Topographic Controls on Vegetation Changes in Alpine Tundra of the Changbai Mountains

Miaomiao Wu,Kai Liu,Xinyuan Tan,Shengwei Zong,Hong He,Dandan Zhao,Yu Liang,Haibo Du

doi:10.3390/f9120756

Abstract

The vegetation of alpine tundra is undergoing significant changes and topography has played a significant role in mediating such changes. The roles of topography varied at different scales. In this study, we intended to identify topographic controls on tundra vegetation changes within the Changbai Mountains of Northeast China and reveal the scale effects. We delineated the vegetation changes of the last three decades using the normalized difference vegetation index (NDVI) time series. We conducted a trend analysis for each pixel to reveal the spatial change and used binary logistic regression models to analyze the relationship between topographic controls at different scales and vegetation changes. Results showed that about 30% of tundra vegetation experienced a significant (p < 0.05) change in the NDVI, with 21.3% attributable to the encroachment of low-altitude plants resulting in a decrease in the NDVI, and 8.7% attributable to the expansion of tundra endemic plants resulting in an increase in the NDVI. Plant encroachment occurred more severely in low altitude than in high altitude, whereas plant expansion mostly occurred near volcanic ash fields at high altitude. We found that plant encroachment tended to occur in complex terrains and the broad-scale mountain aspect had a greater effect on plant encroachment than the fine-scale local aspect. Our results suggest that it is important to include the mountain aspect in mountain vegetation change studies, as most such studies only use the local aspect.

Highlights

Alpine tundra is located in relatively isolated regions and is very sensitive to global environmental change [1,2]
Our study area covers the entire alpine tundra of the Changbai Mountains, which is located along the southern edge of the Eurasian alpine tundra zone, and developing on the upper slopes of a volcanic climate of the alpine tundra is characterized by lowby temperatures, intense volcanic cone cone(Figure (Figure1).1).The
(>80%into of pixels covered by volcanic ash) were less than 0.0

Summary

Introduction

Alpine tundra is located in relatively isolated regions and is very sensitive to global environmental change [1,2]. Alpine tundra in many places around the world has been undergoing dramatic changes in vegetation communities over the past few decades [3,4]. Some changes are considered to be the results of climate warming, while others are attributed to nitrogen deposition. Found a sharp expansion of shrubs in the alpine tundra of European Alps due to increasing temperature [5]. Climate warming in the Swiss Alps reduced snow cover and advanced snowmelt, which altered aboveground biomass allocation [4]. In subalpine tundra in northern Sweden, increased nitrogen caused the replacement of shrubs by fast-growing grasses in this nutrient-poor system [6]

Methods

Results

Discussion

Conclusion