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The relationship between biodiversity and ecosystem functioning across space and time

Bond, Emily M. (2002) The relationship between biodiversity and ecosystem functioning across space and time. Master's Thesis, University of Pittsburgh. (Unpublished)

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Recent empirical studies conducted in disparate ecosystems have shown that greater species diversity has positive effects on ecosystem functioning; however, other studies have found neutral or sometimes negative results. It is still unclear why the relationship between biodiversity and functioning varies among studies, but perhaps, investigating this relationship across spatial and temporal scales will lead to further understanding. One theory predicts that local niche complementarity among species (the partitioning of species based upon niche differentiation) is predicted to positively affect local ecosystem functioning at the local spatial scale. However, more recent theory predicts that greater local diversity may hinder local ecosystem functioning when diversity is enhanced through regional processes. I suggest community assembly as a way to incorporate both the local and regional processes that determine biodiversity and its consequent effects on ecosystem functioning. From this, I propose a hump-shaped relationship between diversity and ecosystem functioning at local spatial scales, but a linear increase of functioning with diversity at regional spatial scales. Thus, species diversity may have different effects on ecosystem functioning across different spatial scales. Species diversity may affect ecosystem functioning differently across time as environmental conditions shift. Through integrating recent theoretical models in ecosystem ecology and empirical examples of food-webs in community ecology, the effects of herbivore diversity on ecosystem functioning (grazing of primary producers) were examined under unchanged (no nutrients added) and changed (nutrients added) environmental conditions. I found that communities with higher species richness and diversity did not significantly differ from lower diversity communities in grazing intensity in the unchanged environments. However, higher diversity communities did have a significant effect on the biomass of primary producers in the nutrient enriched environments, while lower diversity communities did not. This empirical study showed that the functioning of local communities is dependent on the environmental conditions present in the habitat. Overall, this investigation found that the relationship between species diversity and ecosystem functioning may be dependent on spatial scale and environmental changes over time.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Bond, Emily
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairChase, Jonathanjchase@pitt.eduJCHASE
Committee MemberTonsor, Stephentonsor@pitt.eduTONSOR
Committee MemberKalisz, Susankalisz@pitt.eduKALISZ
Date: 6 August 2002
Date Type: Completion
Defense Date: 11 April 2002
Approval Date: 6 August 2002
Submission Date: 3 May 2002
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: biodiversity; ecosystem functioning; environmental change; eutrophication; productivity; spatial scale
Other ID:, etd-05032002-121632
Date Deposited: 10 Nov 2011 19:43
Last Modified: 15 Nov 2016 13:43


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