ABSTRACT

Degradation of meadow ecosystems in the largest alpine region of the world, i.e., the Qinghai-Tibetan Plateau (QTP), is a crucial ecological issue that has ardently discussed in recent years. Many factors, such as livestock overgrazing, climate change and overpopulation of small mammals are treated as important factors that cause the degradation of meadow ecosystems in the QTP. However, there are few hypotheses focus on the potential role of plant compensatory growth on meadow degradation. We proposed a compensatory growth-related hypothesis to understand the potential degradation process of meadow ecosystems in the QTP. We discussed that there are two stages of meadow degradation, i.e. the beginning stage of meadow degradation that is triggered by high-strength overcompensation; and the intensification stage of meadow degradation, which are driven by external factors such as climate warming, small mammals and thawing of permafrost.The mechanism of meadow degradation driven by plant compensatory growth is the asynchronism of plant consumption and the availability of soil nutrients. Our hypothesis that plant compensatory growth drives meadow degradation under the overgrazing condition requires re-examination and modification by testing the balance between soil nutrient cycling rates and the strength of plant compensatory growth in alpine regions.

摘要

在世界上最大的高山地区，即青藏高原，草甸生态系统的退化是一个至关重要的生态问题，近年来已经进行了热烈的讨论。许多因素，例如牲畜过度放牧，气候变化和小型哺乳动物的过剩，都被视为导致QTP草甸生态系统退化的重要因素。但是，很少有假设集中在植物补偿性生长对草地退化的潜在作用上。我们提出了与补偿性增长有关的假设，以了解QTP中草甸生态系统的潜在退化过程。我们讨论了草甸退化的两个阶段，即由高强度过度补偿触发的草甸退化的开始阶段。以及草地退化的加剧阶段，这些因素是由气候变暖，小型哺乳动物和多年冻土融化等外部因素驱动的。植物补偿性生长驱动的草甸退化机制是植物消耗和土壤养分的不同步性。我们的假设是，在过度放牧条件下，植物补偿生长会导致草甸退化，因此需要通过测试土壤养分循环速率与高寒地区植物补偿生长强度之间的平衡来重新检查和修改。