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We use a mechanistically based ecosystem simulation model to describe and analyze the spatial and temporal patterns of terrestrial net primary productivity (NPP) in South America. The Terrestrial Ecosystem Model (TEM) is designed to predict major carbon and nitrogen fluxes and pool sizes in terrestrial ecosystems at continental to global scales. Information(More)
In a decade-long soil warming experiment in a mid-latitude hardwood forest, we documented changes in soil carbon and nitrogen cycling in order to investigate the consequences of these changes for the climate system. Here we show that whereas soil warming accelerates soil organic matter decay and carbon dioxide fluxes to the atmosphere, this response is(More)
Human alteration of Earth is substantial and growing. Between one-third and one-half of the land surface has been transformed by human action; the carbon dioxide concentration in the atmosphere has increased by nearly 30 percent since the beginning of the Industrial Revolution; more atmospheric nitrogen is fixed by humanity than by all natural terrestrial(More)
Decay processes in an ecosystem can be thought of as a continuum beginning with the input of plant litter and leading to the formation of soil organic matter. As an example of this continuum, we review a 77-month study of the decay of red pine (Pinus resinosa Ait.) needle litter. We tracked the changes in C chemistry and the N pool in red pine (Pinus(More)
[1] We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH 4) emissions and consumption in high-latitude soils of the Northern Hemisphere have changed over the past century in response to observed changes in the region's climate. We estimate that the net emissions of CH 4 (emissions minus consumption)(More)
  • J Ole, E I R N A N N, +12 authors U Wittenbergs
  • 2001
The concurrent effects of increasing atmospheric CO, concentration, climate variability, and cropland establishment and abandonment on terrestrial carbon storage between 1920 and 1992 were assessed using a standard simulat~on protocol with four process-based terrestrial biosphere models. Over the long-term (1920-1992), the simulations yielded a tlme history(More)
There is substantial evidence that soil thermal dynamics are changing in terrestrial ecosystems of the Northern Hemisphere and that these dynamics have implications for the exchange of carbon between terrestrial ecosystems and the atmosphere. To date, large-scale biogeochemical models have been slow to incorporate the effects of soil thermal dynamics on(More)
(ii) that the ratio of aboveground biomass to root biomass is 3 :1 {the average value of three studies in Brazilian Amazonia [P. Fearnside, Emissão e Sequestro de CO 2 (Companha Vale do Rio Doce, Rio de Janeiro, 1994), pp. 95–124]}, consistent with a global analysis of root biomass allocation [M. A.logia 111, 1 (1997)]; and (iii) that root biomass increased(More)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. ABSTRACT The Massachusetts Institute of Technology (MIT) Integrated Global(More)
Knowledge of carbon exchange between the atmosphere, land and the oceans is important, given that the terrestrial and marine environments are currently absorbing about half of the carbon dioxide that is emitted by fossil-fuel combustion. This carbon uptake is therefore limiting the extent of atmospheric and climatic change, but its long-term nature remains(More)