Dynamic Patterns of the Vertical Distribution of Vegetation in Heihe River Basin since the 1980s

Zemeng Fan

doi:10.3390/f12111496

Abstract

The vertical distribution of vegetation in Heihe River Basin has presented a significant dynamic change in the different elevation zones since the 1980s. To explore the dynamic patterns of vegetation types located in the different elevation zones of Heihe River Basin, this study collected 440 field sampling datapoints of vegetation types, remote sensing images, climatic observation data, and DEM and preprocessed them. On the basis of the vegetation distribution and the terrain characteristics of Heihe River Basin, this study classified the vertical distribution of vegetation in Heihe River Basin into six vegetation zones, namely, the oasis farmland and desert zone, desert-steppe zone, dry scrub-steppe zone, mountain forest-steppe zone, subalpine scrub-meadow zone, and alpine cold desert-meadow zone. Moreover, the mean annual biotemperature (MAB) and total annual average precipitation (TAP) were used to analyze the relationship between vegetation change and climate change in the different elevation zones. The results show that the change rate of vegetation was up to 25.75% in Heihe River Basin. The area of vegetation that changed in the oasis farmland and desert zone was the largest (7224 km2), and the rate of vegetation that changed in the mountain forest-steppe zone was up to 56.93%. The mean annual biotemperature (MAB) and total annual average precipitation (TAP) in the six elevation zones showed an increasing trend, in which the increased rate of TAP presented a downward trend with the increase of elevation, and that of MAB showed a continuous upward trend with the increase of elevation. The change rate of vegetation was generally higher than that of MAB and TAP in the low and middle vegetation zones. The influence intensity of human activities on vegetation change in the lower and middle elevation zones of Heihe River Basin was greater than that in the high elevation zone between the 1980s and the 2010s. MAB is the major impact factor to vegetation change in the alpine cold zone of Heihe River Basin.

Highlights

The plant community is the product of the interaction between plants and their ambient environment, which is manifested in the adaptability and feedback of vegetation to changes in environmental elements [1,2,3]
In order to explicate the change trend of mean annual biotemperature (MAB) and total annual average precipitation (TAP) in the different elevation zones of Heihe River Basin, this study developed a spatial change index of climate element to calculate the average value of MAB and TAP change from the 1980s (t0 ) to 2010s (t1 ) in the six elevation zones, which this study used to discuss the relationship between vegetation change and climate
The largest increased area of vegetation type is cultivated vegetation that was increased by 684.85 km2 per decade, and the second is mountain coniferous forest that was increased by 360.17 km2 per decade

Summary

Introduction

The plant community is the product of the interaction between plants and their ambient environment, which is manifested in the adaptability and feedback of vegetation to changes in environmental elements [1,2,3]. A large number of studies [7,8] have been efforts to establish the relationship between vegetation and climate by considering biophysical variables such as sunshine duration, ppt, slope, and Kira’s warmth index. These studies mainly focus on analyzing the change of vegetation coverage index (e.g., NDVI) [9], or discussing the response of vegetation change to climate from a horizontal perspective [10], lacking explication from a vertical perspective. Temperature and precipitation are the most important climatic elements, and their spatiotemporal changes will directly affect the spatial distribution and change of vegetation [15]. Under the impacts of climate change and human activities, the ecological environment of Heihe River Basin has shown a series of degradation phenomena. A large number of observations and statistical studies have been made in Heihe River

Methods

Results

Discussion

Conclusion