青藏高原高寒草甸广大牧区由于交通不便、能源短缺和生活习俗等原因，牛粪依然是当地牧民的主要生活能源来源，长期、大量地捡拾牛粪改变了粪斑的数量和面积，使养分在天然草地上无法回到草地生态系统进行再循环，因而对草地植物群落结构和生物量产生一定影响，从而增加了生态风险。为探讨捡拾牛粪对草地的生态影响，本文以青海省河南县高寒草甸生态系统为研究对象，通过对适度放牧草地上牦牛粪开展为期3年的不捡拾、一半捡拾和全部捡拾3个处理的试验研究，探讨捡拾牛粪对高寒草甸生态系统植物经济功能群落特征和生产力的影响。结果表明：牛粪不捡拾处理的草地生产力显著低于半捡拾和全捡拾处理，植物多样性显著低于半捡拾处理，禾草类优良牧草生物量显著高于半捡拾和全捡拾处理，莎草类优良牧草生物量显著高于全捡拾处理；牛粪半捡拾处理比不捡拾处理草地植被丰富度显著提高31.9%，植物多样性显著增加，群落生产力显著提高9.7%(42.6 g·m-2)，优良牧草和可食牧草生物量变化不显著；牛粪完全捡拾比不捡拾处理也显著增加草地植被的丰富度，增幅为10.7%，植物多样性显著增加，群落生产力显著提高4.1%(17.96 g·m-2)，但同时毒杂草显著增多，优良牧草和可食性牧草显著减少，牧草适口性变差。捡拾(半捡和全捡)牛粪会使禾草类和莎草类优质牧草生物量显著减少，莎草类在完全捡拾牛粪区生物量极显著减少70%以上；豆科植物生物量显著增加，在完全捡拾牛粪区生物量极显著增加，可达5倍以上；占总生物量74%~79%的杂类草和毒草的生物量也显著增加，且以半捡拾区增量最多。适度的牛粪捡拾可增加植被的丰富度和多样性，也提高了植被的生物量，并可保证牧草的营养品质和适口性。本项研究结果可以为高寒草甸牧区牛粪的适度捡拾和草地生态系统可持续管理提供科学依据。%In most pastoral areas of the Tibetan Plateau, yak dung is the only life energy source of herdsmen due to inconvenient traffic, energy shortage and life custom. Long term removal of large amount of yak dung from grassland ecosystem changes the amount and area of dung spots which induces nutrition recycle change of grazing grassland. The plant community and biomass of grassland consequently changes and ecological risk rises. To explore the ecological effects of yak dung collection, this paper focused on the characteristics and productivity of plant functional groups under full, half and none yak dung collection treatments in moderate grazing alpine meadow ecosystem in Henan County, Qinghai Province. Plant composition, important values of plant species, vegetation growth and community characteristics of alpine meadow under different dung collection treatments were investigated after three years experiment. The results showed that under yak dung none-collection treatment, grassland productivity was significantly lower than those under half-collection and full-collection treatments, while biodiversity was significantly lower than that under half-collection treatment. The biomass of high quality gramineae forage grass was significantly higher than those under half-collection and full-collection treatments, the biomass of high quality cyperaceae forage grass was significantly higher than that under full-collection treatment. Under yak dung half-collection treatment, biomass was 42.60 g·m-2 with a significant increase of 9.7%compared with non-collection treatment. Vegetation abundance of yak dung half-collection treatment significantly enhanced 31.9%, while high quality forage grasses biomass unchanged compared with non-collection treatment. Under yak dung full-collection treatment, biomass and vegetation abundance significantly increased by 4.1% and 10.7%, respectively, high quality forage grass biomass decreased, meanwhile poisonous weeds biomass increased compared with non-collection treatment. Grass palatability of full-collection treatment got worse. Half or full collection of yok dung reduced the biomass of high quality forage grasses of gramineae and cyperaceae, especially cyperaceae grass biomass reduced by more than 70% under yak dung full-collected treatment. Leguminous grass biomass significantly increased by more than 5 times, while weeds and poisonous weeds biomass accounted for 74%-79%total biomass. It was indicated that moderate collection of yak dung increased vegetation richness and diversity, insured grass palatability, and meantime provided energy resource for herdsman in alpine meadow. The results may provide a principle for yak dung collection and scientific management of moderate grazing alpine meadow ecosystem.
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