Vegetation cover and Soil Organic Carbon along gradients of cattle grazing intensity in the Jornada Basin, July-August 2016

The goal of this Master’s thesis project, which was carried out in July and August of 2016, was to assess the effect of inferred grazing intensity on
1) vegetation cover type and 2) soil organic carbon (SOC) at the Jornada Experimental Range in southern New Mexico. A sampling transect was established
at each of 3 long term cattle water sources (85-106 years old), beginning 5m from the water source and continuing 1500m outward. Soil bulk density,
soil organic carbon, soil organic nitrogen, and dominant plant cover type (shrub, grass, and bare soil) were sampled at 20 locations on each transect.
Two hypotheses evaluated in this study are: 1) higher grazing pressure near the water source will lead to reduced vegetation cover and C inputs into
the soil, leading to higher SOC stocks in soil with far proximity to the water source; and 2) Grazing very close to the water source will exert high
disturbance and deposit SOC via defecation, leading to higher SOC stocks in soil with close proximity to the water source.

本研究为2016年7—8月开展的硕士毕业论文项目，旨在评估新墨西哥州南部约尔纳达实验牧场（Jornada Experimental Range）中，推定的放牧强度对两项指标的影响：1）植被覆盖类型；2）土壤有机碳（Soil Organic Carbon, SOC）。
研究共选取3个拥有85至106年使用历史的长期牛饮水点，每个饮水点均布设一条采样样带，样带以距饮水点5米处为起始点，向外延伸1500米。在每条样带的20个采样点位，分别采集土壤容重、土壤有机碳、土壤有机氮样本，并记录优势植物覆盖类型（灌丛、草本与裸地）。
本研究验证两项假说：1）饮水点附近更高的放牧压力会降低植被覆盖度与土壤碳输入量，最终导致距饮水点越远的土壤有机碳储量更高；2）距饮水点极近处的高强度放牧会带来强烈扰动，并通过排粪沉积补充土壤有机碳，最终使得距饮水点较近的土壤有机碳储量更高。