湖南52县草地资源的类型、等级及利用现状分析

Types,grades,and utilization of grassland resources in 52 counties of Hunan Province

经过40年的发展,湖南省草地类型、面积和分布方面均发生了较大的变化,20世纪80年代草地调查的数据已不能反映现实草地资源现状,要科学地配置草地的生态功能和生产功能,首先需要摸清草地资源的家底。2018年项目组选择湖南52个县进行了草地清查,共设置3030个样地,调查每个样地的经纬度、海拔、坡向、坡位、草地类型、草地等级、盖度、草地产量、石漠化、退化、草地利用情况等。结果表明:52县中,天然草地可分为4个草地类,即暖性灌草丛、热性灌草丛、低地草甸类、山地草甸类,其中热性灌草丛样地数最大,占78.44%;其次是低地草甸类,占16.63%;暖性灌草丛和山地草甸类都较少,合计占4.93%。4个草地类包含了35个草地型,其中F05(白茅)、G01(芦苇)和G02(芦苇、藨草)草地型占比较大。天然草地处于海拔300 m以下的占94.47%,处于300~800 m的占4.54%,而海拔高于800 m的占0.99%。有76.83%的草地分布在阳坡和半阳坡,有71.10%的草地分布在坡中部以上,有14.58%的草地位于河流、湖泊、水库和坑塘的滩涂地。天然草地以Ⅲ等草地为主,占76.15%;天然草地分为8级,1级草地最多,占全体天然草地样地数57.68%。草地利用率低,有67.78%的草地未利用。草地干草产量均较高,干草产量为1000~5000 kg·hm^(-2)的占42.78%,干草产量为5000~20000 kg·hm^(-2)的占41.40%,干草产量大于20000 kg·hm^(-2)有11.93%,与20世纪80年代相比,草地面积大幅度减少。天然草地覆盖情况总体良好,平均覆盖度为81.53%。94.38%的草地样地无石漠化问题,石漠化区域集中分布在湘西武陵山片区、湘中衡邵盆地,以及湘南郴州、永州两市。草地退化面积约为12.73%,邵阳、永州、湘西、郴州、娄底、张家界和衡阳等7个市州存在草地退化问题。本次清查为湖南省草地资源的开发与利用提供了参考。

After 40 years of continuous development,there have been substantial changes in the types,area,and distribution of grassland resources in Hunan Province.The data obtained in the grassland survey in the 1980s no longer reflect the current situation of grassland resources.To scientifically allocate ecological functions and production functions to grassland resources,it is necessary to understand their current situation.To this end,a grassland resources sample plot survey was conducted in 52 counties of Hunan Province in 2018.A total of 3030 sample plots were selected,and the longitude,latitude,altitude,slope aspect,slope position,grassland type,grassland grade,grassland level,coverage,grassland yield,degree of rocky desertification,extent of degradation,and grassland utilization of each sample plot were investigated.Based on the 2018 dataset,the rangeland in the 52 counties was divided into four grassland classes:Warm-temperate shrub tussock,tropical shrub tussock,lowland meadow,and up-land meadow.The majority of the plots(78.44%)were tropical shrub tussock plots,while 16.63%of the plots were lowland meadow and 4.93%of the plots were warm-temperate shrub tussock and up-land meadow.There were 35 types of grassland within the four grassland classes.The grassland types F05(Imperata cylindrica),G01(Phragmites australis),and G02(P.australis and Scirpus triqueter)accounted for the largest proportions.Across the 52 counties,94.47%of the rangeland was below 300 m above sea level(a.s.l.),4.54%was between 300 m and 800 m a.s.l.,and 0.99%was above 800 m a.s.l.The majority of rangeland(76.83%)was distributed on the sunny and semi-sunny slopes;71.10%was distributed above the middle of the slope,and 14.58%was located on the shores of rivers,lakes,reservoirs,and ponds.A large proportion of plots(76.15%)contained grade III pastures,and these pastures were divided into eight levels.Among all the sample plots,57.68%contained level 1 pastures.The utilization rate of rangeland was low,with 67.78%of rangeland not in use.The hay yield of rangeland was higher.The proportion of plots with a hay yield of 1000-5000 kg·ha^(-1)was 42.78%,that with a hay yield of 5000-20000 kg·ha^(-1)was 41.40%,and that with a hay yield of>20000 kg·ha^(-1)was 11.93%.The grassland area in the 52 counties had decreased significantly since the 1980s.The rangeland vegetation cover was generally good,with average cover of 81.53%.The majority of rangeland sample plots(94.38%)showed no rocky desertification.The areas affected by rocky desertification were concentrated in the Wuling Mountain area,the Hengshao Basin,and the cities of Chenzhou and Yongzhou.The proportion of plots with degraded grassland was 12.73%,and grassland degradation was a significant problem in seven cities(Shaoyang,Yongzhou,Xiangxi,Chenzhou,Loudi,Zhangjiajie and Hengyang).This inventory provides a reference for the development and utilization of grassland resources in Hunan Province.