Carbon Stocks and Fluxes in Tropical Lowland Dipterocarp Rainforests in Sabah, Malaysian Borneo

Abstract

Deforestation in the tropics is an important source of carbon C release to the atmosphere. To provide a sound scientific base for efforts taken to reduce emissions from deforestation and degradation (REDD+) good estimates of C stocks and fluxes are important. We present components of the C balance for selectively logged lowland tropical dipterocarp rainforest in the Malua Forest Reserve of Sabah, Malaysian Borneo. Total organic C in this area was 167.9 Mg C ha−1±3.8 (SD), including: Total aboveground (TAGC: 55%; 91.9 Mg C ha−1±2.9 SEM) and belowground carbon in trees (TBGC: 10%; 16.5 Mg C ha−1±0.5 SEM), deadwood (8%; 13.2 Mg C ha−1±3.5 SEM) and soil organic matter (SOM: 24%; 39.6 Mg C ha−1±0.9 SEM), understory vegetation (3%; 5.1 Mg C ha−1±1.7 SEM), standing litter (<1%; 0.7 Mg C ha−1±0.1 SEM) and fine root biomass (<1%; 0.9 Mg C ha−1±0.1 SEM). Fluxes included litterfall, a proxy for leaf net primary productivity (4.9 Mg C ha−1 yr−1±0.1 SEM), and soil respiration, a measure for heterotrophic ecosystem respiration (28.6 Mg C ha−1 yr−1±1.2 SEM). The missing estimates necessary to close the C balance are wood net primary productivity and autotrophic respiration.Twenty-two years after logging TAGC stocks were 28% lower compared to unlogged forest (128 Mg C ha−1±13.4 SEM); a combined weighted average mean reduction due to selective logging of −57.8 Mg C ha−1 (with 95% CI −75.5 to −40.2). Based on the findings we conclude that selective logging decreased the dipterocarp stock by 55–66%. Silvicultural treatments may have the potential to accelerate the recovery of dipterocarp C stocks to pre-logging levels.

Carbon Content of Tree Tissues: A Synthesis

“…This value has been used in large-scale estimates of C pools and fluxes in natural tropical [12][13][14][15] and temperate forests [16][17][18][19], as well as smaller-scale estimates of C stocks in managed forests [20], agroforestry systems [21], tree plantations [22][23][24], and experimental forest sites [25]. However, recent data indicates that the 50% assumption introduces errors of ~5% in forest C stock estimates [2,3,26,27]. For example, in a previous study from a natural Panamanian forest, we found that using a 50% AGB-C conversion factor lead to a systematic overestimate of ~6.8 Mg C ha −1 [2].…”

Teores de carbono em espécies da floresta ombrófila mista e efeito do grupo ecológico

“…Entretanto, estudos indicam que a aplicação desse fator de conversão implica em erros grosseiros na estimativa dos estoques de carbono na biomassa florestal (MARTIN;THOMAS, 2011;MELSON et al, 2011;SANER et al, 2012;MALCZEWSKI, 2007), pondo em risco a credibilidade dos resultados gerados por meio desse artifício. Assumese, nesse caso, que a concentração de carbono é uma função direta e constante da biomassa, desconsiderando as variações inter e intra-específicas nos processos de alocação do carbono.…”

Carbon Stocking in the Natural Forests – The Case of Malaysia

“…Several researchers formulated equations for the determination of biomass (Kato et al, 1978;Chambers et al, 2001;Chave et al, 2005;Kenzo et al, 2009;Blujdea et al, 2012,). Researchers such as Hamdan et al (2011);Hamdan et al (2014); Morel et al (2011);Saner et al (2012); Sato et al (2013) applied the established equations to calculate the forest biomass.…”

“…A report by Saner et al (2012) revealed that the . The approach used to calculate the aboveground forest carbon stocks was based on secondary data obtained from FAO (2010).…”