Impacts of Alternative Timber Harvest Practices on Leaf-Chewing Herbivores of Oak

Abstract:  Studies of the effects of logging on Lepidoptera rarely address landscape-level effects or effects on larval, leaf-feeding stages. We examined the impacts of uneven-aged and even-aged logging on the abundance, richness, and community structure of leaf-chewing insects of white ( Quercus alba L.) and black ( Q. velutina L.) oak trees remaining in unharvested areas by sampling 3 years before and 7 years after harvest. After harvest, white oaks in uneven-aged sites had 32% fewer species of leaf-chewing insects than control sites. This reduction in species richness may have resulted from changes in microclimate (reducing plant quality and/or changing leaf phenology) that affected a much larger total area of each site than did even-aged cuts. For black oak after harvest, species richness in uneven- and even-aged sites increased relative to levels before harvest. Harvesting did not alter total insect density or community structure in the unlogged habitat for either oak species with one exception: insect density on black oak increased in the oldest forest block. Community structure of herbivores of black and white oaks in clearcut gaps differed from that of oaks in intact areas of even-aged sites. Furthermore, both richness and total insect density of black oaks were reduced in clearcut gaps. We suggest that low-level harvests alter herbivore species richness at the landscape level. Treatment effects were subtle because we sampled untreated areas of logged landscapes, only one harvest had occurred, and large temporal and spatial variation in abundance and richness existed. Although the effects of logging were greater in uneven-aged sites, the effects of even-aged management are likely to increase as harvesting continues.     

The Effect of Fragment Shape and Species' Sensitivity to Habitat Edges on Animal Population Size

Abstract:  Habitat fragmentation causes extinction of local animal populations by decreasing the amount of viable "core" habitat area and increasing edge effects. It is widely accepted that larger fragments make better nature reserves because core-dwelling species have a larger amount of suitable habitat. Nevertheless, fragments in real landscapes have complex, irregular shapes. We modeled the population sizes of species that have a representative range of preferences for or aversions to habitat edges at five spatial scales (within 10, 32, 100, 320, and 1000 m of an edge) in a nation-wide analysis of forest remnants in New Zealand. We hypothesized that the irregular shapes of fragments in real landscapes should generate statistically significant correlations between population density and fragment area, purely as a "geometric" effect of varying species responses to the distribution of edge habitat. Irregularly shaped fragments consistently reduced the population size of core-dwelling species by 10–100%, depending on the scale over which species responded to habitat edges. Moreover, core populations within individual fragments were spatially discontinuous, containing multiple, disjunct populations that inhabited small spatial areas and had reduced population size. The geometric effect was highly nonlinear and depended on the range of fragment sizes sampled and the scale at which species responded to habitat edges. Fragment shape played a strong role in determining population size in fragmented landscapes; thus, habitat restoration efforts may be more effective if they focus on connecting disjunct cores rather than isolated fragments.     

Collaborating to Conserve Large Mammals in Southeast Asia

Abstract:  Depressed mammal densities characterize the interior of many Southeast Asian protected areas, and are the result of commercial and subsistence hunting. Local people are part of this problem but can participate in solutions through improved partnerships that incorporate local knowledge into problem diagnosis. The process of involving local people helps build a constituency that is more aware of its role (positive and negative) in a protected area and generates site-specific conservation assessments for management planning. We illustrate the practical details of initiating such a partnership through our work in a Thai wildlife sanctuary. Many protected areas in Southeast Asia present similar opportunities. In local workshops, village woodsmen were led through ranking exercises to develop a spatially explicit picture of 20-year trends in the abundance of 31 mammal species and to compare species-specific causes for declines. Within five taxonomic groups, leaf monkeys (primates), porcupines (rodents), tigers (large carnivores), civets (small carnivores), and elephants (ungulates) had declined most severely (37–74%). Commercial hunting contributed heavily to extensive population declines for most species, and subsistence hunting was locally significant for some small carnivores, leaf monkeys, and deer. Workshops thus clarified which species were at highest risk of local extinction, where the most threatened populations were, and causes for these patterns. Most important, they advanced a shared problem definition, thereby unlocking opportunities for collaboration. As a result, local people and sanctuary managers have increased communication, initiated joint monitoring and patrolling, and established wildlife recovery zones. Using local knowledge has limitations, but the process of engaging local people promotes collaborative action that large mammals in Southeast Asia need.     

Biodiversity Consequences of Genetic Variation in Bark Characteristics within a Foundation Tree Species

Abstract: The developing field of community genetics has the potential to broaden the contribution of genetics to conservation biology by demonstrating that genetic variation within foundation plant species can act to structure associated communities of microorganisms, invertebrates, and vertebrates. We assessed the biodiversity consequences of natural patterns of intraspecific genetic variation within the widely distributed Australian forest tree, Eucalyptus globulus. We assessed genetic variation among geographic races of E. globulus (i.e., provenances, seed zones) in the characteristics of tree‐trunk bark in a 17‐year‐old common garden and the associated response of a dependent macroarthropod community. In total, 180 macroarthropod taxa were identified following a collection from 100 trees of five races. We found substantial genetically based variation within E. globulus in the quantity and type of decorticating bark. In the community of organisms associated with this bark, significant variation existed among trees of different races in composition, and there was a two‐fold difference in species richness (7–14 species) and abundance (22–55 individuals) among races. This community variation was tightly linked with genetically based variation in bark, with 60% of variation in community composition driven by bark characteristics. No detectable correlation was found, however, with neutral molecular markers. These community‐level effects of tree genetics are expected to extend to higher trophic levels because of the extensive use of tree trunks as foraging zones by birds and marsupials. Our results demonstrate the potential biodiversity benefits that may be gained through conservation of intraspecific genetic variation within broadly distributed foundation species. The opportunities for enhancing biodiversity values of forestry and restoration plantings are also highlighted because such planted forests are increasingly becoming the dominant forest type in many areas of the world.     

CO-OPERATION IN THE DEVELOPMENT OF SHARED WATER RESOURCES

This article examines the current status of and recent progress in co-operative arrangements for the development of water resources shared by two or more countries. Such arrangements may range from the simple exchange of data to the design and implementation of major projects and formal resolutions of disputes. Topics which are of growing concern to river-basin organizations include integrated development and management or shared water resources and dealing with the fresh water-maritime interface. The article indicates that optimum co-ordinated development, use and protection of shared water resources is still a distant goal, and that increased institutionalization of co-operation is required. Cet articles passe en reveu l'état actuel et les récents progrés réalisés dans le domaine de la coopération pour la mise en valeur des ressources en eau communes à deux ou plusieurs pays. Cette coopération peut ***revêtir plusieurs formes, allant du simple échange de données à la conception et la réalisation de projects importants ainsi qu'aux règlements officiels de disputes. Les sujets qui intéressent de plus en plus les agences de bassins comprennent la mise en valeur et la gestion intégrées des ressources en eau communes ainsi que les rapports entre les eaux douces et marines. L'article souligne que la meilleure coordination dans les domaines de la mise en valeur, l'utilisation et la sauvegarde des ressources en eau communes constituete encore un but très éloigné et qu'une réglementation accrue est nécessaire. Este articulo examina la situación actual de los acuerdos de cooperación para el desarrollo de recursos hídricos compartidos por dos o más países. Tales acuerdos pueden variar desde el simple intercambio de información al diseño y ejecución de grandes proyectos y la solución formal de disputas. Los asuntos de creciente importancia para las organizaciones encargadas del desarrollo de cuencas comunes incluyen el desarrollo y administración de los recursos compartidos y los problemas de contención de aguas salinas. El artículo indica que la óptima coordinación o utilización y protec-***     

Analysis of Feedstock Supply Costs for Wood-fired Electric Power Plants in Liberia, West Africa

In Liberia, as in many developing countries, electrification of towns and cities throughout the country has long been a major development goal. However, fuel expenditures by the Liberian Electricity Corporation (LEC) for its rural public stations represent a major and growing burden on the financially hard-pressed utility. In this paper we evaluate the economics of supplying wood to rural electric power plants utilizing different sources of feedstock. We also evaluate the cost implications of differences in wood supply requirements based on the use of steam or gasifier technology, and from variation in plant utilization level.
The wood supply we consider as sources are: (1) retired rubber trees; (2) the harvesting of secondary-growth forest just before the land is returned to temporary cultivation; (3) the establishment of commercial short-rotation wood energy plantations; and (4) adding to the system of shifting agriculture the planting of fast-growing wood species. The results indicate that wood can probably be supplied under a wide range of supply and demand conditions for US$1.00–1.70 per GJ. We estimate that wood steam plants can generate power for about $0.09-0.14 per kWh and gasifier plants for $0.10-0.18 per kWh. These costs are well below the present cost of oil-based rural electric power generation in Liberia (about $0.20–0.27 per kWh).     

Water Resources Development in Small Islands Perspectives and Needs*

The paper reviews the special problems of small islands in the field of water resources development. The mode of occurrence of surface and groundwater resources in the smaller Caribbean Islands is described along with the problems which arise from unfavourable hydrological conditions. A brief survey is given of the various types of water supply systems which have been developed to meet the requirements of the resident population and the tourist sector of the islands. Institutional deficiencies are discussed as they relate to the problems being experienced in the management of public water supply agencies and the conservation of water resources.     

Broadsided by broad traits: How to sink science in five dimensions or less

This paper is a conceptual and methodological critique of arguments advanced by Ones and Viswesvaran (1996, this issue) favoring ‘broad’ over ‘narrow’ personality traits for personnel selection and theoretical explanation. We agree with Ones and Viswesvaran that predictors should match criteria in terms of specificity. We depart from them, however, in our view of how traits should be chosen to obtain the best possible prediction and explanation of a complex overall job performance criterion. We argue that the best criterion-related validities will be attained if researchers use a construct-oriented approach to match specific traits (i.e. traits narrower than the Big Five) to those specific job performance dimensions that have been found to be job relevant. We further argue that researchers should focus on development of theories of job performance that incorporate constructs that are both specific and meaningful. If researchers seek to emphasize only overall job performance and personality traits greater than or equal to the Big Five in breadth, we will fail to acquire a great deal of important knowledge about the nature and causes of important aspects of work behavior.