In any case, when the coal is gone, the landscape is left fundamentally altered: lowered by thousands of feet, with forests gone and valleys filled, a drastically simplified ecosystem.
To examine the potential importance of plant community shifts for ecosystem response we simulated a simplified ecosystem with 30 species of initially equal biomass.
Studies of simplified ecosystems with bacteria only or no more than three nonbacterial species seemed to bear out this idea, at least over the short term.
Worldwide, large areas of the tropics are transformed into simplified ecosystems characterised by altered tree species composition and diversity.
During the last century extensive reforestations were carried out throughout the region, but too often produced simplified ecosystems of fast growing species not always well suited to the environmental conditions.
Mathematical models describe the dynamics of simplified ecosystems having different characteristics: 1) different degrees of biotic turnover closure (from open to completely closed); 2) different numbers. of trophic links (including both "top-down", "bottom-up" regulation types); 3) different intensities of input - output flows of the limiting nutrient and its total amount in the system.
Agro-ecosystems are often simplified ecosystems, with few native species and a low complexity of trophic networks, which makes them highly susceptible to invasion by exotic pests or pathogens (Shea and Chesson 2002; Perrings 2011).
To sharpen the tools for modelling biotic interactions, it might be easier to begin with relatively simplified ecosystems where there are fewer interacting species to consider (e.g. arctic, alpine and islands).
Simplified ecosystems where there are relatively few interacting species and sometimes a wealth of existing ecosystem monitoring data (e.g. arctic, alpine or island habitats) offer settings where the development of modelling tools that account for biotic interactions may be less difficult than elsewhere.
We have developed this approach to model a simplified marine ecosystem subject to different fishing policies.
Germ-free and gnotobiotic mice, pig and zebrafish provide simplified model ecosystems that allow detailed evaluation of functions of colonized microbiota or microbes and the corresponding host responses in vivo, as well as their impact on various host physiologies.
