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Ecosystem Carbon (ecosystem + carbon)

Distribution by Scientific Domains
Life Sciences100%

Terms modified by Ecosystem Carbon

  • ecosystem carbon budget
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    Selected Abstracts

    Modeling the effects of fire and climate change on carbon and nitrogen storage in lodgepole pine (Pinus contorta) stands

    GLOBAL CHANGE BIOLOGY, Issue 3 2009
    E. A. H. SMITHWICK
    Abstract The interaction between disturbance and climate change and resultant effects on ecosystem carbon (C) and nitrogen (N) fluxes are poorly understood. Here, we model (using CENTURY version 4.5) how climate change may affect C and N fluxes among mature and regenerating lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Wats.) stands that vary in postfire tree density following stand-replacing fire. Both young (postfire) and mature stands had elevated forest production and net N mineralization under future climate scenarios relative to current climate. Forest production increased 25% [Hadley (HAD)] to 36% [Canadian Climate Center (CCC)], compared with 2% under current climate, among stands that varied in stand age and postfire density. Net N mineralization increased under both climate scenarios, e.g., +19% to 37% (HAD) and +11% to 23% (CCC), with greatest increases for young stands with sparse tree regeneration. By 2100, total ecosystem carbon (live+dead+soils) in mature stands was higher than prefire levels, e.g., +16% to 19% (HAD) and +24% to 28% (CCC). For stands regenerating following fire in 1988, total C storage was 0,9% higher under the CCC climate model, but 5,6% lower under the HAD model and 20,37% lower under the Control. These patterns, which reflect variation in stand age, postfire tree density, and climate model, suggest that although there were strong positive responses of lodgepole pine productivity to future changes in climate, C flux over the next century will reflect complex relationships between climate, age structure, and disturbance-recovery patterns of the landscape. [source]

    Modeled interactive effects of precipitation, temperature, and [CO2] on ecosystem carbon and water dynamics in different climatic zones

    GLOBAL CHANGE BIOLOGY, Issue 9 2008
    YIQI LUO
    Abstract Interactive effects of multiple global change factors on ecosystem processes are complex. It is relatively expensive to explore those interactions in manipulative experiments. We conducted a modeling analysis to identify potentially important interactions and to stimulate hypothesis formulation for experimental research. Four models were used to quantify interactive effects of climate warming (T), altered precipitation amounts [doubled (DP) and halved (HP)] and seasonality (SP, moving precipitation in July and August to January and February to create summer drought), and elevated [CO2] (C) on net primary production (NPP), heterotrophic respiration (Rh), net ecosystem production (NEP), transpiration, and runoff. We examined those responses in seven ecosystems, including forests, grasslands, and heathlands in different climate zones. The modeling analysis showed that none of the three-way interactions among T, C, and altered precipitation was substantial for either carbon or water processes, nor consistent among the seven ecosystems. However, two-way interactive effects on NPP, Rh, and NEP were generally positive (i.e. amplification of one factor's effect by the other factor) between T and C or between T and DP. A negative interaction (i.e. depression of one factor's effect by the other factor) occurred for simulated NPP between T and HP. The interactive effects on runoff were positive between T and HP. Four pairs of two-way interactive effects on plant transpiration were positive and two pairs negative. In addition, wet sites generally had smaller relative changes in NPP, Rh, runoff, and transpiration but larger absolute changes in NEP than dry sites in response to the treatments. The modeling results suggest new hypotheses to be tested in multifactor global change experiments. Likewise, more experimental evidence is needed for the further improvement of ecosystem models in order to adequately simulate complex interactive processes. [source]

    Effects of nutrient additions on ecosystem carbon cycle in a Puerto Rican tropical wet forest

    GLOBAL CHANGE BIOLOGY, Issue 2 2006
    YIQING LI
    Abstract Wet tropical forests play a critical role in global ecosystem carbon (C) cycle, but C allocation and the response of different C pools to nutrient addition in these forests remain poorly understood. We measured soil organic carbon (SOC), litterfall, root biomass, microbial biomass and soil physical and chemical properties in a wet tropical forest from May 1996 to July 1997 following a 7-year continuous fertilization. We found that although there was no significant difference in total SOC in the top 0,10 cm of the soils between the fertilization plots (5.42±0.18 kg m,2) and the control plots (5.27±0.22 kg m,2), the proportion of the heavy-fraction organic C in the total SOC was significantly higher in the fertilized plots (59%) than in the control plots (46%) (P<0.05). The annual decomposition rate of fertilized leaf litter was 13% higher than that of the control leaf litter. We also found that fertilization significantly increased microbial biomass (fungi+bacteria) with 952±48 mg kg,1soil in the fertilized plots and 755±37 mg kg,1soil in the control plots. Our results suggest that fertilization in tropical forests may enhance long-term C sequestration in the soils of tropical wet forests. [source]

    Effects of Vegetation Thinning on Above- and Belowground Carbon in a Seasonally Dry Tropical Forest in Mexico

    BIOTROPICA, Issue 3 2009
    Rodrigo Vargas
    ABSTRACT Mature tropical forests are disappearing and secondary forests are becoming more abundant, thus there is an increasing need to understand the ecology and management of secondary forests. In the Yucatan Peninsula, Mexico, seasonally dry tropical forests are subject to frequent fire, and early-successional stands are extremely dense. We applied vegetation thinning (removal of all stems < 2 cm in diameter) to hasten secondary succession and open the understory to reduce the fire ladder in an 11-yr-old stand. We quantified the effect of vegetation thinning on above- and belowground carbon over 5 yr. Aboveground carbon included all standing vegetation and belowground carbon included fine roots and organic carbon in the Oi, Oe, and Oa soil horizons. Trees with diameter of 2,10 cm and > 10 cm had higher carbon accumulation rates in thinned plots than in control plots. Carbon stored in the Oi-horizon and the Oe > 2 mm fraction remained significantly higher in thinned plots even 5 yr after treatment. Carbon in fine roots was significantly higher in thinned plots, and radiocarbon (14C) data suggest that fine roots in thinned plots were recently produced in comparison with fine roots in control plots. We did not find significant differences in total ecosystem carbon after 5 yr (126 ± 6 and 136 ± 8 Mg C/ha, respectively). These results suggest rapid carbon recovery and support the hypothesis that young tropical forests thinned to hasten succession and reduce the fire hazard may have only a short-term negative impact on carbon accumulation in vegetation and soils. RESUMEN Los bosques tropicales maduros están desapareciendo y los bosques secundarios se han vuelto mas abundantes, por eso hay una creciente necesidad de entender la ecología y el manejo de los bosques secundarios. En la Península de Yucatán, México, los bosques secos de temporal están sujetos a frecuentes fuegos y los bosques secundarios son extremadamente densos. En este estudio se aplicó un aclareo de vegetación (remoción de todos los tallos < 2 cm en diámetro) para acelerar la sucesión secundaria y controlar el riesgo de fuego en un bosque de 11 años. Cuantificamos el efecto del aclaro de vegetación en el carbono arriba del suelo y el carbono bajo el suelo por cinco años. El carbono arriba del suelo incluyó toda la vegetación en pie y el carbono bajo el suelo incluyó raíces finas y el carbono orgánico de los horizontes Oi, Oe y Oa del suelo. Los árboles con diámetro entre 2,10 cm y > 10 cm tuvieron mayor acumulación de carbono en las parcelas de aclareo que en las control. El carbono guardado en el horizonte Oi y en la fracción Oe > 2 mm permaneció con niveles más altos en las parcelas de aclareo incluso cinco años después del tratamiento. El carbono en las raíces finas fue significativamente mayor en las parcelas con aclareo y los datos de radiocarbono (14C) sugieren que las raíces finas en las parcelas con aclareo fueron producidas después que las raíces finas en las parcelas control. No encontramos diferencias en el carbono total del ecosistema entre las parcelas control y las de aclareo después de cinco años (126 ± 6 and136 ± 8 Mg C/ha, respectivamente). Estos resultados sugieren una rápida recuperación del carbono y apoyan la hipótesis de que el aclareo para acelerar la sucesión y controlar el riesgo de fuego en bosques tropicales tempranos solo tiene un efecto negativo a corto plazo en la acumulación de carbono del suelo y vegetación. [source]