Carbon sequestration in boreal jack pine stands following harvesting

Abstract

A large area of boreal jack pine (Pinus banksiana Lamb.) forest in Canada is recovering from clear-cut harvesting, and the carbon (C) balance of these regenerating forests remains uncertain. Net ecosystem CO 2 exchange was measured using the eddycovariance technique at four jack pine sites representing different stages of stand development: three postharvest sites (HJP02, HJP94, and HJP75) and one preharvest site (OJP). The four sites, located in the southern Canadian boreal forest, Saskatchewan, Canada, are typical of low productivity jack pine stands and were 2, 10, 29, and 90 years old in 2004, respectively. Mean annual net ecosystem production (NEP) for 2004 and 2005 was À137 AE 11, 19 AE 16, 73 AE 28, and 22 AE 30 g C m À2 yr À1 at HJP02, HJP94, HJP75 and OJP, respectively, showing the postharvest jack pine stands to be moderate C sources immediately after harvesting, weak sinks at 10 years, moderate C sinks at 30 years, then weak C sinks at 90 years. Mean annual gross ecosystem photosynthesis (GEP) for the 2 years was 96 AE 10, 347 AE 20, 576 AE 34, and 583 AE 35 g C m À2 yr À1 at HJP02, HJP94, HJP75, and OJP, respectively. The ratio of annual ecosystem respiration (R) to annual GEP was 2.51 AE 0.15, 0.95 AE 0.04, 0.87 AE 0.03, and 0.96 AE 0.03. Seasonally, NEP peaked in May or June at all four sites but GEP and R were highest in July. R at a reference soil temperature of 10 1C, ecosystem quantum yield and photosynthetic capacity were lowest for the 2-year-old stand. R was most sensitive to soil temperature for the 90-year-old stand. The primary source of variability in NEP over the course of succession of the jack pine ecosystem following harvesting was stand age due to the changes in leaf area index. Intersite variability in GEP and R was an order of magnitude greater than interannual variability at OJP. For both young and old stands, GEP had greater interannual variability than R and played a more important role than R in interannual variation in NEP. Based on year-round flux measurements from 2000 to 2005, the 10-year stand had larger interannual variability in GEP and R than the 90-year stand. Interannual variability in NEP was driven primarily by early-growing-season temperature and growing-season length. Photosynthesis played a dominant role in the rapid rise in NEP early in stand development. Late in stand development, however, the subtle decrease in NEP resulted primarily from increasing respiration.

Global patterns of ecosystem carbon flux in forests: A biometric data‐based synthesis

“…This technique has been used to determine net ecosystem exchange (NEE) at the site level within three major forest biomes: boreal [e.g., Zha et al, 2009], temperate [e.g., Richardson et al, 2007], and tropical forests [e.g., Bonal et al, 2008]. The extensive measurements from these individual studies have been synthesized to evaluate large-scale patterns of ecosystem carbon fluxes across regional [e.g., Valentini et al, 2000;Law et al, 2002;Kato and Tang, 2008] and global scales [e.g., Baldocchi, 2007;Luyssaert et al, 2007;Yuan et al, 2009;Beer et al, 2010;Mahecha et al, 2010].…”

The use of forest stand age information in an atmospheric CO<sub>2</sub> inversion applied to North America

“…Apps et al (2006) pointed out that the change in ecosystem structures, especially the age-class structure of forests, is at least as important as the change driven by physiological mechanisms. Recently, observations of carbon fluxes derived from the Fluxnet-Canada network using the eddy covariance technique have also reinforced the strong relationships between forest age and carbon fluxes (e.g., Coursolle et al, 2006;Zha et al, 2009).…”

The impact of climate variation and disturbances on the carbon balance of forests in Hokkaido, Japan

“…However, understanding the effect of disturbance on the carbon balance requires data gathered over several decades, from the time the disturbance occurs until the forests reach maturity (Janisch and Harmon, 2002;Grant et al, 2010;Goulden et al, 2011). The changes in carbon stock and carbon flux caused by disturbance have been investigated by using the chronosequence approach, in which flux measurements are made in similar forest stands that differ in age (Howard et al, 2004;Amiro et al, 2006Amiro et al, , 2010Zha et al, 2009;Goulden et al, 2011). Numerical simulation using ecosystem models also has been used to evaluate the longterm effects of disturbance and recovery on the carbon balance (Janisch and Harmon, 2002;Taylor et al, 2008;Ito, 2012).…”