Vertical Distribution of Termites on Trees in Two Forest Landscapes in Taiwan

Termites are a key functional group in the forest ecosystem, but they damage trees. To investigate the termite infestation pattern on the whole tree, we cut 108 blackboard trees, Alstonia scholaris (L.) R. Br., and 50 Japanese cedars, Cryptomeria japonica (L. f.) D. Don, into sections. The bark surface and cross sections of the tree trunk were examined along the axes. A high percentage of blackboard trees (92.6%) was infested by fungus-growing termites, Odontotermes formosanus (Shiraki), but damage was limited to the bark surface at a 2-m height. The infestation rate of dampwood termites, Neotermes koshunensis (Shiraki), was only 4.6% (5/108), and all infestations were associated with trunk wounds. N. koshunensis was found at significantly higher portion of a tree than O. formosanus. Among 50 Japanese cedars, 20 living trees were not infested by any termites, but 26 of the 30 dead trees were infested by subterranean termites, Reticulitermes flaviceps (Oshima), which excavated tunnels in the trunk. The infestation rate at basal sections was higher than that at distal sections. Only one Japanese cedar tree was infested by another dampwood termite, Glyptotermes satsumensis (Matsumura). The two dominant termite species, O. formosanus and R. flaviceps, had subterranean nests and infested trees from bottom up. The two primitive termites N. koshunensis and G. satsumensis had low infestation rates and are most likely to infest trees by alates from top down. The niche segregation in trees of three termite families, Kalotermitidae, Rhinotermitidae, and Termitidae, was distinct.