基于NDVI数据的高寒草甸产量及载畜状况研究——以2019年青海玉树州为例

The Study on Forage Yield and Stocking Rate of Alpine Meadow Based on Normalized Difference Vegetation Index Data

为估算2019年盛草期青海省玉树州高寒草甸产量及理论载畜量,利用归一化植被指数(Normalized difference vegetation index,NDVI)和实测产量数据建立玉树州高寒草甸产量遥感估算模型,在此基础上利用玉树州高寒草甸面积可利用系数、草地可食植物系数和牧草采食率等建立理论载畜量估算模型。结果表明:(1)玉树州高寒草甸NDVI总体呈现由东南向西北递减的空间格局,且全州NDVI均值较低;(2)2019年玉树州高寒草甸产量与NDVI呈极显著相关(P<0.01),反演得出鲜草平均产量为2572.66kg/hm^(2),总产量为1.38×10^(9)kg;(3)运用理论载畜量估算模型得出玉树州高寒草甸理论载畜量为6.64×10^(6)个羊单位,实际载畜量为5.83×10^(6)个羊单位,进而得出2019年玉树州高寒草甸超载率为-12.20%,载畜能力不足;(4)近十年来,玉树州草地畜种结构变化明显,大牲畜存栏量曲线与实际载畜量几乎一致。综上所述,在利用NDVI反演产量的基础上,估算理论载畜量,可为高寒地区合理规划放牧生产活动、防治草地退化、保护生态环境等提供理论依据和决策支持,也可为青海省其他地区草地产量反演和理论载畜量估算提供参考。

To estimate the forage yield and theoretical stocking rate of alpine meadow in the growth season in Yushu Prefecture,Qinghai Province in 2019,a remote sensing estimation model for forage yield of alpine meadow yield in Yushu Prefecture was established by using normalized difference vegetation index(NDVI)and measured grassland yield data.Based on the estimation model of forage yield by remote sensing,the estimation model of theoretical stock rate was established by using the available coefficient of the alpine meadow area,the coefficient of grassland edible plants and the forage intake rate in Yushu Prefecture.The results showed the following aspects:(1)The NDVI of alpine meadow in Yushu Prefecture showed a decreasing spatial pattern from southeast to northwest,especially the average NDVI of entire prefecture was extremely low.(2)The forage yield of the alpine meadow in Yushu Prefecture in 2019 was significantly correlated with NDVI(P<0.01)with the average fresh forage yield of 2572.66 kg/hm^(2)and the total grass yield of 1.38×10^(9)kg.(3)The theoretical stocking rate of alpine meadow in Yushu Prefecture was 6.64×10^(6)sheep unit using the estimation model,while the actual stocking rate was 5.83×10^(6)sheep unit.Based on above theoretical stocking rate,it can be estimated that the overload rate of alpine meadows in Yushu Prefecture was-12.20%in 2019,which indicated that the ability of livestock was insufficient.(4)In recent ten years,the livestock structure on grassland in Yushu Prefecture had changed significantly,and the variation curve of large livestock population was almost consistent with the actual livestock stocking rate.In conclusion,the estimation of theoretical stocking rate based on NDVI retrieved forage yield can provide theoretical basis and decision-making support for rational planning of grazing activities,prevention of grassland degradation,and protection of eco-environment in alpine regions.It also provided references for estimation of grass yield and theoretical stocking rate in other regions of Qinghai Province.