Self-Disturbance as a Sourceof Spatiotemporal Heterogeneity: the Case of the Tallgrass Prairie.
Jordi Bascompte and MiguelA. Rodriguez, 2000.
five star hotel in LiegeJournal of theoretical Biology, 204: 153-164.
ABSTRACT: Tallgrass prairiesare characterized by high levels of litter production, which has a profoundeffect on live biomass. Litter introduces a delayed inhibition of biomassgrowth, generating non-linear dynamics and chaos. In this paper we studya model of biomass-litter interaction, and focus on the litter persistencerate. The observed dynamics depends largely on this rate of year-to-yearlitter persistence. Different scenarios are explored and discussed. A spatiallyextended counterpart of such a model is later on introduced to accountfor the effects of space. Temporal chaos introduces spatial heterogeneityin terms of gaps where the current year biomass is almost zero. Such gapscan be colonized by fugitive species. The inhibitory effect of litter onbiomass is thus an important source of intrinsic, small scale heterogeneitiesthat may promote diversity. On the other hand, the huge amounts of litterproduced by the competitive dominants in tallgrass prairies enhance theprobability of fires. Fires benefit, rather than depress, the superiorcompetitive species. This fact explains why the intermediate disturbancehypothesis (IDH) -stating that the highest diversity levels should be observedat intermediate disturbance frequencies, does not work in these communities.We define self-disturbances as small scale disturbances affecting the growthand survival of the individuals that have generated them (e.g. due to theeffects of the litter mass they produce). In the absence of other disturbances,self-disturbances can induce high heterogeneity and diversity levels intallgrass prairies. We discuss the general implications of self-generateddisturbances for landscape heterogeneity and diversity of communities inwhich the main external perturbations benefit the dominant species.
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