Impacts of tropical forest disturbance on species vital rates

Tropical forests are experiencing enormous threats from deforestation and habitat degradation. Much knowledge of the impacts of these land-use changes on tropical species comes from studies examining patterns of richness and abundance. Demographic vital rates (survival, reproduction, and movement) can also be affected by land-use change in a way that increases species vulnerability to extirpation, but in many cases these impacts may not be manifested in short-term changes in abundance or species richness. We conducted a literature review to assess current knowledge and research effort concerning how land-use change affects species vital rates in tropical forest vertebrates. We found a general paucity of empirical research on demography across taxa and regions, with some biases toward mammals and birds and land-use transitions, including fragmentation and agriculture. There is also considerable between-species variation in demographic responses to land-use change, which could reflect trait-based differences in species sensitivity, complex context dependencies (e.g., between-region variation), or inconsistency in methods used in studies. Efforts to improve understanding of anthropogenic impacts on species demography are underway, but there is a need for increased research effort to fill knowledge gaps in understudied tropical regions and taxa. The lack of information on demographic impacts of anthropogenic disturbance makes it difficult to draw definite conclusions about the magnitude of threats to tropical ecosystems under anthropogenic pressures. Thus, determining conservation priorities and improving conservation effectiveness remains a challenge.     

Old endemics and new invaders: alternative strategies of passerines for living in the Australian environment

Life history parameters of ”old endemics” and ”new invaders” among the Australian passerines were compared, controlling for phylogeny by using current, phylogenetic research methods. Old endemics were found to have significantly smaller clutches and demonstrated significantly more cooperative breeding than the new invaders, whose fledging periods are significantly longer than those of the old endemics. We argue that breeding under conditions of a small annual food increment during the breeding season, as is probably the situtation in Australia, is possible only when clutch size is small, or while breeding cooperatively, or by extending the fledging period. Our data show that the old endemics use the first two options, while the new invaders employ the third. Received: 10 February 1999 / Received in revised form: 10 November 1999 / Accepted: 20 November 1999     

Short-Term Influence of Tank Tracks on Vegetation and Microphytic Crusts in Shrubsteppe Habitat

Artemisia tridentata Nutt.) habitat within the Idaho Army National Guard Orchard Training Area in southwestern Idaho. The purpose of this study was to determine the short-term (1–2 years) influence of tank tracks on vegetation and microphytic crusts in shrubsteppe habitat. The two types of tank tracks studied were divots (area where one track has been stopped or slowed to make a sharp turn) and straight-line tracks. Divots generally had a stronger influence on vegetation and microphytic crusts than did straight-line tracks. Tank tracks increased cover of bare ground, litter, and exotic annuals, and reduced cover of vegetation, perennial native grasses, sagebrush, and microphytic crusts. Increased bare ground and reduced cover of vegetation and microphytic crusts caused by tank tracks increase the potential for soil erosion and may reduce ecosystem productivity. Reduced sagebrush cover caused by tank tracks may reduce habitat quality for rodents. Tank tracks may also facilitate the invasion of exotic annuals into sagebrush habitat, increasing the potential for wildfire and subsequent habitat degradation. Thus, creation of divots and movement through sagebrush habitat by tanks should be minimized.     

Fluctuating sexual dimorphism and differential hibernation by sex in a primate, the gray mouse lemur (Microcebus murinus)

The aim of this study was to investigate reproductive strategies and their consequences in gray mouse lemurs (Microcebus murinus), small solitary nocturnal primates endemic to Madagascar. Previous reports of sexual dimorphism in favor of males and females, respectively, a high potential for sperm competition and pheromonal suppression of mating activity among captive males, led us to investigate mechanisms of intrasexual competition in a wild population. Based on 3 years of mark-recapture data, we demonstrate that sexual dimorphism in this species fluctuated annually as a result of independent changes in male and female body mass. Male body mass increased significantly prior to the short annual mating season. Because their testes increased by 100% in the same period and because their canines are not larger than those of females, we suggest that large male size may be advantageous in searching for estrous females and in enabling them to sustain periods of short-term torpor. In contrast to reports from captive colonies, we found no evidence for two morphologically distinct classes of males. Finally, we also show that most adult males are active throughout the cool dry season that precedes the mating season, whereas most adult females hibernate for several months. This is in contrast to other solitary hibernating mammals, where males typically emerge 1–2 weeks before females. Thus, this first extended field study of M.␣murinus clarified previous conflicting reports on sexual dimorphism and male reproductive strategies in this primitive primate by showing that their apparent deviation from predictions of sexual selection theory is brought about by specific environmental conditions which result in sex-specific life history tactics not previously described for mammals. A general conclusion is that sexual selection can operate more strongly on males without resulting in sexual dimorphism because of independent selection on the same traits in females. Received: 6 July 1997 / Accepted after revision: 28 March 1998     

Future land-use change scenarios for the Black Sea catchment

Plausible future scenarios have been created for the Black Sea catchment, focussing on spatially explicit alternatives for land-use changes. Four qualitative storylines (HOT, ALONE, COOP and COOL) were first developed, based on interpretation of the respective global scenarios (A1, A2, B1 and B2) produced by the Intergovernmental Panel on Climate Change. Quantitative statistical downscaling techniques were then used to disaggregate the outputs of global scenarios at a regional level. The resulting land-use maps were spatially allocated at 1 km resolution in the Metronamica model, using a set of factors related to the identified drivers of change. The land-use change model was calibrated on historical trends of land-cover change (MODIS 2001 and 2008) translated into spatial allocation rules, and future land-use projections (IMAGE, 2001) were adopted. Suitability and constraint maps and population trends were used to regulate the modelling process. The calibrated model was validated by statistical procedures, visual evaluation and stakeholder involvement in order to ensure its plausibility and accuracy. This methodology bridged the gap between the global and regional scales. Four simulated future states were produced for the main land-use classes–forest, grassland, cropland and built-up areas, as well as scrublands, crops/natural vegetation and barren land–for 2025 and 2050. The results suggest that the features highlighted in these scenarios are guided by global trends, such as population rise and decreasing agriculture, but with different growth rates and a variety of spatial patterns, with regional variations resulting from local backgrounds and policy objectives. This study aims to provide future land-use data as a potential geographical tool to assist policy makers in addressing environmental emergencies such as water stress and pollution. In particular, the exploration of plausible futures can support future assessments to comply with the EU Water Framework Directive and Integrated Coastal Zone Management policies around the Black Sea.     

Trade-offs between time, predation risk and life history, and their implications for biogeography: A systems modelling approach with a primate case study

Group sizes are often considered to be the result of a trade-off between predation risk and the costs of feeding competition. We develop a model to explore the interaction between different ecological constraints on group sizes, using a primate (baboons) case study. The model uses climatic correlates of time budgets to predict maximum ecologically tolerable group size, and climatic predictors of predation risk (reflected mainly in predator density and female body mass) to predict minimum tolerable group size for any given habitat. As well as defining the range of sustainable group sizes for a given habitat, the model also allows us to reliably predict our exemplar taxon's biogeographical distribution across Africa. We also explore the life history implications of the model to ask whether baboons form group sizes which maximise survival or fecundity in the classic trade off between these two key life history variables. Our results indicate that, within the range of study sites in our sample, baboons prefer to maximise fecundity. However, the data indicate that in higher predation risk habitats they would switch to maximising survival at the expense of fecundity. We argue that this is due to the fact that interbirth interval and developmental rates have a ceiling that cannot be breached. Thus, while females can shorten interbirth intervals to compensate for increased predation risk, there is a limit to how much these life history variables can be altered, and when this is reached the best strategy is to maximise survivorship.     

Entangling the Complexity of Protected Area Management: The Case of Wolong Biosphere Reserve,Southwestern China

Protected Area (PA) management is a complex issue that requires the consideration of many factors and relationships. A conceptual framework for the analysis of biodiversity change, local human communities, and PA management was put forward, accordingly. Under the framework, we investigated the economic status, livelihood activities, biodiversity use and perceptions of local communities, and the land use history in Wolong Biosphere Reserve, southwestern China through household survey and document review in order to gain a better understanding of the complexity of PA management. According to the land use history, the preservation of agro-biodiversity, and the raising of productivity, ecological rehabilitation and the regulation of the human pressures are indispensable in the management of the reserve. Livelihood activities and the perceptions of local communities were largely determined by the socioeconomic background, which has important implications in solving the conflicts or incompatibilities in the reserve. In Wolong Biosphere Reserve, it is beneficial to support local farmers in solving their socioeconomic problems such as the overabundance of labor force and the lack of livelihood alternatives. Without this, there will be scarcely any effective biodiversity conservation and successful reserve management in the long term.     

DECLINING INTENSITY OF ACID MINE DRAINAGE IN THE NORTHERN APPALACHIAN BITUMINOUS COAL FIELDS: MAJOR ALLEGHENY RIVER TRIBUTARIES1

ABSTRACT: For more than 30 years, a program of continuous monitoring of pH, acidity, alkalinity, and other parameters has been maintained on a network of large streams degraded by acid mine drainage in the northern Appalachian high sulfur coal region. Continuous records since 1952 are available at a number of stations, and at several stations, acidity records date back to 1930. Comparable analysis techniques were maintained over the period of record, assuring the long term continuity of the database. This monitoring program has captured integrated long term trends within large and complex watersheds with numerous and varied types of mine discharges. The focus of this paper is a historical trend analysis of lightly to severely acid degraded major tributaries of the Allegheny River. Over the past three decades, all of the Allegheny River drainage basin stations have demonstrated steady and substantial declines in acidity and associated increases in pH and alkalinity. The average recorded decline in total acidity at four stations monitored since the 1950s was 94 percent. Since the 1970s, acidity declined by an average of 63 percent at 10 stations. Oxidative exhaustion of pyritic minerals exposed by mining is proposed as a major factor influencing these trends.     

Deconstructing a gender difference: driving cessation and personal driving history of older women

PROBLEM: The purpose of this study is to understand the reasons behind older women's driving cessation by comparing the driving histories of Finnish women who either gave up or renewed their drivers license at the age of 70. METHOD: A mail survey was sent to all Finnish women born in 1927 who gave up their license in 1997 (N=1,476) and to a corresponding random sample of women who renewed their license (N=1,494). The total response rate was 42.1%. RESULTS: The length and level of activity of personal driving history were strongly associated with driving cessation and continuation. Ex-drivers tended to have an inactive driving career behind them, whereas drivers had a more active personal driving history. In addition, those women with an active, "male-like" driving history who had decided to stop driving gave reasons for driving cessation that were similar to what is known about older men's reasons to give up driving. The results suggest that the decision to stop driving is related to driving habits rather than gender.     

Sources of Deforestation in Tropical Developing Countries

/ Key causes of tropical deforestation are investigated using cross-sectional data for 90 developing countries for the period 1981-1990. Regression results reveal that deforestation is associated with both development and scarcity. Deforestation accelerates with expanding infrastructure, trade, debt, investment in the human capital base, and resource-based economic expansion. On the other hand, absolute and relative scarcities-manifested by growing population pressures, food and land shortages, fuelwood dependency, and inequalities in access to land-are also key factors explaining forest loss. Thus, results point to a fundamental environmental conundrum: Development is required if countries are to alleviate scarcity-driven forms of forest exploitation but is itself a major cause of deforestation. Can countries balance development goals with forest protection? Setting aside the issue of its practical realization, the paper concludes that forest sustainable development cannot be achieved by implementing simple technical improvements in land-use practices alone. Securing the foundations for the sustainability of the forest base will require that countries address the underlying social processes driving tropical forest loss as well.KEY WORDS: Tropical deforestation; Developing countries; Rural land-use practices; Development; Scarcity.