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Journal ArticleDOI

Effect of rainfall seasonality on carbon storage in tropical dry ecosystems

01 Jul 2013-Journal of Geophysical Research (John Wiley & Sons, Ltd)-Vol. 118, Iss: 3, pp 1156-1167
TL;DR: In this paper, a minimal model linking the seasonal behavior of the ensemble soil moisture, plant productivity, related C inputs through litterfall, and soil C dynamics was developed to understand how rainfall seasonality affects this balance and to provide estimates of long-term C sequestration.
Abstract: [1] While seasonally dry conditions are typical of large areas of the tropics, their biogeochemical responses to seasonal rainfall and soil carbon (C) sequestration potential are not well characterized. Seasonal moisture availability positively affects both productivity and soil respiration, resulting in a delicate balance between C deposition as litterfall and C loss through heterotrophic respiration. To understand how rainfall seasonality (i.e., duration of the wet season and rainfall distribution) affects this balance and to provide estimates of long-term C sequestration, we develop a minimal model linking the seasonal behavior of the ensemble soil moisture, plant productivity, related C inputs through litterfall, and soil C dynamics. A drought-deciduous caatinga ecosystem in northeastern Brazil is used as a case study to parameterize the model. When extended to different patterns of rainfall seasonality, the results indicate that for fixed annual rainfall, both plant productivity and soil C sequestration potential are largely, and nonlinearly, dependent on wet season duration. Moreover, total annual rainfall is a critical driver of this relationship, leading at times to distinct optima in both production and C storage. These theoretical predictions are discussed in the context of parameter uncertainties and possible changes in rainfall regimes in tropical dry ecosystems.
Citations
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01 Dec 2012
TL;DR: In this article, a new global measure of precipitation seasonality is proposed, and application of this method to observations from the tropics shows that increases in variability were accompanied by shifts in seasonal magnitude, timing and duration.
Abstract: Climate change is altering the seasonal distribution, interannual variability and overall magnitude of precipitation. A new global measure of precipitation seasonality is proposed, and application of this method to observations from the tropics shows that increases in variability were accompanied by shifts in seasonal magnitude, timing and duration.

314 citations

Journal ArticleDOI
TL;DR: In this article, the authors studied how individuals, species, and communities in seasonally dry tropical forests (SDTF) will cope with the hotter, drier conditions predicted by climate models.
Abstract: Seasonally dry tropical forests (SDTF) are located in regions with alternating wet and dry seasons, with dry seasons that last several months or more. By the end of the 21st century, climate models predict substantial changes in rainfall regimes across these regions, but little is known about how individuals, species, and communities in SDTF will cope with the hotter, drier conditions predicted by climate models.

207 citations


Cites background from "Effect of rainfall seasonality on c..."

  • ...Belowground ecosystem processes in tropical dry forests are sensitive to intra- and inter-annual variation in precipitation (Rohr et al 2013)....

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01 Jan 2005
TL;DR: Their short leafless period and the capacity to flush by the end of the dry season may also contribute to offset the longer payback period of evergreen species, although it may involve the higher cost of maintaining a deep-root system or a tight control of plant water balance in the shallow-rooted ones.
Abstract: The seasonal savannas (cerrados) of Central Brazil are characterized by a large diversity of evergreen and deciduous trees, which do not show a clear differentiation in terms of active rooting depth. Irrespective of the depth of the root system, expansion of new foliage in deciduous species occurs at the end of the dry season. In this study, we examined a suite of leaf traits related to C assimilation, water and nutrients (N, P) in five deciduous and six evergreen trees that were among the dominant families of cerrado vegetation. Maximum CO2 assimilation on a mass basis (Amass) was significantly correlated with leaf N and P, and specific leaf area (SLA; leaf area per unit of leaf mass). The highest leaf concentrations of both nutrients were measured in the newly mature leaves of deciduous species at the end of the dry period. The differences in terms of leaf N and P between evergreen and deciduous species decreased during the wet season. Deciduous species also invested less in the production of non-photosynthetic leaf tissues and produced leaves with higher SLA and maintained higher water use efficiency. Thus, deciduous species compensated for their shorter leaf payback period by maintaining higher potential payback capacity (higher values of Amass) and lower leaf construction costs (higher SLA). Their short leafless period and the capacity to flush by the end of the dry season may also contribute to offset the longer payback period of evergreen species, although it may involve the higher cost of maintaining a deep-root system or a tight control of plant water balance in the shallow-rooted ones.

198 citations

Journal ArticleDOI
TL;DR: In this article, a continental-scale phenological analysis of African savannas and woodlands was performed to explore the influence of rainy season timing and duration on regional land surface phenology and ecosystem structure.
Abstract: This paper presents a continental-scale phenological analysis of African savannas and woodlands. We apply an array of synergistic vegetation and hydrological data records from satellite remote sensing and model simulations to explore the influence of rainy season timing and duration on regional land surface phenology and ecosystem structure. We find that (i) the rainy season onset precedes and is an effective predictor of the growing season onset in African grasslands. (ii) African woodlands generally have early green-up before rainy season onset and have a variable delayed senescence period after the rainy season, with this delay correlated nonlinearly with tree fraction. These woodland responses suggest their complex water use mechanisms (either from potential groundwater use by relatively deep roots or stem-water reserve) to maintain dry season activity. (iii) We empirically find that the rainy season length has strong nonlinear impacts on tree fractional cover in the annual rainfall range from 600 to 1800 mm/yr, which may lend some support to the previous modeling study that given the same amount of total rainfall to the tree fraction may first increase with the lengthening of rainy season until reaching an “optimal rainy season length,” after which tree fraction decreases with the further lengthening of rainy season. This nonlinear response is resulted from compound mechanisms of hydrological cycle, fire, and other factors. We conclude that African savannas and deciduous woodlands have distinctive responses in their phenology and ecosystem functioning to rainy season. Further research is needed to address interaction between groundwater and tropical woodland as well as to explicitly consider the ecological significance of rainy season length under climate change.

125 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of cropland management changes on organic carbon (SOC) dynamics has not been recently assessed in the tropics, and the authors used random forest regression to identify the determinants of organic carbon accumulation rates depending on the climate, soil characteristics and changes in management practices.

95 citations

References
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Journal ArticleDOI
01 Apr 1963-Ecology
TL;DR: Birch, L. C. Kollros, C. Boggild, O., and J. Keiding as discussed by the authors The linkage map of the house fly, Musca domestic L.
Abstract: Birch, L. C. 1955. Selection in Drosophlila pseudoobscura in relation to crowding. Evolution 9:389399. . 1960. The genetic factor in population ecology. Amer. Nat. 94:5-24. Boggild, O., and J. Keiding. 1958. Competition in house fly larvae. Experiments involving a DDT-resistant and susceptible strain. Oikos 9:1-25. Hiroyoshi, T. 1961. The linkage map of the house fly, Musca domestic L. Genetics 46:1373-1380. Kollros, C. L. 1944. A study of the gene, pearl, in populations of Tribolium castaneumn, Herbst. Unpublished Ph.D. dissertation, University of Chicago.

3,284 citations


"Effect of rainfall seasonality on c..." refers background in this paper

  • ...At these scales, soil microbial biomass can be assumed to be in equilibrium with soil C, so that C is the main driver of respiration [Manzoni and Porporato, 2009; Olson, 1963]....

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Journal ArticleDOI
TL;DR: Rooting patterns for terrestrial biomes are analyzed and distributions for various plant functional groups are compared and the merits and possible shortcomings of the analysis are discussed in the context of root biomass and root functioning.
Abstract: Understanding and predicting ecosystem functioning (e.g., carbon and water fluxes) and the role of soils in carbon storage requires an accurate assessment of plant rooting distributions. Here, in a comprehensive literature synthesis, we analyze rooting patterns for terrestrial biomes and compare distributions for various plant functional groups. We compiled a database of 250 root studies, subdividing suitable results into 11 biomes, and fitted the depth coefficient β to the data for each biome (Gale and Grigal 1987). β is a simple numerical index of rooting distribution based on the asymptotic equation Y=1-βd, where d = depth and Y = the proportion of roots from the surface to depth d. High values of β correspond to a greater proportion of roots with depth. Tundra, boreal forest, and temperate grasslands showed the shallowest rooting profiles (β=0.913, 0.943, and 0.943, respectively), with 80-90% of roots in the top 30 cm of soil; deserts and temperate coniferous forests showed the deepest profiles (β=0.975 and 0.976, respectively) and had only 50% of their roots in the upper 30 cm. Standing root biomass varied by over an order of magnitude across biomes, from approximately 0.2 to 5 kg m-2. Tropical evergreen forests had the highest root biomass (5 kg m-2), but other forest biomes and sclerophyllous shrublands were of similar magnitude. Root biomass for croplands, deserts, tundra and grasslands was below 1.5 kg m-2. Root/shoot (R/S) ratios were highest for tundra, grasslands, and cold deserts (ranging from 4 to 7); forest ecosystems and croplands had the lowest R/S ratios (approximately 0.1 to 0.5). Comparing data across biomes for plant functional groups, grasses had 44% of their roots in the top 10 cm of soil. (β=0.952), while shrubs had only 21% in the same depth increment (β=0.978). The rooting distribution of all temperate and tropical trees was β=0.970 with 26% of roots in the top 10 cm and 60% in the top 30 cm. Overall, the globally averaged root distribution for all ecosystems was β=0.966 (r 2=0.89) with approximately 30%, 50%, and 75% of roots in the top 10 cm, 20 cm, and 40 cm, respectively. We discuss the merits and possible shortcomings of our analysis in the context of root biomass and root functioning.

2,554 citations


"Effect of rainfall seasonality on c..." refers methods in this paper

  • ...Representative soil moisture thresholds for this soil were chosen (after Laio et al. [2001] and Porporato et al. [2004]) as s1= 0.8, sw = 0.2 and x * = 0.4, while we assumed a rooting depth Zr=0.35m—a typical value for dry tropical savannas [Jackson et al., 1996]....

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