Berry Ecosystem carbon exchange in two terrestrial ecosystem mesocosms under changing atmospheric CO 2 concentrations
نویسندگان
چکیده
The ecosystem-level carbon uptake and respiration were measured under dierent CO2 concentrations in the tropical rainforest and the coastal desert of Biosphere 2, a large enclosed facility. When the mesocosms were sealed and subjected to step-wise changes in atmospheric CO2 between daily means of 450 and 900 lmol mol, net ecosystem exchange (NEE) of CO2 was derived using the diurnal changes in atmospheric CO2 concentrations. The step-wise CO2 treatment was eectively replicated as indicated by the high repeatability of NEE measurements under similar CO2 concentrations over a 12-week period. In the rainforest mesocosm, daily NEE was increased signi®cantly by the high CO2 treatments because of much higher enhancement of canopy CO2 assimilation relative to the increase in the nighttime ecosystem respiration under high CO2. Furthermore, the response of daytime NEE to increasing atmospheric CO2 in this mesocosm was not linear, with a saturation concentration of 750 lmol mol. In the desert mesocosm, a combination of a reduction in ecosystem respiration and a small increase in canopy CO2 assimilation in the high CO2 treatments also enhanced daily NEE. Although soil respiration was not aected by the short-term change in atmospheric CO2 in either mesocosm, plant dark respiration was increased signi®cantly by the high CO2 treatments in the rainforest mesocosm while the opposite was found in the desert mesocosm. The high CO2 treatments increased the ecosystem light compensation points in both mesocosms. High CO2 signi®cantly increased ecosystem radiation use eciency in the rainforest mesocosm, but had a much smaller eect in the desert mesocosm. The desert mesocosm showed much lower absolute response in NEE to atmospheric CO2 than the rainforest mesocosm, probably because of the presence of C4 plants. This study illustrates the importance of large-scale experimental research in the study of complex global change issues.
منابع مشابه
Build-up and decline of organic matter during PeECE III
Increasing atmospheric carbon dioxide (CO2) concentrations due to anthropogenic fossil fuel combustion are currently changing the ocean’s chemistry. Increasing oceanic [CO2] and consequently decreasing seawater pH have the potential to significantly impact marine life. Here we describe and analyze the build-up and decline of a natural phytoplankton bloom initiated during the 2005 mesocosm Pelag...
متن کاملHow planting density and grazing intensity affect the above- and below-ground carbon pools in a dryland ecosystem?
Climate change is known as one of the most important environmental challenges. Sequestration of carbon in terrestrial ecosystems is a low-cost option that may be available in the near-term to mitigate increasing atmospheric CO2 concentrations, while providing additional benefits. In this study, we estimated the effects of planting density and grazing intensity on the potential of Atriplex canes...
متن کاملEcosystem assembly and terrestrial carbon balance under elevated CO(2).
Research aimed at understanding how the global carbon balance will change with elevated CO(2) has largely ignored the responses of individual species and genotypes. Yet, plant traits strongly influence the biogeochemical cycling of carbon. Here, we illustrate how differences in inter- and intraspecific responses to elevated CO(2) affect not only physiology and growth, but also higher order biot...
متن کاملRegional and Global Estimation of Terrestrial CO2 Exchange from NIGEC Flux Data
of Proposed Work: We will perform a scaling analysis of terrestrial carbon exchange using several of the NIGEC flux sites in different biomes (forest, C 4 grassland, C 3 agriculture), using a numerical model of the biophysics and biogeochemistry of plants and soils (SiB2), which includes calculations of the surface fluxes of CO 2 , energy, and moisture. This model will be used to analyze local ...
متن کاملConsequences of increased terrestrial dissolved organic matter and temperature on bacterioplankton community composition during a Baltic Sea mesocosm experiment
Predicted increases in runoff of terrestrial dissolved organic matter (DOM) and sea surface temperatures implicate substantial changes in energy fluxes of coastal marine ecosystems. Despite marine bacteria being critical drivers of marine carbon cycling, knowledge of compositional responses within bacterioplankton communities to such disturbances is strongly limited. Using 16S rRNA gene pyroseq...
متن کامل