Refocusing Habitat Fragmentation Research Using Lessons from the Last Decade

Abstract

Habitat alteration is broadly thought to be a primary threat to global biodiversity and has become the dominant topic for conservation biology. However, it is a complex process typically resulting in concurrent loss and increased fragmentation of remaining habitat. Researchers traditionally combined both these processes under a single umbrella term, 'habitat fragmentation', but this practice has ignited a contentious debate since the early 2000s. Over a decade has now past since the emergence of arguments that conservation insight could only be gained by considering loss and fragmentation as independent processes. We examine habitat fragmentation research since these calls for change, and assess the degree to which testing the independent effects of habitat loss and configuration on biodiversity has occurred in the scientific literature. We have found that only modest progress has been made toward this goal (i.e., 18 % of studies) and the majority of researchers continue to treat habitat loss and fragmentation as a single indistinguishable process. We argue that use of consistent definitions and approaches to uncovering specific fragmentation effects is particularly relevant in an era of accelerated human encroachment on natural habitats. Rigorous science on the response by biodiversity to the independent effects of habitat loss and fragmentation provides policy makers with the opportunity to optimize conservation planning efforts. We provide guidelines for how sampling designs and analyses can overcome existing challenges and researchers can search for generality in responses of biodiversity to habitat fragmentation.

Does forest fragmentation cause an increase in forest temperature?

“…1). Additional studies using adequate sampling designs and analyses (see Hadley and Betts 2016) are needed to better Fig. 1).…”

“…Also, the idea that this local-scale gradient scales up to an effect of forest fragmentation on temperature is uncertain and needs to be explicitly evaluated using a landscape approach (McGarigal and Cushman 2002;Hadley and Betts 2016). Also, the idea that this local-scale gradient scales up to an effect of forest fragmentation on temperature is uncertain and needs to be explicitly evaluated using a landscape approach (McGarigal and Cushman 2002;Hadley and Betts 2016).…”

“…Finally, we discuss whether this local gradient can be scaled up to make landscape-scale inferences, particularly considering the two main components of the fragmentation process: forest loss and forest 'division' into small patches (Fahrig 2003(Fahrig , 2017Hadley and Betts 2016;Fig. To assess if such local gradients depend on forest type and matrix composition, we tested for differences in edge-interior temperature gradients among forest types surrounded by different matrices.…”

Tropical Forest Fragmentation Limits Movements, but Not Occurrence of a Generalist Pollinator Species

“…We captured 20 individuals (8 male, 12 female) at forest fragments chosen according to a stratified random sampling design to represent a gradient in patch size (1.47–800 ha) and forest amount (16–78%) within a 1-km buffer from the focal patch (sensu [27]). By randomly sampling within four categories (small patches in landscapes with low amounts of forest, small patches in landscapes with high amounts of forest, large patches in landscapes with low amounts of forest and large patches with high amounts of forest) we were able to insure the full variation was represented.…”

Effects of forest fragmentation on biomass in tropical forests

“…Our protocol also enables examination of the influence of landscape configuration, by applying a random stratified sampling design ( Fig. 2.2B) and/or by statistically controlling collinearity between habitat amount and configuration (see Hadley & Betts, 2016).…”