Regional Ecological Risk Assessment of Wetlands in the Sanjiang Plain with Respect to Human Disturbance

Hui Wang,Kaishan Song,Changchun Song

doi:10.3390/su12051974

Abstract

Characterization of the intensity of regional human disturbances on wetlands is an important scientific issue. In this study, the pole-axis system (involving multi-level central places and roads) was recognized as a proxy of direct risk to wetlands stemming from human activities at the regional or watershed scale. In this respect, the pole-axis system and central place theory were adopted to analyze the spatial agglomeration characteristics of regional human activities. Soil erosion and non-point source (NPS) pollution, indicating the indirect effect of human activities on wetlands, were also considered. Based on these human disturbance proxies, which are considered regional risk sources to wetlands, incorporated with another two indicators of regional environment, i.e., vulnerability and ecological capital indexes, the regional ecological risk assessment (RERA) framework of wetlands was finally established. Using this wetland RERA framework, the spatial heterogeneity of risk grades within the Naoli River Basin, a typical concentrated wetland region in the Sanjiang Plain, was analyzed. The results showed that (1) high- and very high-risk source intensity areas displayed a ring-shape distribution pattern, which reflected the influence of the regional pole-axis system; (2) owing to their high ecological capital value per unit area and vulnerability level, the wetlands had the highest risk grade, as did central places (i.e., those areas where county seats and administration bureaus of farms were located). In terms of proportion, the low-, medium-, high-, and very high-risk areas accounted for 72.0%, 16.8%, 10.1%, and 1.1% of the study area, respectively. The identification and classification of risk sources to wetlands that are related to human activity at the watershed scale could provide clear perspectives in order to reduce severe risk sources to these areas, especially those Ramsor Convention-appointed sites of international importance. Moreover, the assessment framework used in this paper will provide a helpful reference for related research in the future. Finally, the new management guidelines proposed in this paper will be beneficial for lowering the ecological risk level of wetlands at the watershed or regional scale for the Sanjiang Plain or other wetland-concentrated regions.

Highlights

With the “zero-risk environmental management” concept having been proven too rigid, since the 1980s, ecological risk management (ERM) has become increasingly popular, as it accepts certain degrees of environmental risk [1,2,3,4]
A number of methodologies have been developed in the regional ecological risk assessment (ERA) (RERA) field [8], such as the “Three-Step Framework” formulated by the United States Environmental Protection Agency [6,9], the Relative Risk Model (RRM) by Landis and Wiegers [10], the Procedure for Ecological Tiered Assessment of Risk (PETAR) by Moraes et al [11], and the wetland RERA method by Xu et al [3]
The wetland RERA method is a useful framework for wetland ecological risk assessment at the regional scale, incorporating the merits of other methods such as the normalization of multi-risk source-receptor factors of RRM, the grading of PETAR, and the analysis process division of the “Three-Step Framework” [3,4]

Summary

Introduction

With the “zero-risk environmental management” concept having been proven too rigid, since the 1980s, ecological risk management (ERM) has become increasingly popular, as it accepts certain degrees of environmental risk [1,2,3,4]. With the development of ERM, ecological risk assessment (ERA), which provides a scientific foundation for ERM so that eco-environmental damage can be minimized, has become the focus of related research [5]. The RERA is one branch of general ERA, considering the co-occurrence of both risk sources and risk receptors, and focuses on spatial heterogeneity analysis of ecological risk at the regional scale [3]. The wetland RERA method is a useful framework for wetland ecological risk assessment at the regional scale, incorporating the merits of other methods such as the normalization of multi-risk source-receptor factors of RRM, the grading of PETAR, and the analysis process division of the “Three-Step Framework” [3,4]. The RERA plays an important role in both theoretical support and practical guidance for regional sustainable development [12]

Methods

Results

Discussion

Conclusion