Vascular plant abundance and diversity in an alpine heath under observed and simulated global change.

Juha M Alatalo,Ulf Molau,Chelsea J Little,Annika K Jägerbrand

doi:10.1038/srep10197

Abstract

Global change is predicted to cause shifts in species distributions and biodiversity in arctic tundra. We applied factorial warming and nutrient manipulation to a nutrient and species poor alpine/arctic heath community for seven years. Vascular plant abundance in control plots increased by 31%. There were also notable changes in cover in the nutrient and combined nutrient and warming treatments, with deciduous and evergreen shrubs declining, grasses overgrowing these plots. Sedge abundance initially increased significantly with nutrient amendment and then declined, going below initial values in the combined nutrient and warming treatment. Nutrient addition resulted in a change in dominance hierarchy from deciduous shrubs to grasses. We found significant declines in vascular plant diversity and evenness in the warming treatment and a decline in diversity in the combined warming and nutrient addition treatment, while nutrient addition caused a decline in species richness. The results give some experimental support that species poor plant communities with low diversity may be more vulnerable to loss of species diversity than communities with higher initial diversity. The projected increase in nutrient deposition and warming may therefore have negative impacts on ecosystem processes, functioning and services due to loss of species diversity in an already impoverished environment.

Highlights

Distributed evenly across taxa or geography; in most cases the studies originate from Europe and North America[9]
We examine whether initial short-term responses of vascular plants in a sub-arctic alpine heath to a factorial warming and nutrient addition are consistent moving into the medium-term
We hypothesized that 1) dominance hierarchies would shift in response to experimental nutrient addition; and 2) species richness and diversity of vascular plants would increase in response to the nutrient addition and the combined warming and nutrient addition

Summary

Introduction

Distributed evenly across taxa or geography; in most cases the studies originate from Europe and North America[9]. We examine whether initial short-term responses of vascular plants in a sub-arctic alpine heath to a factorial warming and nutrient addition are consistent moving into the medium-term. Dry heath sites are characterized by lichens which often decrease with perturbations[28,31], while lichens constitute a less substantial portion of more moist communities Analysis of this site after three[28] and five years[33] of manipulation showed substantial changes to community structure; we ask whether these short-term responses to simulated global change are good predictors of longer-term responses in heaths. We hypothesized that 1) dominance hierarchies would shift in response to experimental nutrient addition; and 2) species richness and diversity of vascular plants would increase in response to the nutrient addition and the combined warming and nutrient addition

Methods

Results

Conclusion