New Publication | Lags in the Response of Mountain Plant Communities to Climate Change
fern 3016113 640Published in Global Change Biology, this article reviews evidence for three types of lag in the responses of mountain plant communities to climate change, and develops a mechanistic community model to illustrate how species turnover in future communities might lag behind simple expectations based on species range shifts with unlimited dispersal. 

Rapid climatic changes and increasing human influence at high elevations around the world will have profound impacts on mountain biodiversity. However, forecasts from statistical models (e.g. species distribution models) rarely consider that plant community changes could substantially lag behind climatic changes, hindering our ability to make temporally realistic projections for the coming century.

Indeed, the magnitudes of lags, and the relative importance of the different factors giving rise to them, remain poorly understood. This article reviews evidence for three types of lag: 'dispersal lags' affecting plant species spread along elevational gradients, 'establishment lags' following their arrival in recipient communities, and the 'extinction lags' of resident species. Variation in lags is explained by variation among species in physiological and demographic responses, by effects of altered biotic interactions, and by aspects of the physical environment.

Of these, altered biotic interactions could contribute substantially to establishment and extinction lags, yet impacts of biotic interactions on range dynamics are poorly understood. A mechanistic community model is therefore developed to illustrate how species turnover in future communities might lag behind simple expectations based on species’ range shifts with unlimited dispersal. The model shows a combined contribution of altered biotic interactions and dispersal lags to plant community turnover along an elevational gradient following climate warming. The review and simulation support the view that accounting for disequilibrium range dynamics will be essential for realistic forecasts of patterns of biodiversity under climate change, with implications for the conservation of mountain species and the ecosystem functions they provide.

This article stemmed from a workshop organised by MIREN and co-funded by the MRI that took place in 2015.

Alexander JM, Chalmandrier L, Lenoir J, et al. Lags in the response of mountain plant communities to climate change. Global Change Biol. 2017;00:1–17.

The full article is available to download here.