## 2 Materials and Methods
### Net Primary Production and Net Ecosystem Production  
Net primary production (NPP) was measured and quantified for all sample sites of different cover types. The NPP of both aboveground and belowground was quantified [23]. The annual sum of tree growth and litterfall was quantified as aboveground production, while the yearly growth of roots was quantified as belowground production. In each forested sample site (PSF and LPSF), six plots, six of a 10 m radius circle area, were set up 30 m in the distance along a line transect (total length 150 m; adapted from [5; 36]). All trees in each plot were measured for their tree diameter at breast height (DBH) to be later extrapolated using our tree diameter growth model. A total of 120 trees, 20 in each forested site (three PSF and LPSF sites) were randomly chosen in 35 \(\times\) 10 m\({}^{2}\) plots, located 10 m to the 150 m transect. At each site, to create a diameter growth model, tree growth was measured monthly for a year through the installation of tree bands (den-drometer), 1.3 m aboveground (DBH) [37]. In addition, the litterfall accumulation rate was measured using six litterfall traps positioned every 7 m apart along the 35 m transect. Each trap has an area of about 0.23 m\({}^{2}\) and was set up a meter above ground and tied to surrounding trees or wooden poles. Litterfall samples were gathered twice during the wet season (November and December 2015) and four times during dry seasons of two consecutive years (September and October of 2014 and 2015). Samples of litterfall were packed in plastic bags and transported to the laboratory at Bogor Agricultural University, Bogor, Indonesia. After those samples were dried at 60 \({}^{\circ}\)C to constant mass and weighed, the C content was then measured using a LECO Analyzer (dry combustion method/induction furnace). [PERSON] and [PERSON] [22] reported that branch fall production was estimated as 9.89% of the litterfall annual production. Root: shoot ratio in terrestrial biomass [38] was used to estimate the coarse root production, as its ratio to the aboveground biomass of all the forests trees. 12% of the overall annual production of tree, coarse root, and litterfall was used to estimate fine root production [22]. Annual NPP of all trees in PSF and LPSF was thus calculated as a sum of the aboveground and belowground NPP, which captured the annual production of tree growth, coarse and fine root growth, as well as litter and branch fall accumulation. NPP in oil palm estate was assessed through six 10 m radius plots located 30 m apart along a 150 m transect in each sample site (similar to those in the intact and logged forests). The height of the base of their young leaves of all oil palm trees was measured at all OP sites and re-measured two years later. Annual height growth of oil palm trees was calculated by subtracting the initial tree height from the tree height at Year 2, then dividing by two. Annual biomass growth for OP trees was estimated using an allometric equation [39], which was developed in Sumatera and Borneo islands from harvested oil palm trees \(<\)1 to 8 m in height on peatlands [39]. About 75.3% of frond production, which is 68.8% of the tree biomass growth, was used to estimate the pruned from biomass, and about 71.7% of root production, which is 14.2% of the tree biomass growth, was used to estimate dead root biomass [40]. The dead root and pruned from production were summed to quantify the annual NPP of OP sites. As the oil palm estates were less than five years old, the contribution of fruit to the total NPP was neglected. Early serial sites (ES) were measured for their NPP through transect of squared plot design. In each ES site, six 1 m\({}^{2}\) plots were established at 7 m intervals along a 35m transect. All aboveground standing herbaceous biomass and litterfall were harvested in a 1 m\({}^{2}\) plot at the six locations on each site. These ES plots were burned in September 2014, which enabled us to measure the annual aboveground NPP of ES after a year.