Natural mowing grassland resource distribution and biomass estimation based on remote sensing in Hulunber

Abstract: The natural mowing grassland plays an important role in grassland animal husbandry, which is not only the forage reserve resource for ensuring the seasonal balance of grassland and livestock, but also can ensure the safe wintering of livestock as forage grassland and post-disaster emergency rescue of forage grass resources reserves in China. However, the information about the resource distribution and biomass estimate of mowing pasture in natural grassland in China is lacked, which limits the effective utilization of regional forage reserve resources. Therefore, a systematic study on forage harvesting in natural grassland is necessary and important. In this study, the estimation of resource distribution and biomass of Chen Barag Banner in the Hulunber meadow steppe in north-eastern China was carried out by using remote sensing technology and field investigation. The field investigation was conducted in 2015 and the investigation time was from the middle of July to the end of July. The results showed that the area of forage harvesting pasture in the Chen Barag Banner regions was 80.28×104 hm2, which accounted for 90.37% of fixed harvesting pasture and 9.63% of temporary harvesting pasture. Among them, the largest area of forage harvesting pasture appeared in Ewenke village, reaching 2.28×105 hm2, followed by Bayanhada village, east Wuzhuer village, Hohnuor village and west Wuzhuer village; the pasture area of each village was larger than 9.00×104 hm2, and the pasture area of Baorixile village was the smallest, which was 0.64×104 hm2. Combining the simultaneous MODIS-NDVI (normalized differential vegetation index) datum with biomass investigation of cutting pasture, a relation model between MODIS-NDVI and biomass was developed, and the relative error of the production estimation model was 20.56%. It was feasible for the power function model to be applied in remote sensing monitoring. The average biomass of Chen Barag Banner natural cutting grassland was 1.24×103 kg/hm2, and the total biomass was 992.90×106 kg, among which the largest village biomass was Ewenke village, reaching 304.21×106 kg, Bayanhada village was 221.01×106 kg, and the other villages accounted for 47.10% of cutting pasture biomass. Temperate steppe (55.94%) and temperate meadow steppe (31.25%) were the main vegetation types for those pastures, and the lowland meadow steppe (4.89%), mountain meadow (5.94%) and desert steppe (1.99%) were distributed with a small area. The area of temperate grassland and temperate meadow grassland was 44.91×104 and 25.09×104 hm2, and the biomass was 532.04×106 and 330.87×106 kg, respectively. The proportions of grassland area and biomass of other types of grasslands were only 12.81% and 13.09%, respectively. The results have made up for the deficiency for the area data of the region forage harvesting pasture and provided data support for analysis of forage harvesting pasture changes of Chen Barag Banner in the Hulunber meadow steppe of north-eastern China in the future.