Short‐term soil carbon sink potential of oil palm plantations

Abstract

Oil palm plantations cover %14.6 million ha worldwide and the total area under cultivation is expected to increase during the 21st century . Indonesia and Malaysia together account for 87% of global palm oil production and the combined harvested area in these countries has expanded by 6.5 million ha since 1990. Despite this, soil C cycling in oil palm systems is not well quantified but such information is needed for C budget inventories. We quantified soil C storage (root biomass, soil organic matter (SOM) and microbial biomass) and losses [potential soil respiration (R s ) and soil surface CO 2 flux (F s )] in mineral soils from an oil palm plantation chronosequence (11-34 years since planting) in Selangor, Malaysia. There were no significant effects of plantation age on SOM, microbial biomass, R s or F s , implying soil C was in dynamic equilibrium over the chronosequence. However, there was a significant increase in root biomass with plantation age, indicating a short-term C sink. Across the chronosequence, R s was driven by soil moisture, soil particle size, root biomass and soil microbial biomass N but not microbial biomass C. This suggests that the nutrient status of the microbial community may be of equal or greater importance for soil CO 2 losses than substrate availability and also raises particular concerns regarding the addition of nitrogenous fertilizer, i.e. increased yields will be associated with increased soil CO 2 emissions. To fully assess the impact of oil palm plantations on soil C storage, initial soil C losses following land conversion (e.g. from native forest or other previous plantations) must be accounted for. If initial soil C losses are large, our data show that there is no accumulation of stable C in the soil as the plantation matures and hence the conversion to oil palm would probably represent a net loss of soil C.

Variação temporal do efluxo de CO2do solo em sistemas agroflorestais com palma de óleo na Amazônia Oriental

“…Em sistemas jovens, a ocupação do solo pelas raízes finas ainda é localizada e, consequentemente, os impactos sobre carbono do solo e respiração microbiana ainda são pequenos, tendendo a aumentar a medida que o sistema amadurece, quando a ocupação do solo e da parte Variação temporal do efluxo de CO 2 do solo em sistemas agroflorestais com palma de óleo na Amazônia Oriental ACTA AMAZONICA aérea é mais homogênea. Por exemplo, Smith et al (2012) observaram aumento da quantidade de raízes em plantios mais velhos (34 anos) de palma de óleo em relação aos mais novos (11 anos) e Almeida et al (2010) relataram aumento do estoque de carbono do solo de acordo com o aumento da idade de plantios de teca (Tectona grandis) no Mato Grosso.…”

Tropical peat decomposability expressed through physical, chemical and biological properties under varying land management intensities

“…Mature oil palm and acacia plantations may reach high biomass, but the intensive management practices (i.e. weeding, and harvesting) lead to lowered litter deposition, and therefore these plantations do not support peat accumulation (Smith et al 2012). As the litter input rate depends on vegetation type, it is unlikely that the current vegetation types on managed lands have sufficient volume and litter production capacity to maintain peat production (Hertel et al 2009;Smith et al 2012).…”

“…weeding, and harvesting) lead to lowered litter deposition, and therefore these plantations do not support peat accumulation (Smith et al 2012). As the litter input rate depends on vegetation type, it is unlikely that the current vegetation types on managed lands have sufficient volume and litter production capacity to maintain peat production (Hertel et al 2009;Smith et al 2012). Progressing decomposition will therefore take place after deforestation in existing peat depositions, and will alter the properties of the peat formed prior to land-use change.…”

“…Additionally, in cultivated sites either the vegetation does not provide sufficient litter input to support peat accumulation or management practices prevent the accumulation of litter as peat (Hertel et al 2009;Smith et al 2012;Jauhiainen et al, 2016MP). This study observed this phenomenon indirectly as a decreased concentration of labile carbohydrates at the intensively altered sites, where litter production does not sufficiently support peat production.…”

“…The decrease in CO2 emissions is very likely related to peat decomposability, which was seen to decrease with land management intensity in this study (I, II, III). Therefore, the highest measured CO2 emissions from high biomass oil palm and acacia plantations (IPCC 2014) are likely explained by the availability of labile carbohydrates and nitrogen-based fertilizers (Smith et al 2012). Yet, intensive management practices, e.g.…”