INITIAL RESPONSE OF <em>SHOREA</em> WILDLINGS TRANSPLANTED IN GAP AND UNDERSTORY MICROSITES IN A LOWLAND RAIN FOREST

Abstract

Wildlings of six dipterocarp species, Shorea pinanga, S. parvistipulata, S. joharensis, S. hopeifolia, S. parvifolia and S. leprosula were transplanted in gap and understory microsites to assess their survival and growth in a lowland rain forest of West Kalimantan, Indonesia. At the end of the dry season in October 1990, 3^-y-old, bare-rooted wildlings were collected from the understory and transplanted; wildlings that died were replaced in a second planting two weeks later. Mortality within the first few weeks ranged from 40 to 85%. There was no significant difference in wildling survival between the gap and the understory microsites for the first planting. Wildlings in the replacement planting two weeks further into the wet season had less overall mortality and showed significantly higher survival in the gap microsites. Moisture stress, due to the extended dry period beginning before collection and continuing up to the time of wildling transplanting, is proposed as the cause of high mortality. This is supported by a strong positive correlation between species total leaf area per wildling and wildling mortality. High leaf area during times of moisture stress could therefore be a problem for transplanted bare-root wildlings. Greater growth occurred in the gap plots than in the understory plots; however, mean growth was not substantial due to die back and resprouting. These findings suggest that moisture stress can have a significant impact on wildling survival. Wildling collection and planting should therefore take place during wetter periods when soil moisture is high.