Testing non‐equilibrium theory: Effects of grazing on plant community composition and soil nutrient availability in dry southern Mongolian steppes
Large parts of the Central Asian rangelands are dry at mean precipitation levels of ＜ 200 mm, and show a pronounced interannual variability in climate ( CV ＞ 30％ ).The non equilibrium‐( or disequilibrium‐, Gillson & Hoffman, 2007) theory of rangeland science predicts for such environments that climate is the main control with biotic factors including grazersimpact being driven by, rather than driving variables.In this view, degradation threat should be small in dry regions.We tested these assumptions by monitoring vegetation composition in grazed and ungrazed sites in southern Mongolian desert steppes over 8 subsequent years.Our focus was on the relative importance of interannual climate variability vs.grazing impact/ exclusion.Ongoing discussions on the possibility of degradation occurring even under non‐equilibrium conditions prompted us to assess whether grazing alters soil conditions and if possible changes indirectly affect rangeland health.
non‐equilibrium theory diversity small mammals livestock soil conditions
Karsten Wesche Katrin Ronnenberg
Inst.of Biology —GeobotanYand Botanical Garden,Am Kirchtor 1,06108 Halle,Germany
国际会议
呼和浩特
英文
2008-06-29（万方平台首次上网日期，不代表论文的发表时间）