Simulating plant invasion dynamics in mountain ecosystems under global change scenarios

Abstract

Across the globe, invasive alien species cause severe environmental changes, altering species composition and ecosystem functions. So far, mountain areas have mostly been spared from large-scale invasions. However, climate change, land-use abandonment, the development of tourism and the increasing ornamental trade will weaken the barriers to invasions in these systems. Understanding how alien species will react and how native communities will influence their success is thus of prime importance in a management perspective. Here, we used a spatially and temporally explicit simulation model to forecast invasion risks in a protected mountain area in the French Alps under future conditions. We combined scenarios of climate change, land-use abandonment and tourism-linked increases in propagule pressure to test if the spread of alien species in the region will increase in the future. We modelled already naturalized alien species and new ornamental plants, accounting for interactions among global change components, and also competition with the native vegetation. Our results show that propagule pressure and climate change will interact to increase overall species richness of both naturalized aliens and new ornamentals, as well as their upper elevational limits and regional range-sizes. Under climate change, woody aliens are predicted to more than double in range-size and herbaceous species to occupy up to 20% of the park area. In contrast, land-use abandonment will open new invasion opportunities for woody aliens, but decrease invasion probability | MATERIALS AND METHODS | Study areaWe focused on a protected mountain area in the French Alps (Ecrins National Park-ENP), which covers 270,000 ha and is characterized by large environmental and altitudinal gradients (650-4,100 m a.s.l.), with lower altitudes mostly at the peripheries of the park (Fig. S1).The ENP is located at the crossroads of temperate and Mediterranean climates and harbours ca. 2,000 vascular plant species, with so far only very few occurrences of alien species. Currently, twothirds of the park consist of open habitats, managed mostly through traditional agro-pastoral practices such as extensive grazing (80%) and/or mowing (25%), while forests cover ca. 25% of the area. The department Hautes-Alpes (where the ENP is located) is currently the third least populated in France, but since 2006 its population has increased by ca. 1.2% each year, more than twice the national average (Insee, 2014), supporting more than 360,000 tourist beds.Within the department, the ENP is in itself a tourist destination, supported by a network of 740 km of mountain trails and more than 30 mountain huts. | Hybrid simulation modelWe used the spatially explicit hybrid model FATE-HD to simulate spatio-temporal dynamics of resident vegetation and plant invasions under different global change scenarios Boulangeat, Georges, Dentant, et al., 2014). FATE-HD combines species distribution models (SDMs) with process-based modelling to simulate population dynamics (dispersal, germinat...

Geographical and temporal variation of multiple paternity in invasive mosquitofish (Gambusia holbrooki, Gambusia affinis)

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European ornamental garden flora as an invasion debt under climate change

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Functional traits modulate the response of alien plants along abiotic and biotic gradients

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