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dc.contributor.advisorHepburn, Christopher D.
dc.contributor.advisorLee, William G.
dc.contributor.advisorBrownstein, Gretchen
dc.contributor.advisorBaltar, Federico
dc.contributor.authorBagnaro, Antoine Jacques Marcel
dc.date.available2020-11-17T21:56:35Z
dc.date.copyright2020
dc.identifier.urihttp://hdl.handle.net/10523/10579
dc.description.abstractEcotones are landscape features that intervene between adjoining ecosystems. They have attracted attention for their potential role in regulating the exchanges between communities, and thus their potential influence on biogeochemical cycles, population connectivity and species distribution. Ecotones may also act as early warning signals of habitat degradation and climate change effects and are therefore features of interest for conservation and ecosystem-based management. Research on ecotones has been steadily progressing in recent years, however there remains a lack of consensus regarding a conceptual framework for ecotones at the multi-species and multivariate level that ecological communities represent. Hence, the main objective of this work is to propose – and to test – such a framework. This work develops an operational definition of ecotones that (i) relies on the elevated turnover rate in species composition over space to statistically locate ecotones, and (ii) advocates for the linkage, both conceptually and in terms of ecological representations, of ecotones and ecological communities. Ecotone parameters that were previously defined for single species response (i.e. Depth of Edge Influence (DEI), Magnitude of Edge Influence (MEI) and Abruptness of Edge Influence (AEI)) are further adapted to multi-species (i.e. community) response. The concept of (a)symmetry (to describe potential discrepancies in the response of adjoining communities to their intervening ecotone) and the concept of mosaicity (the re-occurrence of community patches along ecotones) are also examined, for a finer description of community responses to ecotones. A methodological approach, coherent with the proposed ecotonal framework, is then designed (available via an associated R-package). This methodological approach is first tested on artificial data, with known patterns, before being applied on real-world data from terrestrial (bog to forest sequence, South Island, New Zealand), benthic (Fiordland, South-West New Zealand) and pelagic (Munida transect, offshore South-East New Zealand) ecosystems. Ecotones could be characterised in all ecosystems. Their locations coincided with environmental transitions, and their parameters (AEI, DEI and MEI) proved comparable among studies. Irregular community edges and edges presenting patterns of asymmetry were commonplace. Mosaicity, however, only occurred along subtle environmental gradients, where biotic interactions apparently shaped community patchiness. The commonly hypothesised peaks of alpha diversity around ecotones were only occasionally reported at the edges of ecosystem dominated by foundations species, in both terrestrial and marine benthic environments. The existence of species ecotonal preferences was also reported in all ecosystems, but not the existence of strictly ecotonal species. Beyond the sole scope of ecotone investigations, the approach developed in this study efficiently revealed ecosystem patchiness, particularly in the case of microbial communities in the pelagic ecosystem. Extracting information on community edge characteristics may also help defining the required patch size for a core community to exist, and may improve predictions regarding community dynamics at the landscape level. Integrating ecotones and communities in inclusive ecological representations thus provides relevant information for ecosystem-based management, and we therefore encourage the integration of ecotones in future research on the spatial structure of ecosystems.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectEcotone
dc.subjectCommunity ecology
dc.subjectFuzzy cluster
dc.subjectBenthic
dc.subjectMicrobial ecosystems
dc.subjectPelagic
dc.subjectVegetation sequence
dc.subjectAssembly rules
dc.titleMeta-ecosystem approach to ecotones. Methods and applications
dc.typeThesis
dc.date.updated2020-11-17T21:18:13Z
dc.language.rfc3066en
thesis.degree.disciplineMarine Science
thesis.degree.nameDoctor of Philosophy
thesis.degree.grantorUniversity of Otago
thesis.degree.levelDoctoral
otago.openaccessOpen
otago.evidence.presentYes
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