PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Temporal and spatial variation in soil respiration in a Bornean tropical rainforest in Sarawak, Malaysia.

Ohashi, Mizue^*,1, Kume, Tomonori^*,2, Kumagai , Tomo'omi ^*,3, Saito, Taku ^*,3, Gyokusen, Koichiro ^*,3, Suzuki , Masakazu^*,2, ¹ Finnish Forest Research Institute, Joensuu, Finland² University of Tokyo, Tokyo, Japan³ Kyusyu University, Fukuoka, Japan

ABSTRACT- Since soil respiration is the largest component of ecosystem respiration, gaining an understanding of changes in soil respiration is indispensable in investigating the process of carbon flow and in estimating the future carbon balance of ecosystems in the face of environmental changes. In the current study, we investigated temporal and spatial variation in soil respiration in relation to temperature and moisture in a Bornean tropical rainforest in the Lambir Hills National Park, Sarawak, Malaysia, in order to gain basic knowledge of soil C dynamics in this ecosystem. The mean rate of soil respiration was 5.32 ± 0.11 SE molCO² m^-2 s^-1, ranging from 0.77 to 24.56 molCO² m^-2 s^-1. Soil respiration changed diurnally according to the change in temperature. The diurnal change in soil respiration showed closer relationships with air temperature than with soil temperature. There was no clear tendency in the seasonality in soil respiration and the range of seasonal variation was 3.53 molCO² m^-2 s^-1. Neither temperature nor moisture had any correlation with the seasonal variation. Soil respiration had high spatial variability and hot spots of soil respiration (> 10 molCO² m^-2 s^-1) appeared on some occasions. Semivariogram analysis revealed autocorrelations in the spatial changes in soil respiration. The range of autocorrelation was from 0.3 m to 17 m. Soil temperature and moisture had positive and negative correlations, respectively, with the spatial change in soil respiration. However, the relationships were not always clear. The results of this study indicate that the spatial variation in soil respiration is much higher than the temporal variation in this forest.

Key words: Tropical rain forest, Forest floor, Carbon cycle, Temperature