牦牛放牧活动范围对高寒草甸冷季牧场植被群落结构和土壤理化性质的影响

The effect of grazing yak's activity range on vegetation community structure and soil physicochemicalcharacteristics in cold season pasture of alpinemeadow

摘要:

【目的】 揭示家畜放牧过程中植物群落格局的变化趋势及放牧家畜的选择性采食和游走规律对草地的干扰范围和程度，为草地管理和草牧业生产提供参考。【方法】 在天祝高寒草甸研究了放牧牦牛冷季牧场出入口及其周围1 000 m 范围内的植被演替规律和土壤变化情况。【结果】 600 m 以外的草地植被多样性显著高于牧场出入口200 m 范围的草地植被多样性，平均草层高度以600~800 m 的范围较低，以出入口周围200 m 的草层高度最高，在400~600 m 的范围内的地上生物量变化较大。随着放牧牦牛的活动范围距离出入口渐远，植被地下生物量和植被盖度显著增加，可食性牧草的种类和数量显著增加（P＜0. 05）。土壤以牧场出入口周围100 m 内的容重最大，土壤水分、土壤渗透速率和土壤饱和持水量最低。土壤全效养分在家畜活动频繁的出入口具有较低的含量，而在家畜活动范围较远的区域具有较高的含量。土壤速效养分在100 m 和＞800 m 的范围具有较高的含量。【结论】 距离牧场出入口较近的草地受践踏和采食频度的影响较高，使得植被物种单一，土壤易被侵蚀，造成了牧场出入口及200 m 附近的草地植被结构发生变化。高寒草地牧场出入口及附近的草地植被和土壤特性变化反映了植被和土壤对放牧强度的响应，在实际的牧场管理中可对出入口进行更换，或在出入口进行补播，以防止草地退化。

Abstract:

【Objective】 The change trend of plant community pattern and the disturbance range and degree ofgrazing animals′ selective feeding and migration rules to grassland were revealed， which provided reference for grasslandmanagement and grassland husbandry production.【Method】 The vegetation and soil changes of grazing yaks atgate of cold season pasture and within 1 000 m range were studied in Tianzhualpine meadow in cold season.【Result】The results showed that the vegetation diversity of the grassland with a range beyond 600 m was significantly higherthan that of the grassland with a range around 200 m. The average grass layer height was lower at 600 to 800 m， andthe highest at 200 m around. The aboveground biomass varied greatly in the range of 400 to 600m. The undergroundbiomass and vegetation coverage increased significantly with the distance far away from pasture gate， and the speciesand quantity of edible herbage increased significantly （P＜0. 05）. The bulk density of soil was the largest within100m of the ring beach， while the soil moisture， soil permeability rate and soil saturated water capacity were the low ‐est. The soil total nutrient content was lower in the area around the ring beach where livestock activity was frequent，and higher in the area where livestock activity was far away. The content of soil available nutrients was higher in therange of 100 m and ＞800 m.【Conclusion】 The grassland near the pasture gate is trampled and fed frequently， whichmakes the vegetation species simple and the soil easy to be eroded， resulting in serious degradation of the grasslandnear 200 m. It is of practical significance to understand the changes of vegetation and soil characteristics for more scientificuse and management of alpine grassland pasture in cold season. In the actual pasture management， the entranceand exit can be replaced， or the re-seeding can be carried out at the entrance and exit to prevent the degradationof the grassland.