Role of small wetlands on the regime shift of ecological network in a wetlandscape

Abstract

Globally, wetlands in many places have been at risk by natural and anthropogenic threats including climate change and land use and land cover change. Because of their significant contribution to providing various ecosystem services, understanding the vulnerability to various threats and the effects of their loss on various scales and aspects is an imminent issue for wetland conservation. On a landscape scale, these wetlands can be distributed in a variety of forms (e.g., by size, bathymetry, geology, etc.) and interconnected by dispersal of inhabiting species. Here, we use the network modeling approach associated with wetland hydrology to analyze potential shifts in an ecological network caused by hydro-climatic and anthropogenic forcings. We focus on the role of small wetlands which are often easily ignored in assessing landscape function because of their minor occupancy in an overall area. Specifically, by manipulating the hydrological status of the small wetlands, an area of which only contributes 0.82%, we observed the degrading effects on the characteristics (mean degree and network efficiency) of resulting ecological networks. Our results suggest that wetland size does not necessarily correlate with network centralities, and the loss of small wetlands acting as high centrality nodes induce a critical regime shift in network structure and function. Although hypothetically tested, because of their high sensitivity to hydro-climatic conditions and vulnerability to land use and land change along with climate change effects, the persisting functional loss of small wetlands is highly expected which eventually leads to trapping in the undesirable state of an ecological network. Our study is expected to provide a framework to evaluate the importance of small wetlands that can be easily ignored from an area-based point of view in a landscape.