A Hierarchical Ecosystem Approach to Evaluate Global Warming Impacts in Three Global Ecoregions

Abstract

Yan Qing Zhang, Xing Min Zhou

Global warming has substantial effects on terrestrial ecosystems in the different ecoregions. A hierarchical ecosystem approach was conducted to analyze global warming influences with global warming impacts on the three distinct global ecoregions. The ecosystem classification of land (ECL) has been developed and integrated into a hierarchical system. Recently, the hierarchical ecosystem classifications in the 300 Dry Domain of the United States, 100 Polar Domain of Canada, and 500 Plateau Domain of China were demonstrated and explored in studying the environmental system changes and global warming impacts. This article presents the distinctive dissimilarity in each ecoregion and demonstrates the ecosystem responses linked to the hierarchical ecosystem structure and ecological function level.

1) In the Dry Domain, the warmer and wetter climate of Utah gave rise to Rocky Mountain subalpine conifer forests and Great Basin pinyon and juniper woodlands suitable for growth, which corresponds to Utah’s Climate life zone and is affiliated with the middle levels of ECL, scale ranging from U7 up to U4. Conversely, in a warmer and drier climate in Utah, annual plant species and invaded species shifted and expanded at the lower levels of ECL, scale ranging from U10 up to U9.

2) In the Polar Domain, a warmer and wetter winter of the Yukon climate influences the Spruce treeline moving northward and to higher elevations, as well as for the Arctic tundra and alpine tundra. Arboreal species grow fast to reach fructification. These typically appeared in the middle levels of ECL with ranging from Y8 up to Y5, and changed the carbon budget to a carbon sink, with a scale ranging from Y4 up to Y2. With a warmer and drier summer, shrubification in Yukon occurs rapidly, in a range from Y6 to Y5. Potentilla shrub and Salix shrub expand to the Arctic tundra region.

3) In the Plateau Domain, the annual air temperature Increased by 0.5o C/10 y over the last 45 years, and the temperature fluctuations have significantly affected the essential changes in the global energy balance and carbon budget in the upper levels of ECL, scale ranging from Q4 up to Q1. However, the precipitation showed no noticeable difference. The alpine tundra vegetation was simulated by the Vegetation Dynamic Simulation Model (VDSM) integrated with scenarios of a global temperature increase of 1 to 3°C. This illustrated the vegetation biomass changes in the lower levels to middle levels of ECL with ranging from Q8 up to Q6, and the vegetation distribution dynamics appeared in upper levels of ECL with ranging from Q4 up to Q1.

PDF