MSAVI: y = 1.6218x~2 - 0.7669x + 0.4611 R~2 = 0.6358 Accuracy 80.55%。A set of new methods of grass health and evaluation was summaried based on remote sensing and spectroscopy technique integrated with the changes of grassland ecosystem of "plant - soil - litter", which could provide reference for related researchers.