Canopy research

Abstract: A method of climbing into the canopy of tall trees is described, using equipment which does not damage the tree and which can be carried by a single person. EPIPHYTIC PLANT DISTRIBUTIONS and densities within the upper canopy of tropical rainforests vary from tree to tree and with location (Went 1940, Richards 1964). Dominance by a given tree species in these forests tends to be lacking, and conspecifics are usually separated by long distances (Richards 1964). Spatial heterogeneity of plant species and of food resources such as flowers, fruits, and new leaves are primary factors in the movements and locations of numerous flying and arboreal animals (McClure 1966, Janzen 1971, Medway 1972, Frankie 1975). Ground-level observations on these subjects are difficult, and quantitative studies are virtually impossible due to obstructing lower vegetation and the inaccessibility of the upper canopy, which ranges from 30 to more than 60 meters. Thus, the animalplant interactions involving pollinators and foragers of canopy trees are largely unexplored. A knowledge of these interactions, however, is of major importance to an understanding of the structure and dynamics of tropical rainforest ecosystems (Regal 1977). Methods providing access and mobility in the canopy are essential for such studies, but most efforts have been put into constructing immobile structures such as towers, catwalks (Muul and Liat 1970), and platforms (Nicholson 1931, Hingston 1932, McClure 1966). Only one to a few trees can be closely studied from these structures, and the view of the canopy is often limited. A dozen towers, for instance, would be needed to study adequately the pollination ecology of a single tree species, so the cost would be pro, hibitive. Tree-climbing methods should be non-injurious to trees and safe for the researcher. Pole-climbers have been extensively employed to climb tropical rainforest trees (Hingston 1932), but the climbing spikes punch holes in the trunks, promoting fungal infections and insect attack. Further, they are often dangerous and difficult to use since contact with the trunk, and with its assorted noxious animals, is necessary. Once the crown is attained, movement is limited to the region of the leader (main stem), and thus access to the peripheral branches is often impossible. Denison et al. (1972) pioneered a methed for climbing large Douglas firs to conduct in situ quantitative studies on arboreal epiphytic community structure. Unfortunately, since long lag bolts are driven into the trunk every few feet to provide climbing support, the arguments against pole-climbers also apply to his procedures. He was the first, however, to apply rock climbing techniques, using rope ascendors (fig. 1-A), for scaling trees. The following method retains Denison's positive contributions while eliminating some of the problems. I report here on a tree-climbing method which is mobile, non-injurious to trees, and inexpensive. It also, provides access to the peripheral branches where flowers and fruits are often found. It was used extensively in the summers of 1974, 1975, and 1976 to study the pollination ecology of an emergent tree, Dipteryx panamensis (Perry and Starrett, ms. in prep.), factors influencing the micro-distributions of arboreal epiphytes (Perry 1978), and the vertical distributions of insect families in a lowland wet forest in Costa Rica (Perry, ms. in prep.). Lowland tropical rainforest canopy and emergent trees are not readily climbed due to the general absence of limbs along the first 25 m of trunk. To avoid touching or injuring the trunk, a rope is climbed which is hung from a high point in the tree. The placing of the rope is achieved by using an 80-lb pull crossbow and weighted arrow to shoot a 30-lb test monofilament line over the tree's crown or high limb. The weighting of the arrow ensures its return to the ground. Tangling of the line is prevented by wrapping it on a spool. A stronger (120to 240-lb test) braided nylon line is needed to lift the climbing rope into place. The braided line is too heavy to shoot directly into the canopy, so it must be pulled into the tree with the first line. A 240-lb test braided nylon line should be used when the rope touches several limbs, for abrasion becomes severe BIOTROPICA 10(2): 155-157 1978 155 This content downloaded from 157.55.39.143 on Wed, 15 Jun 2016 05:21:22 UTC All use subject to http://about.jstor.org/terms