The role of reserves and anthropogenic habitats for functional connectivity and resilience of ephemeral wetlands

Abstract

Abstract. Ecological reserves provide important wildlife habitat in many landscapes, and the functional connectivity of reserves and other suitable habitat patches is crucial for the persistence and resilience of spatially structured populations. To maintain or increase connectivity at spatial scales larger than individual patches, conservation actions may focus on creating and maintaining reserves and/or influencing management on non-reserves. Using a graph-theoretic approach, we assessed the functional connectivity and spatial distribution of wetlands in the Rainwater Basin of Nebraska, USA, an intensively cultivated agricultural matrix, at four assumed, but ecologically realistic, anuran dispersal distances. We compared connectivity in the current landscape to the historical landscape and putative future landscapes, and evaluated the importance of individual and aggregated reserve and non-reserve wetlands for maintaining connectivity. Connectivity was greatest in the historical landscape, where wetlands were also the most densely distributed. The construction of irrigation reuse pits for water storage has maintained connectivity in the current landscape by replacing destroyed wetlands, but these pits likely provide suboptimal habitat. Also, because there are fewer total wetlands (i.e., wetlands and irrigation reuse pits) in the current landscape than the historical landscape, and because the distribution of current wetlands is less clustered than that of historical wetlands, larger and longer dispersing, sometimes nonnative species may be favored over smaller, shorter dispersing species of conservation concern. Because of their relatively low number, wetland reserves do not affect connectivity as greatly as non-reserve wetlands or irrigation reuse pits; however, they likely provide the highest quality anuran habitat. To improve future levels of resilience in this wetland habitat network, management could focus on continuing to improve the conservation status of non-reserve wetlands, restoring wetlands at spatial scales that promote movements of shorter dispersing species, and further scrutinizing irrigation reuse pit removal by considering effects on functional connectivity for anurans, an emblematic and threatened group of organisms. However, broader conservation plans will need to give consideration to other wetland-dependent species, incorporate invasive species management, and address additional challenges arising from global change in social-ecological systems like the Rainwater Basin.

Adaptive invasive species distribution models: a framework for modeling incipient invasions

“…(Mistro et al 2012), and movement among suitable habitat patches (Uden et al 2014). One disadvantage of mechanistic models is the time and effort required to develop them; however, this may be a worthwhile tradeoff in circumstances that require in-depth understanding of the mechanisms of survival and spread, such as under novel climatic conditions (Kearney 2006;Kearney and Porter 2009).…”

Transdisciplinary Application of Cross-Scale Resilience

“…The adaptive cycle provides a conceptual framework for understanding the dynamics of a system that moves through cycles of accumulation, collapse, and renewal, which were already a central focus in archaeological research. Much of this work, however, is largely descriptive and fails to objectively identify underlying scales of deep structure that might drive system dynamics over time [31]. Rather, it relies on human organizational levels and uses resilience theory and the adaptive cycle as an extended metaphor for explaining development and collapse dynamics in archaeological data [113,117].…”

“…The first, network theory, has uncovered rules of topological structure regarding the ways nodes are connected to each other using graph theory [22,28], and examined the extent to which different topologies are resilient to random or targeted node loss [29][30][31]. In ecosystems, nodes are frequently modelled as species, connected to each other in food webs that generate emergent properties of information storage (such as genetic material), material and energy flow, resilience, and adaptive capacity [22,[32][33][34].…”

Surface water network structure, landscape resistance to movement and flooding vital for maintaining ecological connectivity across Australia’s largest river basin

“…Studies modelling Euclidean distance between habitat patches (e.g., Pyke 2005;Fortuna et al 2006;Ribeiro et al 2011;Peterman et al 2013;Uden et al 2014) may misrepresent connectivity by ignoring how landscape conditions influence an organism's dispersal ability (Mazerolle and Desrochers 2005;Van Buskirk 2012;Pittman et al 2014). Studies have used least-cost path modelling based on resistance to movement surfaces to incorporate how the landscape matrix can influence amphibian movement (e.g., Compton et al 2007;Decout et al 2012), but these approaches rely on two potentially simplistic assumptions: that movement potential can be related to a single optimal path between habitats, and that an organism can select that path based on a complete knowledge of the landscape they are traversing (Fahrig 2007;McRae et al 2008;Pinto and Keitt 2009).…”