TERI Terrestrial Ecosystems Research Initiative   TERI Conceptual transect approach Europe is an extremely variegated continent in terms of climate, soil, vegetation and land-use. Given the occurring and expected changes, it is essential that the research be integrated into a Europe-wide picture. The conceptual transect approach provides this European dimension, as it permits (i) the integration of research along major environmental gradients most representative of European environmental conditions, (ii) the concentration of research on a relatively limited number of sites where different ecosystem types, largely characteristic of Europe, can be intensively studied and compared, and (iii), as a result of (i) and (ii), the extrapolation of results to the European scale. Specific transects will therefore be set up as part of TERI on which observational and experimental work will be carried out. When adequately selected and properly designed, transects are a major tool for global change research, and will help assessing changes at the European scale. Transects are not to be understood as straight geographical lines, but as bands displaying clear environmental variations and wide enough to incorporate most characteristic ecosystem types of Europe (Fig. 2). An essential element in transect studies is the execution of experiments at sites across the transects. The results from such experiments and the accompanying measurements describing the site conditions will be used to interpolate relationships between sites, extrapolate in space, and allow predictions concerning the future to be made. Fig. 2. Example of potential distribution of TERI transects along major European gradients of environmental change from boreal to mediterranean and from oceanic to continental conditions. Lines do not a priori determine the future location of TERI sites. The overall goal in the European transect approach is to test hypotheses concerning how existing physical and chemical climate and land-use affect the sinks and sources of carbon and nitrogen, the hydrological cycle, ecosystem structure and function. Experiments conducted at sites along transects can also yield information concerning the interactive effects of changes in land-use, climate and atmospheric composition on the biogeochemical cycles, biodiversity and dependent processes (including feedback effects). TERI should be conceived as a long-term endeavour. Many processes only affect ecological processes or can be perceived over long periods of time. These are (i) slow processes (plant succession, soil organic matter dynamics...), (ii) subtle processes often hidden by the variability of the determinants, (iii) highly variable processes rendering difficult the distinction of the trend (signal) from the noise (e.g. processes highly variable on the short term but with a slow dynamic pattern), (iv) cumulative processes or with a delayed response, (v) multifactorial or complex processes involving a number of determinants, species or interactive phenomena, and (vi) episodic or extreme event-driven processes (e.g. fire, storms, rinder pest...). Long-term ecological research will enable to better formulate and test ecological theories, adress global problems, and provide managers with pertinent elements of decision-taking (e.g. in the context of sustainable development). Under such a perspective, it is of primary importance that: be studied the direct, indirect, cumulative and feedback effects of the major determinants of ecosystem functioning; these determinants be simultaneously identified with respect to their synergetic or antagonistic effects; in natural or controlled experiments, gradients of pressures and changes be prefered to predetermined levels of the variable to study (identification of thresholds). Projects to be selected within TERI must have an obvious European dimension; the transect approach cannot be properly implemented at the local and national scale. As a result, projects selected within TERI will not duplicate national projects. However, synergy and coordination between national and European initiatives are strongly recommended in order to yield the maximum return of the committed resources at both levels. Sites along transects The implementation of the scheme will be conducted through experiments established along major environmental gradients primarily defined by temperature and rainfall patterns. These experiments will be carried out on sites where could be found ecosystems, agrosystems and land/freshwater interface systems most characteristic of Europe. A site should be of ecological significance for the research, the main requirement being for experiments which can generate results to be compared and integrated with results originating from other sites along the enviromental gradient. Processes should not be studied in isolation from each other, but in such a way that an integrated understanding on how ecosystems function will be reached. Therefore, a site study must encompass linkages between the research themes promoted by TERI: the overall approach will be ecosystemic, not thematic. Given the number of former and on-going studies on monospecific systems (forests or croplands), preference will be given to the study of multispecific systems, e.g. croplands as affected by weeds, pests or pathogens. Environment & Climate Homepage | Joint Actions - Environment & Climate / MAST | 08.02.2000