Forecasted homogenization of high Arctic vegetation communities under climate change

Abstract

AbstractAimClimate change results in increasing temperature and modified precipitation regimes in the High Arctic. Models can help anticipate the consequences on future biotic dynamics, e.g. vegetation. In rugged terrain, forecasts should consider fine‐scale spatial variability in environmental conditions that are proximally linked to plant performance. Here, we forecasted Arctic plant community response to future climate change using high‐resolution environmental variables.LocationZackenberg in the High Arctic of Greenland.MethodsUsing a combination of remote‐sensing data and field measurements, we interpolated soil moisture and temperature at 1 m resolution together with spatial data on snow cover and solar radiation. We calibrated stacked species distribution models (S‐SDMs) with data from 200 vegetation plots. To explore the sensitivity of Arctic communities to climate change, we forecasted these models under simulated increases in temperature and changes (positive or negative) in snow cover and soil moisture, corresponding to more winter and/or summer precipitation and higher frequencies of summer droughts.ResultsS‐SDMs associated with high‐resolution environmental variables were able to reproduce the spatial variation in species richness and plant community structure along a mountain slope in Zackenberg. Model forecasts under climate change revealed that most species reacted to a combination of changes in soil moisture and temperature, and changes in these two variables resulted in an extensive restructuring of the distributions of species assemblages. In most scenarios, a gradual homogenization of communities was forecasted due to shrub expansion.Main conclusionsIncreasing temperatures and altered soil moisture were predicted to turn the currently highly heterogeneous tundra landscape at Zackenberg into homogenous dwarf‐shrub tundra. Such homogenization of vegetation communities may have profound ramifications for species, interaction webs, and ecosystem processes via modifications to the surface albedo, energy and water balance, as well as snow accumulation and permafrost.