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

Abstract

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 as a hierarchical system. Recently, the hierarchical ecosystem classifications in 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 tries to present the distinctive dissimilarity in each ecoregion and demonstrate the ecosystem responses linked to the hierarchical ecosystem structure and ecological function level. 1) In the Dry Domain, the warmer and wetter of Utah’s climate gave rise to Rocky Mountain subalpine conifer forests and Great Basin pinyon and juniper woodlands suitable for growing, which correspond to their Utah’s Climate life zone, and are affiliated with the Middle levels of ECL ( U7 up to U4). Conversely, in a warmer and drier of Utah’s climate, annual plant species and invaded species shifted and expanded at the lower levels of ECL (U10 up to U9). 2) In the Polar Domain, a warmer and wetter winter of Yokon climate influence 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 are typically appeared in the middle levels of ECL (Y8 up to Y5) and changed the carbon budget to a carbon sink (Y4 up to Y2). With a warmer and drier summer, Shrubification in Yukon is happening rapidly (Y6 up to Y5 ). Potentilla shrub and Salix shrub expand to the arctic tundra region. 3) In the Plateau Domain, an annual air temperature increases by 0.5o C/10y 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 (Q4 up to Q1). However, the precipitation showed no noticeable difference. The alpine tundra vegetation simulated by the Vegetation Dynamic Simulation Model (VDSM) integrated with scenarios of a global temperature increase of 1 to 3°C. It illustrated the vegetation biomass changes in the lower levels to middle levels of ECL (Q8 up to Q6 ) and the vegetation distribution dynamics had appeared in upper levels of ECL ( Q4 up to Q1) .