The global abundance of tree palms

Aim: Palms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change. Location: Tropical and subtropical moist forests. Time period: Current. Major taxa studied: Palms (Arecaceae). Methods: We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co‐occurring non‐palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure. Results: On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long‐term climate stability. Life‐form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non‐tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above‐ground biomass, but the magnitude and direction of the effect require additional work. Conclusions: Tree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests

A sustainable future supply of sediment for the Ganges-Brahmaputra delta?

Recent research highlights that delta submergence is an important issue for the Ganges-Brahmaputra-Meghna (GBM) delta. The only factor that could potentially offset losses in delta surface elevation is a sustainable supply of fluvial sediment. River sediments therefore have considerable economic and social value for ecosystem services and those they support. Analysis, using the HydroTrend model, indicates that an increase in the climate-driven supply of fluvial sediment to the GBM delta has the potential, through accelerated aggradation on the delta surface, to offset some of the adverse impacts of climate change due to rising sea levels in the Bay of Bengal. However, anthropogenic disconnections, such as dams, flood defences and polders disturbances, have the possibility to negatively affect this process

Food security and nutritional outcomes among urban poor orphans in Nairobi, Kenya

The study aims to inform policies and practice targeted at improving the welfare of orphans living in urban poor communities. The relationship between orphanhood and nutritional status remains unclear, suggesting further context specific studies. The study was conducted between January and June 2007 among orphans and non-orphans aged 6-14 years, living in informal settlements of Nairobi, Kenya. Anthropometric measurements: weight and height were taken using standard procedures and z-scores generated using the National Center for Health Statistics (NCHS)/WHO reference. Data on food security was collected through interviews with children and their caregivers separately. A composite food security measure was derived from the caregiver and child responses. Comparisons with regard to food security and nutritional outcomes were made between orphans and non-orphans and among orphan types. Multiple regression analysis was done to determine factors related to vulnerability with regards to food security and nutritional outcomes. Orphans were more vulnerable than non-orphans to issues of food security, but not nutritional status, with paternal orphans being the most vulnerable orphan group. Other factors associated with vulnerability were age, sex and ethnicity of the child; relationship of child to the household head; age, sex and education level of the household head; household socio-economic status; number of dependants; and location of residence and household head’s education. The differential effects of these factors suggest targeted interventions