Estimation of whole-tree and stand-level methane emissions from the stems of Alnus japonica in a cool-temperate forested peatland
Abstract
We measured methane (CH4) fluxes at the stem surfaces of canopy trees in a forested peatland of northern Japan to estimate: 1) the CH4 emission rates from the stems of individual trees and 2) the stem CH4 emission rates at the stand level. The study site was located ca. 1 km south of Lake Tofutsu, a brackish lake in eastern Hokkaido. An experimental plot was established in an area dominated by Alnus japonica trees. For seven A. japonica, the stem CH4 fluxes were measured using a static closed-chamber method. Three of the sample trees were used to estimate the whole-tree stem CH4 emissions. The CH4 flux was measured at six heights (0.15 - 5.15 m above the ground at 1 m intervals) on the stem of each tree, using a scaffold constructed beside the tree. The stand-level stem CH4 emissions were estimated from the CH4 fluxes measured 0.15 m above the ground; the relationship between stem height and CH4 flux and the relationship between diameter at breast height and whole-tree CH4 emissions were determined. Stem CH4 emission rates were highest at the lowest measurement position on the stem (height 0.15 m), and decreased with stem height for all measurements. Nevertheless, significant CH4 emissions were detected 5.15 m above the ground. The relationship between stem height and CH4 emissions fit a power function. The estimated CH4 emission rate from the stem surface of an individual tree was 1.91 ± 1.24 and 0.68 ± 0.18 mg tree-1 h-1 for late-August and mid-September, respectively. The estimated stem CH4 emissions at the stand level varied seasonally, with the highest rate of 556 mg ha-1 h-1 in September.
- Publication:
-
EGU General Assembly Conference Abstracts
- Pub Date:
- April 2016
- Bibcode:
- 2016EGUGA..18.3399T