摘要
气候变化和人类干扰使青藏高原的草地退化日趋严重,特别是过度放牧导致的草地退化现象尤为突出;然而,牦牛作为青藏高原分布广且数量多的重要家畜,其不同放牧强度对高寒草甸土壤理化性质与细菌群落的影响仍不明晰。在川西北高原典型高寒草甸开展牦牛放牧强度试验,设置了对照组(禁牧)、轻度放牧(1头牦牛/hm^(2))、中度放牧(2头牦牛/hm^(2))和重度放牧(3头牦牛/hm^(2))4个放牧强度,每个强度设置3个重复。两年放牧实验后的结果表明:短期的重度放牧导致土壤有效磷显著增加,而其它土壤性质在各放牧强度变化不显著;随着放牧强度的增加,土壤细菌α多样性呈先增加后减少的趋势,其主要原因是牦牛活动为细菌的生长繁殖提供了有利的营养条件,但由于放牧的持续时间较短,变化不显著;就优势菌而言,土壤绿弯菌门中存在光合自养细菌,在重度放牧下显著高于对照组,其它各菌门在不同放牧强度下无显著差异;土壤氮与硝化螺旋菌门呈正相关,速效磷与酸杆菌门也呈显著正相关,均说明放牧强度对土壤细菌类群的影响是通过土壤性质间接实现的。本实验通过研究不同牦牛放牧强度下的土壤细菌群落结构,为放牧策略的制定提供了基础数据支持,为草地退化的防治提供理论依据。
As an important part of China, the Qinghai-Tibetan Plateau plays a vital role in the balance of global ecosystems. Climate change and human activities have led to grassland degradation on the Qinghai-Tibetan Plateau, especially overgrazing-induced grassland degradation. However, as one of the most dominated livestock on the Qinghai-Tibetan Plateau, the effects of different yak grazing intensities on soil physicochemical properties and microbial communities and structures still remain unclear. To address yak grazing effect on soil bacterial communities, we conducted a yak grazing intensity experiment in a typical alpine meadow of the Northwest Sichuan Plateau. According to local investigations and previous experiment, we set four grazing intensities, including control group(no grazing), light grazing(1 yak/hm^(2)), moderate grazing(2 yak/hm^(2)), and heavy grazing(3 yak/hm^(2)). After two years of grazing experiments, we found that heavy grazing significantly increased soil available phosphorus and short term grazing reduced the bulk density in the 0—10 cm soils, while other soil properties showed no responses to different grazing intensities. The possible reason may be that the effect of grazing on soil physicochemical properties was long-term, and the short-term grazing intensity of yak was difficult to change soil properties. The α diversity of soil bacteria increased firstly and then decreased with the increasing grazing intensity, but the changes were not statistically significant due to the short duration of grazing experiment. On the one hand, yak grazing could provide available nutrients for the growth of bacteria through dung and urine. On the other hand, high grazing intensity changed the root distribution and root exudates of plants, and increased ultraviolet radiation reduced the diversity of bacteria. In terms of the dominant bacteria, the Chloroflexi was significantly higher under no-grazing than that under heavy grazing, which has photosynthetic autotrophic bacteria. In contrast, other phylum had no significant differences among grazing intensities. With the increase of grazing intensity, the relative abundance of Actinobacteri and Firmicutes increased firstly and then decreased, while Acidobacteria and Gemmatimonadetes showed reverse trends. The β diversity of soil bacteria showed that grazing intensity had no significant effect on bacterial community structure. Soil total nitrogen is positively correlated with Nitrospira. There was a significantly negative correlation between soil total phosphorus and Acidobacteria, but soil available phosphorus was also significantly positive related to Acidobacteria, indicating that grazing intensity indirectly affect soil bacteria may be through changing soil properties. This study provides basic data to grazing managements and a theoretical basis to the restoration of degraded grasslands.
作者
王永宏
田黎明
艾鷖
陈仕勇
泽让东科
WANG Yonghong;TIAN Liming;AI Yi;CHEN Shiyong;MIPAM Tserang Donko(Institute of Qinghai-Tibetan Plateau,Southwest Minzu University,Chengdu 610041,China;Key Laboratory for Bio-resource and Eco-environment of Ministry of Education,College of Life Sciences,Sichuan University,Chengdu 610065,China;College of Animal and Veterinary Sciences,Southwest Minzu University,Chengdu 610041,China)
出处
《生态学报》
CAS
CSCD
北大核心
2022年第4期1549-1559,共11页
Acta Ecologica Sinica
基金
国家自然科学基金(42001055)
中央引导地方-自由探索项目(20ZYZYTS0020)
西南民族大学中央高校基本科研业务费专项(2020NQN27)和研究生创新型科研项目(CX2020SZ22)。
关键词
高寒草甸
牦牛放牧
放牧强度
土壤理化性质
土壤细菌群落
alpine meadow
yak grazing
grazing intensity
soil physicochemical properties
soil bacterial community
