Multiple scales of spatial heterogeneity control soil respiration responses to precipitation across a dryland rainfall g
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Multiple scales of spatial heterogeneity control soil respiration responses to precipitation across a dryland rainfall gradient H. L. Throop & M. K. Seely & V. J. Marufu & Summer Drylands Program Participants
Received: 20 January 2020 / Accepted: 17 June 2020 # Springer Nature Switzerland AG 2020
Abstract Aims Soil respiration (Rs) is a major pathway for carbon release to the atmosphere. We explored variability in dryland Rs response to rainfall pulses at multiple levels of spatial heterogeneity: 1) along a hyper-arid to arid rainfall gradient, 2) across soil surfaces that differ in stability and composition, and 3) among different geomorphic and vegetation patch types. Methods We measured in situ Rs responses for 48 h following simulated rainfall pulses in the Namib Desert. Data Deposition Information: The data associated with this manuscript are availble in Dryad at: https://doi.org/10.5061/dryad. fj6q573qp Responsible Editor: Matthew A. Bowker. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11104-020-04614-0) contains supplementary material, which is available to authorized users. H. L. Throop School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA H. L. Throop School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA H. L. Throop (*) : V. J. Marufu Faculty of Natural Resources and Spatial Sciences, Namibia University of Science and Technology, Private Bag 13388, Windhoek, Namibia e-mail: [email protected] M. K. Seely : Summer Drylands Program Participants Desert Research Foundation of Namibia, PO Box 20232, Windhoek, Namibia
Working across the rainfall gradient, we compared Rs responses on two soil surfaces. Each soil surface had two vegetation/geomorphic patch types that differed in organic matter sources and transport processes, with one characterized by depositional inputs and one characterized by erosional losses. Results Soil respiration was highly responsive to rainfall pulses, although soil surfaces and patch types often exerted more control on Rs than did rainfall pulses. Rainfall generally had proportionally greater influence on Rs with higher annual rainfall. Greater Rs occurred on stable than unstable soil surfaces and in depositional than erosional patch types. Conclusions Large differences in Rs among rainfall zones, soil surfaces, and patch types point to the need to carefully consider multiple scales of spatial heterogeneity when interpreting dryland biogeochemical fluxes. Keywords Arid . Hyper-arid . Carbon cycle . Climate change . Fog desert . Namib Desert
Introduction Soil respiration (Rs) is the second-largest flux in the global carbon (C) cycle, with an estimated mean flux of 91 Pg C y−1 that appears to be rising due to changes in climate and land use (Hashimoto et al. 2015; Raich and Schlesinger 1992). The role of drylands (systems where the aridity index, mean annual rainfall divided by mean annual potential evapotranspiration is 5 mm ranged among sites from 237 to 540 days
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