JapanFlux2024 CN-In7 Inner Mongolia light 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 Light grazing site,two sheep per hectare were grazed during the grazing period. Grass condition was better than that of natural grassland. 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，以探究放牧强度对内蒙古半干旱区草原退化的影响，并明确该区域草原的载畜量。试验于1991年秋季启动，持续至1995年秋季。试验在距奈曼站（Naiman Station）东北1.6km处的典型草原布设一块260m×200m的矩形放牧试验区，该区域已于1991年开展微气象观测。试验场地通过刺铁丝围栏划分为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，以确保观测期内盛行风向（南风）下的风程达到最大值。自1992年5月起，四块区域分别采用不同放牧密度（即各区域饲养的绵羊数量存在差异）开展放牧处理。三块75m×200m区域的放牧强度分别设置为6、4和2只羊/公顷，依次对应重度放牧区、中度放牧区与轻度放牧区。轻度放牧区在放牧期内的载畜量为2只羊/公顷，其草地状况优于天然草原。本研究采用鲍恩比热平衡法（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（CO₂）湍流通量进行测定。