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Accueil du site → Doctorat → États-Unis → 1999 → Spatial interactions and demography within a community of desert perennial shrubs

University of Illinois at Chicago (1999)

Spatial interactions and demography within a community of desert perennial shrubs

Miriti, Maria Nkore

Titre : Spatial interactions and demography within a community of desert perennial shrubs

Auteur : Miriti, Maria Nkore

Université de soutenance  : University of Illinois at Chicago

Grade : Doctor of Philosophy (PhD) 1999

Résumé
I conducted analyses of spatial pattern and demographic analyses of more than 10,000 individuals within twenty-three species of desert perennial shrubs and cacti located in a permanent mapped hectare near the Cottonwood Springs ranger station of Joshua Tree National Park. These analyses were used to explore the relative roles of biotic and abiotic factor that influence plant-plant interactions among conspecifics. Uniform patterns of distribution among conspecifics were rare, suggesting that water mediated negative plant-plant interactions are not common within the species at this site. However, the presence of near conspecific neighbors was found to impose a demographic cost in lowered population growth rates for population subsets in which plants had neighbors throughout their ontogeny. A study of ontogenetic variation in the response to neighbors strongly suggested that juveniles benefit from adult neighbors, but that this benefit switches to a cost as plants increase in size. These patterns suggest either facilitation among conspecific plants or that other biotic and/or abiotic factors override advantages that might be gained from large distances among neighbors. Experimental manipulations support a role of facilitation among both conspecific and heterospecific individuals. The influence of spatial process on plant demography is highlighted.

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Page publiée le 16 février 2015, mise à jour le 28 mars 2019