H11G-1434
Factors Governing Stemflow Production from Plantation Grown Teak Trees in Thailand
Monday, 14 December 2015
Poster Hall (Moscone South)
Nobuaki Tanaka, University of Tokyo, Bunkyo-ku, Japan, Delphis F Levia Jr, University of Delaware, Newark, DE, United States, Yasunori Igarashi, HyARC Hydrospheric Atmospheric Research Center, Nagoya, Japan, Natsuko Yoshifuji, Forestry and Forest Products Research Institute, Tsukuba, Japan, Katsunori Tanaka, JAMSTEC, Yokohama, Japan, Tantasirin Chatchai, Faculty of Forestry, Kasetsart University, Bangkok, Thailand, Kazuki Nanko, Forestry & Forest Products Research Institute, Ibaraki, Japan, Masakazu Suzuki, University of Tokyo, Tokyo, Japan and Tomo'omi Kumagai, Nagoya University, Nagoya, Japan
Abstract:
Stemflow (SF) is recognized as an important process delivering water, solute, and particulate fluxes to spatially localized areas of the forest floor. Using both long-term SF data from nine even-aged deciduous teak trees grown in the same plantation and meteorological data from a nearby tower, this study seeks to better understand how: (1) specific biotic and abiotic factors control stand-scale SF production of teak; and (2) various biotic and abiotic factors affect tree-to-tree variations in teak SF production. A conventional regression analysis of SF volume against rainfall indicates that, for five individuals among the nine, SF was more efficiently produced in the leafless than in the leafed. However, for the other individuals, there was no such a relation, suggesting tree-to-tree variation in the response of SF to canopy status. A boosted regression tree (BRT) analysis setting daily basis SF funneling ratios (SFF) of the nine trees as dependent variables, indicates that SFF was intricately controlled by a variety of biotic and abiotic factors. The top six influential factors were, in descending order, rainfall duration, tree height, rainfall intensity, air temperature, wind speed, and antecedent dry period length having positive, negative, positive, negative, positive, and negative influence on SFF, respectively. Although teak exhibits drastic intra-annual changes in leaf phenology, leaf area index (LAI) had an unexpectedly small influence on SFF on a stand scale. Additional BRT analyses focusing on individuals with the maximum and the minimum SFF values (among the nine individuals) showed that there was considerable tree-to-tree variation in an array of the influential variables for SFF, even though they were planted in the same year and grown in the same plot. In addition to this difference, the BRT analyses also showed that response of SFF to LAI differs between the two individuals. The differentiating responses to LAI depending on individuals may be the reason for the apparent small influence of LAI on stand-scale SFF. This research clarifies some of the factors that control SF production for valuable teak trees at both individual tree and stand scales.
