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Historical vegetation studies have been of limited use in total aboveground biomass (AGB) estimation because they only report incomplete data consisting of tree diameter‐class distributions or plot‐level summaries, rather than data on each tree individual. To address this issue, we assessed an existing method (ST‐n) and developed three new methods (ST‐p, PL‐n and PL‐p) for estimating total AGB using only incomplete data from tropical forest plots. ST‐n and ST‐p apply to studies with tree diameter‐class distributions (or stand tables, "ST"), whereas PL‐n and PL‐p apply to studies with plot‐level summary variables ("PL") in the form of total tree basal area, mean tree diameter, and total number of trees. ST‐n and PL‐n are non‐parametric ("n") methods that do not impose any form on the underlying distribution of tree diameters. In contrast, ST‐p and PL‐p are parametric ("p") methods that involve fitting probability distributions of tree diameter to the data. We applied the methods to incomplete data from 58 1‐ha plots in Panama and 300 1‐ha pseudo‐plots (generated by randomly sampling tree diameters from empirical distributions for three larger plots) in Southeast Asia, and four allometric equations. For these two regions and equations, ST‐p gave low total proportional errors (TPEs, as measured by proportional root‐mean‐square error) of 1%–8%. In contrast, ST‐n gave moderate to large TPEs of 10%–66%. PL‐n and PL‐p gave low to moderate TPEs of 5%–30%. The methods have great potential to expand the pool of large‐scale baseline AGB assessments to historical studies with incomplete data. [ABSTRACT FROM AUTHOR]

Abstract: Carbon emissions from drained peatlands converted to agriculture in South‐East Asia (i.e., Peninsular Malaysia, Sumatra and Borneo) are globally significant and increasing. Here, we map the growth of South‐East Asian peatland agriculture and estimate CO2 emissions due to peat drainage in relation to official land‐use plans with a focus on the reducing emissions from deforestation and degradation (REDD+)‐related Indonesian moratorium on granting new concession licences for industrial agriculture and logging. We find that, prior to 2010, 35% of South‐East Asian peatlands had been converted to agriculture, principally by smallholder farmers (15% of original peat extent) and industrial oil palm plantations (14%). These conversions resulted in 1.46–6.43 GtCO2 of emissions between 1990 and 2010. This legacy of historical clearances on deep‐peat areas will contribute 51% (4.43–11.45 GtCO2) of projected future peatland CO2 emissions over the period 2010–2130. In Indonesia, which hosts most of the region's peatland and where concession maps are publicly available, 70% of peatland conversion to agriculture occurred outside of known concessions for industrial plantation development, with smallholders accounting for 60% and industrial oil palm accounting for 34%. Of the remaining Indonesian peat swamp forest (PSF), 45% is not protected, and its conversion would amount to CO2 emissions equivalent to 0.7%–2.3% (5.14–14.93 Gt) of global fossil fuel and cement emissions released between 1990 and 2010. Of the peatland extent included in the moratorium, 48% was no longer forested, and of the PSF included, 40%–48% is likely to be affected by drainage impacts from agricultural areas and will emit CO2 over time. We suggest that recent legislation and policy in Indonesia could provide a means of meaningful emission reductions if focused on revised land‐use planning, PSF conservation both inside and outside agricultural concessions, and the development of agricultural practices based on rehabilitating peatland hydrological function. [ABSTRACT FROM AUTHOR]

Harmful non-indigenous species (NIS) impose great economic and environmental impacts globally, but little is known about their impacts in Southeast Asia. Lack of knowledge of the magnitude of the problem hinders the allocation of appropriate resources for NIS prevention and management. We used benefit-cost analysis embedded in a Monte-Carlo simulation model and analysed economic and environmental impacts of NIS in the region to estimate the total burden of NIS in Southeast Asia. The total annual loss caused by NIS to agriculture, human health and the environment in Southeast Asia is estimated to be US$33.5 billion (5th and 95th percentile US$25.8–39.8 billion). Losses and costs to the agricultural sector are estimated to be nearly 90% of the total (US$23.4–33.9 billion), while the annual costs associated with human health and the environment are US$1.85 billion (US$1.4–2.5 billion) and US$2.1 billion (US$0.9–3.3 billion), respectively, although these estimates are based on conservative assumptions. We demonstrate that the economic and environmental impacts of NIS in low and middle-income regions can be considerable and that further measures, such as the adoption of regional risk assessment protocols to inform decisions on prevention and control of NIS in Southeast Asia, could be beneficial. [ABSTRACT FROM AUTHOR]