JapanFlux2024 CN-In8 Inner Mongolia medium grazing

We designed the field experiments to study the effects of the grazing strength on the degradation of grassland and to know the grazing capacity at the grassland in semi-arid area in Inner Mongolia.The experiments started in1991 autumn and continued to autumn in1995. An experimental grazing section (260m X 200m in rectangular area) was established on the grassland (1.6km north-east from the Naiman Station),where the micro meteorological observation had been conducted in1991,as the site of typical grassland. The experimental site was divided by barbwire fence to three 75m X 200m rectangular areas and one 35m X 200m area. The longer side of the four rectangles was directed to north-south to obtain the maximum fetch for the prevailing wind direction (south) during the observation period. Each of the four areas was treated by different grazing densities (different sheep numbers in each area) from May1992. The grazing strength of the three 75m X 200m areas was set as 6, 4 and 2 sheep/ha,namely "Heavy grazing site", "Medium grazing site" and "Light grazing site", respectively. In the Medium grazing site,four sheep per hectare were grazed during the grazing period. Grass condition was a little bit poorer than that of natural grassland with traditional grazing. The turbulent fluxes of sensible heat, latent heat, CO2 were measured using the Heat balance Bowen ratio method and the Gradient method.本研究设计野外定位试验，以探究放牧强度对草原退化的影响，并明确内蒙古半干旱区草原的放牧承载能力。试验于1991年秋季启动，持续至1995年秋季。 本研究在奈曼站东北1.6km处的典型草原布设试验放牧区（矩形区域，面积为260m×200m），该区域于1991年已开展微气象观测。 试验场地采用铁丝网围栏划分为3块75m×200m的矩形区域与1块35m×200m的区域。 四块矩形区域的长边均沿南北向布设，以使观测期内盛行南风的风区长度达到最大值。 自1992年5月起，四块区域分别采用不同的放牧密度（即各区域放牧绵羊数量各异）进行试验处理。 三块75m×200m区域的放牧强度分别设定为6只/公顷、4只/公顷与2只/公顷，依次对应重度放牧区、中度放牧区与轻度放牧区。 中度放牧区在整个放牧周期内的放牧强度为4只/公顷。 该试验草原的植被状况略逊于传统放牧模式下的天然草原。 本研究采用波文比-能量平衡法（Heat balance Bowen ratio method）与梯度法（Gradient method），对感热通量、潜热通量及二氧化碳湍流通量进行观测。