A review of the ecosystem functions in oil palm plantations, using forests as a reference system

Abstract

Oil palm plantations have expanded rapidly in recent decades. This large-scale land-use change has had great ecological, economic, and social impacts on both the areas converted to oil palm and their surroundings. However, research on the impacts of oil palm cultivation is scattered and patchy, and no clear overview exists. We address this gap through a systematic and comprehensive literature review of all ecosystem functions in oil palm plantations, including several (genetic, medicinal and ornamental resources, information functions) not included in previous systematic reviews. We compare ecosystem functions in oil palm plantations to those in forests, as the conversion of forest to oil palm is prevalent in the tropics. We find that oil palm plantations generally have reduced ecosystem functioning compared to forests: 11 out of 14 ecosystem functions show a net decrease in level of function. Some functions show decreases with potentially irreversible global impacts (e.g. reductions in gas and climate regulation, habitat and nursery functions, genetic resources, medicinal resources, and information functions). The most serious impacts occur when forest is cleared to establish new plantations, and immediately afterwards, especially on peat soils. To variable degrees, specific plantation management measures can prevent or reduce losses of some ecosystem functions (e.g. avoid illegal land clearing via fire, avoid draining of peat, use of integrated pest management, use of cover crops, mulch, and compost) and we highlight synergistic mitigation measures that can improve multiple ecosystem functions simultaneously. The only ecosystem function which increases in oil palm plantations is, unsurprisingly, the production of marketable goods. Our review highlights numerous research gaps. In particular, there are significant gaps with respect to socio-cultural information functions. Further, there is a need for more empirical data on the importance of spatial and temporal scales, such as differences among plantations in different environments, of different sizes, and of different ages, as our review has identified examples where ecosystem functions vary spatially and temporally. Finally, more research is needed on developing management practices that can offset the losses of ecosystem functions. Our findings should stimulate research to address the identified gaps, and provide a foundation for more systematic research and discussion on ways to minimize the negative impacts and maximize the positive impacts of oil palm cultivation.

Minimum forest cover required for sustainable water flow regulation of a watershed: a case study in Jambi Province, Indonesia

“…The forests in Jambi Province, Indonesia, have been largely transformed into plantations (Drescher et al, 2016), resulting in inhabitants experiencing water shortages during the dry season and a dramatic increase in flooding frequency during the wet season (Merten et al, 2016;Tarigan, 2016a) because plantations promote higher levels of direct runoff than forested lands (Bruijnzeel, 1989(Bruijnzeel, , 2004Tarigan et al, 2016b;Dislich et al, 2017). However, this negative impact of plantation expansion could be minimized by maintaining an adequate proportion of forested land as a watershed, which raises the following question: what is the minimum proportion of forest cover that is required in a watershed to support adequate water flow regulation?…”

Expansion of oil palm and other cash crops causes an increase of the land surface temperature in the Jambi province in Indonesia

“…Forest cover in the Sumatran provinces of Riau, North Sumatra and Jambi declined from 93 to 38 % of provincial area between 197738 % of provincial area between and 200938 % of provincial area between (Mietti-nen et al, 2012. These large-scale transformations, observed as land cover change, and land use intensification have led to substantial losses in animal and plant diversity, ecosystem functions and changed microclimatic conditions Dislich et al, 2016;Drescher et al, 2016). Additionally, these changes directly alter vegetation cover and structure and land surface properties such as albedo, emissivity and surface roughness, which affect gas and energy exchange processes between the land surface and the atmosphere (Bright et al, 2015).…”

Agroecological practices in oil palm plantations: examples from the field

“…Conversion of those ecosystems into oil palm plantations has led to severe biodiversity losses (Fitzherbert et al, 2008;Foster et al, 2011;Koh and Wilcove, 2008;Savilaakso et al, 2014) and greenhouse gas emissions (Achten and Verchot, 2011;Bessou et al, 2014;Germer and Sauerborn, 2008;Reijnders and Huijbregts, 2008;Zulkifli et al, 2009). Further ecosystem services, such as erosion prevention, soil fertility or mitigation of extreme events, may be negatively impacted following the conversion of natural forests to oil palm plantations as an upper bound for possible changes in ecosystem functions (Dislich et al, 2016). Conversion of natural forests and peatlands to oil palm plantations or any other agricultural activity should be avoided as often as possible from an ecological point of view.…”