Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Assessment of the effects of natural and managed landscape processes on multiple indices of ecological function in semi-arid Australia

Auteur : Vapp Christopher

Université de soutenance : Deakin University

Grade : Master of Sustainability 2022

Résumé
Context : A key value of biodiversity conservation is to ensure adequate provision of organismal-based ecological functions that underpin ecosystem processes and resilience. Research evaluating how multiple species-mediated ecological functions respond to ecosystem, environmental or anthropic processes remains rare. The diversity or rates are assumed to be directly proportional to changes in species diversity, composition, and abundance. However, the loss or recovery of species can result in complex changes to the diversity and rates of ecological functions that may occur at any given ecological scale.
Aim : Develop and assess a multimeric monitoring framework to determine if differences in habitat type and predator management (i.e., exclusion fencing) influenced a suite of animal-mediated ecological functions.
Methods : 11 indices of ecosystem function measured at 22 sites were compared using multivariate (i.e. PerManova) and univariate analyses (GLMM) to evaluate the effects of environmental factors on overall and individual-based functional responses.
Results : The multivariate analysis showed significant variation between sites grouped by habitat type (Pr<0.05) and ecological fence treatment (Pr<0.05) while also having no significant difference in group variance. Univariate analysis showed sites inside the ecological fenced exclosure had significant increases in bioturbation leaf litter depth, seed predation and seedling presence while bioturbation seedling recruitment showed decreased rates. Habitat type showed significant variation in ground level vegetation coverage, average leaf litter depth and macropod grazing. Three indices, bioturbation dig count herbaceous vegetation cover and average leaf litter depth, showed significant variation due to the interactive effects of fence treatment and habitat type.
Conclusions : The use of functional indices allowed quantification of shifts in the distribution and rates of functions across the ecosystems that would be undetected by measures of population abundance. As a conservation tool this framework can quickly and easily be deployed to identify current variations in ecosystem functions within and between systems on multiple scales

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