Predicting parameters of degradation succession processes of Tibetan &amp;lt;i&amp;gt;Kobresia&amp;lt;/i&amp;gt; grasslands

L Lin,X W Guo,Y G Du,X L Xu,G M Cao,F W Zhang,Y K Li,S L Liu

doi:10.5194/se-6-1237-2015

Abstract

Abstract. In the past two decades, increasing human activity (i.e., overgrazing) in the Tibetan Plateau has strongly influenced plant succession processes, resulting in the degradation of alpine grasslands. Therefore, it is necessary to diagnose the degree of degradation to enable implementation of appropriate management for sustainable exploitation and protection of alpine grasslands. Here, we investigated environmental factors and plant functional group (PFG) quantity factors during the alpine grassland succession processes. Principal component analysis (PCA) was used to identify the parameters indicative of degradation. We divided the entire degradation process into six stages. PFG types shifted from rhizome bunchgrasses to rhizome plexus and dense-plexus grasses during the degradation process. Leguminosae and Gramineae plants were replaced by sedges during the advanced stages of degradation. The PFGs were classified into two reaction groups: the grazing-sensitive group, containing Kobresia humilis Mey, and Gramineae and Leguminosae plants, and the grazing-insensitive group, containing Kobresia pygmaea Clarke. The first group was correlated with live root biomass in the surface soil (0–10 cm), whereas the second group was strongly correlated with mattic epipedon thickness and K. pygmaea characteristics. The degree of degradation of alpine meadows may be delineated by development of mattic epipedon and PFG composition. Thus, meadows could be easily graded and their use adjusted based on our scaling system, which would help prevent irreversible degradation of important grasslands. Because relatively few environmental factors are investigated, this approach can save time and labor to formulate a conservation management plan for degraded alpine meadows.

Highlights

Alpine grasslands are one of the most important grassland types on earth, and they are distributed across the tundra zone of northern Eurasia and North America
Alpine grasslands represent one of the major natural types of pastures for pastoralists living in alpine regions, especially for those living on the Tibetan Plateau, where livestock grazing is the most important human activity (Zhang et al, 2003)
The succession process of the alpine Kobresia grassland involved the replacement of plant functional groups (Fig. 2)

Summary

Introduction

Alpine grasslands are one of the most important grassland types on earth, and they are distributed across the tundra zone of northern Eurasia and North America. Livestock mainly affects alpine grasslands through two ways Their grazing can affect the structure and composition of plant community, and the constitution of plant life forms and ecotypes in alpine grasslands (de la Paix et al, 2013; Zhao et al, 2013; Mekuria and Aynekulu, 2013). L. Wang et al, 2007; Foggin, 2008) This reduces the role of alpine grasslands in soil and water protection (Wen et al, 2010; Brandt et al, 2013; You et al, 2014). Such grazing-induced degradation of alpine grasslands was observed in the early 2000s L. Wang et al, 1997; Liu et al, 2008; Wang et al, 2009; Harris, 2010; Lin et al, 2013a, b), mainly because livestock number increased from approximately 0.8 × 108 in 1997 to 1.08 × 108 sheep units in 2011 on the Tibetan Plateau (Yang, 2002; He et al, 2008; Sun, 2012)

Methods

Results

Discussion

Conclusion