Predicting tree diversity across the United States as a function of modeled gross primary production.

At the regional and continental scale, ecologists have theorized that spatial variation in biodiversity can be interpreted as a response to differences in climate. To test this theory we assumed that ecological constraints associated with current climatic conditions (2000-2004) might best be correlated with tree richness if expressed through satellite-derived measures of gross primary production (GPP), rather than the more commonly used, but less consistently derived, net primary production. To evaluate current patterns in tree diversity across the contiguous United States we acquired information on tree composition from the USDA Forest Service's Forest Inventory and Analysis program that represented more than 17,4000 survey plots. We selected 2693 cells of 1000 km2 within which a sufficient number of plots were available to estimate tree richness per hectare. Our estimates of forest productivity varied from simple vegetation indices indicative of the fraction of light intercepted by canopies at 16-d intervals, a product from the MODIS (Moderate Resolution Imaging Spectro-radiometer), to 8- and 10-d GPP products derived with minimal climatic data (MODIS) and SPOT-Vegetation (Systeme Pour l'Observation de la Terre), to 3-PGS (Physiological Principles Predicting Growth with Satellites), which requires both climate and soil data. Across the contiguous United States, modeled predictions of gross productivity accounted for between 51% and 77% of the recorded spatial variation in tree diversity, which ranged from 2 to 67 species per hectare. When the analyses were concentrated within nine broadly defined ecoregions, predictive relations largely disappeared. Only 3-PGS predictions fit a theorized unimodal function by being able to distinguish highly productive forests in the Pacific Northwest that support lower than expected tree diversity. Other models predicted a continuous steep rise in tree diversity with increasing productivity, and did so with generally better or nearly equal precision with fewer data requirements.     

Scaling range sizes to threats for robust predictions of risks to biodiversity

Assessments of risk to biodiversity often rely on spatial distributions of species and ecosystems. Range‐size metrics used extensively in these assessments, such as area of occupancy (AOO), are sensitive to measurement scale, prompting proposals to measure them at finer scales or at different scales based on the shape of the distribution or ecological characteristics of the biota. Despite its dominant role in red‐list assessments for decades, appropriate spatial scales of AOO for predicting risks of species’ extinction or ecosystem collapse remain untested and contentious. There are no quantitative evaluations of the scale‐sensitivity of AOO as a predictor of risks, the relationship between optimal AOO scale and threat scale, or the effect of grid uncertainty. We used stochastic simulation models to explore risks to ecosystems and species with clustered, dispersed, and linear distribution patterns subject to regimes of threat events with different frequency and spatial extent. Area of occupancy was an accurate predictor of risk (0.81<|r|<0.98) and performed optimally when measured with grid cells 0.1–1.0 times the largest plausible area threatened by an event. Contrary to previous assertions, estimates of AOO at these relatively coarse scales were better predictors of risk than finer‐scale estimates of AOO (e.g., when measurement cells are <1% of the area of the largest threat). The optimal scale depended on the spatial scales of threats more than the shape or size of biotic distributions. Although we found appreciable potential for grid‐measurement errors, current IUCN guidelines for estimating AOO neutralize geometric uncertainty and incorporate effective scaling procedures for assessing risks posed by landscape‐scale threats to species and ecosystems.     

Park isolation in anthropogenic landscapes: land change and livelihoods at park boundaries in the African Albertine Rift

Regional Environmental Change - Landscapes are changing rapidly in regions where rural people live adjacent to protected parks and reserves. This is the case in highland East Africa, where many...     

Implications from Mitochondrial DNA for Management to Conserve the Eastern Barred Bandicoot (Perameles gunnii)

On mainland Australia, the eastern barred bandicoot, Perameles gunnii , is confined to a relic wild population numbering less than 100 individuals in the city of Hamilton. Animals derived from this population are being bred in captivity in order to promote their recovery. The species also exists in Tasmania, where tittle is known of its conservation and taxonomic status. Mitochondrial DNA variability was compared within and between populations of P. gunnii using restriction fragment length polymorphisms. Genetic variability was found to be high among P. gunnii in Hamilton compared to those in Tasmania (higher diversity index, nucleotide sequence divergence, and greater number of haplotypes), despite the known decline and subdivision of the Hamilton population. Restriction fragment length polymorphisms distinguished animals from the east and the west of Hamilton and from the north and south of Tasmania. Nucleotide sequence divergence was substantial (2.2–2.5%) between Hamilton and Tasmania. Implications are that captive breeding and reintroduction should be designed to genetically represent the structure within Hamilton in order to minimize inbreeding and that the introduction of Tasmanian P. gunnii would not benefit the Hamilton population. It is concluded that mitochondrial DNA markers clearly can provide useful information about the history and current status of endangered marsupial populations, to the benefit of conservation management.     

Unusual sources of aluminium and heavy metals in potable waters

Aluminium in water supplies derives from natural sources and from the use of Al₂(SO₄)₃ in water treatment. Heavy metals such as Pb, Cu, Zn and Cd can be added to water from pipework and solder. However, it is apparent that AI and other metals in potable waters can derive from deposits on pipe walls which can be subsequently mobilised when the supply and/or treatment process is changed. Concentrations of Al in domestic supply water of the Llanbrynmair area have been shown to increase from 1 g to 50 g L^–1 during its 18 km journey along the water main. Similarly, Pb concentrations in a public building in the Aberystwyth area are found to be extremely elevated due to the metal's mobilisation from encrustations occurring on the copper pipework.     

Restoration and protection of aqueous environments by utilizing aquatic organisms

Summary Past and current uncontrolled dumping, land application and accidental spills of recalcitrant, toxic environmental pollutants such as DDT and polychlorinated biphenyls (PCBs) pose a continued world-wide environmental threat, in particular to aquatic environments. Bioaccumulative contaminants are rapidly absorbed out of water-borne ambient environments and concentrated in the tissues of living aquatic organisms at concentrations that can range from thousands to millions of times greater than levels in the ambient environment. These absorbed levels are high enough to cause dysfunction in the organisms and potential harmful effects to humans. An established technology capable of remediating the low contaminant levels originating in the ambient aquatic environment does not currently exist. This paper proposes the macro-bioremediation process whereby certain fish and other macroscopic aquatic organisms could be used to filter, concentrate and remove bioaccumulative contaminants from polluted aqueous systems. Contaminant removal would involve the harvesting and subsequent restocking of aquatic organisms capable of bioaccumulating high contaminant levels in relatively short time periods. Tissues of harvested organisms could be composted with specialized fungus and bacteria to fully degrade the recalcitrant contaminants. The macro-bioremediation process could be used at numerous geographic locations for the restoration of natural aquatic environments, supplemental wetlands treatment and for waste-water, hazardous waste and sludge treatment augmentation.     

First-trimester amniotic fluid and extraembryonic coelomic fluid acetylcholinesterase electrophoresis

Acetylcholinesterase (AChE) gel electrophoresis was performed on samples of amniotic fluid and extraembryonic coelomic fluid obtained by high resolution transvaginal ultrasound-guided amniocentesis from 38 women between 8 and 12 weeks of pregnancy. AChE was positive in 33 per cent (12/36) of the amniotic fluid samples; the percentage of positive results decreased as gestation advanced. AChE was positive in 32 per cent (9/28) of the extraembryonic coelomic fluid samples. In 81 per cent (21/26) of matched samples, the AChE results were identical in the two fluids. Amniotic fluid and extraembryonic coelomic fluid AChE electrophoresis cannot be used to diagnose neural tube defects prior to 12 weeks of gestation.     

Repeat maternal serum testing in multiple marker down's syndrome screening programmes

The effect of repeat testing in maternal serum multiple marker screening for Down's syndrome was estimated using samples stored in an antenatal serum bank. Human chorionic gonadotropin (hCG) and unconjugated oestriol (uE₃) levels were determined in 142 pairs of routinely collected samples which had already been tested for alpha-fetoprotein (AFP). For each marker, about two-thirds of the pairs of values were within 20 per cent of each other and most were within 40 per cent. A multivariate Gaussian model was used to estimate the detection and false-positive rates for different repeat testing policies. A policy of repeat testing those with a high risk of a Down's syndrome term pregnancy given age and marker levels would reduce the false-positive rate but there would also be a reduction in the detection rate. For example, using all three markers and a 1 in 250 cut-off risk, the estimated false-positive rate would fall from 5·3 to 3·8 per cent but the detection rate would decrease from 58 to 55 per cent. A policy of repeating those with either high or borderline risks would produce a modest improvement in screening efficiency. Repeating the 11 per cent with a risk exceeding 1 in 500 yields an estimated false-positive rate of 5·0 per cent and a detection rate of 60 per cent. A policy of selective repeat testing is not recommended as it would not substantially improve screening efficiency. Nonetheless, if a repeat test has been performed, the parameters given in this paper will enable an unbiased estimate of the Down's syndrome risk to be calculated for individual women.     

The impact of screening for open neural tube defects in England and Wales

Using information derived from the voluntary system of notification of congenital malformations in England and Wales, the birth prevalence of anencephaly and spina bifida was estimated to have declined by 80 per cent from 31.5 to 6.2 per 10 000 between 1964–1972 and 1985. Over the same period, notified terminations of pregnancy with a suspected fetal central nervous system abnormality increased from less than 1 per cent to 56 per cent of neural tube defect births and central nervous system terminations combined, accounting for 31 per cent of the decline in births. Routinely collected national statistics provide a method for monitoring the impact of screening for open neural tube defects. However because they are incomplete and lack detail an alternative method of monitoring is needed. This paper includes an outline of such a method, together with the results of a pilot study designed to assess the feasibility of monitoring screening in the Oxford Region.