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Title: Mammalian community responses to a gradient of land-use intensity on the island of Borneo
Author: Wearn, Oliver
ISNI:       0000 0004 6346 8858
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2016
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Southeast Asian rainforests have, in recent decades, experienced the highest rates of deforestation and logging across the major tropical regions. This has left a vast estate of degraded forest in the region, which is under threat from further degradation and conversion to agriculture, principally for the expansion of oil palm (Elaeis guineensis) plantations. However, knowledge of the relative conservation value of different land-uses in the region is still limited, and a robust quantitative basis for resolving land-use tradeoffs, in particular between agricultural yield and biodiversity, is lacking. I aimed to assess terrestrial mammal species richness, abundance and β-diversity across a gradient of land-use intensity (old-growth forest, logged forest and oil palm) in Sabah, Malaysian Borneo. Overall mammal species richness was conserved even in the intensively-logged forests that I sampled, as were the majority of apparent old-growth specialists. Oil palm, on the other hand, harboured a highly depauperate mammal community. These broad patterns were echoed for overall mammal abundance, as well as in the potential ecosystem functions of mammals that I examined. However, I found evidence that the fundamental drivers of community assembly were altered across the land-use gradient and so, consequently, were patterns of β-diversity. Fine-grained β-diversity, in particular, was highest across the land-uses in logged forest, reflecting the increased environmental heterogeneity in this habitat. In addition, community composition and species abundance were not stable across land-uses. Omnivores and herbivores were more abundant in logged forest compared to old-growth forest, and only a limited number of carnivore species persisted in oil palm. Invasive species increased in abundance with land-use intensity. My findings underline the conservation importance of the large areas of degraded forest in Southeast Asia, and the extremely limited value offered by oil palm. If sustainability of the palm oil industry is to be achieved, new plantations should be diverted away from all remaining unfragmented forests, both old-growth and degraded forests alike.
Supervisor: Ewers, Robert Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral