基于无人机高光谱遥感的典型草原打草对植被表型差异分析

Analyses of Typical Steppe Cutting Grass on Vegetation Phenotypes Differences Based on UAV Hyperspectral Remote Sensing

打草是畜牧业工作中的重要内容,直接关系到牧草的表型特征,并且对地表温湿度、地表反射率甚至草地生态系统产生一定的影响。以锡林郭勒盟东乌珠穆沁旗北部的典型草原打草场为试验区,采用无人机(UAV)载Cubert S185高光谱成像仪、ASD(Analytical Spectral Device)地物光谱仪等设备,采集了打草场打草前后的牧草高光谱数据及地面样方生物量,分析了已打草和未打草区域植被表型特征差异。从光谱反射率曲线特征来看,未打草区域植被反射率和离散程度均高于已打草区,地面光谱仪和无人机高光谱影像上的表现结果一致。从窄波段植被指数特征来看,归一化植被指数(NDVI)、比值植被指数(SRI)和Voglemann红边指数(VOGI)等指数在2个区域均表现正常,且打草区的值高于未打草区,其中,VOGI指数差异最明显。未打草区域和已打草区域地上生物量与实际产草量存在一定差异。从分析结果来看,打草前后草场植被表型差异明显,原因主要有2个,其一,与典型草原主要优势种(针茅Stipa capillata L.)的形态特征有关;其二,由于打草后植物的绿色根系会留在地上,所以打草和采集地上生物量不同。

Cutting grass is an important part of animal husbandry work,which will directly change the phenotypic characteristics of forage grass and also have certain impacts on surface temperature and humidity,surface reflectivity and even grassland ecosystems. The typical steppe pastures in the northern part of the East Ujimqin Banner of Xilin Gol League was used as the experimental area. Then,using unmanned aerial vehicle(UAV)-mounted Cubert S185 hyperspectral imager,ASD(Analytical Spectral Device)ground object spectrometer and other equipment,the forage hyperspectral data and the biomass of the ground sample were collected before and after cutting grass,and the differences of vegetation phenotypic characteristics between cut and uncut grass area were analyzed. From the characteristics of the spectral reflectance curve,the reflectivity and dispersion of vegetation in the uncut grass area were higher than that in the cut grass area and the performance results of the ground spectrometer and the UAV hyperspectral image were consistent. From the characteristics of the narrow band vegetation index,the Normalized difference vegetation Index(NDVI),the Simple Ratio Index(SRI)and the Voglemann Red Edge Index(VOGI)were all normal in the two areas and the value of the cut area was higher than that of the uncut area and the difference in VOGI index was the most obvious. There were some differences between the aboveground biomass and the actual grass yield in the uncut area and the cut area. From the analysis results,there were obvious differences in the phenotype of grassland vegetation before and after cutting grass. The first one was related to the morphological characteristics of the main dominant species(Stipa capillata L.)in typical steppe and the second one was that the green roots of plants would be left on the ground after cutting grass.Therefore,cutting and collecting aboveground biomass were different.