The boom in mineral markets: How long might it last?

The commodity price boom that emerged in 2004 has proved far more persevering than its predecessors of 1950 and 1973. Some analysts have suggested that it may represent the start of a “supercycle” caused by the voracious raw materials demand from China and other emerging economies, with prices remaining high for 20-30 years. We offer an alternative explanation. For a variety of reasons, the establishment of new capacity in minerals and energy to match the accelerated demand trends is more time consuming than commonly assumed, and may take a decade or longer. As soon as the new capacity is in place, however, the boom will be punctuated. Prices may collapse much earlier in the event of a severe recession that cuts the growth in commodity demand.     

Biodegradation of nitrogen-enriched lignite

Biodegradation of nitrogen-enriched lignite by soil bacteria previously acclimated in hydrogen peroxide-acetic acid lignitic substrate was carried out to assess the effects of nitrogen functional groups on the biodegradation of lignite. Chlorination, oxidation plus nitration, and ammoniation were applied in an attempt to modify the chemical structure of lignite so as to obtain a lignitic substrate that is more compatible to the enzymatical system of ordinary soil bacteria than that of unmodified lignite. Incorporation of nitrogen containing functional groups into lignite structure achieved 4.71 wt%, a value five times higher than that usually found in unmodified (raw) lignite. Data collected through a 16 day incubation time, monitoring production as well as depletion of both nitrate and organic acids, concluded that biodegradation was expedited by the incorporation of nitrogen into the structure of lignite. Twenty-eight compounds were identified based on the results from GC/MS analysis of the products.     

Bromeliad-living spiders improve host plant nutrition and growth

Although bromeliads are believed to obtain nutrients from debris deposited by animals in their rosettes, there is little evidence to support this assumption. Using stable isotope methods, we found that the Neotropical jumping spider Psecas chapoda (Salticidae), which lives strictly associated with the terrestrial bromeliad Bromelia balansae, contributed 18% of the total nitrogen of its host plant in a greenhouse experiment. In a one-year field experiment, plants with spiders produced leaves 15% longer than plants from which the spiders were excluded. This is the first study to show nutrient provisioning in a spider-plant system. Because several animal species live strictly associated with bromeliad rosettes, this type of facultative mutualism involving the Bromeliaceae may be more common than previously thought.     

Modeling biodiversity dynamics in countryside landscapes

The future of biodiversity hinges to a great extent on the conservation value of countryside, the growing fraction of Earth's surface heavily influenced by human activities. How many species, and which species, can persist in such landscapes (and analogous seascapes) are open questions. Here we explore two complementary theoretical frameworks to address these questions: species-area relationships and demographic models. We use the terrestrial mammal fauna of Central America to illustrate the application of both frameworks. We begin by proposing a multi-habitat species-area relationship, the countryside species-area relationship, to forecast species extinction rates. To apply it, we classify the mammal fauna by affinity to native and human-dominated habitats. We show how considering the conservation value of countryside habitats changes estimates derived from the classic species-area approach We also examine how the z value of the species-area relationship affects extinction estimates. Next, we present a framework for assessing the relative vulnerability of species to extinction in the countryside, based on the Skellam model of population dynamics. This model predicts the minimum area of contiguous native habitat required for persistence of a species, which we use as an indicator of vulnerability to habitat change. To apply the model, we use our habitat affinity classification of mammals and we estimate life-history parameters by species and habitat type. The resulting ranking of vulnerabilities is significantly correlated with the World Conservation Union (IUCN) Red List assessment.     

Searching for Networks: Ecological Connectivity for Amphibians Under Climate Change

Environmental Management - Ecological connectivity depends on key elements within the landscape, which can support ecological fluxes, species richness and long-term viability of a biological...