Interactions Between the Carbon and Nitrogen Cycles and the Role of Biodiversity: A Synopsis of a Study Along a North-South Transect Through Europe

Abstract

The NIPHYS/CANIF project of the EEC has provided the unique opportunity to examine forest ecosystem processes and diversity along a transect through Europe ranging from north Sweden to central Italy. The main objectives of this study were (I) to identify and quantify effects of N deposition on ecosystem processes, particularly the C cycle, by extending the range of observations across a deposition maximum in central Europe, and (2) to study feedback effects between ecosystem processes and biodiversity. The study resulted in a very comprehensive and consistent set of data on ecosystem processes over a 5-year period. However, in contrast to earlier large-scale ecosystem studies (IBP: Reichle 1981; Acid Rain Programme: Last and Watling 1991), the samples were collected and data generated by the same scientists at all sites. This assured comparisons of results on a broad geographic scale. In addition, key parameters were assessed by different methods, and integrating parameters were collected for different processes, in order to test and verify predictions made at higher and lower scales, ranging from physiological responses to ecosystem level processes.In the following we attempt to reassess the data presented in detail in the preceding chapters and seek for an integrated analysis that addresses the following general questions:• What regulates the C and N fluxes in forest ecosystems? • Are there thresholds and non linear responses?• What are net ecosystem productivity (NEP) and net biome productivity (NBP) in managed systems and can they be inferred from process studies? • What role does biodiversity play in ecosystem functioning? Change of Ecosystem Processes Along the European TransectThe study of a transect through Europe was confronted with a range of intrinsic problems, one of which relates to the weather pattern. If a high-pressure cell resulted in dry and hot weather in Scandinavia, very wet conditions are found in southern Europe, and vice versa. Thus, it was difficult to collect data under conditions of comparable water status along such a transect in a single year. Even though the project lasted 5 years, we were not able to study the effects of the interannual variability of key parameters. The changing weather pattern, however, gave confidence that we are dealing with general (long-term) patterns in this analysis. Another problem arises

Modelling soil carbon sequestration of intensively monitored forest plots in Europe by three different approaches

“…Thus, in the long term the soil is the ultimate sink or source of CO 2 for these ecosystems. Current hypotheses suggest that increased N deposition causes an increased rate of soil organic matter accumulation at least in two ways due to an increased leaf/needle biomass and litter production (Schulze et al, 2000) and a reduced decomposition of organic matter (Berg and Matzner, 1997;Harrison et al, 2000). Bragazza et al (2006), however, found higher decomposition rates in recently formed peat samples under higher atmospheric N supplies.…”

Respiration of wood ant nest material affected by material and forest stand characteristics

“…However, since the availability of carbon is very important for the respiration of organisms (Schulze et al 2000), we calculated the respiration per g C and…”

Comparison of carbon-stock changes, eddy-covariance carbon fluxes and model estimates in coastal Douglas-fir stands in British Columbia

“…Comparisons between EC tower measurements of ΣNEP and inventory plot measurements of ΔC stocks have been completed at a number of sites globally (Schulze et al 2000;Granier et al 2000;Law et al 2001;Barford et al 2001;Ehman et al 2002;Curtis et al 2002;Miller et al 2004;Black et al 2005;Gough et al 2008;Kominami et al 2008;Yashiro et al 2010;Gielen et al 2013;Babst et al 2014), and at two sites of the Canadian Carbon Program (CCP), Boreal Ecosystems Research and Monitoring Sites (BERMS) station, located in the boreal forest of northern Saskatchewan (Theede 2007). Over a ten-year interval (1994 -2004), Theede (2007) found a convergence of 15.6 ± 4.0 MgC ha −1 10 −1 years (inventory plots) and 18.2 ± 8.09 MgC ha −1 10 −1 years (EC tower) at the Old Aspen site and 5.8 ± 2.0 MgC ha −1 10 −1 years (inventory plots) and 6.9 ± 1.6 MgC ha −1 10 −1 years (EC tower) at the Old Jack Pine site.…”