Alatalo Juha M, Little Chelsea J, Jägerbrand Annika K, Molau Ulf
Department of Ecology and Genetics, Uppsala University, Campus Gotland, 621 67 Visby, Sweden.
VTI, Swedish National Road and Transport Research Institute, Box 55685, 102 15 Stockholm, Sweden.
Sci Rep. 2015 May 7;5:10197. doi: 10.1038/srep10197.
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.
预计全球变化将导致北极苔原地区物种分布和生物多样性的变化。我们对一个营养物质匮乏且物种稀少的高山/北极石南群落进行了为期七年的因子增温及养分操控实验。对照样地中维管植物的丰度增加了31%。在养分处理以及养分与增温相结合的处理中，植被覆盖度也出现了显著变化，落叶灌木和常绿灌木减少，草本植物在这些样地中过度生长。莎草的丰度最初随着养分添加显著增加，随后下降，在养分与增温相结合的处理中降至初始值以下。添加养分导致优势等级从落叶灌木转变为草本植物。我们发现，增温处理使维管植物的多样性和均匀度显著下降，增温与添加养分相结合的处理使多样性降低，而添加养分则导致物种丰富度下降。这些结果提供了一些实验证据，表明物种稀少、多样性低的植物群落可能比初始多样性较高的群落更容易遭受遭受物种多样性丧失。因此，预计养分沉降和气候变暖的加剧可能会对本就贫瘠的环境中的生态系统过程、功能和服务产生负面影响，因为物种多样性会丧失。
