退化梯度上滇西北高山草甸植物群落的补偿生长能力

为探究退化梯度上滇西北高山草甸植物群落补偿生长能力及其维持机制,本研究于2018年7月–9月在滇西北的3个草甸退化梯度[重度退化(heavy degradation, HD)、中度退化(medium degradation, MD)、无退化对照(control,CK)]上开展原位刈割试验以分析草甸植物的补偿生长能力,同时采集、分析相应土壤样品的理化性质用于分析草甸植物补偿生长能力的维持机制。结果表明:1)随退化程度增加,草甸植物群落总盖度、平均高度及地上生物量逐渐降低;2)随退化程度增加,土壤容重、土壤含水率、平均粒径、总氮含量及土壤有机碳含量逐渐降低;土壤pH、速效氮含量在退化梯度间没有显著差异(P> 0.05),土壤有效磷含量的排序为MD> CK> HD;3)各退化梯度的草甸植物群落均发生了超补偿生长,且超补偿生长能力在退化梯度间没有显著差异(P> 0.05)。禾本科和杂类草植物的超补偿生长能力在退化梯度间没有显著差异,莎草科植物的超补偿生长能力排序为HD> MD> CK;4)相较于禾本科和莎草科,杂类草的超补偿生长能力受土壤理化性质的影响更小;...

Study on the compensatory growth of alpine meadows along a degradation gradient in northwestern Yunnan Province

To identify the compensatory growth ability of alpine meadows and the mechanisms underlying the process of land degradation in northwestern Yunnan province(NYP),this study specified three degradation levels,i.e.,heavy degradation(HD),moderate degradation(MD),and control(CK).An in situ mowing experiment was conducted to test the strength of alpine meadow compensatory growth across these three degradation levels from July to September 2018.Meanwhile,soil samples were collected and soil physical and chemical properties,such as bulk density,moisture,average particle size,pH,total organic carbon,total nitrogen,available nitrogen,and available phosphorus,were measured.The results showed that the total coverage,average height,and aboveground biomass of alpine meadows decreased along the degradation gradient.Regarding soil variables,the soil bulk density,soil moisture,average particle size,total nitrogen,and total organic carbon decreased along the degradation gradient.There were no significant differences in soil pH or available nitrogen content among degradation gradients,while the order of available phosphorus was MD>CK>HD.Additionally,the over-compensatory phenomenon was detected across all degradation levels,and there was no significant difference in the strength of over-compensatory growth among the degradation levels.The strength of over-compensatory growth of Gramineae and forbs did not change significantly across the degradation gradient,whereas the strength of over-compensatory growth of Cyperaceae increased as degradation level increased,i.e.CK