bluuebunny/crossref_metadata_2025_split huggingface dataset:
Utility of added substrates in shrimp culture.
Authors: Tidwell J. H. , Bratvold D. 
Published: November 2017

Abstract

This paper reviews the status of research on substrate additions in shrimp and prawn culture for human consumption. Shrimp natural habitat, diet and culture systems are different for the nursery and juvenile grow-out stages of the life cycle. Freshwater shrimp exhibit strong territoriality, which can be substantially minimized by providing layers of horizontal surface that increase the available territory per unit volume of water. In contrast, marine shrimp do not exhibit such strong territorial behaviour. Therefore, surface conditions in marine shrimp systems have more commonly been vertical, to roughly mimic sea grass structures and enhance natural production associated with periphyton. Substrate orientation and densities in relation to shrimp stocking densities are discussed. Marine benthic diatoms (periphyton) play a key role in the growth and development of abalone. Substrates are the essential factor for larval settlement of abalone.
Periphyton ecology, exploitation and management: knowledge gaps and directions for future research.
Authors: Verdegem M. C. J. , Dam A. A. van , Azim M. E. , Beveridge M. C. M. 
Published: November 2017

Abstract

This chapter discusses the role of periphyton in aquatic ecosystems, periphyton structure, grazing pressure, periphyton assimilation by aquatic animals, nutritive quality, regeneration, periphyton-based aquaculture, polyculture, water quality, environmental health, dissemination of periphyton technology and ecological approaches in periphyton-based aquaculture.
The impact of heavy metals on the microbial diversity of podzolic soils in the Kola Peninsula.
Authors: Evdokimova G. A. 
Published: November 2017

Abstract

The diversity of frequently occurring genera and species of microorganisms in soils polluted by heavy metals (Cu, Ni, Co) and sulfur compounds was investigated at various distances (0.2-50 km) from the Severonikel enterprise in the Kola Peninsula (Russia). The 4 zones studied are described as the epicentre, impact zone (woody vegetation mostly destroyed, with only depressed regeneration of Betula pubescens subsp. czerepanovii), and the buffer and background zones (dwarf shrub pine forests). A decrease of species diversity of fungi, algae and especially the prokaryotic component of microbial communities (viz. the non-spore-forming gram-negative bacteria, cyanobacteria and streptomycetes) was established along the background to epicentre gradient. The homeostasis of the microbial communities of podzolic soils has been changed as a result of heavy metal concentrations in the soils amounting to 300-400 mg kg-1 for copper and 600-700 mg kg-1 for nickel.
Landscape degradation by smelter emissions near Sudbury, Canada, and subsequent amelioration and restoration.
Authors: Winterhalder K. 
Published: November 2017

Abstract

A century of sulfur dioxide fumigation, copper and nickel particulate deposition, fire, soil erosion and enhanced frost action resulting from mining and smeltering has created 17, 00 ha of barren land and 72 000 ha of stunted, open birch-maple (Betula/Acer) woodland in the Sudbury area of Ontario, Canada. The primary factor limiting plant colonization is the acidic, aluminium-, copper- and nickel-toxic properties of the soils, although certain plant species have developed genetically based metal tolerance. In the revegetation programme, manual surface application of ground limestone, with or without an accompanying fertilizer and/or grass-legume seed application, leads to immediate colonization by woody species including birch (Betula spp.), aspen (Populus tremuloides) and willows (Salix spp.), and more than 3000 ha have been treated in this way by the Regional Municipality of Sudbury since 1978. Native coniferous species (Pinus spp.) have also been planted in groups to form a seed source for future colonization.
Ozone impacts on California forests.
Authors: Miller P. R. , Arbaugh M. J. 
Published: November 2017

Abstract

The history of ozone effects on the forests of southern California (USA) can be traced by records of crown condition or stem growth. For example, during the period from 1945 to 1972 the growth increment of ponderosa pine (Pinus ponderosa) near the town of Blue Jay in the San Bernardino Mountains decreased every year and then began to recover to pre-1945 levels between 1973 and 1991. The growth recovery was coincident with an improvement of ozone air quality in the nearby South Coast Air Basin of California. Ozone injury on ponderosa pine in the southern Sierra Nevada was first discovered in the early 1970s. Despite general improvements of air quality in upwind urban regions, crown injury to sensitive ponderosa pines was detectable and measurable at numerous locations in the California mountains by the mid-1990s. This paper describes the methods for evaluating ozone injury and interpreting effects at the individual tree and ecosystem levels.
Ozone in the Mediterranean region: evidence of injury to vegetation.
Authors: Sanz M. J. , Millán M. M. 
Published: November 2017

Abstract

Over the last 25 yr, the Mediterranean basin has become heavily industrialized, and as a consequence, reports of air pollution damage to forested areas in southern European countries have increased since the late 1970s. Among pollutants, ozone appears to be one of the most potentially dangerous, both because the meteorological conditions present in the Mediterranean region are particularly favourable to its formation and persistence, and because it is the most ubiquitous. The available evidence strongly suggests that ozone occurs at sufficient concentrations to cause injury to sensitive plant species, including trees. Foliar injury caused by ambient ozone exposures has been clearly identified on native herbs, shrubs and tree species within several areas in southern Europe. However, ozone uptake and response are modulated by environmental factors such as drought. Recent studies suggest a complex interaction between high radiation, drought and ozone response in Mediterranean tree species such as Aleppo pine (Pinus halepensis). More data are required before a full evaluation of the impact of ozone on Mediterranean forests can be achieved. Furthermore, additional research is needed to better understand and characterize the response of the Mediterranean ecosystems.
Revitalization and restoration of boreal and temperate forests damaged by air pollution.
Authors: Kozlov M. V. , Haukioja E. , Niemelä P. , Zvereva E. , Kytö M. 
Published: November 2017

Abstract

The influence of industrial pollution on the health of boreal and temperate forests has long been recognized as a serious scientific and applied problem. Numerous field experiments have been established to determine practical measures for both the alleviation of pollution impacts on stand vitality and the rehabilitation of forest ecosystems. At the incipient stages of forest damage, the impacts of acidic deposition and heavy metals can be mitigated by the application of limestone and other compensatory fertilizers and by the adoption of silvicultural measures which increase tree vigour. In clearcuts and areas of extensive tree mortality surrounding major sources of pollution, the regeneration of forests is hindered by the unfavourable abiotic environment and soil toxicity, which requires soil detoxification and other site preparation measures. Under conditions of continuous pollution impact, it is possible to reduce soil erosion in deforested habitats by planting native, metal-tolerant woody plants such as willows (Salix borealis [Salix myrsinifolia]) and birches (Betula pubescens subsp. czerepanovii). Both the vigour of stands impacted by pollution and the establishment of trees in heavily polluted sites can be enhanced by the removal or reduction of co-occurring environmental stressors such as wind and/or drought. Although a large number of studies have been carried out in the field of forest restoration, the large-scale practical application of these to boreal and temperate forests damaged by pollution is still restricted to a very few areas.
International activities to reduce pollution impacts at the regional scale.
Authors: Bull K. , Fenech G. 
Published: November 2017

Abstract

At the regional scale there has been much effort made to introduce international agreements on pollution control over the last two decades. In Europe in the 1980s, much of the early focus was upon simple flat rate controls based upon emission limits or technology. Some countries adopted the best available technology or the precautionary principle for their emission controls. In the 1990s, the move towards effects-based approaches have made use of the development of critical loads maps and our knowledge of long-range atmospheric transport resulting from models and measurements at monitoring sites. An effects-based sulfur protocol for the UN ECE Convention on Long-Range Transboundary Air Pollution is now being followed by a multi-pollutant, multi-effect protocol which will address effects of sulfur, nitrogen and ozone. This will be supported by European Community strategies on acidification and ozone effects (which will also consider the effects of excess nutrient nitrogen) and emission ceilings directives. In North America bilateral agreements have been used to reduce sulfur emissions and their impacts internationally; Canada has indicated that further action will be needed in the future to address outstanding acidification problems. In general, emissions have fallen in line with protocol obligations across Europe, while similar changes have taken place in North America. There are differences for many individual countries, however, with some achieving more while others, usually those who are not parties to particular protocols, much less. Overall, sulfur emissions will probably be around 20% of their maximum in the mid-1980s by 2010: this has benefits both internationally but also more locally where individual sources often have significant impacts on ecosystems. Improvements in sulfur emissions are placing more emphasis on the need to control nitrogen pollutant emissions. In addition, future consideration will need to be taken of the large costs associated with high levels of protection and whether that protection is justifiable or attainable; for this, better information on benefits will be needed.
Population genetics.
Authors: Yeh F. C. 
Published: November 2017

Abstract

Population genetics is the quantitative study of the amount and distribution of genetic variation in populations, and the dynamics of the underlying genetic processes. This chapter provides an introduction to the analysis of gene and genotype frequencies and the measurement of genetic variation at individual and population levels. The basic mathematical models that form the framework for such analyses are developed (e.g. The Hardy-Weinberg Principle) and these are used to explore the effects of mutation, random genetic drift, sex, migration and selection on population genetic structure. The final section deals with the more complex analysis of multilocus genetic structure.
Genetic tools: the use of biochemical and molecular markers.
Authors: Glaubitz J. C. , Moran G. F. 
Published: November 2017

Abstract

Several types of genetic marker are available to forest conservation geneticists, including isozymes, terpenes, restriction fragment length polymorphisms (RFLPs), microsatellites, random amplified polymorphic DNAs (RAPDs) and amplification fragment length polymorphisms (AFLPs). The techniques underlying these markers are explained in terms that are accessible to those unfamiliar with molecular biology. The strengths and weaknesses of the various marker systems are elucidated via comparison. Guidelines are given for choosing the appropriate markers for particular applications in conservation genetics.
Small population processes.
Authors: Savolainen O. , Kuittinen H. 
Published: November 2017

Abstract

Some forest tree populations have small geographical distributions or occur in fragmented populations, and the distribution of more species is becoming fragmented as land use increases. In fragmented populations the genetic variability within populations is reduced, and the variance between populations increases. In small populations, homozygosity increases because of inbreeding. This may have deleterious consequences because of inbreeding depression. The rates of inbreeding and drift depend on the genetically efficient population size. Even populations with large census size can be genetically small if only part of the individuals participate in reproduction, or if there is clonal reproduction. A short bottleneck will have minor effects on overall variation, whereas a long term reduction in population size will deplete variability. Similarly, once variability is depleted due to a long term bottleneck, the recovery of variation by mutation takes a long time after the increase of population size. Because of the long time to reach equilibrium between mutation and drift, the current population sizes do not always correlate positively with the level of variability. For neutral loci such as molecular markers, the distributions of allele frequences depend mainly on the balance between mutation, migration and drift, but the level and distribution of quantitative variation is more likely to be affected as well by selection.
Selection.
Authors: Namkoong G. , Koshy M. P. , Aitken S. 
Published: November 2017

Abstract

The power of selection in changing the genetic make-up of populations and species has been demonstrated through both breeding of artificial populations and study of natural populations. Genetic conservation of forest trees requires consideration of the process of selection, not in isolation but in combination with the effects of other evolutionary forces including mutation, migration and genetic drift and on how the interpopulational genetic diversity is affected. Whether it is better for the conservation of genetic diversity to promote, maintain or mute the effects of selection is situation-dependent, as the former may increase the average fitness of populations under current environmental conditions but will reduce the ability of populations to adapt to future conditions.
Disease threats and the conservation genetics of forest trees.
Authors: Byrne M. 
Published: November 2017

Abstract

Disease has had major impacts on forest trees and the ecosystems they support. Disease expression is a result of complex plant-pathogen interactions and disease severity is often related to whether the pathogen is endemic or has been introduced. The genetic effects of disease include changes in the distribution and frequency of resistance genes, fragmentation and reduction in population size. Disease control involves containment and quarantine in the field, and increasing the resistance of populations. Disease effects have implications for conservation, both in situ and ex situ. In situ conservation preserves the coadaption of host-pathogen systems and allows the continued evolution of resistance. Ex situ conservation collections provide the gene pool from which disease resistance selection and breeding will be achieved, and therefore should encompass as wide a range of genotypes as possible.
Hybridisation and forest conservation.
Authors: Carney S. E. , Wolf D. E. , Rieseberg L. H. 
Published: November 2017

Abstract

Despite the presence of many barriers to interspecific reproduction, hybridization is common among plants and in some groups of animals. It is especially common in plants living in disturbed habitats, on islands, and when introduced species are involved. Numerous outcomes are possible, including an increase in genetic variation, adaptation to novel environments, the merging of species and the formation and maintenance of stable hybrid zones. Several models regarding the formation and maintenance of hybrid zones have been proposed, and they differ in whether selection is environment-dependent or environment-independent, the fitness of hybrids and the importance of dispersal. There are many rare plants and animals that are threatened by hybridization with relatives. In these cases there are two possible outcomes that are relevant to conservation biology: outcrossing depression and genetic assimilation. Factors that affect the probability of extinction due to hybridization are discussed, as well as management implications. In rare cases, hybridization may also be used to save species on the brink of extinction.
Effect of forest tree domestication on gene pools.
Authors: El-Kassaby Y. A. 
Published: November 2017

Abstract

The little available information on the domestication of forest tree species is mainly devoted to the genetic consequences of domestication rather than the process itself. Domestication of forest tree species is fragmented and follows the classical horizontal organization of management systems, thus making evaluation difficult. However, systematic monitoring of the various steps of the domestication process (selection-breeding methods and strategies, and seed and seedling production) has identified cases of unintentional directional selection where genetic diversity could be affected. Phenotypic selection has been proven effective in capturing most of the genetic variation existing in natural populations. The progress from breeding population to production populations did not substantially reduce genetic variability; however, the chance for rare, endemic allelic loss increased with a reduction in number of parental trees in seed orchards. Use of a breeding strategy that provides for sampling over several geographical locations and selection for various goals, as well as adaptation to different environments (i.e. Multiple Population Breeding System) was demonstrated to be effective. Generally, understanding the species biology and the role of biology on genetic diversity is of great importance. The need for change and/or the implementation of management practices is effective in maintaining the genetic variability.
Genetic markers as a tool for bioindication in forest ecosystems.
Authors: Müller-Starck G. , Schubert R. 
Published: November 2017

Abstract

Bioindication measures the response of individuals and populations to stress with main emphasis on anthropogenically induced change of environment. Forest ecosystems reveal a high indicative potential for the verification of long-term environmental stress. This study aims at a greater efficiency of bioindication via integration of genetic markers as indicators, which are a response variable not currently being employed for this purpose. Principles of adaptation to stress are outlined and influences of environmental stress on genetic structures are classified. A set of selected genetic parameters is suggested for utilization in bioindication. It includes indicators for climate change with respect to thermic impacts and indicators for environmental stress governed by air pollution. Chances of molecular tools for bioindication are described with respect to such genes encoding heat shock proteins, stilbene synthase as well as cinnamyl alcohol dehydrogenase enzymes, and the species-specific detection and quantification of pathogens. Five major problems in bioindication are discussed and the importance of genetic tools in bioindication is pointed out.
Rethinking stakeholder involvement in biodiversity conservation projects.
Authors: Enters T. 
Published: November 2017

Abstract

According to the conventional wisdom of biodiversity conservation, the economic activities of rural people were viewed as threats to the undisturbed functioning of natural ecosystems and their genetic diversity. Thus, representative samples of ecosystems were put under strict protection. The poor success rate of such measures has lead to the exploration of alternative conservation approaches. Most notable among these are community involvement and the devolution of resource management responsibilities. These approaches are also problematic as they are based on numerous - sometimes untested - assumptions regarding the interest, commitment and skills of local people, the notion of stable and homogenous communities and the superiority of community-based natural resource tenure and knowledge systems. The success, in both critical social and biological terms, of biodiversity conservation efforts hinges on abandoning naive assumptions. It is important to challenge the 'received wisdom' about livelihood strategies of 'forest-dependent' people, stakeholder involvement, community cohesion and the interest of local people in forest conservation and management. It is just as crucial to reconsider the new 'conservation-through-development' orthodoxies that have influenced project designs and policies in recent decades and to stress that many issues surrounding forests and their sustainable use are very location specific.
Politics, policies and the conservation of forest genetic diversity.
Authors: Kanowski P. J. 
Published: November 2017

Abstract

The conservation of forest genetic diversity is a dominant theme in environmental politics in the late 20th century. Debate has focused on several issues central to the Convention on Biological Diversity: sovereignty over and access to genetic resources, the sharing of benefits and costs, the dynamic between conservation and use, and the relationship between economic efficiency and social and environmental objectives. Multilateral intergovernmental resolution of these issues is proving difficult, but various innovative approaches have emerged in particular situations. These initiatives are characterized by their diversity and flexibility, and by the establishment of partnerships between interested parties. Policies for the conservation of forest genetic diversity, therefore, need to be based on the recognition and accommodation of the diversity of interests and rights. They need also foster coordination, integration and innovation at the policy level, and acknowledge institutional capacity. Realizing these goals is perhaps more challenging than developing the technical elements of genetic conservation policies, in which we are considerably assisted by scientific advances reviewed elsewhere in this book. Key technical issues with a significant policy dimension are the respective roles of in situ and ex situ conservation, the identification of priority areas for conservation, the integration of on-reserve and off-reserve management, and assessment of the effects of forest management on genetic diversity. These issues are being addressed principally through the development of integrated conservation strategies, reappraisal of the role and management of protected areas, and the development and evaluation of sustainable forest management regimes.
Forest conservation genetics: limitations and future directions.
Authors: Boshier D. H. , Young A. G. 
Published: November 2017

Abstract

Maintenance of tree populations with sufficient genetic variation to adapt to future conditions, whether in reserves or in production systems, is essential. Given the limited resources available for conservation, genetic criteria will, however, generally form only one component within strategies that reflect the integral nature of factors such as demography, ecology and genetics, as components of natural systems. The circumstances under which genetic aspects may be limiting are discussed, while recognizing the limits to the use of genetic information and the need for integrated conservation strategies. Limitations of current approaches and knowledge are also considered along with the direction of more recent and future work such as: genetic adaptation of trees within more complex forest environments, the integration of metapopulation and demographic models and modelling of the effects of climate change. The need for more research is highlighted, with the generation of baseline information, as well as the use of a range of model species from which species may be grouped into management guilds being identified as priorities.