Impact of Global Warming on Mountain and Polar Ecosystems: What Have Artificial Warming Experiments Told?

Abstract

 Artificial warming experiments on alpine, subalpine, boreal, and subboreal ecosystems are reviewed to understand the impacts of global warming on the ecosystems of these regions. Among various warming methods, passive warming methods, especially open top chambers (OTC), have mainly been used in these outland regions due to limited electricity supplies and need for regular maintenance. Many researchers have studied the effects of experimental warming on variable ecological variables. The authors classify those variables into: (1) phenology, (2) plant growth, (3) plant reproduction, (4) plant community and diversity, (5) net primary production, and (6) biogeochemical cycle. After reviewing the effects on these variables observed with warming experiments, the following are discussed: i) differences in response speed between ecological variables, ii) local environment-dependence of warming effects, and iii) possible solutions to undesirable side-effects of OTC, such as snow deposition change, followed by future challenges for warming experiments in the ecosystems of these regions.