Carbon isotopes reveal soil organic matter dynamics following arid land shrub expansion

Connin, Sean L.; Virginia, Ross A.; Chamberlain, C. Page

doi:10.1007/s004420050172

Cited by 134 publications

(79 citation statements)

References 61 publications

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“…SOC pools with slow turnover rates can carry the imprint of previous vegetation for centuries to millennia, as revealed by carbon isotopes (Dzurec et al 1985, McPherson et al 1993, Connin et al 1997, Ehleringer et al 2000. A high proportion of these pools may dilute the association between SOC profiles and vegetation types if the vegetation had changed previously at some of the sites analyzed here.…”

Section: Discussionmentioning

confidence: 84%

The Vertical Distribution of Soil Organic Carbon and Its Relation to Climate and Vegetation

Jobbágy

Jackson

2000

Ecological Applications

1,417

130

1,790

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Abstract. As the largest pool of terrestrial organic carbon, soils interact strongly with atmospheric composition, climate, and land cover change. Our capacity to predict and ameliorate the consequences of global change depends in part on a better understanding of the distributions and controls of soil organic carbon (SOC) and how vegetation change may affect SOC distributions with depth. The goals of this paper are (1) to examine the association of SOC content with climate and soil texture at different soil depths; (2) to test the hypothesis that vegetation type, through patterns of allocation, is a dominant control on the vertical distribution of SOC; and (3) to estimate global SOC storage to 3 m, including an analysis of the potential effects of vegetation change on soil carbon storage. We based our analysis on Ͼ2700 soil profiles in three global databases supplemented with data for climate, vegetation, and land use. The analysis focused on mineral soil layers.Plant functional types significantly affected the vertical distribution of SOC. The percentage of SOC in the top 20 cm (relative to the first meter) averaged 33%, 42%, and 50% for shrublands, grasslands, and forests, respectively. In shrublands, the amount of SOC in the second and third meters was 77% of that in the first meter; in forests and grasslands, the totals were 56% and 43%, respectively. Globally, the relative distribution of SOC with depth had a slightly stronger association with vegetation than with climate, but the opposite was true for the absolute amount of SOC. Total SOC content increased with precipitation and clay content and decreased with temperature. The importance of these controls switched with depth, climate dominating in shallow layers and clay content dominating in deeper layers, possibly due to increasing percentages of slowly cycling SOC fractions at depth. To control for the effects of climate on vegetation, we grouped soils within climatic ranges and compared distributions for vegetation types within each range. The percentage of SOC in the top 20 cm relative to the first meter varied from 29% in cold arid shrublands to 57% in cold humid forests and, for a given climate, was always deepest in shrublands, intermediate in grasslands, and shallowest in forests (P Ͻ 0.05 in all cases). The effect of vegetation type was more important than the direct effect of precipitation in this analysis. These data suggest that shoot/root allocations combined with vertical root distributions, affect the distribution of SOC with depth.Global SOC storage in the top 3 m of soil was 2344 Pg C, or 56% more than the 1502 Pg estimated for the first meter (which is similar to the total SOC estimates of 1500-1600 Pg made by other researchers). Global totals for the second and third meters were 491 and 351 Pg C, and the biomes with the most SOC at 1-3 m depth were tropical evergreen forests (158 Pg C) and tropical grasslands/savannas (146 Pg C).Our work suggests that plant functional types, through differences in allocation, help to control SOC distri...

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Section: Discussionmentioning

confidence: 84%

The Vertical Distribution of Soil Organic Carbon and Its Relation to Climate and Vegetation

Jobbágy

Jackson

2000

Ecological Applications

1,417

130

1,790

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“…Indeed, it has been observed that the influence of organic matter on soil aggregation is related to the decomposability of the material (Tisdall and Oades 1982). In arid and semiarid regions, decomposition rates can be slow or rapid depending on climate patterns, evapotranspiration rates, latent heat flux, and the spatial heterogeneity of these factors (Schlesinger et al 1990, Connin et al 1997. On the Colorado Plateau, threshold levels of soil moisture and temperature dictate decomposition rates (Fernandez et al 2006).…”

Section: Comparison With Models From Mesic Systemsmentioning

confidence: 99%

Untangling the biological contributions to soil stability in semiarid shrublands

Chaudhary

Bowker

O'Dell³

et al. 2009

Ecological Applications

161

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Abstract. Communities of plants, biological soil crusts (BSCs), and arbuscular mycorrhizal (AM) fungi are known to influence soil stability individually, but their relative contributions, interactions, and combined effects are not well understood, particularly in arid and semiarid ecosystems. In a landscape-scale field study we quantified plant, BSC, and AM fungal communities at 216 locations along a gradient of soil stability levels in southern Utah, USA. We used multivariate modeling to examine the relative influences of plants, BSCs, and AM fungi on surface and subsurface stability in a semiarid shrubland landscape. Models were found to be congruent with the data and explained 35% of the variation in surface stability and 54% of the variation in subsurface stability. The results support several tentative conclusions. While BSCs, plants, and AM fungi all contribute to surface stability, only plants and AM fungi contribute to subsurface stability. In both surface and subsurface models, the strongest contributions to soil stability are made by biological components of the system. Biological soil crust cover was found to have the strongest direct effect on surface soil stability (0.60; controlling for other factors). Surprisingly, AM fungi appeared to influence surface soil stability (0.37), even though they are not generally considered to exist in the top few millimeters of the soil. In the subsurface model, plant cover appeared to have the strongest direct influence on soil stability (0.42); in both models, results indicate that plant cover influences soil stability both directly (controlling for other factors) and indirectly through influences on other organisms. Soil organic matter was not found to have a direct contribution to surface or subsurface stability in this system. The relative influence of AM fungi on soil stability in these semiarid shrublands was similar to that reported for a mesic tallgrass prairie. Estimates of effects that BSCs, plants, and AM fungi have on soil stability in these models are used to suggest the relative amounts of resources that erosion control practitioners should devote to promoting these communities. This study highlights the need for system approaches in combating erosion, soil degradation, and arid-land desertification.

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“…However, deserts are important to include in large-scale models because drylands cover a quarter of the earth's land surface (Reynolds 2001), are expanding in area (Dregne 1983), and are rapidly changing. For example, in addition to tremendous human population growth (Geist and Lambin 2004), deserts are experiencing wide-spread woody plant expansion, which has been associated with increases in productivity (Hibbard et al 2003), soil fertility (McCulley et al 2004), deep root biomass (Connin et al 1997), and soil respiration rates (McCulley et al 2004). Further, climate change is predicted to increase precipitation variability and potentially exacerbate aridity in some desert systems (Christensen et al 2007;Seager et al 2007).…”

Section: Introductionmentioning

confidence: 99%

The temperature responses of soil respiration in deserts: a seven desert synthesis

et al. 2010

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The temperature response of soil respiration in deserts is not well quantified. We evaluated the response of respiration to temperatures spanning 67°C from seven deserts across North America and Greenland. Deserts have similar respiration rates in dry soil at 20°C, and as expected, respiration rates are greater under wet conditions, rivaling rates observed for more mesic systems. However, deserts differ in their respiration rates under wet soil at 20°C and in the strength of the effect of current and antecedent soil moisture on the sensitivity and magnitude of respiration. Respiration increases with temperature below 30°C but declines for temperatures exceeding 35°C. Hot deserts have lower temperature sensitivity than cold deserts, and insensitive or negative temperature sensitivities were predicted under certain moisture conditions that differed among deserts. These results have implications for large-scale modeling efforts because we highlight the unique behavior of desert soil respiration relative to other systems. These behaviors include variable temperature responses and the importance of antecedent moisture conditions for soil respiration.Electronic supplementary material The online version of this article

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Carbon isotopes reveal soil organic matter dynamics following arid land shrub expansion

Cited by 134 publications

References 61 publications

The Vertical Distribution of Soil Organic Carbon and Its Relation to Climate and Vegetation

The Vertical Distribution of Soil Organic Carbon and Its Relation to Climate and Vegetation

Untangling the biological contributions to soil stability in semiarid shrublands

The temperature responses of soil respiration in deserts: a seven desert synthesis

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