Roland Cochard

Natural Hazards Mitigation Services of Carbon-Rich Ecosystems

The year 2011 has been the costliest ever in terms of economic losses caused by natural disasters. This has been partly attributed to increasing natural hazard effects caused by global warming and land use changes (in particular deforestation). This chapter provides an overview of risk-relevant issues and an evaluation of the role of carbon(C)-rich ecosystems within the overall context of natural disaster risk. Hazard mitigation ecosystem services which are discussed include the regulation of global, regional and local climates (via C storage, evapo-transpiration, and albedo); the provision of structural stability to soil substrates (reducing risks of shallow landslides, and erosion during flooding); retention and transpiration of water (reducing flooding frequencies and intensities in catchments); and the buffering against solid and fluid mass impacts (landslides, rockfalls, snow avalanches, wind-driven sea waves, storm surges, and tsunamis). The information provided may serve to advance the valuation of ecosystems and support development-relevant decision-making, especially in regions prone to natural disasters. It is highlighted that heedless destruction of ecosystems will come at an increasingly higher cost to current and future generations, with progressively fewer options to maintain or reinstate their services. Hence, sensible foresight stipulates a precautionary approach when dealing with the remaining ‘ecosystem capital’.

Putting Ant-Acacia Mutualisms to the Fire

Various complex trade-offs determine the vitality and survival of acacias in dynamic savannas. Recently, T. M. Palmer et al. (“Breakdown of an ant-plant mutualism follows the loss of large herbivores from an African savanna,” Reports, 11 January, p. [192][1]) illustrated how exclusion of large

Aquatic faunal abundance and diversity in relation to synthetic and natural pesticide applications in rice fields of Central Thailand

Despite wetland conversion to intensive rice production Central Thailand remains a center for wetland biodiversity in Southern Asia. Fauna inhabiting rice fields (many species perform important ecosystem services) are, however, increasingly threatened by pesticide uses. In Ayutthaya and Ang Thong Provinces 40 conventionally and 31 organically managed farms were visited to investigate how abundance and diversity of aquatic fauna in rice fields relate to pesticide regimes. In the dry and wet seasons fields were surveyed for plankton, aquatic macro-invertebrates, fishes, and waterfowl. Using multivariate statistics pesticide variables and biophysical field parameters (determined in a previous study) were assessed as potential predictors of abundance/diversity of faunal groups. Effects of pesticide regimes on aquatic fauna were nontrivial. Phytoplankton was lowered under exposures to herbicides and natural insecticides. Zooplankton (except amoeboids) was unaffected or increased on pesticide-exposed fields, probably suffering lower predation. Biophysical aspects partly explained abundance/diversity of aquatic insects, but abundance/diversity was generally higher on fields treated with natural rather than synthetic insecticides. Fishes and waterfowl tended to be less abundant on fields exposed to synthetic insecticides and herbicides. Detailed findings may interest agro-ecologists, medical entomologists, and conservation biologists. Further research incorporating wider landscape aspects and including pesticide-free reference sites is suggested.

Uses, toxicity levels, and environmental impacts of synthetic and natural pesticides in rice fields – a survey in Central Thailand

Nowadays, pesticides are used pervasively in Asian rice production areas. Nonetheless, information is scarce regarding chemicals’ application and synergistic toxicity and longer-term impacts on paddy ecosystems. In Phranakhon Si Ayutthaya and Ang Tong (AT) provinces, 40 conventionally and 31 organically managed farms were visited. The farmers provided information on types and levels of pesticides used, and indices describing pesticide ‘toxic exposures’ were calculated. In the dry and wet seasons, the fields were surveyed for soil organic carbon (OC) and nitrogen (N) and rice densities and sizes. Using multivariate statistics, interrelationships among variables were investigated. Overall, 12 types of herbicides (all synthetic), 27 insecticides (13 natural), and 6 molluscicides (1 natural) were recorded. Pesticide exposures differed between provinces; organic farms used more natural products. OC was positively correlated with ‘toxic exposure’ levels, probably resulting from effects of pesticides on carbon-reducing processes. Additionally, molluscicides and herbicides explained OC levels. N varied spatially, probably resulting from flooding regimes; management influences were unnoticeable. In the dry season, rice growth was decreased on fields exposed to plentiful synthetic insecticides, whereas in the wet season, use of herbicides and molluscicides enhanced the growth. Further research is advisable to better establish long-term costs and benefits of different pesticide regimes in rice fields.