Date Published: September 11, 2019
Publisher: Public Library of Science
Author(s): Miki Nomura, Ralf Ohlemüller, William G. Lee, Kelvin M. Lloyd, Barbara J. Anderson, Tina Heger.
Land cover change is a key component of anthropogenic global environmental change, contributing to changes in environmental conditions of habitats. Deforestation is globally the most widespread and anthropogenically driven land cover change leading to conversion from closed forest to open non-forest habitat. This study investigates the relative roles of geographic features, characteristics of species climatic niche and species traits in determining the ability of open-habitat plant species to take advantage of recently opened habitats. We use current occurrence records of 18 herbaceous, predominantly open-habitat species of the genus Acaena (Rosaceae) to determine their prevalence in recently opened habitat. We tested correlation of species prevalence in anthropogenically opened habitat with (i) geographic features of the spatial distribution of open habitat, (ii) characteristics of species climatic niche, and (iii) species traits related to dispersal. While primary open habitat (naturally open) was characterised by cold climates, secondary open habitat (naturally closed but anthropogenically opened) is characterised by warmer and wetter conditions. We found high levels of variation in the species prevalence in secondary open habitat indicating species differences in their ability to colonise newly opened habitat. For the species investigated, geographical features of habitat and climatic niche factors showed generally stronger relationships with species prevalence in secondary open habitat than functional traits. Therefore, for small herbaceous species, geographical features of habitat and environmental factors appear to be more important than species functional traits for facilitating expansion into secondary open habitats. Our results suggested that the land cover change might have triggered the shifts of factors controlling open-habitat plant distributions from the competition with forest trees to current environmental constraints.
The global land surface has been substantially modified by human activity. In the last two decades alone, c. one-tenth (3.3 million square km) of global wilderness areas was lost . As the original (or natural) vegetation and physical properties of an area are modified, the available habitat to species and the environmental conditions will change and affect which species and ecosystems are found in that area . This, in turn, will alter the biodiversity and functional composition of ecosystems [3–5]. Deforestation is a typical example of anthropogenic land cover change and, at the most basic level, results in a change from closed forest habitat to more open habitat, i.e., non-forest habitat, usually scrubland or grassland. Deforestation occurred in many parts of the world following human settlement (e.g., North America , Europe  and New Zealand ) and is ongoing; 2.3 million square kilometres forest was lost globally between 2000 and 2012 . Species distributions are strongly dependent on the environmental conditions that make up habitat, and therefore, species are susceptible to land cover change [10–12]. Understanding how species respond to such structural habitat change is important for predicting how ongoing anthropogenic land cover change may influence future species assemblages. Here, we investigate the relative contribution of landscape structure, species climatic niches and species functional traits to plant species’ expansion into recently opened habitats.
We investigated the climate conditions of pre-human and current open habitat and the prevalence of species from an open-habitat genus (Acaena) in secondary, i.e., recently opened habitat. We quantified the relative importance of three sets of factors–geographic landscape features, species’ climatic niches and the species’ dispersal traits for the ability of species to utilise secondary open habitat. Our main findings are; 1) open habitat was absent from warmer regions across New Zealand in pre-human times but it is available in these climates now; 2) open habitat is now available to a much larger extent in wetter regions than it was in pre-human times; 3) Secondary open habitat is generally located in warmer regions than primary open habitat; 4) Geographical features of species habitat and climatic niche factors showed stronger relationships with the species’ prevalence in secondary open habitat than functional traits associated with dispersal.
Land cover change is a key component of global environmental change driving the redistribution of species as a consequence of human activity. Change from closed forest to open habitat is a typical feature of anthropogenic environmental change providing new and more area suitable for open-habitat species. Habitats opened up by recent anthropogenic activity are characterised by warmer climatic conditions than habitats that were naturally open. This reflects the globally ubiquitous pattern of high deforestation rates in areas more easily accessible and more suitable for agriculture. Anthropogenic activity has opened new parts of the available climate space for open-habitat species. We found that overall geographical and environmental factors were more important than species functional traits for potentially facilitating expansion into secondary habitats. Our results suggested that land cover change might have triggered the shifts of factors controlling open-habitat plant distributions from the competition with forest trees to current environmental constraints.