Local vulnerability as an advantage: mangrove forest management in Pará state,north Brazil,under conditions of illegality

When ecosystems are threatened or scientific knowledge of the effects of human action is uncertain, legislative prohibition is often adopted. This paper examines how the criminalization of mangrove tree use affects ecosystem management outcomes. We explore the biological, economic and social sustainability effects of the legal ban on mangrove use on the coast of Bragança, Pará, north Brazil. There are two main categories of mangrove users in this area: firstly, local subsistence users who also derive some financial incomes from mangrove sale. Their mangrove use is intertwined with household livelihood strategies and they display self-initiated planning and action towards sustainable management; secondly, more mobile, purely commercial users who are responsible for most commercial mangrove exploitation and who employ regionally sequential, predatory resource exploitation strategies. These users are typically based at some distance from the exploited areas and share neither local livelihood strategies nor sustainability agendas. The current outright ban on any utilization of mangrove flora seems to undermine biological sustainability, is economically inefficient and generates normative insecurity, conflict and social polarization. The ineffectiveness of the outright legal prohibition of mangrove tree use in terms of sustainable coastal management leads us to investigate alternative management options. We suggest that the legalization of local mangrove utilization and the strengthening of local users rights and responsibilities to control outsiders in a co-management framework, as proposed in the Brazilian extractive reserves (RESEX) approach, is most likely to advance ecologically, economically and socially sustainable mangrove management. It is demonstrated that a legal recognition of local entitlements to mangrove trees would reduce social vulnerability and therefore move forest management outcomes into more desirable directions.

The Influence of Agroforestry and Other Land-Use Types on the Persistence of a Sumatran Tiger (<Emphasis Type="Italic">Panthera tigris sumatrae</Emphasis>) Population: An Individual-Based Model Approach

The importance of preserving both protected areas and their surrounding landscapes as one of the major conservation strategies for tigers has received attention over recent decades. However, the mechanism of how land-use surrounding protected areas affects the dynamics of tiger populations is poorly understood. We developed Panthera Population Persistence (PPP)—an individual-based model—to investigate the potential mechanism of the Sumatran tiger population dynamics in a protected area and under different land-use scenarios surrounding the reserve. We tested three main landscape compositions (single, combined and real land-uses of Tesso-Nilo National Park and its surrounding area) on the probability of and time to extinction of the Sumatran tiger over 20 years in Central Sumatra. The model successfully explains the mechanisms behind the population response of tigers under different habitat landscape compositions. Feeding and mating behaviours of tigers are key factors, which determined population persistence in a heterogeneous landscape. All single land-use scenarios resulted in tiger extinction but had a different probability of extinction within 20 years. If tropical forest was combined with other land-use types, the probability of extinction was smaller. The presence of agroforesty and logging concessions adjacent to protected areas encouraged the survival of tiger populations. However, with the real land-use scenario of Tesso-Nilo National Park, tigers could not survive for more than 10 years. Promoting the practice of agroforestry systems surrounding the park is probably the most reasonable way to steer land-use surrounding the Tesso-Nilo National Park to support tiger conservation.     

Visualization of TCE recovery mechanisms using surfactant-polymer solutions in a two-dimensional heterogeneous sand model

This research focused on the optimization of TCE dissolution in a physical two-dimensional model providing a realistic representation of a heterogeneous granular aquifer. TCE was infiltrated in the sand pack where it resided both in pools and in zones of residual saturation. Surfactant was initially injected at low concentration to minimize TCE remobilization at first contact but was incrementally increased later during the experiment. Xanthan gum was added to the injected surfactant solution to optimize the sweep efficiency through the heterogeneous medium. Photographs and digital image analysis illustrated the interactions between TCE and the injected fluids. During the polymer flood, the effects of heterogeneities inside the sand pack were greatly reduced by the increased fluid viscosity and the shear-thinning effects of the polymer. The polymer also improved the contact between the TCE ganglia and the surfactant-polymer solution, thereby promoting dissolution. Surfactants interacted with the polymer reducing the overall viscosity of the solution. At first contact with a 0.5%(mass) surfactant solution, the TCE pools drained and some remobilization occurred. However, no TCE bank was formed and TCE did not penetrate into any previously uncontaminated areas. As a result, TCE surface area was increased. Subsequent surfactant floods at higher surfactant concentrations did not trigger more remobilization. TCE was mainly dissolved by the solution with the highest surfactant concentration. Plugging from bacterial growth or microgel formation associated to the polymer at the inflow screen prevented the full completion of the experiment. However, more than 90% of TCE was recovered with the circulation of less than 6 pore volumes of surfactant-polymer solution.