Raymundo, Maia, Caballes, Ciemon Frank, Mayfield, Margaret M., and Hock, Karlo (2022) Informed selection of corridors through network and graph analyses to enhance dispersal potential through an agricultural matrix. Landscape Ecology, 38. pp. 449-461.

PDF (Published Version) - Published Version Restricted to Repository staff only

 

1

Abstract

Context: Climate change is causing range shifts in the distribution of many species, but fragmentation and human-altered landscapes are preventing the movement of many of these affected species to more suitable environments. The establishment of corridors to enable dispersal are often costly and laborious and generally prioritize large or highly mobile animals and trees but are rarely considered for herbaceous species which often have associated native insect communities. Further, assessing the quality of habitats is not often considered in landscape connectivity modeling but is important to ensure that species of interest are not only able to move through a landscape but are able to survive as well. Here, we present a novel concept of using road verges as corridors to connect high quality habitats.

Objectives: Using a fragmented agricultural landscape in the southwest Western Australian wheatbelt as a case study, we aim to assess the current level of connectedness of remnant woodlands to support dispersal potential and propose an ecologically (corridors supporting herbaceous species) and economically (shortest links along already existing corridors) feasible way of connecting suitable remnants using road verges.

Methods: We assessed the landscape for the presence of native herbaceous plants in woodland remnants and along road verges as an ecological indicator of habitat suitability. We established a fixed maximum dispersal distance of 100 m based on existing literature in our models to evaluate the dispersal potential of herbaceous annual forbs. We then assessed remnants for habitat quality and level of connectedness across the landscape to come up with ‘importance scores’ for each remnant (or remnant importance). Using graph theory and network analyses, we identified the shortest possible paths to connect remnants of high importance.

Results: Our results show that the current level of fragmentation in the landscape is not able to support single dispersal events based on biologically realistic dispersal distances of 100 m. In addition, majority of the remnants were unlikely to support the herbaceous plants that we included in this study and, by proxy, other species with similar ecological requirements. This unsuitability is primarily due to soil type and high levels of residual phosphorus fertilizer. Roadside verges may be used to support recruitment of herbaceous plants in this system compared to abandoned agricultural fields as they are often already maintained by the local governments and have not been altered by agricultural development. Given this, the use of road verges as corridors should be considered for some species, particularly in cases where industrialized fields are not able to support native flora. Our results point to the need to consider alternative corridor options and to incorporate remnant importance in landscape connectivity studies in order to prioritize connecting remnants that can support both movement and survival of the target species. Assessing remnant importance also enables more efficient placements of corridors across an industrialized landscape particularly when resources may be lacking.

Conclusions: Evaluating the quality and connectedness of habitat fragments and determining the most efficient dispersal pathway using readily available software and analytical approaches are effective ways to strategically establish dispersal corridors for native plants. This study advances our understanding of how common features in heavily modified agricultural landscapes can be used to connect remaining suitable habitats and facilitate the dispersal and survival of herbaceous annual plants.This study advances our understanding of how common features in heavily modified agricultural landscapes can be used to connect remaining suitable habitats and facilitate the dispersal and survival of herbaceous annual plants.

Actions (Repository Staff Only)

Item Control Page