Soil CO₂ efflux and soil carbon balance of a tropical rubber plantation

Abstract

Natural rubber is a valuable source of income in many tropical countries and rubber trees are increasingly planted in tropical areas, where they contribute to land-use changes that impact the global carbon cycle. However, little is known about the carbon balance of these plantations. We studied the soil carbon balance of a 15-year-old rubber plantation in Thailand and we specifically explored the seasonal dynamic of soil CO2 efflux (F S) in relation to seasonal changes in soil water content (W S) and soil temperature (T S), assessed the partitioning of F S between autotrophic (R A) and heterotrophic (R H) sources in a root trenching experiment and estimated the contribution of aboveground and belowground carbon inputs to the soil carbon budget. A multiplicative model combining both T S and W S explained 58 % of the seasonal variation of F S. Annual soil CO2 efflux averaged 1.88 kg C m?2 year?1 between May 2009 and April 2011 and R A and R H accounted for respectively 63 and 37 % of F S, after corrections of F S measured on trenched plots for root decomposition and for difference in soil water content. The 4-year average annual aboveground litterfall was 0.53 kg C m?2 year?1 while a conservative estimate of belowground carbon input into the soil was much lower (0.17 kg C m?2 year?1). Our results highlighted that belowground processes (root and rhizomicrobial respiration and the heterotrophic respiration related to belowground carbon input into the soil) have a larger contribution to soil CO2 efflux (72 %) than aboveground litter decomposition. (Résumé d'auteur

Stand age‐related effects on soil respiration in rubber plantations (Hevea brasiliensis) in southwest China

“…The annual mean R S ranged from 90.29 ± 5.28 to 190.60 ± 6.24 mg CO 2 -C m −2 hr −1 , which was within the normal range of reported R S values in rubber plantations in Thailand (15 years old, 214.61 mg CO 2 -C m −2 hr −1 ) (Satakhun et al, 2013), Malaysia (5 years old, 202.09 mg CO 2 -C m −2 hr −1 ) (Mande, Abdullah, Aris, & Nuruddin, 2014), and China in Xishuangbanna (15 years old, 87.26 mg CO 2 -C m −2 hr −1 ) (Song et al, 2014) and in Hainan (5 to 33 years old, 114.50 to 136.53 mg CO 2 -C m −2 hr −1 , respectively) (Wu, Guan, et al, 2013). Soil respiration had a clear seasonal variation, with higher values in the rainy, warm season than in the dry, cold season, which was in line with the results of previous studies in rubber plantations and tropical forests (Rowland et al, 2014;Sha et al, 2005;Wu, Guan, et al, 2013;Zhou, Sha, Shen, & Zheng, 2008).…”

Carbon costs and benefits of Indonesian rainforest conversion to plantations

“…The fraction of heterotrophic CO 2 (fRh) in total soil CO 2 efflux was not determined. However, the fraction of CO 2 from heterotrophs reported in previous studies for rubber 32 and oil palm 33 monocultures ranged from 0.31 to 0.46 and from 0.20 to 0.70, respectively. Applying these portions to our sites, ecosystem C storage changes between −1.7 and + 0.7 kg C ha −1 y −1 in rubber plantations and −2.6 and + 2.3 Mg C ha −1 y −1 in oil palm plantations (Fig.…”

“…Additionally, the range of heterotrophic contribution in soil CO 2 efflux under oil palms was reported for individual management zones and soil moisture 33 , suggesting a more narrow range for soil CO 2 efflux averaged over a year at plantation scale. The fraction of soil heterotrophic CO 2 was extracted from a study on rubber monocultures with higher tree density and older age than the studied plots 32 . The reported range likely underestimates the contribution of heterotrophic CO 2 at our sites because it implies that roots respiration in rubber monocultures is similar to roots respiration in rainforest despite strong decrease in coarse and fine root biomass (Supplementary Table 2 ).…”

Assessing the Potential Contribution of Latex from Rubber (Hevea Brasiliensis) Plantations as a Carbon Sink

“…The findings of this study on the comparison of aboveground carbon (AGC), belowground carbon (BGC) and latex carbon indicated that as the rubber tree grows and accumulates more age in years, the carbon pools also accumulate more carbon Nguyen (2013). The differences in sequestered carbon by the pools indicated that aboveground carbon pool is significantly associated with higher amounts of carbon relative to BGC and latex carbon across different age categorisations (Satakhun et al, 2013). The differences in AGC in comparison to both BGC and latex carbon content widens with age (Egbe et al, 2012;Negash & Kanninen, 2015).…”