Browsing by Author "Jong, Ying Wei"

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Open Access
CARBON STOCKS IN NORTHEASTERN GABON AND POLICY IMPLICATIONS FOR RUBBER TREE CONCESSIONS
(2019-04-24) Jong, Ying Wei
Agricultural activities such as oil palm and rubber production have the potential to grow the economies and increase employment in tropical nations, but measures must be taken to offset the negative environmental effects of converting forests into monocultures. One approach to reconciling agricultural development with environmental degradation is to direct agricultural expansion towards low carbon landscapes such as cleared lands and secondary forests. This approach is tested by estimating carbon stocks and flux in northeastern Gabon, Central Africa at the selectively logged ORG concession that is proposed to be converted to a rubber tree plantation. Gabon is in the process of developing its agricultural sector, thus understanding the implications of converting forest into plantations is critical for implementation of best practices for estimating carbon stocks and reducing carbon emissions. This study demonstrates that even within degraded secondary forests in Gabon the mean carbon density (123.8 Mg C ha-1) remains relatively high in comparison to degraded forest in other tropical countries. This value is lower than the mean carbon density in Gabon (160-167 Mg C ha-1) (Bombelli et al., 2009; Saatchi et al., 2011), but substantially higher than the 75 Mg C ha-1 carbon threshold recommended by the High Carbon Stock protocol (HCS; HCS Steering Group Committee, 2017). The carbon density distribution within the ORG concession is related to habitat type: forests on slopes had the highest mean carbon density compared to swamps, which were dominated by low-carbon palm species, and flat terra firma forest, the majority of which had been previously cleared for subsistence agriculture. Through growth and succession, secondary forest should attain carbon densities similar to primary forest, which means there are high environmental opportunity costs of converting secondary forest to plantations. Overall, converting the ORG concession into a rubber plantation will lead to net carbon emissions. If development of the area goes forward, measures should be taken to reduce emissions and prolong carbon retention, such as minimizing soil disturbance, extending harvest rotations, making rubber wood furniture, and setting aside high carbon areas, such as slopes, as offsets.
Open Access
Expected carbon emissions from a rubber plantation in Central Africa
(Forest Ecology and Management, 2021-01-15) Jong, Ying Wei; Beirne, Christopher; Meunier, Quentin; Mekui Biyogo, Andréana Paola; Ebang Mbélé, Alex; Stewart, Christopher G; Poulsen, John R
The development of agriculture on degraded lands is increasingly seen as a strategy to boost food availability and economic productivity while minimizing environmental degradation and loss of forests. To understand the effects of agricultural production on forest carbon, we quantify the aboveground carbon (AGC) of a degraded forest in northeast Gabon (the Olam Rubber Gabon concession) designated for development to a rubber plantation. Combining field measurements from 19 1-ha tree plots and aerial LiDAR, we estimate forest AGC stocks and emissions under four development scenarios: no development, 30-year rubber rotation, extended rubber rotation (replanting of plantation in stages at 30 and 40 years), and 30-year oil palm rotation. On average, the degraded forest in the study area stored 123.8 Mg C ha−1, a mean AGC lower than the Gabon average (141.6 Mg C ha−1) but substantially higher than the 75 Mg C ha−1 threshold recommended by the High Carbon Stock protocol. Converting secondary forest to plantation might incur high environmental opportunity costs from lost carbon sequestration through forest succession and growth. In this study, we estimate that a rubber plantation can sequester similar amounts of AGC as secondary forest by the end of a 30-year rotation; however, the time-averaged AGC of regenerating secondary forests under no development would be 184% higher than a mature rubber plantation with a 30-year rotation, 169% higher than an extended rubber rotation, and 512% higher than a 30-year oil palm rotation. When degraded forest is developed for agriculture, measures should be taken to avoid emissions and prolong carbon retention. We specifically estimate carbon retention from extended harvest rotations and conserving high carbon value areas as set-asides and highlight recommendations from the literature such as minimizing soil disturbance and creating rubber timber products (e.g. furniture). To minimize carbon emissions from agriculture, crop plantation area should be minimized at national and regional scales in highly forested countries, and new plantations should be coupled explicitly with effective forest restoration actions, through suitable regulation and planning, to mitigate or compensate for their climate and biodiversity impacts.