Protected reserves within tropical forests managed fortimber production: recommendations using Bolivia as a case study

The Bolivian forestry law requires that 10 per cent of areas under forest management must be set aside as 'ecological reserves', serving as protected areas from resource extraction. These guidelines appear to be based largely on reserve design theory from the conservation biology literature including recommendations for large, contiguous blocks of reserves interconnected with other protected areas through corridor networks. Such recommendations, however, are largely applicable to protected areas that are embedded within fragmented landscapes or where there is significant threat of deforestation. In contrast, protected areas within managed forests in Bolivia are surrounded by areas of largely intact forest subjected to low-intensity reduced impact logging and where logging occurs with a felling cycle not less than 20 years. Following an analysis of the current Bolivian law, conservation goals, and pertinent literature, we argue that issues of size and connectivity are perhaps less important within landscapes dominated by areas under forest management for timber production compared to protected areas imbedded within fragmented landscapes. It may, therefore, be more effective to disperse ecological reserves throughout management units to protect critical habitat and sites prone to damage from logging

Soil Effects on Forest Structure and Diversity in a Moist and a Dry Tropical Forest

Soil characteristics are important drivers of variation in wet tropical forest structure and diversity, but few studies have evaluated these relationships in drier forest types. Using tree and soil data from 48 and 32 1 ha plots, respectively, in a Bolivian moist and dry forest, we asked how soil conditions affect forest structure and diversity within each of the two forest types. After correcting for spatial effects, soil-vegetation relationships differed between the dry and the moist forest, being strongest in the dry forest. Furthermore, we hypothesized that soil nutrients would play a more important role in the moist forest than in the dry forest because vegetation in the moist forest is less constrained by water availability and thus can show its full potential response to soil fertility. However, contrary to our expectations, we found that soil fertility explained a larger number of forest variables in the dry forest (50 percent) than in the moist forest (17 percent). Shannon diversity declined with soil fertility at both sites, probably because the most dominant, shade-tolerant species strongly increased in abundance as soil fertility increased

Assessing the future global impacts of ozone on vegetation.

Ozone is a major secondary air pollutant, the current concentrations of which have been shown to have significant adverse effects on crop yields, forest growth and species composition. In North America and Europe, emissions of ozone precursors are decreasing but in other regions of the world, especially Asia, where much less is known about its impacts, they are increasing rapidly. There is also evidence of an increase in global background ozone concentrations, which will lead to significant changes in global ozone exposure over this century, during which direct and indirect effects of other changes in the global atmosphere will also modify plant responses to ozone. This paper considers how far our current understanding of the mechanisms of ozone impacts, and the tools currently used for ozone risk assessment, are capable of evaluating the consequences of these changing global patterns of exposure to ozone. Risk assessment based on relationships between external concentration and plant response is inadequate for these new challenges. New models linking stomatal flux, and detoxification and repair processes, to carbon assimilation and allocation provide a more mechanistic basis for future risk assessments. However, there are a range of more complex secondary effects of ozone that are not considered in current risk assessment, and there is an urgent need to develop more holistic approaches linking the effects of ozone, climate, and nutrient and water availability, on individual plants, species interactions and ecosystem function