Temperature influences carbon accumulation in moist tropical forests

Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames 50011, USA.
Ecology (Impact Factor: 4.66). 02/2006; 87(1):76-87. DOI: 10.1890/05-0023
Source: PubMed


Evergreen broad-leaved tropical forests can have high rates of productivity and large accumulations of carbon in plant biomass and soils. They can therefore play an important role in the global carbon cycle, influencing atmospheric CO2 concentrations if climate warms. We applied meta-analyses to published data to evaluate the apparent effects of temperature on carbon fluxes and storages in mature, moist tropical evergreen forest ecosystems. Among forests, litter production, tree growth, and belowground carbon allocation all increased significantly with site mean annual temperature (MAT); total net primary productivity (NPP) increased by an estimated 0.2-0.7 Mg C x ha(-1) x yr(-1) x degrees C(-1). Temperature had no discernible effect on the turnover rate of aboveground forest biomass, which averaged 0.014 yr(-1) among sites. Consistent with these findings, forest biomass increased with site MAT at a rate of 5-13 Mg C x ha(-1) x degrees C(-1). Despite greater productivity in warmer forests, soil organic matter accumulations decreased with site MAT, with a slope of -8 Mg C x ha(-1) x degrees C(-1), indicating that decomposition rates of soil organic matter increased with MAT faster than did rates of NPP. Turnover rates of surface litter also increased with temperature among forests. We found no detectable effect of temperature on total carbon storage among moist-tropical evergreen forests, but rather a shift in ecosystem structure, from low-biomass forests with relatively large accumulations of detritus in cooler sites, to large-biomass forests with relatively smaller detrital stocks in warmer locations. These results imply that, in a warmer climate, conservation of forest biomass will be critical to the maintenance of carbon stocks in moist tropical forests.

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Available from: James W. Raich, Aug 10, 2015
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    • "Litter quantity and quality in forests are likely to change as a consequence of climate change. Many studies have shown that litter quantity and quality are altered by elevated atmospheric carbon dioxide (CO 2 ) concentration (Norby et al. 2005; Liu et al. 2005; Hickler et al. 2008; Clark et al. 2010; Ellsworth et al. 2012), changes in rainfall distribution patterns and rising temperature (Martínez-Vilalta et al.; 2012; Doughty et al.; 2014; Raich et al. 2006; Zhou et al. 2013). Because litter represents a major pathway for C cycling between vegetation and soil in forest ecosystems, changes in aboveground litter quantity and quality could have important consequences for C cycling. "
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    ABSTRACT: Aims This study investigated the effects of changes in litter quantity and quality on litter decomposition, soil respiration, and soil organic carbon (SOC) in subtropical forests. Methods The experiment had a nested factorial design with three factors: (1) successional stage with three levels (early, mid and mature), (2) litter type with two levels (Schima superba Gardn. et Champ. and Ormosia pinnata (Lour.) Merr.), and (3) litter addition with five levels (0, 218, 436, 654 and 873 g·m−2·yr−1, respectively). Results In all forests, an increase in litter input increased litter decomposition, litter carbon (C) loss and soil respiration but did not alter SOC content after 2.5 years. The increases in litter decomposition, litter C loss, and soil respiration in response to increased litter input were greater with the lower quality Schima superba litter than with the higher quality Ormosia pinnata litter. Litter quality did not affect SOC content at any of the three forest sites. The responses of litter decomposition and soil respiration to increasing litter input differed depending on forest successional stage. Conclusions In subtropical forests, increases in litter production under climate change may accelerate C cycling. Net soil C storage in subtropical forests, however, may not change over short time scales in response to increased litter input.
    Plant and Soil 07/2015; 392(1-2). DOI:10.1007/s11104-015-2450-4 · 2.95 Impact Factor
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    • "Similarly, AGC does not consistently increase with temperature. In moist forests, AGC has been positively related to mean annual temperature (Raich et al., 2006), while in wet forests a negative association has been found (Stegen et al., 2011). Moreover, forest stand variables (e.g. "
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    ABSTRACT: AimTo develop an integrative framework to evaluate variation in aboveground carbon storage (AGC). A model that can be applied to understand and predict how global-change drivers influence tropical carbon sinks.LocationOld-growth tropical forests world-wide.Methods Using structural equation modelling (SEM), we propose an a priori model to evaluate the direct and indirect effects of climate, stand variables (basal area, tree diameter and wood density at plot level) and liana abundance on AGC. Our model indicated that stand variables increased AGC while liana abundance decreased AGC indirectly via negative effects on stand variables. We used a multigroup SEM to test the generality of our framework using a standardized dataset of 145 plots (0.1 ha) in dry, moist and wet tropical forests.ResultsOur model explained over 85% variation in AGC and showed a positive and consistent relationship between stand variables and AGC across forests types. The effects of climate on AGC were indirect rather than direct, with negative effects of temperature in all forests. Liana abundance reduced tree diameter and basal area in moist forests, but did not affect AGC in wet or dry forests.Main conclusionsOur results suggest that climate affects AGC indirectly, via its direct influence on stand variables and liana abundance. The effects of lianas on AGC result from reductions in stand variables and are as important as climate for moist forests, which harbour the greatest tropical carbon pools. Our model was consistent across forest types. This highlights the usefulness of an integrative framework to improve predictions of the effects of drivers of global change on tropical carbon sinks.
    Global Ecology and Biogeography 04/2015; 24(8). DOI:10.1111/geb.12304 · 6.53 Impact Factor
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    • "The CO 2 efflux from the soil to the atmosphere is 98 ± 12 Pg C year −1 , about ten times greater than that from fossil fuel combustion and deforestation combined (Bond-Lamberty and Thomson 2010), which means that small changes in soil C dynamics may induce a significant increase of the atmospheric CO 2 concentration. With increasing atmospheric CO 2 concentration and temperature, the input of exogenous substrate to soil via plant residue or root exudation might increase (Cheng 1999; Raich et al. 2006). Moreover , soil has many microbial hotspots which receive a high input rate of exogenous C, such as the rhizosphere, detritusphere , drillosphere and some other biopores (Kuzyakov 2010). "
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    ABSTRACT: The priming effect (PE) is one of the most important interactions between C input and output in soils. Here we aim to quantify patterns of PE in response to six addition rates of (13)C-labeled water-soluble C (WSC) and determine if these patterns are different between soil organic and mineral layers in a temperate forest. Isotope mass balance was used to distinguish WSC derived from SOC-derived CO2 respiration. The relative PE was 1.1-3.3 times stronger in the mineral layer than in the organic layer, indicating higher sensitivity of the mineral layer to WSC addition. However, the magnitude of cumulative PE was significantly higher in the organic layer than in the mineral layer due to higher SOC in the organic layer. With an increasing WSC addition rate, cumulative PE increased for both layers, but tended to level off when the addition rate was higher than 400 mg C kg(-1) soil. This saturation effect indicates that stimulation of soil C loss by exogenous substrate would not be as drastic as the increase of C input. In fact, we found that the mineral layer with an WSC addition rate of 160-800 mg C kg(-1) soil had net C storage although positive PE was observed. The addition of WSC basically caused net C loss in the organic layer due to the high magnitude of PE, pointing to the importance of the organic layer in C cycling of forest ecosystems. Our findings provide a fundamental understanding of PE on SOC mineralization of forest soils and warrant further in situ studies of PE in order to better understand C cycling under global climate change.
    Oecologia 03/2015; 178(4). DOI:10.1007/s00442-015-3290-x · 3.09 Impact Factor
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