Patch dynamics of soil biotic feedbacks in the Sonoran Desert |
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Authors: | BJ Butterfield JM Briggs |
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Institution: | 1. Regents Professor, Caesar Kleberg Wildlife Research Institute, Texas A&M University–Kingsville, Kingsville, TX 78363, USA;;2. Assistant Professor, Departamento de Recursos Naturales Renovables, Universidad Autónoma Agraria Antonio Narro, Saltillo, Coahuila 25050, México;;3. Project Leader, Panhandle Wildlife Areas, Texas Parks and Wildlife Department, Paducah, TX 79248, USA;4. Assistant Professor, Department of Ecology, Montana State University, Bozeman, MT 59717, USA;1. Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University, Chengdu 611130, China;2. Faculty of Life Science, Sichuan Normal University, Chengdu 610041, China |
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Abstract: | Soil fertility in arid ecosystems is spatially and temporally heterogeneous, due primarily to biotic feedbacks from perennial plants. While the “island of fertility” effect is well-established, little is known about the influence of plant functional characteristics on soil nutrients, or changes in nutrient levels following mortality or microsite succession. To assess these patterns, we studied a functionally diverse Sonoran Desert ecosystem in which all microsite state transitions were determined. The woody species (Ambrosia deltoidea, Larrea tridentata, Parkinsonia microphylla) significantly enhanced soil organic matter, nitrogen and phosphorous levels (referred to generally as fertility) to varying degrees. Effect sizes differed significantly among species but were surprisingly similar. However, following mortality, fertility remained constant beneath Ambrosia and increased significantly beneath decaying Parkinsonia, contrary to expected declines. These results suggest that nutrients are recycled within a microsite, resulting in similar pool sizes beneath live plants across species, regardless of morphological or phonological differences. Microsites occupied by cacti exhibited no differences from bare soil, indicating that cacti may erase islands of fertility. However, nitrate and phosphate levels spiked following mortality of the large cactus, Carnegiea gigantea. In general, fertility effects were correlated with morphological characteristics that should be applicable across most arid systems. |
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