Chris McElhinny

Contribution of illegal hunting, culling of pest species, road accidents and feral dogs to biodiversity loss in established oil-palm landscapes

Abstract Context. Understanding the ecological impacts of the palm-oil industry on native fauna requires information on anthropogenic threats that may cause species decline or local extinction. Aim. The main aim of the study was to assess wildlife deaths caused by illegal hunting, road accidents and introduced predators in established oil-palm landscapes in Peninsular Malaysia. Methods. Between April and October 2009, we interviewed 362 oil-palm workers at 36 sites, including large industrial estates and semi-traditional smallholdings. Key results. Our results showed that (1) illegal hunting by oil-palm workers in different oil-palm management systems was not statistically significant (P = 0.097), (2) native fauna were more often destroyed as pests in smallholdings than in conventional and eco-friendly plantation estates (P = 0.005), (3) non-local poachers conducted illegal activity more often in smallholdings than in conventional and eco-friendly plantation estates (P = 0.011), (4) road accidents were reported to kill more native fauna in conventional plantation estates than in smallholdings and eco-friendly plantation estates (P < 0.001) and (5) feral dogs were reported as killing more native fauna in eco-friendly plantation estates than in conventional plantation estates and smallholdings (P = 0.034). Conclusion. In addition to the conversion of native forest to oil-palm monocultures, various other anthropogenic threats can have a substantial effect on wildlife in oil-palm landscapes. Implications. To improve the conservation value of oil-palm landscapes, we recommend that palm-oil stakeholders should implement anti-poaching patrols, organise conservation programs to educate workers, reduce vehicle speeds on roads within oil-palm landscapes, and control local populations of feral dogs.

The effect of seed trees on regrowth development in a mixed-species eucalypt forest

Summary Previous studies have shown that the retention of overwood can have suppressive effects on the development of regrowth. In this study we compared the effect of retaining seed trees (mature Eucalyptus pilularis), and removing seed trees, on the regrowth of E. pilularis and the more tolerant eucalypt species such as E. microcorys, E. propinqua, E. acmenoides, and E. paniculata. The study utilised a mixed hardwood stand located within Pine Creek State Forest, near Coffs Harbour in north-eastern New South Wales. The stand had been regenerated in 1972 leaving 15 seed trees/ha. Half of the seed trees were removed in 1990. Measurements of height, diameter, and distance of regrowth trees to the seed trees indicated that the height of regrowth was significantly affected by distance from seed tree (removed or retained). This suppressive effect was significantly more pronounced for E. pilularis than for more tolerant species. Height development of the regrowth improved significantly where seed trees had been removed. For the intolerant species the height-to-diameter ratio decreased with distance from seed tree (removed or retained), whereas for tolerant species the height to diameter ratio remained constant over all distances. The results of this study confirm that intolerant eucalypt species are more sensitive to overstorey competition than more tolerant species, and that the relative loss of production from the retention of mature trees may be smaller in mixed stands consisting of tolerant and intolerant eucalypt species than in mono-specific stands of intolerant species.

The effect of gap size on growth and species composition of 15-year-old regrowth in mixed blackbutt forests

Summary In north-eastern New South Wales (NSW) the Regional Forest Agreement process has transferred more than 400 000 ha of state forests to national park, and restricted silviculture to ‘single tree selection’ and a light form of ‘Australian group selection’. While these silvicultural systems are theoretically well suited to ecologically sustainable forest management, there is concern that in their current form they are not achieving adequate regeneration or optimising the growth of that regeneration. This is of particular concern for mixed-species blackbutt forest, for which there is no quantitative research concerning the growth and composition of regeneration within group-selection gaps. We address this issue by: (1) quantifying the effect of gap size, and other gap characteristics including distance from gap edge, on the growth of regeneration; and (2) assessing the effect of gap size on the composition of regeneration. We use the answers to these questions to recommend a gap size for group selection silviculture in mixed-species blackbutt forests in north-eastern NSW. We measured attributes describing the growth and composition of regeneration in nine circular group-selection gaps in mixed—species blackbutt forest near Coffs Harbour and Wauchope. These gaps contained 14.5–15.5-y-old regeneration and provided three replicates of small (0.27–0.3 ha), medium (0.45–0.67 ha) and large (0.93–0.97 ha) gaps. ANOVA testing indicated significantly (P < 0.05) lower height, diameter and volume growth of dominant blackbutt stems up to five metres from gap edge. Outside this zone growth remained fairly constant, indicating dominant blackbutt trees were susceptible to suppression only in close proximity to gap edges. Multiple regression analysis confirmed the relatively short distance from gap edges over which suppression occurred, with distance to closest gap edge explaining a small proportion of the variation in the models fitted for tree—and plot-level growth. The origin of blackbutt regeneration within gaps was a significant effect in tree-level growth models, with planted stems having increased diameter and volume growth compared with stems regenerated from natural seedfall. Gap size had no significant effect on the composition of regeneration. We conclude that for the range of gaps tested, 1-ha gaps are optimal for growth because they minimise the proportion of gap within 5 m of the retained forest edge, without altering composition. Larger gaps have also been shown to have operational and economic benefits compared with smaller gaps.