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Soil respiration patterns and controls in limestone cedar glades

Cartwright, Jennifer, Hui, Dafeng
Plant and soil 2015 v.389 no.1-2 pp. 157-169
drought, ecosystems, grasslands, hydrology, indigenous species, limestone, model validation, models, plants (botany), saturated conditions, soil depth, soil organic matter, soil respiration, soil temperature, soil water content, summer, vegetation cover
AIMS: Drivers of soil respiration (R ₛ) in rock outcrop ecosystems remain poorly understood. We investigated these drivers in limestone cedar glades, known for their concentrations of endemic plant species and for seasonal hydrologic extremes (xeric and saturated conditions), and compared our findings to those in temperate grasslands and semi-arid ecosystems. METHODS: We measured R ₛ , soil temperature (T ₛ), volumetric soil water content (SWC), soil organic matter (SOM), soil depth, and vegetation cover monthly over 16 mo and analyzed effects of these variables on R ₛ . RESULTS: Seasonally, R ₛ primarily tracked T ₛ (r² = 0.77; P < 0.01), however R ₛ was depressed during a summer drought. SOM was highly variable spatially, and incorporating SOM effects into the R ₛ model dramatically improved model performance. Both shallow soil and sparse vegetation cover were also associated with lower R ₛ . CONCLUSIONS: Soil depth, SOM, and vegetation cover were important drivers of R ₛ in limestone cedar glades. Seasonal R ₛ patterns reflected those for mesic temperate grasslands more than for semi-arid ecosystems, in that R ₛ primarily tracked temperature for most of the year.