Quantifying the Relative Importance of Climate Change and Human Activities on Selected Wetland Ecosystems in China

Yongcai Dang,Haibo Du,Michael Sunde,Hongshi He,Dandan Zhao

doi:10.3390/su12030912

Abstract

Climate change and human activities are important factors driving changes in wetland ecosystems. It is therefore crucial to quantitatively characterize the relative importance of these stressors in wetlands. Previous such analyses have generally not distinguished between wetland types, or have focused on individual wetland types. In this study, three representative wetland areas of the upper, middle and lower reaches of the Heilongjiang River Basin (HRB) were selected as the study area. An object-based classification was used with Landsat TM data to extract the spatial distribution of wetland in 1990, 2000 and 2010. We then quantified the relative importance of climate change and human activities on the wetlands by using the R package “relaimpo” package. The results indicated that: (1) the effects of human activities on wetland changes were greater (contribution rate of 63.57%) than climate change in the HRB. Specifically, there were differences in the relative importance of climate change and human activities for wetlands in different regions. Wetlands of the upper reaches were more affected by climate change, while wetlands in the middle and lower reaches were more affected by human activities; (2) climate change had a greater impact (contribution rate of 65.72%) on low intensity wetland loss, while human activities had a greater impact on moderate and severe intensity wetland loss, with respective contribution rates of 57.22% and 70.35%; (3) climate change had a larger effect on the shrub and forested wetland changes, with respective contribution rates of 58.33% and 52.58%. However, human activities had a larger effect on herbaceous wetland changes, with a contribution rate of 72.28%. Our study provides a useful framework for wetland assessment and management, and could be a useful tool for developing wetland utilization and protection approaches, particularly in sensitive environments in mid- and high-latitude areas.

Highlights

The wetland ecosystems of the mid- and high-latitudes account for about 64% of the naturally occurring wetlands worldwide [1], and play an important role in flood protection, streamflow maintenance, biodiversity and human health [2,3]
The results indicated that climate change had a relatively larger impact (65.72%) on wetland loss categorized as mild (Figure 7b,c), while moderate and severe wetland losses were influenced by human activities, with contribution rates of 57.22% and 70.35% in the Heilongjiang River Basin (HRB), respectively
The results showed that human activities played a larger role in herbaceous wetland changes, whereas climate change had a larger impact on the shrub and forested wetland areas, with respective contribution rates of 58.33% and 52.58% in the HRB (Figure 8a)

Summary

Introduction

The wetland ecosystems of the mid- and high-latitudes account for about 64% of the naturally occurring wetlands worldwide [1], and play an important role in flood protection, streamflow maintenance, biodiversity and human health [2,3]. Approximately 87% of global wetlands have been lost since the 18th century [4] and wetland loss has been severe in mid-high latitude regions and continues to be threatened [1]. Climate change has affected wetlands’ hydrological processes by altering the ratio of precipitation and evapotranspiration [9], as well as indirectly affected wetlands through changes to wetland vegetation [10] and the biogeochemical cycle [11,12]. Wetland ecosystems of the mid-high latitudes are exceptionally vulnerable to such climatic and anthropogenic changes [1]

Objectives

Methods

Results

Discussion

Conclusion