Catherine Yule

The rise of palm oil as the world's most consumed vegetable oil has coincided with exponential growth in palm oil research activity. Bibliometric analysis of research outputs reveals a distinct imbalance in the type of research being undertaken, notably a disproportionate focus on biofuel and engineering topics. Recognising the expansion of oil palm agriculture across the tropics and the increasing awareness of environmental, social and economic impacts, we seek to re-orient the existing research agenda towards one that addresses the most fundamental and urgent questions defined by the palm oil stakeholder community. Following consultation with 659 stakeholders from 38 countries, including palm oil growers, government agencies, non-governmental organisations and researchers, the highest priority research questions were identified within 13 themes. The resulting 279 questions, including 26 ranked as top priority, reveal a diversity of environmental and social research challenges facing the industry, ranging from the ecological and ecosystem impacts of production, to the livelihoods of plantation workers and smallholder communities. Analysis of the knowledge type produced from these questions underscores a clear need for fundamental science programmes, and studies that involve the consultation of non-academic stakeholders to develop 'transformative' solutions to the oil palm sector. Stakeholders were most aligned in their choice of priority questions across the themes of policy and certification related themes, and differed the most in environmental feedback, technology and smallholder related themes. Our recommendations include improved regional academic leadership and coordination, greater engagement with private and public stakeholders of Africa, and Central and South America, and enhanced collaborative efforts with researchers in the major consuming countries of India and China.

River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth's biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented "next-generation biomonitoring" by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.

Large-scale conversion of tropical forests into agricultural plantations, particularly oil palm (OP) across South East Asia exerts enormous pressure on freshwater systems. To mitigate impacts on aquatic ecosystems, the retention of riparian buffer zones along stream banks are often advocated for freshwater management. However, there is a severe lack in ecological information available on tropical stream systems advising on the efficacy of different riparian buffer types (with varying quality) to mitigate stream physico-chemical properties after conversion for agricultural use. To test the hypothesis that greater riparian disturbance will have negative effects on stream geomorphology and water quality, we assessed the impacts of riparian vegetation structure and density on stream chemical and physical properties in different riparian buffer types commonly used in OP plantations subjected to a gradient of disturbance: (i) Native forest (NF); (ii) OP - forested buffer (OPF); (iii) OP - untreated palms buffer (no fertilizer and pesticide application) (OPOP); and (iv) OP - treated palms (OPNB). Across the disturbance gradient, riparian species diversity and density decreased with taller trees and high foliage cover. Foliage cover heavily influenced the amount of light received at the stream, bank and buffer zone that concur with stream water temperatures. In-stream litter substrate decreased with increased riparian disturbance. OP streams had higher phosphorus and potassium concentrations that can be attributed to the use of fertilizers while sodium concentrations were higher in NF streams. Generally, OPF was most similar to NF sites whereas OPOP and OPNB sites had similar characteristics showing that riparian vegetation type influences the physical and chemical characteristics of streams. Thus, the use of high quality riparian buffers with forested riparian vegetation in OP plantations to reduce the impacts of land conversion on streams is supported. © 2017 The Authors.

Background: Tropical peat swamp forests (TPSF) are globally significant carbon stores, sequestering carbon mainly as phenolic polymers and phenolic compounds (particularly as lignin and its derivatives) in peat layers, in plants, and in the acidic blackwaters. Previous studies show that TPSF plants have particularly high levels of phenolic compounds which inhibit the decomposition of organic matter and thus promote peat accumulation. The studies of phenolic compounds are thus crucial to further understand how TPSF function with respect to carbon sequestration. Here we present a study of cycling of phenolic compounds in five forests in Borneo differing in flooding and acidity, leaching of phenolic compounds from senescent Macaranga pruinosa leaves, and absorption of phenolics by M. pruinosa seedlings. Results: The results of the study show that total phenolic content (TPC) in soil and leaves of three species of Macaranga were highest in TPSF followed by freshwater swamp forest and flooded limestone forest, then dry land sites. Highest TPC values were associated with acidity (in TPSF) and waterlogging (in flooded forests). Moreover, phenolic compounds are rapidly leached from fallen senescent leaves, and could be reabsorbed by tree roots and converted into more complex phenolics within the leaves. Conclusions: Extreme conditions-waterlogging and acidity-may facilitate uptake and synthesis of protective phenolic compounds which are essential for impeded decomposition of organic matter in TPSF. Conversely, the ongoing drainage and degradation of TPSF, particularly for conversion to oil palm plantations, reverses the conditions necessary or peat accretion and carbon sequestration.