Occupancy and habitat of otter species across human-modified landscapes in Sabah, Malaysia
The conversion of continuous forest into agricultural crop plantation is a global conservation concern, particularly oil palm in Southeast Asia. Land-use changes are known to negatively affect biodiversity resources, and several mitigation strategies have been devised to minimize these harmful effec...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2020
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| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/42026/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/42026/2/FULLTEXT.pdf https://eprints.ums.edu.my/id/eprint/42026/ |
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| Summary: | The conversion of continuous forest into agricultural crop plantation is a global conservation concern, particularly oil palm in Southeast Asia. Land-use changes are known to negatively affect biodiversity resources, and several mitigation strategies have been devised to minimize these harmful effects. In oil palm plantation, one of the strategies is retaining forest fragments flanking rivers or streams, i.e., the riparian reserves, within the monoculture landscape. Although maintaining riparian reserves in human-modified landscapes has been accepted as a useful approach to enhance biodiversity resources or mitigate biodiversity loss in converted habitats, it remains unclear how riparian reserves may affect individual animal species, such as the otters, in the oil palm landscapes. The present study investigates the impact of land-use changes: logged forest (LF), heavily degraded forest (HDF), riparian reserve within oil palm plantation (RR), and oil palm plantation without riparian reserve (ROP) on otter occupancy as well as microhabitat structures in relation to otter presence. The study sites were located at the 'Stability of Altered Forest Ecosystem' (SAFE) project experimental area in and around the Kalabakan Forest Reserve, south-central Sabah, Malaysia. Visual signs surveys, i.e., based on footprints, spraint, and direct observation were conducted in 36 stream segments from 18 streams to detect otters' presence. Overall, a total of 162 otter signs were found in 16 of the 18 streams surveyed, and two species of otters were detected: the Asian Small-clawed Otter (Aonyx cinereus) and the Smooth-coated Otter (Lutrogale perspicillata). Areas in oil palm plantations were found to have higher otter occupancy compared to forested areas, with the highest occupancy recorded in ROP (1.00) followed by RR (0.96), LF (0.47), and HDF (0.41). This indicates that oil palm plantations and the riparian buffers are useful and may provide a functional habitat for the otter population in the oil palm plantation landscape. Several microhabitat structures were found to be positively associated with otter presence. The GLM analysis showed that substrates with a higher proportion of exposed soil or a combination of exposed soil and rocks; and a lower proportion of exposed rocks supported higher otter presence. The proximity to oil palm plantations is also a good predictor of otter presence with a positive effect, where streams located closer to plantations contained higher signs of otters. In contrast, the otters' presence was negatively affected by a narrow stream, narrow stream banks, smaller bank tree trunks, and stream located further away from the nearest human settlement. In general, the study revealed that retaining riparian buffers within oil palm dominated landscapes can be a useful strategy in the conservation of otter species. Thus, it is crucial to ensure the maintenance of riparian reserves in areas within oil palm plantations. This should be mandatory and monitored appropriately. Proper research needs to be conducted to design riparian reserves with suitable buffer width, particularly to cater to more susceptible s |
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