Biodiversity response to rapid successive land cover conversions in human-dominated landscapes

Much of the world's formerly “intact” land cover has been modified by humans with major impacts on biodiversity. Extensive areas of already modified land are now being subjected to yet further land cover conversions. Indeed, in many places, land cover and land use are changing repeatedly and frequently. Here, we use ecological theory to develop a new conceptual framework with associated postulates about how biodiversity could respond to repeated and rapid changes in land cover (over timespans of years to decades). 

Our framework focuses on five drivers: (1) conversion completeness, (2) persistence of biological, chemical, and physical legacies from previous land cover type to a new kind of cover, (3) number of previous land cover conversions, (4) time elapsed since land cover change, and (5) levels of contrast between the previous and new land cover. We predicted that biodiversity responses to repeated conversions in human-generated land cover would be a function of the main effects of these five drivers, as well as complex interactions among them (e.g. each new land cover type may act as a filter for species assemblages and interact in complex spatio-temporal ways with the previous land cover). Biodiversity responses may therefore be species- and land cover type specific, and not be readily predictable from insights provided by studies of single landscape conversions from an intact to a human-dominated ecosystem. 

Ignoring the impacts of successive land cover conversions on biodiversity could lead to increased biodiversity loss with each land cover conversion. Therefore, impact assessments are needed each time a new land cover conversion is proposed. Policies and management actions need to focus on the maintenance and/or restoration of remnant vegetation and other kinds of natural features (like large trees and wetlands) with each land cover conversion.