Effects of an African grass invasion on Hawaiian shrubland nitrogen biogeochemistry |
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| Authors: | Gregory P. Asner Susan W. Beatty |
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| Affiliation: | (1) Department of Geography, University of Colorado, 80309-0260 Boulder, CO, USA;(2) Present address: Department of Environmental, Population, and Organismic Biology, University of Colorado, 80309 Boulder, CO, USA;(3) CIRES/CSES, University of Colorado, Campus Box 216, 80309-0216 Boulder, CO, USA |
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| Abstract: | African perennial C4 grasses are highly successful invaders in Hawaiian ecosystems. We examined the effects of African molasses grass (Melinis minutiflora Beauv.) on Hawaiian shrubland nitrogen (N) dynamics without the influence of fire disturbance. Vegetation tissue carbon and nitrogen chemistry, soil inorganic N pools, net N mineralization rates, and total soil N were studied in three adjacent areas: a monospecificMelinis grassland, a mixed grass/shrubland mosaic, and an un-invaded shrubland.Melinis plots within the mosaic area exhibited the largest inorganic N pools and fastest net N mineralization rates, but were temporally variable with grass phenology. Un-invaded shrubland plots contained the smallest inorganic N pools and lowest net N mineralization rates. Grass foliar C:N and litter C:N were lower than those of common shrubland species, providing one possible link between species and ecosystem N dynamics at this site. The combined effects of N cycle modification, successful light competition, and fire-cycle enhancement make the invasion ofMelinis a significant perturbation to Hawaiian shrubland ecosystem function and successional dynamics. ei]Section editor H Lambers |
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| Keywords: | African grasses biological invasions ecosystem processes Hawaii Melinis minutiflora nitrogen cycle |
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