The influence of fire on carbon distribution and net primary production of boreal Larix gmelinii forests in north-eastern China

Authors


Chuankuan Wang, tel +1 608 262 6369, fax +1 608 262 9922, e-mail ckwang@calshp.cals.wisc.edu

Abstract

The boreal larch forest of Eurasia is a widespread forest ecosystem and plays an important role in the carbon budget of boreal forests. However, few carbon budgets exist for these forests, and the effects of wildfire, the dominant natural disturbance in this region, on carbon budgets are poorly understood. The objective of this study was to quantify the effects of wildfire on carbon distribution and net primary production (NPP) for three major Dahurian larch (Larix gmelinii Rupr.) forest ecosystems in Tahe, Daxing'anling, north-eastern China: Larix gmelinii–Ledum palustre, Larix gmelinii–grass and Larix gmelinii–Rhododendron dahurica forests. The experimental design included mature forests (unburned), and lightly and heavily burned forests from the 1.3-million-ha 1987 wildfire. We measured carbon distribution and above-ground NPP, and estimated fine root production from literature values.

Total ecosystem carbon content for the mature forests was greatest for Larix–Ledum forests (251.4 t C ha−1) and smallest for Larix–grass forests (123.8 t C ha−1). Larix–Ledum forests contained the smallest vegetation carbon (13.5%), while Larix–Rhododendron contained the largest vegetation carbon (63.1%). Fires tended to transfer carbon from vegetation to detritus and soil. Total NPP did not differ significantly between the lightly burned and unburned stands, and averaged 1.58, 1.29 and 1.01 t C ha−1 year−1 for Larix–grass, Larix–Rhododendron and Larix–Ledum lightly burned stands, respectively. Above-ground net primary production (ANPP) of heavily burned stands was 92–95% less than unburned and lightly burned stands. The estimated carbon loss during the 1987 fire showed substantial variability among forest types and fire severity levels. Depending upon the assumptions made about the fraction of the landscape occupied by the three larch forest types, the 1987 conflagration in north-east China released 2.5 × 107−4.9 × 107 t C to the atmosphere. This study illustrates the need to distinguish between the different larch forests for developing general carbon budgets.

Ancillary