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Results From The LTER Plot At LambirResults From The LTER Plot At Lambir

Results From The LTER Plot At Lambir

Preliminary results from the LTER plot have been written up and presented at two meetings, the first being the International Symposium on " The Tropical Rain Forest in a Global Greenhouse" which was held in Matsuyama, Japan from 21-22 January 1994 and the other being the Workshop on " Long Term Ecological Research of Tropical Rain Forest in Sarawak" which was held in Kuching, Sarawak, Malaysia from 25-27 July 1994. The papers presented at the Workshop in Malaysia have been included in its proceedings (Lee et al, 1995)7 . The results have also been written and published in both Japanese and Malaysian scientific journals by various scientists.

Some interesting results have already emerged from the First Phase of the LTER Study.

Forest Architecture

The use of electronic tachometers equipped with automatic distance meters to demarcate the 52-hectare plot resulted in a very detailed and accurate survey of the plot. The compass directions and zenith angles to elevation at the base of the respective land marks were also carefully surveyed by using tachometers and by following conventional land survey methods. The altitude difference between the lowest and the highest points in the plot was ca. 150m. The accurate survey enabled a topography map to be prepared (Yamakura et al, 1995)8 .The basic statistics of the topographic variables, such as altitudes, angles, directions and convexities of slopes were calculated for the respective 20m x 20m quadrats to which the plot was divided. The calculated statistics suggested the steeply sloped, sharply undulating and complexly bifurcated topography of the plot. These topographic features might be expressed by the term "broken topography" and seemed to fragment a whole entity of the plant habitat into small local fractions, which could be strongly related to the richest flora in Lambir among all the forests of the old world.

Species diversity

Chai et al. (1995)9 conducted a preliminary survey of the species diversity of the plot immediately following the completion of the first census. In all 358,905 stems above 1 cm dbh were recorded which translate to 6902 stems per hectare. This compares with 6705 stems per hectare for Pasoh Forest Reserve in Negri Sembilan, Peninsular Malaysia (Manokaran et al. 1992)10. Seventy-two families were recorded for Lambir, with seventy-eight for Pasoh; and 278 genera recorded in Lambir compared with 294 for Pasoh. In terms of species, however, 1083 species were recorded compared with 820 for Pasoh, indicating the very high species diversity at Lambir.

Comparison between Lambir and Pasoh

Location Lambir Pasoh Difference
Size of plot (ha) 52 50 +2
No. of families 72 78 -6
No. of genera 278 294 -16
No. of species 1083 820 -263

The questions can be asked 'why is there such a high diversity in an area whose soils are basically low nutrient in nature?' and 'what are the implications for restoration of deforested sites with poor soils?' An inference that can be drawn is that perhaps a multi-species planting approach rather than a monoculture approach should be taken.

Ecology of Dryobalanops

Itoh et al (1995)11 surveyed the spatial distribution of Picturetwo Dryobalanops (Kapur) spp., D. aromatica (Kapur peringgi) and
D. lanceolata (Kapur paji), of the family Dipterocarpaceae that co-exist in the mixed dipterocarp forest. Their spatial distributions were studied in the LTER plot, where the topography is highly heterogeneous. Distributions of the two species were highly segregated from each other in relation to their topography. The mean density of D. aromatica was positively correlated to the degree of concavity of surface relief, while that of D. lanceolata was negatively correlated. It was concluded that they co-exist in the plot by occupying different niches of the heterogeneous habitat mosaic and their distributions tend not to overlap.

Hirai et al (1995)12 examined soil property and topography in relation to the distribution of D. aromatica and D. lanceolata. Soil morphology, physico-chemical properties and soil microbiological property were examined. D. aromatica is located only on the upper slopes, but D. lanceolata occurs on both upper and lower slopes. The texture of the soils under D. aromatica is almost always sandy, while those under D. lanceolata tend to be sandy to clayey. The organic layer of soils under D. aromatica tends to be thicker suggesting a slower rate of decomposition. Soil color of subsurface horizons was duller in soils under D. lanceolata than D. aromatica, reflecting the dominance of more reductive conditions in soils under D. lanceolata. In addition soils under D. lanceolata contain large fragments (gravels), not found in D. aromatica soils, suggesting that soils under D. aromatica may be at a more stable pedogenic condition. Exchangeable cations such as Ca, Mg and K and total content of K, Mg, P and Na are higher for D. lanceolata soils than for D. aromatica, representing a higher fertility for the former. The proportion of air phase and volume of macropore and the value of sand content are higher for D. aromatica soils, showing that D. aromatica soils drain more freely. The fungal colonies are ten times higher in D. aromatica soils, a result which rather contradicts the chemical analysis if a higher fungal level indicates higher soil fertility. The results suggest that D. aromatica emerges on sandy soils where drier soil condition and lower nutrient status prevail, while D. lanceolata occurs on either clayey or sandy soils with a predominance of reduced condition. Higher soil fertility may possibly assist the activity and establishment of D. lanceolata to get over the reductive condition, which are sometimes unfavourable for tree roots. The results of the soil survey suggest that topography may not be the only factor in determining the spatial distribution of Dryobalanops.

Palmiotto (1995)13 mapped the spatial distribution of soil textural classes and the patterns of organic layer thickness in 1992. The soil texture was determined in the field together with measurements of litter depth, root mat thickness and the percentage of canopy cover. Seven soil textural classes were mapped. Coarser textured, high erodable soils (i.e. sandy loam and sandy clay loam soils) dominated two-thirds of the plot. Finer textural classes (i.e. clay and clay loam soils) dominated the south central section of the plot with distinct patches occurring along the eastern border. This occurrence of clay-rich soil in this south-eastern corner of the plot may explain the restriction of the distribution of Dryobalanops lanceolata to this area. Both leaf litter thickness and root mat thickness increased with increasing coarseness of soil texture. Mean thickness in clay loams were 1.1�0.3 cm, while that in sandy loam was 6.1�0.4 cm. Canopy density did not vary significantly between soil textural classes.

The forest canopy as a source of biodiversity

Emergent and tall trees are the major components of the forest structure. Tree diversity is ten times higher in tropical rain forests than in temperate forests and this latitudinal pattern is explained mostly by primary production. In tropical rain forests, which receive solar radiation throughout the year, trees can distribute themselves in multiple layers, in the manner that different plants utilise various light conditions. This multi-layer profile is a basis for high diversity of other life forms of plants and animals. The multi-layer profile produces various habitat condition in rain forests. Only 1% of the sunlight reaches the forest floor, gradually absorbed by leaves of plants above. Most primary production and reproduction occur at
canopy layersPicture more than 25m above the forest floor. The centre of insect distribution in rain forests is also the canopy in response to the intensity of primary production and reproduction of plants. This explains why the canopy is important as a source of biodiversity. Yet the canopy of the tropical rain forest is the least investigated of ecosystems due mainly to the difficulty in accessing it. Thus the canopy observation system in Lambir provides the facility and is of extreme importance the study of plant-plant and plant-animal relationships. It also provides the basis for a census of insect fauna, insect seasonal dynamics, pollination ecology, studies on the genetic structure of plants and plant phenology.

Cultural treatment of transplanted wildings

Palmiotto (1995)14 studied the use of plastic shelters on wildings lifted from the forest floor at the field station at Lambir. A plastic shelter consisted of a large translucent plastic sheet slung over a wooden frame measuring 120 cm. At the roof peak and 60 cm at the side. Within this shelter were stored the transplanted wildings. He noted that mortality of transplanted wildings of six forest tree species was reduced by enclosing the newly collected wildings in a plastic shelter for two to four weeks. Mortality 4 to 8 weeks after transplanting was significantly lower in the groups of wildings placed in a plastic shelter (mean = 5.2�11.2%, n=34, range=0-53.8%) than in the groups of wildings stored in a forest nursery (mean = 24.10�22.6%, n=53, range=0-87.5%). The plastic shelter created an environment of high relative humidity which prevented desiccation and facilitated the re-establishment of the wilding roots systems that may have been damaged during collection.

Survivorship and growth of dipterocarp seedlings

The survivorship and growth of seedlings of four dipterocarp species (Dipterocarpus actangulus, D. globosus, Dryobalanops aromatica and D. lanceolata) were studied for 2.5 years in Lambir Hills National Park (Itoh et al., 1995). Predispersal seed predation rates were larger for D. globosus (75%) than D. lanceolata (27-34%) and D. aromatica (18-26%). Less than 20% of the two Dryobalanops seeds were damaged by vertebrates after seed dispersal. During the period from seed dispersal to the time when the seedlings had shed cotyledons, more dispersed seeds died in the two Dipterocarpus (ca 90%) than the two Dryobalanops (ca 60-70%). The major mortality factors during this period were uprooting and seed/seedling predation by insects and vertebrates. After the seedlings shed cotyledons, all species showed constant mortality rates of 34, 15-16, 17 and 6%/year for D. actangulus, D. lanceolata, D. aromatica and D. globosus respectively in the forest understorey. Mortality was lower in less shaded conditions than in more shaded ones for D. aromatica and D. actangulus, but not significantly different for D. lanceolata and D. globosus. A majority of dead seedlings were killed by fallen branches or were found standing with wilted leaves, probably due to water stress. No significant correlation was found between seed/seedling mortality and distance from mother trees or the initial density of seeds/seedlings of all species. The mean leaf production was positively correlated with the estimated diffuse light factor of their habitats for each species. The study gave some positive evidence for the divergence of regeneration niches among the four dipterocarp species studied, and negative evidence for density- and distance- dependent seedling mortality.

General flowering of tropical rainforests in Sarawak



7Lee, H. S., Ashton, P. S. & Ogino, K. (eds.) (1995) Long Term Ecological ResearcPictureh of Tropical Rain Forest in Sarawak. Proceedings of the Workshop on "Long Term Ecological Research in relation to Forest Ecosystem Management", Kuching, Sarawak, Malaysia, 25-27 July 1994. Reports of A New Program for Promotion of Basic Sciences. Studies of Global Environmental Change with Special Reference to Asia and Pacific Regions, Vol. II-3, Ehime University, March 1995.
8Yamakura, T., Kanzaki, M., Itoh, A., Ohkubo, T., Ogino, K., Chai, E. O. K., Lee, H. S. & Ashton, P. S. 1995b. Topography of a large-scale research plot established within a tropical rain forest at Lambir, Sarawak. Tropics 5(1/2) : 41-56.
9Chai, E. O. K., Lee, H. S. & Yamakura, T. 1995. Preliminary results from the 52-hectare Long Term Ecological Research Plot at the Lambir National Park, Sarawak, Malaysia. In Lee, H. S., Ashton, P. S. & Ogino, K. ( eds.) Long Term Ecological Research of Tropical Rain Forest in Sarawak. ibid.
10Manokaran, N., LaFrankie, J. V., Kochumen, K.M., Quah, E. S. Klahn, J. E., Ashton, P. S. & Hubbell, S. P. 1992. Stand table and distribution of species in the fifty hectare research plot at Pasoh Forest Reserve. Forest Research Institute, Malaysia.
11Itoh, A., Yamakura, T., Ogino, K., Lee, H. S., Ashton, P. S. 1995. Relationship between topography and distributions of two emergent species, Dryobalanops and D. lanceolata (Dipterocarpaceae), in a tropical rain forest, Sarawak. In Lee, H. S., Ashton, P. S. & Ogino, K. (eds.) Long Term Ecological Research of Tropical Rain Forest in Sarawak. ibid
12Hirai, H., Matsumura, H., Hirotani, H. & Sakurai, K. 1995. Soils and the distribution of Dryobalanops and D. lanceolata in mixed dipterocarp forest - a case study at Lambir Hills National Park, Sarawak, Malaysia. In Lee, H. S., Ashton, P. S. & Ogino, K. ( eds.) Long Term Ecological Research of Tropical Rain Forest in Sarawak. ibid.
13Palmiotto, P. A. 1995. Preliminary characterization of soil texture and organic matter thickness in 52 ha. of lowland mixed dipterocarp forest, Lambir Hills National Park, Sarawak, Malaysia. In Lee, H. S., Ashton, P. S. & Ogino, K. (eds.) Long Term Ecological Research of Tropical Rain Forest in Sarawak. ibid.
14Palmiotto, P. A. 1995. Plastic shelters reduce mortality of transplanted wildings of forest tree used for experimental purposes. In Lee, H. S., Ashton, P. S. & Ogino, K. (eds.) Long Term Ecological Research of Tropical Rain Forest in Sarawak. ibid