Title: Construction of a canopy observation system in a tropical rainforest of Sarawak
Abstract: We constructed a canopy observation system, comprised of two tree towers at heights > 50 m above the ground and 9 spans of aerial walkway with the total length of 300 m, in a lowland mixed dipterocarp forest in Lambir Hills National Park, Sarawak, Malaysia in 1992-1993. This paper illustrates the construction procedures and discusses methodology for studies of the rainforest canopy. In the early 1980s, pioneer works in tropical rainforests revealed that the canopy of tropical rainforests was the center of most plant productivity and reproduction (Sutton et al. 1983; Whitmore 1984), and animal abundance (Erwin 1983, 1988; Stork 1987a, 1987b, 1988a, 1988b; Rees 1983), varying with distribution of food and shelter resources. These findings stimulate the development of techniques to access the canopy, which reaches 40 to 70 m above ground. Several access methods have been developed, e. g. ropes and ascenders (Mitchell 1982; Perry 1978, 1984; Dial & Tobin 1994), raft (Halle & Pascal 1992), crane (Joyce 1991; Illueca & Smith 1993), tower and walkway (Mitchell 1982). Each method has advantages and disadvantages, and must be selected to fit the purposes of a study. The Canopy Biology Program in Sarawak (CBPS) started in 1 99 1 to study plant phenology, seasonal changes in insect abundance and interactions between plants and animals in canopy layers (Inoue & Hamid 1994). Rainfall in the Southeast Asian tropics changes greatly from month to month with varying periodicity (Inoue & Nakamura 1 990; Inoue et al. 1993). Of these periods, the most predominant occurs every 4 to 6 years and is caused by the El Nino and Southern Oscillation, (and the drought 1 Corresponding author. 2 Present address: Center for Ecological Research, Kyoto University, Otsu 520, Japan. which follows lasts for up to 10 months). The drought triggers a general flowering of mixed dipterocarp forests in this region (Ashton et al. 1988; Ashton 1993; Appanah 1993). To understand patterns of plant phenology in such a changing environment, we need to monitor plant phenology and insect abundance for at least one episode of the season. CBPS plans to conduct bimonthly censuses of both plants and insects along a fixed route in the canopy for at least one episode. We have employed the combination of tree towers and aerial walkways as the best access method for the long-term observations described above. Rafts cannot be set in the same location for long periods due to potential harmful effects on trees. And, due to existence of emergent trees, rafts are difficult to land on the irregular canopy surface in Southeast Asian rainforests. A crane cannot cover an area greater than its boom length, and its construction disturbs the forest during the transportation of materials and construction of base plates. Single rope techniques are inconvenient for routine censuses. Tree towers and aerial walkways had already been constructed in various places in Southeast Asia (Pasoh, Peninsular Malaya; Poring, Sabah; Semengoh, Sarawak among others). We have modified previous methods to fit our long-term use and have integrated methods to cover a wide area of canopy. We have constructed two tree towers extending >50 m and connected by 9 spans of aerial walkway that pass through various
Publication Year: 1995
Publication Date: 1995-01-01
Language: en
Type: article
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Cited By Count: 51
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