摘要
综述了放牧对草地土壤物理特性(容重、渗透率)和化学特性(有机质、全氮、全磷等)的影响。由于草地土壤生态系统本身的复杂性和弹性,放牧对草地土壤特性的影响并没有一致的结论。一般而言,随着放牧强度的增加,牲畜的践踏作用变强,土壤容重逐渐增加,土壤的渗透性降低,导致土壤的含水量下降,随着土壤深度增加其影响减弱。但在有机质含量很低的沙质土壤中,超载过牧造成有机质含量降低,土壤的团粒结构减少,稳定性团聚体减少,土壤结构遭到破坏,使得土壤容重降低。放牧对土壤有机质的影响受多种因素的影响,如温度、降水、植被、土壤和管理措施(持续放牧、轮牧、围栏等),所以有机质的动态转化过程十分复杂,已有的文献放牧管理对土壤有机质的影响有3类结论:无影响、增加和降低。放牧家畜通过采食、践踏、排泄等行为直接或间接地影响土壤中氮的含量,随放牧强度增加,土壤全氮含量呈现出降低、不变和增加等。土壤磷对放牧的响应也有不同的研究报道,有的认为随放牧强度的增加,土壤全磷下降,而速效磷增加,也有研究认为长期放牧对草地的全磷和速效磷变化不大。不合理的放牧是造成土壤退化的最普遍原因,故认识不合理放牧导致草原土壤退化的过程和机制,对遏止草原退化、实现草地畜牧业的可持续发展具有重要的意义。
The published literature was reviewed for effects of grazing on soil physical properties （bulk density, water infiltration） and chemical properties （soil organic matter, total nitrogen, and total phosphorus）. The effects on soil properties were inconsistent because of the complexity and resilience of grassland soil ecosystems to perturbation. In general, because the impact of livestock trampling led to increased soil bulk density as grazing intensities increased, and to reduced soil infiltration and water holding capacity, although this phenomenon decreased as soil layers increased. Soil bulk density may decrease in sandy soil with lower organic matter con- tent, because overgrazing reduces soil organic matter thus influencing the stability of soil aggregates and resulting in a collapsed soil structure. The trans effects of grazing on soil organic matter are formation process of organic matter is very complicated because the affected by many factors, such as temperature, precipitation, vege- tation, soil and management measures （e. g. continuous grazing, rotation grazing, and enclosure）. The effects of grazing on soil organic matter is not consistent in the published literature： It may increase, decrease, or have no-effect. Livestock interacts with soil nitrogen content of grassland by feeding, trampling and excreting. Based on reported literature, total nitrogen may be increased and decreased or show no change as grazing inten- sity is increased. The effect of grazing on soil phosphorus is different. Soil total phosphorus is reduced while a- vailable phosphorus is increased as grazing intensity is increased. However, some researchers report that soil total phosphorus and available phosphorus of grasslands have little change under long-term grazing conditions. Overgrazing is the most common cause of soil degradation. The awareness of this process and mechanism of overgrazing is of great significance for curbing grassland degradation and achieving sustainable development of grassland animal husbandry.
出处
《草业学报》
CSCD
北大核心
2010年第4期204-211,共8页
Acta Prataculturae Sinica
基金
973课题(2007CB108902)资助
关键词
放牧
草地生态系统
土壤理化特性
grazing
grassland ecosystem
soil physical and chemical characteristics
