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Accueil du site → Doctorat → Australie → Wild pollinator communities of native woodlands and commercial almond plantations in a semi-arid Australian landscape : Implications for conservation of insects and ecosystem services

Charles Sturt University (2014)

Wild pollinator communities of native woodlands and commercial almond plantations in a semi-arid Australian landscape : Implications for conservation of insects and ecosystem services

Saunders, Manu E

Titre : Wild pollinator communities of native woodlands and commercial almond plantations in a semi-arid Australian landscape : Implications for conservation of insects and ecosystem services

Auteur : Saunders, Manu E

Université de soutenance : Charles Sturt University

Grade : Doctor of Philosophy (PhD) 2014

Résumé
Understanding how monocultures of introduced crop species interact with native ecosystems and wildlife in the surrounding landscape is vital for the ecological management of agroecosystems, and can have far-reaching benefits for biodiversity conservation and crop yields. Insects make essential contributions to ecosystem functions in all types of ecosystems and many functions are synergistically linked, like pollination and biological pest control. Thus, the conservation of invertebrate communities in agricultural landscapes is paramount. Although many studies have investigated pollinator communities using field crops (e.g. canola), more information is needed on how plantations of deciduous tree crops influence local insect communities, as these agroecosystems can create permanent spatial and temporal homogeneity across agricultural landscapes. I sampled potential wild pollinators in commercial almond plantations and native mallee vegetation in northwest Victoria, Australia, over two almond flowering seasons in late winter of 2010 and 2011. The aim of the study was to provide information on the abundance, richness and composition of insect pollinator communities at this time, which is the critical life stage for both almond trees (reproduction) and insects (emergence and reproduction). In particular, I focused on comparing patterns of insect community distribution relative to environmental attributes of mallee vegetation and almond plantations, with the goal of identifying how plantations might influence the conservation of wild insect communities, and thus enhance ecosystem service provision in commercial plantations. Overall, I found that potential wild pollinators were using almond plantations in the Victorian mallee during the almond flowering season. However, their movement into plantation interiors was limited by homogeneous vegetation structure and a lack of essential resources, such as temporal continuity of food resources and the availability of nesting sites. Wild pollinators, particularly native bees, were more abundant in small almond orchards with weedy ground cover across orchard floors, compared to both monoculture plantations and native mallee vegetation. In small orchards surrounded by a heterogeneous agricultural mosaic landscape, abundance and richness of pollinator groups were negatively associated with the proximity of native vegetation. However, in broadacre xii monoculture plantations, most pollinator taxa were limited to edges near native mallee vegetation, or within remnant patches of mallee in the plantation interior. In particular, native bees were only collected in remnant mallee patches inside the plantations, rather than in blocks of almond trees. Before and after almond flowering, when resources inside plantations were limited, pollinator groups were mostly associated with sites that provided alternative foraging and nesting resources, such as leaf litter, ground cover vegetation or the presence of herbivorous insect prey. The work presented in this thesis has two-fold significance. My results provide valuable information on potential wild pollinators using Australian almond plantations, which has the capacity to motivate the adoption of ecological management goals among growers and enhance awareness of the essential contribution of wild insects to ecosystem functions. I also highlight important knowledge gaps in our understanding of the diverse invertebrate fauna of the Victorian mallee regions, an area of high conservation value, which can inform future research and conservation goals.

Mots clés : Agroecosystem Mallee Orchard Plantation Wild pollinators

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Page publiée le 17 janvier 2015, mise à jour le 5 juillet 2017