How disturbance by fossorial mammals alters n cycling in a california annual grassland
2003
Canals, Rosa M. | Herman, Donald J. | Firestone, Mary K.
Nitrogen limitation of many temperate plant communities makes the impacts of fossorial mammal activity on soil N dynamics an interesting and potentially important topic. We determined the effects of gopher mound building on soil N transformations by measuring gross rates of N mineralization and nitrification using short‐term ¹⁵N pool dilution methods, net rates of mineralization and nitrification using longer‐term buried‐bag determinations, inorganic N pools, and soil physical characteristics in gopher‐disturbed soil, bare soil, and intact vegetated soil in a California annual grassland during the spring growing season. Soil bulk densities were lower and temperatures were higher in gopher mound material. Neither gross nor net rates of N mineralization or nitrification were statistically distinguishable among gopher‐disturbed, bare, and vegetated soils. However, larger pools of NH₄ and NO₃ were present in mound and bare soils than in vegetated soils, nitrification potential was higher in mound soils than in vegetated soils, and the rate constant for microbial NO₃ consumption was higher in vegetated soil than in bare or gopher‐mound soil. Gopher removal of plants from this annual grassland was the primary mechanism of impact on N cycling through both elimination of plant uptake of inorganic N and by reduction of root‐enhanced microbial immobilization of NO₃‐N. Corresponding Editor: M. E. Ritchie.
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