The Spatial Pattern of the Upper Limit of Montane Deciduous Broad-Leaved Forests and Its Geographical Interpretation in the East Monsoon Realm of China

Jing Wang,Yonghui Yao,Baiping Zhang

doi:10.3390/f12091225

Abstract

Montane deciduous broad-leaved forests (MDB) are mainly distributed in the east monsoon realm of China. The upper limit of MDB significantly varies from mountain to mountain. However, the spatial pattern of the upper limit of MDB and its underlying drivers are still unknown. In this study, we conducted hierarchical multiple regression to quantify the effect of climatic factors, peak elevation, and cold tolerance of dominant species on the geographical distribution of the upper limit of MDB on 75 mountains in the east monsoon realm of China. The results show that: (1) the upper limit of MDB in the east monsoon realm of China, 2800 m, is the highest in Taibai peak of the Qinling mountain ranges, from where it tends to decrease both northward and southward. (2) The upper limit of MDB on the mountains with climatic treeline is mainly affected by climatic factors, the minimum temperature of the coldest month (MinT), and the precipitation seasonality (PS), with an R2 of 0.733. (3) The upper limit of MDB on both temperate and subtropical mountains without climatic treeline is affected by MinT, PS, peak elevation, and cold tolerance of dominant species together, with an R2 of 0.793 and 0.748, respectively. (4) The dominant species of the upper limit of MDB significantly differ temperate and subtropical ranges, the former of which is mainly in the genus Betula, and the latter of which is in the genus Quercus. The upper limit of MDB with the genus Fagus as dominant species is only distributed in the mountains towards the south of the Qinling mountain ranges. (5) The warmth index (WI) at the upper limit of deciduous broad-leaved forest on the mountains with climatic treeline is about 60 °C month, which is lower than that at the northernmost boundary of the latitudinal distributed deciduous broad-leaved forest (90 °C month). Our study revealed the spatial pattern and geographical drivers of the upper limit of MDB, improved our understanding of differences in MDB vegetation among different mountain ranges, and provided climatic correlates for predicting the dynamics of the upper limit of MDB under climate change.

Highlights

We found that the upper limits of montane deciduous broad-leaved forest (MDB) on the mountains without climatic treeline in in both the temperate and subtropical climate zones were influenced by peak elevation, both the temperate and subtropical climate zones were influenced by peak elevation, and and the coefficient of determination respectively
The current study showed that the upper limit of MDB on the temperate mountains without climatic treeline was negatively correlated with precipitation seasonality (PS), while that on the subtropical mountains was positively correlated with PS
The highest upper limit of MDB occurs on the Taibai peak of the Qinling mountain ranges, with an elevation of 2800 m, and the warmth index (WI) at the highest upper limit of MDB is as low as 60 ◦ C month

Summary

Introduction

The altitudinal distribution of deciduous broad-leaved forests on mountains has rarely been explored [4,5,6]. The monsoon region in the Eastern China has developed many montane deciduous broad-leaved forest (MDB) belts due to its significant climatic gradient, numerous mountains, and complex topography [7,8]. It has become an ideal area for exploring the pattern and drivers of the upper limit of MDB, since the species richness of MDB in the east monsoon realm of China is higher than that in America and Europe [1,9]

Objectives

Discussion

Conclusion