Quantifying the timescales over which exogenous and endogenous conditions affect soil respiration

Understanding how exogenous and endogenous factors and above‐ground–below‐ground linkages modulate carbon dynamics is difficult because of the influences of antecedent conditions. For example, there are variable lags between above‐ground assimilation and below‐ground efflux, and the duration of ante...

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Bibliographic Details
Published in:The New phytologist 2014-04, Vol.202 (2), p.442-454
Main Authors: Barron‐Gafford, Greg A, Cable, Jessica M, Bentley, Lisa Patrick, Scott, Russell L, Huxman, Travis E, Jenerette, G. Darrel, Ogle, Kiona
Format: Article
Language:English
Subjects:
antecedent conditions
Bayesian modeling
Carbon
Carbon - physiology
Carbon Dioxide - physiology
Data collection
Desert Climate
Dynamics
Ecosystem
Ecosystem models
Ecosystem structure
Ecosystems
Efflux
Habitats
lag effects
mesquite
Microhabitat
Microhabitats
Modeling
Moisture content
Photosynthesis
Plant Leaves - physiology
Plants
Poaceae
Prosopis
Prosopis velutina
Respiration
Shrubs
Soil
Soil conditions
Soil dynamics
Soil ecology
Soil respiration
Soil temperature
Soil temperature regimes
Soil water
Temperature
vegetation
Water
woody plant encroachment
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Summary:Understanding how exogenous and endogenous factors and above‐ground–below‐ground linkages modulate carbon dynamics is difficult because of the influences of antecedent conditions. For example, there are variable lags between above‐ground assimilation and below‐ground efflux, and the duration of antecedent periods are often arbitrarily assigned. Nonetheless, developing models linking above‐ and below‐ground processes is crucial for estimating current and future carbon dynamics. We collected data on leaf‐level photosynthesis (Aₛₐₜ) and soil respiration (Rₛₒᵢₗ) in different microhabitats (under shrubs vs under bunchgrasses) in the Sonoran Desert. We evaluated timescales over which endogenous and exogenous factors control Rₛₒᵢₗ by analyzing data in the context of a semimechanistic temperature–response model of Rₛₒᵢₗ that incorporated effects of antecedent exogenous (soil water) and endogenous (Aₛₐₜ) conditions. For both microhabitats, antecedent soil water and Aₛₐₜ significantly affected Rₛₒᵢₗ, but Rₛₒᵢₗ under shrubs was more sensitive to Aₛₐₜ than that under bunchgrasses. Photosynthetic rates 1 and 3 d before the Rₛₒᵢₗ measurement were most important in determining current‐day Rₛₒᵢₗ under bunchgrasses and shrubs, respectively, indicating a significant lag effect. Endogenous and exogenous controls are critical drivers of Rₛₒᵢₗ, but the relative importance and the timescale over which each factor affects Rₛₒᵢₗ depends on above‐ground vegetation and ecosystem structure characteristics.
ISSN:0028-646X
1469-8137
DOI:10.1111/nph.12675