Study On Dynamic Changes Of Vegetation Coverage And Grass Yield During The Exuberant Growth Period Of Herbage In Hezuo City

The natural grassland of the Hezuo is located at the transitional section between the northeastern edge of the Qinghai-Tibet Plateau and the western part of the Loess Plateau,It is an important means of production for a few ethnic minorities to survive.This study combines"3S"technology with ground survey using the LandsatTM image of the same phase in 2017 as the data source.Through the pixel bisection model method,the Study was done on the dynamics of vegetation coverage and grass yield in the Growing Grassland in the Hezuo in 2017.The purpose of the study provides reference for the rational protection,utilization and improvement of the grassland ecological environment of natural grassland.The results showed that:1.The average vegetation coverage of the alpine meadow and the mountain meadow at the study area on June was 55.79%and 54.54%,on July it was 72.69%,68.81%and on August it was 78.89%,76.53%.With the growth period of herbage growing,the average coverage of alpine meadow and meadow vegetation increased and on July its increase is the largest.2.The study area on June,alpine meadow and mountain meadow vegetation coverage were in grade II coverage(50%?F?75%)which was accounted for the largest proportion of grassland.It accounts for 79.05%and 75.24%of the total area of alpine meadow and mountain meadow.Vegetation coverage in July was also accounted for the largest proportion of class II,It accounts for 52.61%and 65.54%of the total area of alpine meadow and mountain meadow followed by level I(75%?F?100%).It also accounts for 45.03%and 29.60%of the total area of alpine meadow and mountain meadow.The coverage of vegetation on August is the largest proportion of grade I.It accounts for 77.34%and 66.90%of the total area of alpine meadow and mountain meadow.As the growth period of pasture continues,the vegetation coverage of alpine meadow and mountain meadow change from grade II to I.3.In the study area,the yield of average fresh edible grasses at alpine meadow on June,July and August were 1214.85 kg/hm~2,4797.75 kg/hm~2 and 5550.9kg/hm~2.Total fresh grass production was 80,600 t and 318,000 t and 367,700 t;At the mountain meadow,the yield of the average fresh edible grasses in June,July and August were 1781.4 kg/hm~2,4309.2 kg/hm~2 and 5233.8 kg/hm~2.Total fresh grass production was 103,300 t and 249,500 t and 303,100t.The average fresh edible forage yield and total yield were increased with the extended growth period.The biggest increase was in July.The average fresh grass production in alpine meadow and mountain meadow increased by 294.93%and 141.90%respectively compared with the end of June.4.With the growth of forage in alpine meadow and mountain meadow the yield of fresh forage from June(<200kg/mu)to July(200kg/mu~500kg/mu)and August(300kg/mu~500kg/mu)Changing from low output to high output.The biggest increase was in July.At the end of June,July and August,the total fresh grass production of edible pasture reached 183,900 t,567,400 t and 670,800 t.5.At Alpine meadow and mountain meadow in grass growth period,the yield of edible forage grass was calculated by 367,700 t and 303,100t.It can feed 151,100 and12,4600 sheep units.The cumulative provision of 275,600 sheep units forage use throughout the year.