The effect of resource availability on community dynamics and properties in experimental microcosms
by Li, Wei, Ph.D., MIAMI UNIVERSITY, 2008, 132 pages; 3375113

Abstract:

What causes change of community diversity, stability, or invasibility is of long-standing interest to ecologists. Despite the attention focused on these essential themes, the roles of resource availability in connecting these broad ecological topics, or helping find potential mechanisms underlying observed patterns are still unclear. My studies focus on a resource-based view of these ecological themes using laboratory microcosms as model systems, with specific questions surrounding each theme addressed.

In the diversity-resource theme, I focused on the relation between species richness (most empirical and theoretical studies use richness as a measure of diversity) and productivity (manipulated by changing the nutrient concentration of a standard growth medium). Specifically, I tested whether the productivity-richness relation varied with different observational scale and ecosystem size, and whether the relation between productivity and compositional dissimilarity was modified when historical effects were minimized. Results showed that the productivity-richness relation varied with observational scale, but was unrelated to ecosystem size. Also, there was a different form of scale dependence than previous field research reported.

In the stability-resource theme, I tested the effects of two types of resources, nutrients and space, and of one aggregate community property, richness, on stability. Since richness is known to affect stability and be affected by both nutrient and space, I did not manipulate richness, but instead allowed it to be determined by the combining effects of nutrients and space. Results showed that the effects of nutrients and space on stability were generally mediated by their effects on richness, and the focal level of biological organization at which stability was measured would determine their relative power in predicting stability.

In the invasibility-resource theme, I provided an empirical test of the fluctuating resource hypothesis by creating resource pulses, manipulating the timing of invasion arrival and the timing of resource pulse supply. Meanwhile, potentially confounding effects of other factors were reduced by using microcosm systems. Results showed that resource pulses promoted invasion success, and invaders generally benefited more from low-frequency large-magnitude resource pulses than from resources supplied in a more constant rate. However, invaders might not get the most benefit when their arrival coincided with the intermittent resource enrichment.

 
AdviserMartin H. H. Stevens
SchoolMIAMI UNIVERSITY
SourceDAI/B 70-09, p. , Dec 2009
Source TypeDissertation
SubjectsPlant biology; Ecology
Publication Number3375113
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