Abstract:

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.

Key words: Hunan, grassland resources, grassland type, grassland grade, utilization