Struggling to maintain native plant diversity in a peri-urban reserve surrounded by a highly anthropogenic matrix

Abstract

High human density and land use intensity often coincide with biodiversity hotspots making peri-urban reserves a keystone for conserving natural remnants in a highly anthropogenic matrix. Particularly, intense propagule pressure by alien plant species can pose a threat to native biodiversity. However, little is known about the factors that determine invasibility and the role of roads and other human disturbances for such small protected areas. Within a peri-urban reserve close to the city of Concepción, south-central Chile, we investigated the influence of different site and landscape characteristics on the richness of native and alien plant species across different habitat (ruderal, road and forest sites) and forest types (native and alien dominated forests). Compared to other protected areas, alien species were frequently found in this reserve indicating the importance of urban areas as source for alien species. Aliens concentrate around disturbed ruderal and road sites, facilitating their spread into the reserve. Natural forest areas are less invaded until now. Within forests alien plant species richness was, however, positively associated to the proximity to disturbed landscapes. Forests dominated by alien tree species within the reserve are not the source for alien species within natural forests, but they negatively affect native species richness by replacing adequate seed sources. In order to prevent a further spread of alien species into peri-urban reserves, large scale anthropogenic disturbances should be minimized, already invaded sites must be monitored and buffer-zones protecting reserves from surrounding land use activities should be established. Communicated by David Hawksworth. Electronic supplementary material The online version of this article (

Native Plant Diversity and Composition Across a Pinus radiata D.Don Plantation Landscape in South-Central Chile—The Impact of Plantation Age, Logging Roads and Alien Species

“…Furthermore, the concurrent high diversity and abundance of native species hints towards an interaction between native and alien species as stated by the biotic resistance hypothesis, which assumes that high local native richness provides low niche vacancy for aliens [76]. In the study area, high native and low alien species numbers along natural forest roads also reflect available seed sources in the vicinity that are decisive for native species diversity along roads in south-central Chile [63]. The continuous construction of new logging roads (personal observation) within the plantation landscape though, will further increase the pressure by alien species as it facilitates their spread across the landscape.…”

“…Herbicide application after harvesting, as seen in newly established young plantations may have already decreased typical forest species in medium-aged plantations (e.g., Crypotcarya alba, Nothofagus glauca, Lithraea caustica, Azara integrifolia; Table A2). To counteract a further decrease in native diversity, the maintenance of natural forests as seed sources within a plantation landscape [63,64] as well as the retention and propagation of native tree species within plantations instead of a complete removal of residual understory vegetation in course of site preparation can be important options to maintain and increase native biodiversity [36,62,65].…”

“…Relevant species are for example Agrostis capillaris, Rubus ulmifolius or Genista monspessulana that frequently occurred in mature plantations and at forest roads across the management cycle. R. ulmifolius and G. monspessulana are two prominent invasive alien species in central Chile, which show a high plasticity in their invaded range allowing an adaptation to novel environments such as light limited understories [63,74]. G. monspessulana was the only indicator species at mature plantation roadsides and also occurred at roadsides of the natural forest underlining the invasion potential in the long-term, as seen within natural forest fragments of different sizes in central Chile [75].…”

Inverted invasions: Native plants can frequently colonise urban and highly disturbed habitats

“…). Restoration ecology typically focuses on increasing the proportion of native species present in a habitat (Heinrichs & Pauchard ). However, methods of restoration often do not follow a clear structure in the selection of native species to be re‐planted or conserved in an area.…”

Road Expansion and the Fate of Africa's Tropical Forests

“…Road infrastructure development such as the proposed superhighway contribute to urbanization by attracting land speculators and settlers (Anderson, 2017;Haines, 2017) which in conjunction with the highway would have devastating impacts on ecosystem functioning and threaten biodiversity (Riley et al, 2005;Pauchard et al, 2006;McKinney, 2008;Heinrichs and Pauchard, 2015). For instance, the Cross River National Park harbors roughly 20% of the planet's butterfly species which if constructed the superhighway would threaten.…”