Differential use of stored sperm during oviposition in the damselfly Calopteryx splendens xanthostoma (Charpentier)

Female Calopteryx splendens xanthostoma (Charpentier) (Odonata), have two discrete sperm storage organs, the bursa copulatrix and the paired spermathecae. We used the Random Amplified Polymorphic DNA(RAPD) profiling technique to determine from which sperm storage organ spermatozoa were used to fertilise eggs during behaviourally distinct oviposition bouts. During oviposition bouts following remating sperm from the bursa copulatrix are largely used to fertilise eggs, but when females avoid remating before an oviposition bout the sperm used to fertilise eggs are derived mainly from the paired spermathecae. Our observations suggest that female C. s. xanthostoma can avoid male paternity assurance mechanisms by a combination of behavioural and anatomical adaptation: the reason(s) they do so is unclear. Received: 28 November 1995/Accepted after revision: 5 August 1996     

Role of buffer strips in management of waterway pollution: A review

A buffer strip can perform a multitude of functions, and these include channel stability, a filter for sediment and nutrients, water purification (e.g., bacteria and pathogens), a nondisturbance area, and the provision of terrestrial and stream habitat. These functions are reviewed with specific application to Australian conditions, and methods for modeling their performance are outlined. The primary focus is on the use of buffer strips to minimize waterway pollution from diffuse sources since their use is often justified on this basis. Particular attention is given to the conditions under which a buffer strip will act as an effective filter and the conditions under which it will fail. Buffer strips are most effective when the flow is shallow (nonsubmerged), slow, and enters the buffer strip uniformly along its length. Their sediment trapping performance decreases as the sediment particle size decreases. Nutrients are often preferentially attached to fine sediment. As a result, buffer strips are better filters of sediment than of nutrients. Buffer strips should only be considered as a secondary conservation practice after controlling the generation of pollutants at their source and, to be effective, buffer strips should always be carefully designed, installed, and maintained.     

Vulnerability of Canadian aquatic ecosystems to nuclear accidents

Several cesium and strontium bioaccumulation models are used widely in national and international guidance for ecological and human health risk assessments for radiocesium (¹³⁴Cs and ¹³⁷Cs) and radiostrontium (⁹⁰Sr), but have not been used to make predictions of radiological risk from nuclear accidents under variable environmental conditions on broad geographical scales. In this paper, we first present models for predicting the bioaccumulation of cesium and strontium by aquatic biota based on ambient concentrations of dissolved potassium and calcium, respectively, and then test these models using independent data from aquatic ecosystems at Canadian nuclear sites. Secondly, models yielding the best predictions across a wide range of input parameters were selected to estimate bioaccumulation factors (BAFs) for cesium and strontium in aquatic ecosystems across Canada, using trophic level of organisms and dissolved potassium for cesium and calcium concentrations for strontium as predictor variables, and presented as contour maps of radiological risk. The models show that risk from bioaccumulation of cesium and strontium can vary by several orders of magnitude depending on site-specific environmental conditions and trophic ecology. Overall, our results suggest that single-parameter approaches taken by regulatory standards may either over- or under-predict radiological risk at many locations, and are thus not readily suitable to inform siting decisions for new nuclear developments.     

Context matters: matrix vegetation influences native and exotic species composition on habitat islands

The extensive research on plant communities of natural-habitat islands has primarily focused on the "islands." The island analogy, however, potentially limits understanding of processes influencing composition on habitat islands because the nature of their matrix is overlooked. We determine how plant community structure of the surrounding matrix influences vegetation on volcanic outcrops in the modified landscape of Banks Peninsula, New Zealand. Our primary purpose is to address whether the matrix is more important for recently established exotic species than it is for well-established native species and whether such invasion by exotics has led to homogenization of the outcrop flora. To test this, we examined our data at three spatial scales: that of the entire outcrop flora, between individual outcrops and their immediate surrounding matrix, and between individual outcrop faces and the individual relevés of the immediate surrounding matrix. We found that 81% of the native flora and 90% of the exotic flora also occur in the matrix. This high level of species shared between the outcrop and matrix persists at the scale of individual outcrop faces (68% of the total flora of individual faces is shared with the matrix). We predicted that floras from different outcrops would vary in their distinctiveness from their immediate matrix. We found Bray-Curtis distance coefficient values to range from 0.26 to 0.64; these were even higher at the outcrop-face scale. Variability in outcrop distinctiveness relates primarily to the outcrop face properties of area, vegetation height, and soil depth, and matrix properties of vegetation structure and vegetation heterogeneity. The effect of the vegetation structure of the matrix is more pronounced on the exotic than on the native outcrop flora. The component of composition and structure of the matrix that was independent of outcrop properties and local environment accounts for similar levels of explainable variation in total and native composition (29-31%), but considerably more (40%) in composition of exotic species. Our results support our prediction that, as the surrounding matrix becomes more modified, invasion by exotics makes outcrop vegetation less distinct from its matrix.     

Review of strategic planning guidance in Scotland

In Scotland, land use planning decisions have been aided by a series of National Planning Guidelines published over a period of nearly 20 years. The Guidelines represent a distinctive contribution to planning practice and have enabled the Scottish Office to inform local authorities of governmental policy on key land use issues. The Guidelines have been accompanied by Land Use Summary Sheets, providing assessments of specific land resources, and Circulars setting down ministerial policy. These instruments have attracted considerable interest outwith Scotland and their future development is also of wider significance. Current proposals seek to change these arrangements and, in particular, to replace the Guidelines with National Planning Policy Guidelines. The effects of the proposed changes are reviewed and discussed.     

Regional reports or structure plans? Opportunities for strategic planning in England and Wales

The British Government is proposing a new system of single‐tier development plans for England and Wales, with clear implications for the strategic level of planning. This paper considers a proposal by the Committee of Inquiry into Town and Country Planning set up by the Nuffield Foundation, for a revised strategic planning network which includes a ‘local strategy’. The paper considers the lessons to be drawn from the use of regional reports in Scotland since the early 1970s and concludes on a note of caution for the Government's proposals.     

Land clearance not dieback continues to drive tree loss in a Tasmanian rural landscape

Tree cover has declined markedly since European settlement in the agricultural areas of Australia due to land clearing and natural and stress-induced senescence of remnant trees combined with widespread regeneration failure. These decreases in tree cover have seldom been quantified on a landscape scale, but are important in understanding losses in carbon storage and biodiversity across large areas of the continent. We used historical aerial photography and satellite imagery to study changes in tree canopy cover in the southern Tasmanian Midlands, one of the oldest agricultural regions in Australia. Tree cover at 1,000 random sites was assessed from imagery captured on four occasions between 1947 and 2010. Tree cover was stable between 1947 and the 1970s, but decreased from 33 % in the 1970s to 21 % in 2010. The decrease appeared driven by transition from some cover to no cover, rather than from more cover to less cover, because sites with tree cover in 2010 showed little net change during the study period. Statistical modelling showed soils derived from igneous rocks lost more cover than did the less fertile sedimentary soils, and contrary to the expectations, if drought was the cause of cover loss, sun-exposed north-facing sites did not lose more cover than south-facing ones. We argue that these temporal and spatial patterns of tree cover change are consistent with tree clearing rather than loss of remnant isolated trees due to drought-induced dieback.     

Protected area downgrading,downsizing, and degazettement as a threat to iconic protected areas

Protected areas (PAs) are expected to conserve nature and provide ecosystem services in perpetuity, yet widespread protected area downgrading, downsizing, and degazettement (PADDD) may compromise these objectives. Even iconic protected areas are vulnerable to PADDD, although these PADDD events are often unrecognized. We identified 23 enacted and proposed PADDD events within World Natural Heritage Sites and examined the history, context, and consequences of PADDD events in 4 iconic PAs (Yosemite National Park, Arabian Oryx Sanctuary, Yasuní National Park, and Virunga National Park). Based on insights from published research and international workshops, these 4 cases revealed the diverse pressures brought on by competing interests to develop or exploit natural landscapes and the variety of mechanisms that enables PADDD. Knowledge gaps exist in understanding of the conditions through which development pressures translate to PADDD events and their impacts, partially due to a lack of comprehensive PADDD records. Future research priorities should include comprehensive regional and country-level profiles and analysis of risks, impacts, and contextual factors related to PADDD. Policy options to better govern PADDD include improving tracking and reporting of PADDD events, establishing transparent PADDD policy processes, coordinating among legal frameworks, and mitigating negative impacts of PADDD. To support PADDD research and policy reforms, enhanced human and financial capacities are needed to train local researchers and to host publicly accessible data. As the conservation community considers the achievements of Aichi Target 11 and moves toward new biodiversity targets beyond 2020, researchers, practitioners, and policy makers need to work together to better track, assess, and govern PADDD globally.