践踏干扰对碧塔海高寒草甸植被茎叶性状、物种多样性和功能多样性的影响

高寒草甸具有重要的生态服务功能,然而固有脆弱性使其极易遭受气候变化和人为干扰等多重因素的影响。作为滇西北旅游资源中重要的组分之一,高寒草甸吸引了大批游客前往开展徒步旅行活动,但伴随着的践踏干扰作用会不可避免地对高寒草甸生态系统带来负面影响。然而,目前关注践踏干扰对滇西北高寒草甸植被的影响,特别是植被功能性状和功能多样性如何发生变化方面的研究还十分欠缺。以云南省香格里拉市碧塔海自然保护区内的典型高寒草甸生态系统为研究对象,采用实验践踏的方式(一共5种不同强度的践踏处理)来模拟旅游活动对草甸植被的干扰作用,并以草甸植被的茎叶性状特征为切入点,重点探讨践踏干扰对茎叶性状的平均大小和变异程度的影响,以及物种丰富度(以物种形态分类为基础)和功能丰富度(以功能性状为基础)之间的关系。研究结果显示,随着践踏强度的增加,植株高度和叶片大小的平均值,而不是茎叶性状的变异程度,出现明显下降趋势。此外,物种丰富度和功能丰富度均随践踏强度的增强而减小,且两者之间呈现显著正相关关系。然而,较之轻度践踏实验组,重度践踏实验组中的功能均匀度和功能分离度水平均有所增加,表明践踏干扰可能会在短期内打破优势种对资源的绝对占有格局和减少物种间的生态位重叠程度。尽管高寒草甸对人类践踏活动有一定的承受能力,但气候变化和人为干扰等多重因素势必会改变和影响高寒草甸群落的结构和功能可持续性,这也对高寒草甸的保护与管理工作提出了更加紧迫的要求。

The effect of trampling disturbance on functional traits, species diversity, and functional diversity of alpine meadows in Bitahai Nature Reserve

Alpine meadows provide important ecosystem goods and services. However, their inherent vulnerability makes them susceptible to multiple stress factors such as global climate change and anthropogenic disturbance. As an important component of the tourism resources of northwestern Yunnan, China, alpine meadows have attracted numerous tourists each year. However, trampling disturbance caused by hiking activities could inevitably impose negative effects on alpine meadows in northwestern Yunnan. Furthermore, little attention has been paid to the effect of trampling disturbance on the vegetation species of alpine meadows in this region. In particular, research on changes in vegetation functional traits and functional diversity in the wake of trampling disturbance is very limited. The present study focused on a typical alpine meadow ecosystem located in Bitahai Nature Reserve, Shangri-la, Yunnan. Using experimental trampling with five different levels of trampling intensities, we simulated the disturbance scenario caused by hiking activities. By examining the characteristics of the stem and leaf traits of meadow vegetation, the study evaluated the effect of trampling disturbance on the means and variations in stem and leaf traits, as well as the relationship between species richness (based on species morphology classification) and functional richness (based on species functional traits). The results showed that increasing the trampling intensity, decreased the mean values of the vegetation height and leaf size, although it was not the case for the variations in stem and leaf traits. Moreover, both species and functional richness decreased with increasing trampling intensity, and there was a significant positive correlation between the two factors. However, for groups exposed to intense trampling treatment, functional evenness and functional divergence displayed an increasing pattern, indicating that trampling disturbance might have shifted the role and prevalence of dominant plants and reduced the niche overlap among competing species, at least for short term. Although alpine meadows have specific abilities to withstand human activities, human interference and climate change will inevitably change and impede the structural and functional sustainability of alpine meadow communities. Therefore, the effective protection and management of alpine meadows are urgent, and more science-oriented guidance is needed.