The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.

Tropical peatlands are globally important for their high carbon storage and unique biodiversity, but are currently under severe threat in South East Asia from expansion of oil palm plantations. A large part of this expansion in Peninsular Malaysia arises from smallholder oil palm plantations that follow varied cropping practices, yet their impact on the environment is largely unexplored. This research aimed to study and evaluate the environmental and belowground microbial impacts of different smallholder cropping systems relative to forested peatlands in North Selangor, Peninsular Malaysia. Specifically, GHG measurements using closed chambers, and peat sampling were carried out in both wet and dry seasons. Microbial phenotypic community structure was determined using phospholipid fatty acid (PLFA) analysis. Relative to forested peatlands, the agricultural plantations had increased pH, temperature and bulk density, decreased organic content, and peat moisture, with a pineapple intercropping site as the only exception. These effects were most pronounced in 2 nd generation mono-cropping systems. Soil microbial community structure, dominated by Gram-positive bacteria under all land-use types, differed significantly between agricultural sites and forest, and also showed significant seasonal variation. There was a general increase in non-specific fatty acids and a decrease in Gram-positive fatty acids in agricultural sites from forest, however microbial community structure were similar in most agricultural sites. CO2 emissions were greatest at the forest site and showed no seasonal variations, however most of the forest CO2 emissions were most likely due to high autotrophic contribution from roots. CH4 emissions were under 1 mg m-2 hr-1 for all the agricultural sites, while forest peat surface absorbed similar low quantity of CH4. Overall, the changes in peat properties and loss of C was greatest in the 2 nd generation mono-cropping, while the intercropping systems ameliorated these effects by maintaining most of the forest peat organic content and causing relatively smaller changes in pH, moisture and bulk density. It is clear that oil palm intercropping have an ameliorating effect on environmental impacts caused by the expansion of oil palm plantations into peatlands.

The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.

The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.

Tropical peatlands are unique and globally important ecosystems for carbon storage that are generally considered nutrient poor. However, different nutrient and trace element concentrations in these complex ecosystems and their interactions with carbon emissions are largely unknown. The objective of this research was to explore the concentrations of macro‐ and micronutrients and othertrace elements in surface peats, and their relationship with greenhouse gas emissions in North Selangor peatlands subjected to different land use. All nutrient and trace element concentrations except chromium exhibited significant differences between sites. Most macronutrients and some micronutrients showed significant differences between seasons, typically with a reduction over time from wet to dry seasons, possibly due to leaching. CO2 emissions were positively related to organic matter content and manganese concentrations and negatively correlated with selenium. CH4 emissions were positively correlated with organic matter content, manganese, copper, barium, cobalt and aluminium, and negatively correlated with molybdenum, selenium, lithium and vanadium. This research has detected loss of essential nutrients over time, aiding to increase nutrient limitation in tropical peatlands due to drainage. The observed significant correlation between trace elements and greenhouse gas emissions strengthens the importance of including trace element analyses in understanding the biogeochemical functions of these understudied peatlands.