Evaluation for natural grassland utilization intensity based on GPS and UAV remote sensing for grassland biomass inversion

Abstract: Natural grassland is the most important material basis for the survival of grazing livestock husbandry. Assessment of the utilization of natural grassland provides decision-making basis for livestock management department to implement the natural grassland development projects, and has important research and application value for promoting the sustainable development of the grazing livestock husbandry. However, grassland degradation is getting worse. And overgrazing is one of the main causes of grassland degradation. Therefore, it is particularly important to monitor natural grassland utilization timely and accurately. Grazing is one of the most important ways to utilize natural grassland and has an important impact on the sustainable development of the ecosystem. What’s more, grassland is the basis for developing grassland animal husbandry, and grassland biomass is one of the important indicators to determine whether the utilization of natural grassland resources is reasonable. Hence, we put forward that the process of natural grassland utilization was an interactive process between grazing behavior and vegetation growth. Therefore, we studied the evaluation method of the utilization of natural grassland, during which we took grazing behavior and grassland vegetation growth into account at the same time. Firstly, the herd trajectory data acquired from global positioning system (GPS) weaned on the head of sheep was used to analyze feeding intensity. In order to quantify grazing pressure, a feeding intensities (FI) map was created using a grid cell method with the tracking data recorded by the global positioning system (GPS). Secondly, the grassland biomass data was gained by using unmanned aerial vehicle (UAV) remote sensing data. With the existing remote sensing estimation model, the grassland yield distribution of natural grassland was estimated. Thirdly, the feeding intensity and natural grassland biomass was fused by using the multi value extraction point method, and the feeding intensity and grassland biomass of different regions could be obtained. The feeding intensity and biomass were classified, respectively. Finally, according to the hierarchical relationship between the feeding intensity and the biomass, the information about utilization of grassland in various regions was obtained. When the feeding intensity and the natural grassland biomass could meet the following relationship, the information about utilization of grassland could be obtained. If the levels of feeding intensity and biomass were equal, the grassland was moderately used. If the level of feeding intensity was greater than that of biomass, the grassland was overused. If the level of feeding intensity was less than that of biomass, the grassland was light used. Taking pasture of Regiment 151 of the Eighth Division of the Xinjiang Production and Construction Corps as an example, the research area was monitored and assessed. The results showed that the area of grassland that was moderately used in Zone 3 in the study area was the largest, which was 612 m2, while in other areas, more than 50% of the area was unreasonably used. The method is of great significance to the rational use of grassland, rotational grazing, and the healthy development of livestock husbandry.