Unsuitable Sites Research Articles

Modelling the dynamics of introduced populations in the narrow‐endemic Centaurea corymbosa: a demo‐genetic integration

Summary In the context of the restoration of an endangered species, population viability analysis represents a useful tool for assessing the effectiveness of different possible management strategies before implementation. However, despite the consensus that demographic and genetic mechanisms are both involved and interact in the process of extinction, few attempts have been made to examine their combined impacts on population viability in a particular species. We integrated specific data resulting from 10‐year multidisciplinary investigations into a descriptive model to simulate the dynamics of an introduced population of the rare self‐incompatible plant species Centaurea corymbosa. The model allowed us to examine the interplay between demographic processes and genetic self‐incompatibility in the particular habitat conformation of the species, alternating suitable and unsuitable sites within a population along cliffs. Population growth and extinction risk were compared for different introduction strategies. Population persistence mainly depended on the number of introduced seeds and on their initial spatial distribution within the population (single vs. multisite introduction). In most cases, a multisite introduction resulted in faster population growth and higher viability than a single‐site introduction. As expected, a strong negative impact of the self‐incompatibility system was observed on population dynamics and viability. However, because of positive feedback between demographic and genetic processes, this impact differed among introduction strategies: it was less severe when seeds were distributed among suitable sites, which also limited the loss of self‐incompatibility alleles. Moreover, self‐incompatibility contributed to the positive relationship between flowering plant density and fertilization rate. Synthesis and applications. Our results provide strong management guidelines for future introductions of C. corymbosa regarding the number of seeds required (> 800) and the benefits of introducing them into several sites to achieve population persistence. Further, the study highlights the general importance of integrating demography and genetics to compare the effectiveness of different management strategies.

Geographical information systems-based models for offshore floating marine fish cage aquaculture site selection in Tenerife, Canary Islands

The present study focuses on the development of a standard methodology for selection of suitable sites for oishore (exposed) marine ¢sh-cage farming (£oating cages) of seabream (Sparus aurata )a nd seabass (Dicentrarchus labrax) in an island environment, using Tenerife as an example. Site selection is a key factor in any aquaculture operation, aiecting both success and sustainability and can solve con£icts between diierent activities, making a rational use of the coastal space. Site selection was achieved by using geographical information systems (GIS)-based models and related technology to support the decision-making process. The framework for spatial multicriteria decision analysis used in this study began with a recognition and de¢nition of the decision problem. Subsequently, 31 production functions (factors and constraints) were identi¢ed, de¢ned and subdivided into eight submodels. These were then integrated into a GIS database in the form of thematic layers and later scored for standardization. At this stage, the database was veri¢ed by ¢eld sampling to establish the quality of data used. The decision maker’s preferences were incorporated into the decision model by assigning weights of relative importance to the evaluation under consideration. These, together with the thematic layers, were incorporated using multicriteria evaluation techniques and simple overlays to provide an overall assessment of possible alternatives. The integration, manipulation and presentation of the results by means of GIS-based models in this sequential and logical £ow of steps proved to be very eiective for helping the decision-making process of site selection. Tenerife has very favourable environmental conditions for culture of marine ¢sh and there are no totally unsuitable sites for cage farming identi¢ed in this study. On the other hand, there are few very suitable sites (high scores) either, principally due to the heavy use of the coastline and the con£icts between diierent users. From the 228 km 2 of available area for siting cages in the coastal regions with depth less than 50 m, the total area suitable for siting cages (scores 6^8) was 37 km 2 . There are only 0.51km 2 of very suitable areas (score 8) and approximately 5.37 km 2 of suitable (score 7), most of these being located in the southeast of the island. These relatively small areas of suitability should be put into the context of the wider use of the coastal environment around Tenerife.

Is there a future for wild grapevine (Vitis vinifera subsp. silvestris) in the Rhine Valley?

The wild grapevine, Vitis vinifera L. subsp. silvestris (Gmelin) Hegi, is considered to be an endangered taxon in Europe, mainly as a consequence of the introduction of pathogens from North America and of the destruction of its habitat. In the Rhine Valley, nearly all populations disappeared due to river management, the intensi.cation of forestry, and the introduction of phylloxera. After a growing awareness of the need to preserve endangered forest ecosystems, attempts to reintroduce wild grapevine in the Rhine Valley were performed, particularly in the French nature reserves Erstein and Offendorf since 1992. However, regular surveys of the plants indicate the rapid decline of the populations. In 2002, we proposed to summarise the knowledge accumulated after 10 years of experiments. Results indicate that from the initial 91 individuals planted in 1992, only 14 survived in 2002 (2 in Erstein, 12 in Offendorf). The failure of the experiment may be explained by several factors: unsuitable sites (too shady, absence of support for the young plants), absence of monitoring, vandalism or predation. According to these results and recent knowledge of the ecology of the plant and of vines in general, new transplantation experiments are proposed in which the plants will be monitored during their establishment in the forests. The success of this second transplant (50 plants per reserve) will be enhanced by restoration projects of the Rhine River dynamics, with partial re-flooding. Floods should help to avoid, or at least to reduce, pest and disease expansion on future adult plants.

INCREMENTAL COSTS AND BENEFITS SHAPE NATAL DISPERSAL: THEORY AND EXAMPLE WITH HEMILEPISTUS REAUMURI

Incremental (distance-dependent) costs and benefits of dispersal have received less attention than those that are qualitative. We present a dynamic programming model of settling behavior using parameters estimated from a field study of dispersal in desert isopods, Hemilepistus reaumuri, which walk up to thousands of meters before settling in new or already-established burrows each spring. The model shows that incremental costs of dispersal lead to right-skewed population dispersal patterns, in contrast to cost-free systems or those with unitary costs (i.e., a one-time cost of leaving a group or patch). In the model, continuous variation in habitat quality, as opposed to discrete suitable vs. unsuitable sites, allows for trade-offs with dispersal costs that lead to shifts in the likelihood of settling in a patch of a given quality. Thus, measurement of quantitative costs and benefits of movement are needed to understand population dispersal distributions. These costs or benefits may be observable during or after movement, and we examined both pre- and postsettling incremental consequences of dispersal. The daily mortality rate of traveling isopods was 4.2% during the dispersal season, higher than that of settled individuals. Successful settlers traveled more slowly, but burrows started in midseason were most likely to succeed. More distant burrows failed more often, suggesting either an additional cost of movement or a difference in the quality of individuals traveling different distances. The predicted mean dispersal duration from the simulations matched observed values closely, but was based on an unrealistic assumption of perfect knowledge of habitat quality, suggesting some other factor favors longer times before settling. Reproductive success was much higher in re-used burrows than in new burrows, making them a possible incentive for long-distance movements.

Getting Out of the Woods

Abstract The number and area of nature reserves in China have increased significantly in the last 2 decades. This massive increase has not been matched by a corresponding enhancement of management inputs and capabilities. Six major problems in protected area (PA) management are identified in this article: selection of unsuitable sites for conservation, shortage of funding, rising people–park conflicts, the paper park syndrome, multiple but disparate management agents, and lack of international experience. Five management quandaries are discussed to highlight the major dilemmas, ie, whether the reserves should exclude traditional resource-tapping activities, whether non-governmental organizations (NGOs) should be encouraged to help management agents, whether the management should earn income from the reserves, whether they should be the umpire or a player in the utilization of natural resources in reserves, and whether an integrated management structure should supersede the present compartmentalized arrang...

Grafting Fraser Fir onto Rootstocks of Selected Abies Species

Orthotropic shoots (tips of primary axes) from 3-year-old Fraser fir seedlings [Abies fraseri (Pursh) Poir.] were grafted onto rootstocks of Fraser fir, Korean fir (A. koreana Wils.), momi fir (A. firma Sieb. & Zucc.), Nordmann fir (A. nordmanniana (Steven) Spach.), Turkish fir (A. bornmuelleriana Mattf.), and West Virginia balsam fir from Canaan Valley (Canaan fir) [A. balsamea (L.) Mill. var. phanerolepis Fern.]. Firstyear survival in the greenhouse was 92% to 98% except for momi fir (83%). The percentage of grafted plants with orthotropic shoots was 92% to 98%, except for Korean (81%) and momi fir (86%). Plants were subsequently established in replicated field experiments on three sites in the piedmont and mountains of North Carolina. In general, leader elongation of grafted Fraser fir scions was greater than leader growth on nongrafted transplants, including Fraser fir. Differences in survival appear to reflect interspecific variation in resistance to phytophthora root rot and/or tolerance of warm environments. Grafting may offer the potential to grow Abies Christmas trees on previously unsuitable sites, or to reclaim or continue using sites already seriously impacted by root rot.

Asphalt Plug Joints: Refined Material Tests and Design Guidelines

Highway builders and rehabilitators throughout the United States use asphalt plug joints (APJs) in bridge expansion joints according to manufacturers’ recommendations. Joint performance varies widely, as indicated in recent surveys. State departments of transportation are installing joints in unsuitable sites or are overlooking other sites where APJs may work well. Rational design guidelines for APJs have been developed. The research suggests suitable applications, material characterization, design guidelines, and validation procedures. Two critical material properties are required to qualify APJ material: relaxation and glass-transition temperature. Both properties may be obtained by using a slight modification of the AASHTO standard thermal specimen, restrained specimen asphalt test. This modified standard test was conducted, and the results were compared with those of the near-full-scale test. Design guidelines are based on field observations, material tests, near-full-scale testing, analytical evaluations, and a survey of the experiences of state departments of transportation. Design recommendations are provided, and joint design changes are proposed to help mitigate the present shortcomings.

Priority assessment for conversion of Norway spruce forests through introduction of broadleaf species

Serious damage to Norway spruce ( Picea abies L. Karst) in Central and Western Europe together with increasing preference for forests with natural species composition emphasise the necessity to convert Norway spruce plantations on unsuitable sites and outside of its natural distribution. Site related priority assessment of Norway spruce replacement by Fagus sylvatica L., Quercus robur L., Acer pseudoplatanus L. and Fraxinus excelsior L., respectively, was calculated using a geographical information system for a management unit of 1248 ha in Upper Austria. Three matrix overlays combining soil depth with soil skeleton and vegetation type with gleyification resulted in different risk categories for Norway spruce. Further matrix overlay with Norway spruce stocking indicated sites with high conversion priority. Suitability indices of broadleaf species were evaluated using indexing overlay, allowing to weight map attributes of seven site parameters. This calculation was done separately for each species studied. Combination of these suitability indices with the conversion priority of Norway spruce led to site-related introduction priorities. The largest areas were found for Q. robur, followed by F. sylvatica. The higher suitability of Q. robur compared to F. sylvatica was explained by its superior adaptation to the acidic, shallow and partially gleyic soils in the area. The introduction of F. excelsior was generally not found advisable. The advantage of this method over the use of classic site classification was seen in the direct implementation of current stand characteristics into the decision rules.

Local Explanations of Landscape Patterns: Can Analytical Approaches Approximate Simulation Models of Spatial Processes?

Research over the last 100 years has demonstrated the importance of space for ecological processes. Given this importance, it may seem natural to start investigations into broad-scale ecological processes with a comprehensive, broad-scale spatial map. Here we argue that it may sometimes be possible to answer important questions about spatial processes using crude spatial information obtained when a comprehensive map is not available. To present our argument, we first develop a simple simulation model for a perennial plant reproducing and dying on a landscape with different arrangements of suitable and unsuitable sites. We then develop a simple, analytical approximation to predict the fraction of suitable sites that are occupied by the simulated plants. The analytical approximation summarizes the spatial map by using a single parameter that gives the probability that a site adjacent to a suitable site is suitable. Comparing the predictions of both approaches highlights three points: (a) The role of the spatial environment in ecological processes may play out at the local scale. Therefore, studying the local-scale processes may provide insights into landscape patterns. (b) The predictions from the analytical approximation fail noticeably when suitable sites are rare and are distributed randomly (rather than clumped) on the map. In these situations, patches of interconnected suitable sites are very small, and populations within small patches may go extinct via demographic stochasticity. This illustrates how analytical approximations can be used to identify cases when local-scale spatial processes are not sufficient to understand the ecological consequences of space. (c) For many natural systems, constructing the appropriate environmental map needed to study ecological processes is difficult or impossible. However, summary characteristics such as those employed by the analytical approximation may be estimated directly in nature. Therefore, even in the absence of an explicitly spatial broad-scale map, it may be possible to study spatial processes by understanding which local-scale characteristics of space are important.

Landfills in Karst Terrains

State and Federal regulations have established restrictions for location of hazardous waste and municipal, solid waste landfills. Regulations require owners/operators to demonstrate that the hydrogeology has been completely characterized at proposed landfills, and that locations for monitoring wells have been properly selected. Owners/operators are also required to demonstrate that engineering measures have been incorporated in the design of the municipal solid waste landfills, so that the site is not subject to destabilizing events, as a result of location in unstable areas, such as karst terrains. Karst terrains are typically underlain by limestone or dolomite, and may contain a broad continuum of karst features and karst activity. Preliminary investigation of candidate sites will allow ranking of the sites, rejection of some unsuitable sites, and selection of a few sites for additional studies. The complexity of hydrogeologic systems, in karst terrains, mandates thorough hydrogeologic studies to determine whether a specific site is, or can be rendered, suitable for a land disposal facility. Important components of hydrogeologic studies are: field mapping of structural and stratigraphic units; interpretation of sequential aerial photographs; test drilling and geophysical analyses; fracture analyses; seasonal variation in water-levels; spatial variation of hydraulic characteristics of the aquifer and aquiclude; velocitymore » and direction of movement of ground water within aquifers; determination of control for recharge, discharge, and local base level; and evaluation of the effects of man's activities, such as pumping, dewatering and construction.« less

Can the growing human population feed itself?

A review is presented of the optimist and pessimist viewpoints on rapid population growth and the ability to met food supply needs for a population of 10 billion by 2050. The author concludes that neither position is completely correct. The important consideration is not how to grow more food but how to implement agricultural methods that may improve food productivity. How to achieve this goal at acceptable environment costs will be a challenge because the unused cultivable land is of lower quality and the costs of expanding irrigation will be significantly higher owing to unsuitable sites. Where productivity is already high as in China there is a question as to how much more improvement is possible. These concerns only recognize costs in terms of agricultural products and not costs in terms of deforestation loss of species soil erosion and pollution from pesticides and runoff off fertilizer. There are too many uncertainties that prevent prediction of future food prices. Food prices are likely to rise but the impact will be felt more by the poor. What is plausible is a slow increase in dietary intake significant annual changes in food availability and prices and expansion of agriculture through increased crop yields more intensive farming practices and increased cultivation of arable land. Progress will be uneven and there will be low-income countries with little or no reserves of fertile land or water countries with misguided government intervention that keeps nutrition levels low an countries beset with famine drought and civil unrest or political instability Technologically it is feasible to improve the quantity and quality of food over time but the costs may be too great for poor countries. A governments ability to design and implement effective policies dealing with rapid population growth and rising poverty and environmental degradation will determine the course of events. There is not doubt that unchecked population growth rates will make this task more difficult.

The proximal promoter and the start site cooperate to specify correct U1 snRNA transcription initiation by RNA polymerase II.

In this work, we attempted to gain insight into the detailed mechanism allowing correct transcription initiation of U1 snRNA genes by RNA polymerase II. Abolition of the CA motif residing at -1/+1 in the Xenopus U1 gene leads to a loss of the ability of the promoter to direct accurate initiation. A discrete site is selected only if a purine preceded by a pyrimidine is positioned at 58/57 bp downstream of the center of the PSE. The PSE alone is unable to designate a discrete initiation site. Rather, it serves to set the location of an initiation window without discriminating suitable from unsuitable initiation sites. The latter role is devoted to a PyPu sequence positioned at -1/+1. Therefore, it is the concomitant action of the PSE and an essential PyPu positioned at the proper distance from this promoter that specifies correct U1 snRNA transcription initiation by RNA polymerase II.

BRIDGES AND CULVERTS REDUCED IN SIZE AND COST BY USE OF CRITICAL FLOW TRANSITIONS.

This Paper describes an innovative concept for designing channel transitions which will converge wide, shallow, sub-critical flows into high-velocity critical flows. The flows are then passed through deep, narrow throats that are cheaply culverted or bridged. The outflow is finally diverged, spread and decelerated before being passed downstream with minimum head losses. These 'minimum energy' or 'maximum discharge' designs were first used in Australia in 1961. They offer a means of passing large flows through much smaller, more efficient and more economical culverts and bridges, without the considerable upstream afflux that is the bane of conventional hydraulic structures. The design procedures have accurately predicted performances in the field. The usual problems of erosion, siltation, debris and energy dissipation are discussed and shown to be either absent or manageable. The concept is very useful in many instances, including that of increasing the capacity of many suitable floodplain bridges at minimal cost. Much experience is recorded, a worked example is presented, and both appropriate and unsuitable sites are described. (A)

PLANNING FOR GROUNDWATER SOURCE HEAT PUMPS

Development of groundwater as a resource lies in its wise use and reuse. The challenge facing water managers is the role groundwater will play in balancing demands for water use in industrial, agricultural, domestic and energy applications. Shallow near-surface groundwater (less than 80m) provides heating and cooling in more than 6 000 locations in Canada. Regional scale groundwater planning for heat pumps can identify suitable (and unsuitable) sites for sustainable groundwater use.A classification system was developed and tested in the 1 400 km Region of Waterloo, Ontario, Canada. Seven parameters in the groundwater heat pump system: topography, bedrock geology, soils, groundwater availabilty, water table and percolation rate, were entered into a matrix of ground water heat pump evaluation. Groundwater heat pump suitability is determined by quantification of physical variables, which are ranked, aggregated, and presented in map form. The procedure is responsive to local physical conditions and concerns. ...

Experience with ventriculo-pleural shunts.

Ventriculo-pleural shunting for the management of hydrocephalus was initially introduced by Ransohoff in 1954. However, because of the reported cases of pleural effusion with this procedure, the operation has not achieved popularity in the management of hydrocephalus. In the course of a review of 1,500 patients with hydrocephalus treated at the Hospital for Sick Children over the years 1960-1981, we encountered 59 patients who had been treated with a ventriculo-pleural shunt during the years 1971-1981. The commonest reason for insertion of the ventriculo-pleural shunt was a preexisting infected ventriculo-peritoneal shunt. 12 of the 59 patients developed pleural effusions, and 6 of these 12 patients were under 11 months of age. The incorporation of an antisiphon device in the shunting system seemed to decrease the possibility of a pleural effusion. 23 of the 59 patients continue to function on their inserted ventriculo-pleural shunt, and in 9 of these the shunts have been functioning for over 5 years. Ventriculo-pleural shunting seems to be a safe and simple form of diversionary CSF bypass. The risk of pleural effusion seems to be highest in the infant, but can occur at any age. However, even in the infant the ventriculo-pleural shunt provides a good temporary site for diversion of CSF when the peritoneal cavity is contaminated or hazardous to shunt function. Ventriculo-pleural shunting provides a valuable alternative for the management of hydrocephalus in those patients where the heart or the peritoneal cavity are unsuitable sites.

Oviposition attractants and repellents of mosquitoes

Infusions of various organic materials have been known to modify ovipositional behavior of gravid female mosquitoes. Previously, we found that an infusion of Purina Laboratory Chow elicited negative ovipositional behavior inCulex pipiens quinquefasciatus Say andCulex tarsalis Coquillett. In the present chemical studies, the Purina Laboratory Chow infusion, fermented for 10 days, was distilled to give an active distillate which, upon ether extraction, gave an active ether extract. Fractionation of the ether extract yielded an active acidic fraction and inactive nonacidic fraction. Gas Chromatographie analysis on Porapak R and AT-1200-H3PO4 columns of the acidic fraction showed the presence of acetic, propionic, isobutyric, butyric, isovaleric, and caproic acids. In bioassay tests, these lower aliphatic carboxylic acids, individually and in combination, exhibited ovipositional repellency against the two species of mosquitoes at the concentration of 6 × 10−2%. At this concentration, butyric acid caused 100% mortality in first-instar larvae ofC. p. quinquefasciatus. Gravid female mosquitoes might have acquired, through evolutional adaptation, the ability of avoiding ovipositing in unsuitable sites in which toxic compounds might be detrimental to the survival and development of their offspring.

Transbronchial needle aspiration for lung cancer patients, especially for the cases in which cancer cells were negative in the specimens taken by the brushing method

Cancer cells were negative in the specimens taken from 4 cases by the transbronchial peripheral brushing method through bronchoscope. These lesions had originated in the unsuitable sites for taking the specimens for diagnosis. It was suggested that the transbronchial aspiration cytology with a needle improved by us is suitable for the establishment of diagnosis of such lesions.

A Methodology for Power Plant Site Selection at the Reconnaissance Level

A methodology was developed and applied to identify the principal candidate sites at which major steam electric generating facilities to serve the Long Island area could be located. The selection criteria included not only economic and engineering considerations but social and environmental factors refleeting changing and often intangible public values. From 68 candidate sites, five were selected through a series of steps in which analysis and judgment were combined to overcome the problems of preliminary information and uncertainty. These successive steps eliminated unsuitable sites on the basis of a qualification review and a preference review. A refined analysis of the favorable sites revealed patterns of value-free dominance among them.

Host Discrimination: Isolation of Hydrocarbons from Dufour's Gland of a Braconid Parasitoid1

Many hymenopteran parasitoids are able to recognize hosts that are parasitized and, consequently, reject them as unsuitable sites for oviposition. For some of these parasitoids this discriminatory ability results from the detection of a marking material, or spoor factor, left on the host (Rabb and Bradley 1970, Salt 1937) or in its immediate vicinity during a previous ovipositional attack by a female (Greany and Oatman 1972, Price 1970).

Underlying Determinants of Housing Location: a Case Study from Swaziland

It is a comparatively recent development that places housing not only as one of the main targets in the national plan, but also as a vital means of achieving other social and economic objectives.1 Admirable though this may be, a number of difficulties can arise in practice, particularly with regard to the question of new housing where many dwellings may be on unsuitable sites and require relocation or extensive redevelopment. The point is that remedial measures are likely to have only short-term effects, unless several underlying – and often conflicting – variables are taken into account. Four such variables have assumed importance in the planning for future housing needs in the Greater Manzini Area of Swaziland, and it is the purpose of this article to illustrate how policies relating to industrial location, urban growth, and housing, interact with the tenurial system in force.