Turner, Ian Mark
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Publication The seedling survivorship and growth of three Shorea species in a Malaysian tropical rain forest(1990) Turner, I.M.; BOTANYInvestigated the establishment and seedling survival of Shorea curtisii, S. multiflora and S. pauciflora at Pantai Aceh Forest Reserve, Penang. Under shaded conditions none of the species grew beyond the 2-leaf stage over their 1st year. Shorea multiflora seedlings suffered a 72% mortality, significantly lower than that of S. pauciflora (89%) and S. curtisii (93%). The major cause of mortality appeared to be drought, though S. curtisii was also prone to predation by small mammals. In a gap, S. curtisii seeds probably germinated less well but seedling survival (28% vs 7%) and growth were better than canopy-shaded conspecifics. Seedlings in gaps escaped small mammal predation. -from AuthorPublication Species loss in fragments of tropical rain forest: A review of the evidence(1996-04) Turner, I.M.; BOTANY1. A review of the literature shows that in nearly all cases tropical rain forest fragmentation has led to a local loss of species. Isolated fragments suffer reductions in species richness with time after excision from continuous forest, and small fragments often have fewer species recorded for the same effort of observation than large fragments or areas of continuous forest. 2. Birds have been the most frequently studied taxonomic group with respect to the effects of tropical forest fragmentation. 3. The mechanisms of fragmentation-related extinction include the deleterious effects of human disturbance during and after deforestation, the reduction of population sizes, the reduction of immigration rates, forest edge effects, changes in community structure (second- and higher-order effects) and the immigration of exotic species. 4. The relative importance of these mechanisms remains obscure. 5. Animals that are large, sparsely or patchily distributed, or very specialized and intolerant of the vegetation surrounding fragments, are particularly prone to local extinction. 6. The large number of indigenous species that are very sparsely distributed and intolerant of conditions outside the forest make evergreen tropical rain forest particularly susceptible to species loss through fragmentation. 7. Much more research is needed to study what is probably the major threat to global biodiversity.Publication Artificial nest and seed predation experiments in tropical lowland rainforest remnants of Singapore(1998-07) Wong, T.C.M.; Sodhi, N.S.; Turner, I.M.; BIOLOGICAL SCIENCESTropical lowland rainforests of Southeast Asia are continually being fragmented and lost at an alarming rate. Little is known about the consequences of this large-scale habitat modification. Using artificial nest and seed experiments, we determined predation rates in forest remnants (2.5-1100 ha in area) of Singapore and Pulau Ubin. Singapore (641 km2) is highly urbanised with only 5% of the native forest cover remaining, whereas Pulau Ubin (11 km2) is relatively less developed with about 60% of the native forest cover remaining. We specifically determined if predation rates varied in relation to: (i) distance from edge, (ii) forest types, (iii) forest areas, (iv) isolation, (v) edge to area ratio, (vi) canopy closure, and/or (vii) area (Singapore vs Pulau Ubin). Overall, 80.5% (n = 328) of artificial ground nests were depredated, of which 55.3% were predated by small mammals. For seeds, 98.2% (n = 219) experimental stations were predated. Generally, the predation rate did not vary significantly in relation to the distance from the edge, though a primary forest remnant had lower artificial nest and seed predation rates than the other remnants. Pulau Ubin remnants were found to have lower predation rates than remnants on Singapore island. No significant correlations were found between predation rates and remnant area, isolation from other remnants, or the edge/area ratio, or canopy density. Relatively high predation rates in some tropical secondary and primary forest remnants may greatly influence plant regeneration and bird community structure.Publication The effect of fertilizer application on dipterocarp seedling growth and mycorrhizal infection(1993-03) Turner, I.M.; Brown, N.D.; Newton, A.C.; BOTANYIn three independent experiments, application of fertilizers had no effect on the growth of dipterocarp seedlings. The experiments involved application of: (1) NPK at a rate of 10 gm-2 N, P2O5 and K2O to Shorea macroptera Dyer seedlings grown in pots of forest soil under nursery conditions in Penang, Malaysia; (2) N at a rate of 10 g m-2 and/or P at a rate of 5 g m-2 in a factorial design to 8-month-old Shorea curtisii Dyer ex King seedlings growing wild in coastal hill dipterocarp forest in Penang, Malaysia; (3) NKP at a rate of 10 g m-2 three times over 10 months to Hopea beccariana Burck seedlings growing wild in lowland mixed dipterocarp forest in Sabah, Malaysia. In Experiment 1, fertilizer application significantly increased the extent of ectomycorrhizal (ECM) infection of the S. macroptera roots, and fertiliezed seedlings. These preliminary results suggest that dipterocarp seedlings may only be responsive to fertilizer addition when grown at very low nutrient availabilities, and that ECM infection may be of great importance to seedling growth under such conditions. © 1993.Publication Foliar defences and habitat adversity of three woody plant communities in Singapore(1995) Turner, I.M.; BOTANYPublication Adinandra belukar: an anthropogenic heath forest in Singapore(1992-10) Sim, J.W.S.; Tan, H.T.W.; Turner, I.M.; BOTANYAdinandra belukar is a species-poor forest dominated by Adinandra dumosa (Theaceae) found in Singapore and southern Peninsular Malaysia. It is the product of secondary succession after exhaustive agricultural exploitation on land cleared of primary lowland rain forest. A high degree of similarity in vegetation between different sites was found for seven 225 m2 plots in a dinandra belukar in Singapore. Adinandra dumosa was dominant or codominant in all plots, generally found in association with the woody species Dillenia suffruticosa, Fagraea fragrans, and Rhodamnia cinerea, the climber Gynochthodes sublanceolata, the fern Dicranopteris linearis and the terrestrial orchid Bromheadia finlaysoniana. All sites had extremely acidic (pH 3.3-3.9) surface (0-20 cm) mineral soils with very low total nitrogen (0.06-0.14%) and total phosphorus (11-29 μg g-1) contents and very high carbon/nitrogen ratios (33-48). Adinandra belukar is interpreted as a heath forest because of its floristic and physiognomic similarities with this forest formation. © 1992 Kluwer Academic Publishers.Publication HOW TOUGH ARE SCLEROPHYLLS(ACADEMIC PRESS LTD, 1993-04-01) TURNER, IM; CHOONG, MF; TAN, HTW; LUCAS, PW; Dr Mei Fun, Amy Choong; ANATOMY; TROPICAL MARINE SCIENCE INSTITUTE; BOTANYFracture toughness was estimated for a ‘least tough’ path in the leaves of woody species from three sclerophyllous plant communities. Most of the species from Mediterranean, tropical heath forest and lowland tropical rain forest habitats had very tough leaves, with toughness generally 600-1300 J rrT2, which is two to four times higher than soft- leaved tropical pioneer trees. The toughest leaf (2032 J m-2), Parishia insignis, came from the canopy of the lowland rain forest. Leaves from the shaded understorey of the rain forest did not appear any less tough than those from the canopy. © 1993 Annals of Botany Company.Publication Relationships between herb layer and canopy composition in a tropical rain forest successional mosaic in Singapore(1996-11) Turner, I.M.; Tan, H.T.W.; Chua, K.S.; BOTANYClusters of four circular forest plots, 0.2 ha in total area, were inventoried for canopy tree (≥30 cm gbh) and terrestrial herb floristic composition at 46 sites in the Central Catchment Nature Reserve, Singapore. The Nature Reserve covers a complex mosaic of lowland tropical forest of different successional stages, with much of the area covered in secondary forest 50-100 years old developed on exhausted agricultural soils. A total of 449 species of tree and 59 species of terrestrial herb were recorded from the clusters. Facultatively-terrestrial epiphytes were excluded from the analysis. Possible reasons for the low herb diversity are discussed. There was a marked similarity between ordinations (detrended correspondence analysis) of the clusters based on tree canopy composition weighted by species relative contribution to cluster total basal area and the herb flora composition, with a highly significant correlation between first axis scores of the two ordinations. Both ordinations showed the three clusters from freshwater swamp forest to be highly distinctive from the rest. The two forest strata exhibited a parallel response to the successional gradient, though the low diversity and patchy distribution of the herb flora blurred the distinction between primary and secondary communities more clearly seen in canopy composition.Publication Rapid assessment of tropical rain forest successional status using aerial photographs(1996) Turner, I.M.; Wong, Y.K.; Chew, P.T.; Bin Ibrahim, A.; BOTANYFour forest structural types were recognized and mapped from 1:20.000 black-and-white aerial photographs of the 2000 ha Central Catchment Nature Reserve in Singapore. These types were an essentially treeless unit of grassy areas and fern thickets (Type 1), a low forest with uniform canopy of many small trees (Type 2), a taller forest with larger trees (Type 3), and a yet taller forest with a structurally more heterogeneous canopy with some very large-crowned trees present (Type 4). The three vegetation units containing trees were sampled using clusters of circular plots totalling 0.2 ha each, in which all trees ≤30 cm gbh were measured and identified. Increasing canopy height and tree size among the structural types were reflected in increasing total basal area of the sample clusters. Mean tree species richness also increased with structural complexity. Ordination of the clusters based on their floristic composition showed that Type 4 was very varied but generally distinct from Types 2 and 3, which were much less diverse and not distinct from one another floristically. TWINSPAN was used to analyze the important floristic differences between the sample clusters. It was found that Types 2 and 3 were dominated by early successional species including Adinandra dumosa, Macaranga conifera and species of Calophyllum and Garcinia. Type 4 was typified more by the presence of species of Burseraceae and Dipterocarpaceae - primary forest trees. This mosaic of different successional stages is supported by the known history of the area, with massive deforestation in the mid and late 19th century. We conclude that the interpretation of aerial photographs is a useful tool for the fine-scale rapid assessment of the successional status of lowland tropical forest and can be used to infer relative levels of forest diversity. As such it can be of value in the rational management of tropical forest conservation areas.Publication Tree species richness in primary and old secondary tropical forest in Singapore(1997) Turner, I.M.; Wong, Y.K.; Chew, P.T.; Bin Ibrahim, A.; BIOLOGICAL SCIENCESIf secondary succession can accumulate species rapidly, then tropical secondary forests may have an important role to play in the conservation of biodiversity. Data on the floristic composition of forest stands in the Central Catchment Nature Reserve, Singapore, have been analysed to investigate the diversity of approximately 100-year-old tropical secondary forest. Classification using TWINSPAN indicated that three floristic communities could be recognized from 59 0.2 ha plots enumerated for trees > 30 cm gbh. These were two types of secondary forest, both dominated by Rhodamnia cinerea (Myrtaceae) and dryland primary forest. The secondary forest was developed on land abandoned after use for agriculture at the end of the 19th century. The 16 primary forest plots contained a total of 340 species, more than the 281 recorded from the 43 plots of the two secondary forest types combined. The mean species number per plot in the more diverse of the two secondary forests was only about 60% of the primary forest. Thus the secondary forest, despite a century or so for colonization by species and the presence of contiguous primary forest, was still significantly less diverse than primary forest areas. It is concluded that secondary forest cannot be assumed to accrete biodiversity rapidly in the tropics, and may not be of direct value in conservation. However, other indirect roles, such as providing resources for native animals, and buffering and protecting primary forest fragments may make the protection of secondary forest worthwhile.