In many tropical regions, the rapid expansion of monoculture plantations has led to a sharp decline in forest cover, potentially degrading the ability of watersheds to regulate water flow. Therefore, regional planners need to determine the minimum proportion of forest cover that is required to support adequate ecosystem services in these watersheds. However, to date, there has been little research on this issue, particularly in tropical areas where monoculture plantations are expanding at an alarming rate. Therefore, in this study, we investigated the influence of forest cover and oil palm (Elaeis guineensis) and rubber (Hevea brasiliensis) plantations on the partitioning of rainfall into direct runoff and subsurface flow in a humid, tropical watershed in Jambi Province, Indonesia. To do this, we simulated streamflow with a calibrated Soil and Water Assessment Tool (SWAT) model and observed several watersheds to derive the direct runoff coefficient (C) and baseflow index (BFI). The model had a strong performance, with Nash–Sutcliffe efficiency values of 0.80–0.88 (calibration) and 0.80–0.85 (validation) and percent bias values of −2.9–1.2 (calibration) and 7.0–11.9 (validation). We found that the percentage of forest cover in a watershed was significantly negatively correlated with C and significantly positively correlated with BFI, whereas the rubber and oil palm plantation cover showed the opposite pattern. Our findings also suggested that at least 30 % of the forest cover was required in the study area for sustainable ecosystem services. This study provides new adjusted crop parameter values for monoculture plantations, particularly those that control surface runoff and baseflow processes, and it also describes the quantitative association between forest cover and flow indicators in a watershed, which will help regional planners in determining the minimum proportion of forest and the maximum proportion of plantation to ensure that a watershed can provide adequate ecosystem services.

It is often cited that large scale oil palm plantation were responsible for forest cover changes in Sumatra and Kalimantan. Objective of the research was to identify whether oil palm concessions were the direct cause of intact forest cover changes in study area. The study areas are situated at Jambi Province, Indonesia and are experiencing rapid expansion of oil palm plantation. We used Landsat temporal images from year 1988, 1990, 2000, 2007, and 2013 to detect forest cover change. We also made use Carnegie Landsat Analysis System–Lite (CLASlite) fractional cover module to differentiate undisturbed (intact), disturbed (logged) forest and also oil palm growing stages on Landsat images. Our study showed that, there were only 8% of oil palm plantation development occurred by direct clearing of intact forest in the study area in the last 25 years. Oil palm concessions in the last 25 years were mostly developed on logged forest, agroforests, and shrub lands

Peatlands are especially important but fragile tropical landscapes. The importance of peatlands is owing to their ability to 1) sequester a considerable amount of terrestrial carbon, 2) store freshwater, and 3) regulate floods during the rainy season. Nowadays, extensive peatland degradation occurs because of peatland utilization for agriculture purposes, causing severe environmental consequences such as carbon emission, loss of biodiversity, risk of flooding, and peat fire. Meanwhile, local planners and decision makers tend to overlook the long-term strategic function of peatlands for carbon storage and hydrological regulation, preferring peatland utilization for short-term economic benefits. The objective of our study is to quantify the total ecosystem services (except biodiversity) of a tropical peatland landscape in various peat-utilization scenarios to help build awareness among local planners and decision makers on the strategic tradeoff between peatland utilization and restoration. Studies on the total ecosystem services in a tropical peatland landscape involving hydrological regulation are still rare. Based on the net present value calculation, provisioning services, carbon regulation, and hydrological regulation in our study area account for 19, 70, and 11% of the total ecosystem services, respectively. Based on uncertainty analysis, at any combination of the social cost of carbon emission (within a range of USD 52.7–USD 107.4) and discount rate (within a range of 5–10%), the enrichment of peatlands with paludiculture crops (e.g., jelutong) shows superior ecosystem services compared to other peatland-utilization scenarios. Conversely, planting peatlands with monoculture crops, which are associated with peatland drainage, shows a rapid decrease in the total ecosystem services. The fluvial carbon export in our study, which is often neglected in a peatland carbon budget, increases the estimate of the total carbon budget by 8%. Restoring undrained peatlands with paludiculture crops such as jelutong contributes positively to carbon sequestration and potentially reduces carbon emissions by 11%. These quantitative findings can help local planners and decision makers in understanding the tradeoff between the long-term benefits of peatland restoration and the short-term economic benefits of peatland utilization for monoculture crops.

Multifunctional landscapes, such as agroforestry, that improve soil health are essential in sustaining terrestrial life by supporting various ecosystem services (ESs). However, decision-making often requires more attention to soil health because its parameters have no market value. In this study, we aim to evaluate soil health parameters in cacao agroforestry and monoculture and their degradation due to erosion and to estimate their indirect use value (IUV). We develop a soil health economic valuation approach bridged by ESs because the economic valuation of ESs tends to be better studied. We estimated the IUVs of the eight soil health parameters by using the direct proxy revealed prevalence valuation method on the basis of the valuation of the four ESs they support: water regulation, climate regulation, nutrient retention and biodiversity. The total IUVs for cacao agroforestry were USD 633 with Endoaquepts and USD 723 with Dystrudepts and for cacao monoculture were USD 415 with Endoaquepts and USD 575 with Dystrudepts. Soil carbon has the highest contribution to IUV, followed by soil nitrogen. Agroforestry not only increases IUV but also minimises its decrease due to erosion. Despite economic valuations being subject to uncertainty, these results encourage the internalisation of soil health values in sustainable land management design.