Item talk:Q148061

Soil respiration patterns and controls in limestone cedar glades

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 dramativally 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.