Modeling the long-term effects of fuelwood harvests on Pinyon-Juniper Woodlands

In the Southwestern United States, increasing demand for firewood has quickly promoted pinyon-juniper woodlands to commercial status. Slow recovery rates for pinyon and juniper and inadequate mensuration data present significant obstacles to predictive management efforts. Many National Forest districts have witnessed continued fuel use for at least the past 100 years. To explore the need for long-term analysis at the district level, we have developed FORMAN I, a computer simulation written in FORTRAN IV that models prolonged fuel harvesting and its impact on pinyon-juniper woodlands. The technique is well-suited for historical analyses and we comply with an initial application that involves the suggested impact of prehistoric peoples on a marginal woodland in Chaco Canyon, New Mexico. To accentuate the significance of the simulation, we have deliberately overestimated woodland parameters while maintaining conservative annual rates for firewood procurement. A low-density woodland (less than 14.8 cords/ha) is completely depleted within 200 years when subjected to tenth-through-twelfth century estimates of human demography for the canyon. Interesting conclusions are drawn from the lack of pinyon-juniper recovery at Chaco over the past millennium. Traditional assumptions, such as the pristine state of Southwestern vegetation prior to historic settlement and subsequent invasion of marginal grasslands by pinyon and juniper, are questioned.     

EVALUATING INLAND WATERWAY NAVIGATION IMPROVEMENT PROJECTS: THE CASE OF THE BONNEVILLE LOCK

ABSTRACT: The period of time from identification of a possibly desirable inland waterway transportation project to its actual implementation has been observed to be inordinately long. It is Hypothesized that at Least one cause of delays in project approval and implementation is a analytical credibility associated with project feasibility analysis conducted by the U.S. Army Corps of Engineers. This paper examines this hypothesis in terms of the proposal to construct a new, expanded lock at the Bonneville Dam on the Columbia River. The principle finding is that the analysis conducted by the Corps is conceptually flawed, methodologically questionable, internally inconsistant, and inappropriately narrow in scope.     

AN EXAMINATION OF LAND USE - NUTRIENT EXPORT RELATIONSHIPS1

ABSTRACT: Lake and watershed management strategies and recent environmental legislation dictate that nonpoht nutrient sources associated with storm water runoff must be assessed. Accordingly, a nutrient flu assessment for phosphorus and nitrogen is conducted through an extensive literature review of nutrient export studies. These studies are reevaluated. The nutrient export coefficients are screened according to sampling design criteria and compiled according to land use. The ecological mechanisms within each land use influencing the magnitude of nutrient flux are also discussed     

Determination of atrazine in rainfall and surface water by enzyme immunoassay

Rainwater and surface water from four sites in Germany (Bavaria and Lower Saxony) were analyzed for atrazine by enzyme immunoassay from June 1990 until October 1992. The limit of quantification of the immunoassay was 0.02 μg/L with a middle of the test at 0.2 μg/L. About 60 % of the samples contained measurable amounts of atrazine. Seasonal trends were observed, with the highest concentration in the summer months of up to 4 μg/L for rainwater and up to 15 μg/L for surface waters. The highest concentrations were found in agricultural areas, while in the investigated national parks up to 0.56 μg/L could be detected in rain water. This points to long-range atmospheric transport from agricultural areas to pristine national parks. Samples from forest stands usually showed higher atrazine concentrations than samples from open fields. Deposition rates of 10 – 50 μg/m² · yr were observed in the national parks and 10–180 μg/m² · yr at the agricultural sites. Comparison of results obtained by enzyme immunoassay and GC/MS showed a good correlation of r = 0.95.     

Exposure,epidemiology, and mechanism of the environmental toxicant manganese

It has become increasingly apparent that global manganese (Mn) pollution to air and water is a significant threat to human health. Despite this recognition, research is only beginning to comprehend the detrimental effects of exposure. Mn, while essential, is particularly harmful to the central nervous system, and overexposure is symptomatic of several neurological disorders. At-risk populations have been identified, but it is still unclear whether typical exposure levels have any long-term consequences. Those at an elevated risk have diminished intellectual function, learning and memory, and mental development. While the overall mechanism of toxicity is undetermined, Mn has been found to induce oxidative stress, exacerbate mitochondrial dysfunction, dysregulate autophagy, and promote apoptosis, ultimately enhancing neurodegeneration. Extrapolation of this in vitro and in vivo data to humans is difficult. There is a definite need to correlate epidemiological studies with causative effects. It is imperative that research efforts endure, so threats are appropriately identified and exposure properly regulated.     

Sources and factors controlling the disposal of biodegradable municipal solid waste in urban and rural areas of Cyprus

An inventory of sources of biodegradable municipal soil waste (BMSW) was constructed for urban and rural areas in the EU accession region of Cyprus. Composition analysis was performed on source-separated BMSW collected from households in the rural Ergates Community and an urban area within the Agglanjia Municipality. The data were statistically scrutinized to identify the main factors influencing the quantities of BMSW disposed by urban and rural communities in Cyprus. The results were extrapolated to predict the quantities and types of BMSW disposed by the entire communities. Significantly more BMSW was disposed in the urban area compared to the rural community due to lower diversion rates for green waste and the disposal of food waste from commercial sources. The quantity of food waste collected from households was influenced by socio-economic (household size, income, percentage of children) and behavioural (feeding of food waste to domestic animals, consuming processed 'ready' food) factors, whereas garden size, the type of vegetation, the reuse of trimmings and home composting were the main factors controlling the disposal of green waste.     

The African environment: from transition to stability

Summary The African environment is in a state of transition: this allows a unique opportunity of motivating and training the citizens and leaders of tomorrow to achieve environmental stability on that continent. A framework for thought on the matter is presented here.Has previously taught in the UK and NigeriaScientific Advisor to Commonwealth Human Ecology Council. To whom all correspondence should be addressed.     

Maximum Plant-Community Endemism at Intermediate Intensities of Anthropogenic Disturbance in Bolivian Montane Forests

Abstract: I compared the endemism of four plant groups (Araceae, Bromeliaceae, Palmae, Pteridophyta) along gradients of increasing anthropogenic forest disturbance, from undisturbed mature forest to disturbed forest (logged, grazed, or burned), secondary forest, secondary scrub, and finally pasture, at 16 sites in the Bolivian Andes. I measured endemism as the mean inverse range size (number of 1° cells) of all species per study group encountered in each habitat and site. Overall, endemism was significantly higher in disturbed forest than in mature forest, but it declined in more strongly disturbed habitats. To explain the relationship of range size to habitat disturbance, I propose that endemic species are somewhat competitively inferior to other co-occurring taxa, limited in their ability to establish and maintain new populations following dispersal and thus to expand their ranges. Within their established ranges, endemic species depend on natural habitat disturbances to prevent their competitive exclusion by other species, so they profit from a certain level of anthropogenic disturbance. This pattern and the explanatory hypotheses should be subjected to critical evaluation. Although the pattern does not apply to every endemic tropical plant species, it indicates that conservation of part of the endemic tropical forest flora may be achieved in forest areas subject to sustainable forest use without the need to completely exclude human activities.     

Accumulation of trinitrotoluene (TNT) in aquatic organisms: part 2--Bioconcentration in aquatic invertebrates and potential for trophic transfer to channel catfish (Ictalurus punctatus)

The potential of TNT to accumulate in aquatic organisms was assessed by determining bioconcentration factors for TNT and TNT biotransformation products using two benthic invertebrates (Chironomus tentans and Lumbriculus variegatus), and by determining the bioaccumulation factor of TNT and TNT biotransformation products due to TNT exposure via feeding for channel catfish (Ictalurus punctatus). In all three species, TNT was rapidly biotransformed resulting in minimal accumulation. The bioconcentration factors for parent TNT ranged from 3 to 4 ml g(-1) for the invertebrates studied, while the TNT bioaccumulation factor for catfish via oral exposure of food pellets was 2.4x10(-5) g g(-1) based on the concentration of TNT in the food pellet. As indicated by this small bioaccumulation factor, TNT accumulation in channel catfish through trophic transfer would be negligible compared to aqueous exposure (previously reported BCF of 0.79 ml g(-1)). TNT extractable biotransformation products accumulated to a greater degree than parent TNT for all three species. In addition, a large fraction of the radioactivity within all three species resisted solvent extraction. The highest bioconcentration factors occurred in L. variegatus with extractable radioactivity measuring 76 ml g(-1) and total radioactivity measuring 216 ml g(-1). Because the bioaccumulation of TNT is very low compared to the bioaccumulation of its biotransformation products, further research including identifying and determining the relative toxicities of these biotransformation products is necessary to fully evaluate the environmental risk posed by exposure to TNT.     

Identifying socioeconomic and biophysical factors driving forest loss in protected areas

Protected areas (PAs) are a commonly used strategy to confront forest conversion and biodiversity loss. Although determining drivers of forest loss is central to conservation success, understanding of them is limited by conventional modeling assumptions. We used random forest regression to evaluate potential drivers of deforestation in PAs in Mexico, while accounting for nonlinear relationships and higher order interactions underlying deforestation processes. Socioeconomic drivers (e.g., road density, human population density) and underlying biophysical conditions (e.g., precipitation, distance to water, elevation, slope) were stronger predictors of forest loss than PA characteristics, such as age, type, and management effectiveness. Within PA characteristics, variables reflecting collaborative and equitable management and PA size were the strongest predictors of forest loss, albeit with less explanatory power than socioeconomic and biophysical variables. In contrast to previously used methods, which typically have been based on the assumption of linear relationships, we found that the associations between most predictors and forest loss are nonlinear. Our results can inform decisions on the allocation of PA resources by strengthening management in PAs with the highest risk of deforestation and help preemptively protect key biodiversity areas that may be vulnerable to deforestation in the future.