Swiss Alps

Understanding the traits mediating species’ responses to climate change is a cornerstone for predicting future community composition and ecosystem function. Although species’ eco-physiological properties determine their response to environmental change, most trait-based studies focus on a small subset of easily measured morphological traits as proxies for physiology. This choice may limit our ability to predict the impacts of climate change on species’ demography, and obscure the underlying mechanisms. We conducted a transplantation experiment along a 1000-m elevation gradient in the Alps to quantify the degree to which changes in plant abundance due to climate warming were predicted by eco-physiological performance versus common morphological traits.

Forecasting the trajectories of species assemblages in response to ongoing climate change requires quantifying the time lags in the demographic and ecological processes through which climate impacts species’ abundances. Since experimental climate manipulations are typically abrupt, the observed species responses may not match their responses to gradual climate change. We addressed this problem by transplanting alpine grassland turfs to lower elevations, recording species’ demographic responses to climate and competition, and using these data to parameterise community dynamics models forced by scenarios of gradual climate change.

Climate warming is releasing carbon from soils around the world, constituting a positive climate feedback. Warming is also causing species to expand their ranges into new ecosystems. Yet, in most ecosystems, whether range expanding species will amplify or buffer expected soil carbon loss is unknown. Here, we used two whole-community transplant experiments and a follow-up glasshouse experiment to determine whether the establishment of herbaceous lowland plants in alpine ecosystems influences soil carbon content under warming.

As climate changes, species? ability to spatially track suitable climate depends on their spread velocity, a function of their population growth and dispersal capacity. When climate changes faster than species can spread, the climate experienced at species? expanding range edges may ameliorate as conditions become increasingly similar to those of the range core. When this boosts species? growth rates, their spread accelerates. Here, we use simulations of a spreading population with an annual life history to explore how climatic amelioration interacts with dispersal evolution and local adaptation to determine the dynamics of spread.

Phenological shifts, changes in the seasonal timing of life cycle events, are among the best documented responses of species to climate change. However, the consequences of these phenological shifts for population dynamics remain unclear. Population growth could be enhanced if species that advance their phenology benefit from longer growing seasons and gain a pre?emptive advantage in resource competition. However, it might also be reduced if phenological advances increase exposure to stresses, such as herbivores and, in colder climates, harsh abiotic conditions early in the growing season.