Carbon and nitrogen balances for six shrublands across Europe

Abstract

[1] Shrublands constitute significant and important parts of European landscapes providing a large number of important ecosystem services. Biogeochemical cycles in these ecosystems have gained little attention relative to forests and grassland systems, but data on such cycles are required for developing and testing ecosystem models. As climate change progresses, the potential feedback from terrestrial ecosystems to the atmosphere through changes in carbon stocks, carbon sequestration, and general knowledge on biogeochemical cycles becomes increasingly important. Here we present carbon and nitrogen balances of six shrublands along a climatic gradient across the European continent. The aim of the study was to provide a basis for assessing the range and variability in carbon storage in European shrublands. Across the sites the net carbon storage in the systems ranged from 1,163 g C m À2 to 18,546 g C m À2 , and the systems ranged from being net sinks (126 g C m À2 a À1 ) to being net sources (À536 g C m À2 a À1 ) of carbon with the largest storage and sink of carbon at wet and cold climatic conditions. The soil carbon store dominates the carbon budget at all sites and in particular at the site with a cold and wet climate where soil C constitutes 95% of the total carbon in the ecosystem. Respiration of carbon from the soil organic matter pool dominated the carbon loss at all sites while carbon loss from aboveground litter decomposition appeared less important. Total belowground carbon allocation was more than 5 times aboveground litterfall carbon which is significantly greater than the factor of 2 reported in a global analysis of forest data. Nitrogen storage was also dominated by the soil pools generally showing small losses except when atmospheric N input was high. The study shows that in the future a climate-driven land cover change between grasslands and shrublands in Europe will likely lead to increased ecosystem C where shrublands are promoted and less where grasses are promoted. However, it also emphasizes that if feedbacks on the global carbon cycle are to be predicted it is critically important to quantify and understand belowground carbon allocation and processes as well as soil carbon pools, particularly on wet organic soils, rather than plant functional change as the soil stores dominate the overall budget and fluxes of carbon.

Calluna vulgaris-dominated upland heathland sequesters more CO2 annually than grass-dominated upland heathland

“…These estimates are within the range of published C sequestration values, with similar shrub-dominated sites ranging from 0.3 to − 2.9 t C ha −1 yr − 1 (Larsen et al, 2007;Beier et al, 2009;Kiely et al, 2009) and upland graminoid dominated sites ranging from −0.1 to −6.4 t C ha −1 yr −1 (Fitter et al, 1997;Flanagan and Johnson, 2005;Allard et al, 2007;Soussana et al, 2007;Kiely et al, 2009).…”

Carbon Storage in Cold Temperate Ecosystems in Southern Patagonia, Argentina

“…In this ecosystem, the C root/shoot ratio ranged between 0.17 and 0. budget at all J. tridens shrubland sites and ranged from 70 (for 10-20% shrub cover) to 160 Mg C ha -1 (for 60-70% shrub cover) where soil C constitutes more than 90% of the total carbon in the ecosystem. This is consistent with Beier et al (2009) who reported that soil C constitutes 95% of the total carbon in six shrublands along a climatic gradient across the European continent.…”

Designing a regional nitrogen cycle module of grassland for the IAP-N model

“…In addition to the management related import and export, gaseous exchange in many different forms (e.g., NO, NO 2 , HNO 3 , N 2 O, NH 3 , and N 2 ), as well as input by rain and leaching of N-compounds with the soil water, had been measured. Beier et al (2009) presented N balances of six shrublands along a climatic gradient across the European continent. Nitrogen storage was also dominated by the soil pools, generally showing small losses except when atmospheric N input was high.…”