bluuebunny/crossref_metadata_2025_split huggingface dataset:
Air pollution and forests in heavily industrialized regions: an introduction.
Authors: Oleksyn J. , Innes J. L. 
Published: November 2017

Abstract

Air pollution represents a threat to many forests, particularly in the Russian Federation. Various types of air pollution affect forests, with the most significant pollutants being sulfur dioxide, fluorides, heavy metals and ozone. In the past, these have been responsible for the destruction of substantial areas of forest. In North America and Western Europe, such effects have now been brought under control, and steps are being taken to aid the recovery of damaged ecosystems. Eastern Europe remains in a transition stage, with only a poor understanding of the complex factors causing the declines of specific forests. In the Russian Federation, the pollution in some areas remains at very high levels, although economic developments in the 1990s have resulted in lower pollution emissions associated with lower production. However, the damage in some areas of the country continues to expand, with more than 1 million hectares in the vicinity of Noril'sk, Siberia, showing visible signs of damage, and an estimated 7 million hectares affected. International initiatives to control pollution on a multilateral or bilateral basis have resulted in significant improvements. Similar initiatives by the research community could result in major benefits.
The impacts of air pollution on the northern taiga forests of the Kola Peninsula, Russian Federation.
Authors: Rigina O. , Kozlov M. V. 
Published: November 2017

Abstract

Copper-nickel smelters in the Kola Peninsula of Russia, emitting 350-750 kt of sulfur dioxide annually, have caused visible damage to forests over 39 000 km2 and forest death over 600-1000 km2. Individual and population responses of the forest-forming woody plants to pollution are reasonably documented, whereas changes in other components of the forest ecosystems are less well known, and almost no data exist about pollution effects on the functioning of the ecosystems present in the area. The spatial representativeness of the plots used in earlier studies was insufficient for the detailed mapping of forest condition in the region. Remote sensing analysis, supported by ground truth data, has overcome this problem, and has also provided information on the history of pollution impacts in the area. Although the development of predictive models has been delayed by the limited information available about both the emissions and their impacts, forest degradation is expected to continue for some time, even if the emissions are terminated.
Gene flow in forest trees.
Authors: Hamrick J. L. , Nason J. D. 
Published: November 2017

Abstract

Pollen and seed immigration into forest tree populations promotes genetic continuity by transferring genetic variation among populations. The homogenizing effects of gene flow, therefore, counter the disruptive effects of selection and genetic drift. Gene flow rates are typically estimated in two ways: indirectly from the distribution of genetic variation among populations or directly via the detection of immigrant pollen and seed. Gene flow rates estimated indirectly from spatial genetic structure measure effective rates of immigration pooled over several populations and generations. Reviews of the distribution of allozyme genetic variation demonstrate that tree species typically possess more genetic diversity than herbaceous species and that more of this variation occurs within individual populations. These data support the conclusion that tree species generally experience more gene flow than most herbaceous species. In only a few studies have the relative contributions of pollen and seed flow been distinguished. These indirect estimates indicate that pollen dispersal is responsible for much higher levels of gene migration than seed dispersal. Genetic markers can be used to directly estimate gene flow by detecting immigrant pollen and seed genotypes. The relatively few direct measurements of gene flow into tree populations demonstrate that gene immigration via pollen is often more than 25% over distances of several hundred metres. Direct estimates of seed movement are rare but indicate that seed flow is more restricted than pollen flow over comparable distances. This conclusion is tentative, however, as seed movement has not been characterized for tree species with light, wind-borne seeds or with strong-flying animal vectors.
Effects of logging and other forms of harvesting on genetic diversity in humid tropical forests.
Authors: Ratnam W. , Boyle T. J. 
Published: November 2017

Abstract

Commercial harvesting of timber through logging is a major form of disturbance in many areas, but the variety of products harvested from tropical forests is immense: wood, fruit and other foods, medicinal plants, construction materials and many more. Commercial logging has been separated from other types of human use to reflect the relative importance of logging in all types of forest. In a comprehensive study of logging in tropical forests, genetic diversity (expected heterozygosity, He, for isozyme data and Shannon Diversity Index, H, for RAPD data) was reduced by 5.0-23.4% after logging for five species with different life history strategies. Generally, the order of reduction in number of individuals corresponded with the order of reduction in genetic diversity. Daemonorops verticillaris exhibited the highest loss of alleles (13.8%) most probably due to death of individuals following logging damage to supporting trees and being trampled during extraction of felled trees. No significant differences in outcrossing rates were observed between logged and unlogged stands for Shorea leprosula and Dryobalanops aromatica. No adverse changes in genetic diversity measures of Parkia speciosa, Scaphium macropodum, Shorea leprosula, Garcinia malaccensis, Daemonorops verticillaris and Labisia pumila were detected in two regenerated stands (13.5% and 40.7% disturbances) compared to an unlogged stand in the mixed dipterocarp lowland forest indicating maintenance of genetic diversity in regenerated stands after a single low intensity logging event. In comprehensive studies on collection of non-timber forest products in the Biligiri Rangan Hills of south India, a significant effect on recruitment of Phyllanthus emblica, the fruits of which are harvested for food and as a base for numerous traditional medicines, was observed. Harvesting of fruits or flowers tend to have a more direct or dramatic effect on regeneration and genetic diversity than harvesting of leaves, bark or other non-reproductive parts of the plants.
Forest fragmentation.
Authors: Young A. G. , Boyle T. J. 
Published: November 2017

Abstract

Forest fragmentation is a pervasive threat to forest ecosystems throughout the world. Reduced overall numbers of individuals, decline in mean population sizes and the separation of forest remnants by non-forest land can affect the main genetic processes of genetic drift, gene flow, selection and mating. The three most obvious possible genetic effects of forest fragmentation are: (a) loss of genetic diversity at the population and species level (b) increased interpopulation structure (c) increased inbreeding. Responses are likely to vary depending on the ecological characteristics of the species involved, such as their breeding system, dispersal syndrome, longevity and ploidy level. Although empirical data are sparse, results suggest that while genetic variation may decrease with reduced remnant population size, not all fragmentation events lead to genetic losses, with the interaction between local population size and isolation being important in determining levels of genetic diversity. Similarly, while inbreeding may increase in fragmented populations, sometimes even fairly dramatic shifts in pollinator guilds due to fragmentation do not appear to affect the rate of cross fertilization. Overall, genetic effects of fragmentation are less easy to predict than expected, being determined, as they are, by the scale of fragmentation, the biology of the affected species and their associated pollinators and dispersers. More data are required in order to make sensible predictions regarding the likely response of a forest ecosystem to a given fragmentation event.
Effects of environmental pollution on the genetics of forest trees.
Authors: Geburek T. 
Published: November 2017

Abstract

Important aspects of environmental pollution on the genetics of forest trees are reviewed and include: (a) a description of the variation in response to gaseous and metal pollutants among forest tree species and within-species variation on the family and clonal level; (b) heritability of plant response to gaseous pollutants; (c) a genetic assessment of polluted tree populations by means of gene markers; (d) altered gene expression triggered by environmental stress; and (e) investigation of whether environmental pollution triggers evolutionary processes in forest tree populations. In most forest tree populations (provenances), differences in resistance to gaseous and non-gaseous pollutants exist. Generally slow-growing and genetically highly variable tree populations seem to be less affected by different gaseous pollutants than fast-growing and genetically less variable tree populations. Intraspecific variation in resistance to pollutants increases from the provenance to the family level and is greatest among single trees (clones). Heritability estimates of resistance to gaseous air pollutants in forest trees are mainly high. Inheritance to pollution seems to be polygenic and in some cases is probably pleiotropic with respect to other stress factors. While genetic control of response to environmental stress (e.g. number of genes, gene dose, epistatic effects) is often known in herbaceous plants, knowledge in forest trees is still missing. Results of gene marker studies in polluted forest tree populations indicate that groups of trees (subpopulations, artificial subsets) with high genetic variation tend to be more tolerant to heterogeneous environmental stress than less variable ones. Environmental pollutants repress and/or induce plant genes.
Sampling the gene pools of forest trees for ex situ conservation.
Authors: Brown A. H. D. , Hardner C. M. 
Published: November 2017

Abstract

A population approach to sampling the genetic resources of forest species is inherent in the prominence of the 'provenance' concept in forest management. It is known from the sampling theory for selectively neutral alleles that the main quantity of interest, the allelic richness or number of alleles per locus actually present in a sample, is expected to increase linearly with increasing population size. In contrast, the allelic richness of the sample increases in proportion to the logarithm of the sample size. This implies that the reward for extra sampling effort at a site follows the law of diminishing returns. An adequate sample is defined as one that includes with 95% certainty, at least one copy of an allele with arbitrary frequency 0.05 and this requires 59 unrelated gametes. Larger samples are needed when there are several alleles at the boundary frequency - the worst-case scenario of 20 equally frequent alleles requires a doubling of the size. Fruits are often the unit of sampling in trees species and we examine the effect of single versus multiple paternity of fruit on the number of fruit required. When paternity is unknown, a worst-case scenario is that all the fruit from one individual form a single full-sib array. It follows that fruit should be sampled from at least 15 trees to be sure of an adequate sample. Strategies for the sampling of many populations depend on the amount of genetic diversity in each population and the genetic divergence between them. The best strategy accords priority to so-called 'local' common alleles, or those that exceed 0.10 in frequency in only one region or population. Such alleles make up an appreciable fraction (10-20%) of the genetic resources of trees. This strategy is in line with the provenance concept and contrasts with samples of 172-plants-per-species, which is an approach recently advocated by Lawrence and colleagues.
Magnitude and implications of gene flow in gene conservation reserves.
Authors: Adams W. T. , Burczyk J. 
Published: November 2017

Abstract

A practical means of long term genetic conservation in forest trees is to establish natural (in situ) populations (i.e. gene resource management units, GRMUs) or ex situ plantings as gene conservation reserves. Results from pollen contamination studies in conifer seed orchards, however, indicate that gene flow in such reserves could be extensive. Although gene flow can be beneficial in terms of introducing new genetic variants, immigration of genes from domesticated populations is likely to reduce total genetic diversity within reserves and potentially lower their fitness. The prudent position on gene flow in reserves, therefore, is to limit it as much as possible. Pollen gene flow can be eliminated in ex situ plantings by controlled mating. If controlled mating is not feasible, applying pollen management techniques to increase pollen production within the plantings relative to external sources can minimize gene flow. Strategies for reducing gene flow in GRMUs are to make reserves as large as possible, include buffer zones around reserves (perhaps planted with an exotic species), and to assure that natural regeneration, or seed collection for artificial regeneration, occurs in heavy seed-crop years. Gene flow in forest trees is still poorly understood and the effectiveness of various approaches to limit gene flow in reserves, especially in GRMUs, cannot be quantified with any accuracy. Thus, research on gene flow in forest trees should receive high priority.
Criteria and indicators for the conservation of genetic diversity.
Authors: Boyle T. J. 
Published: November 2017

Abstract

Conservation of genetic diversity is usually one aspect of more complex management goals. It is associated with sustainable forest management, which is a concept that is difficult to measure or assess. The use of criteria and indicators, which outline conditions that should be met if forest management is to be deemed sustainable, offers a solution to this problem. The most important characteristic of an effective indicator is the practicality of assessment in a short period. As genes are inherently difficult to detect, this has usually resulted in the adoption of vague or very indirect indicators of genetic diversity. An approach is described which uses the assessment of processes which maintain genetic diversity as surrogate measures of genetic diversity itself. Using this conceptual framework, a number of indicators and verifiers (the variables actually measured) are proposed. Even given such an approach, problems related to the establishment of thresholds and choice of species to assess remain. Possible solutions to these problems are proposed, but empirical testing is required to verify the validity of such an approach.
Chile: the evolution of the Agricultural Advisory Service for small farmers: 1978-2000.
Authors: Berdegué J. A. , Marchant C. 
Published: November 2017

Abstract

This chapter describes and analyses four stages that can be recognized in the evolution of Chile's Agricultural Advisory Services (AAS) for small farmers: period of maximum liberalization (1978-83); period of maximum uniformity (1983-90); the 'Improvement Plan' (1990-96); and the AAS (1997-2000). It is concluded that Chile's extension system has evolved from one promoting increased yields of basic commodities to one which is now focused on the competitive participation of small farmers' economic organizations in an open economy. Some of the most important design issues that have driven the changes put in place through time are outlined.
Federal Republic of Germany: contracting for agricultural extension in Thuringia.
Authors: Currle J. , Hoffmann V. , Kidd A. D. 
Published: November 2017

Abstract

This chapter examines the changes in extension in Thuringia, Germany. For instance, a significant proportion of the state budget for extension has been contracted to private extension companies since 1998. The impacts of contracting out are discussed, as well as lessons learned from Thuringia's experience.
The Netherlands: going Dutch in extension, 10 years of experiences with privatized extension.
Authors: Proost J. , Duijsings P. 
Published: November 2017

Abstract

This chapter examines the privatization of the Netherlands' national agricultural extension and research services in 1990. It outlines some of the most outstanding changes in terms of: client orientation; skills; planning; and monitoring clients. Contracting for advisory services is discussed, as well as the supportive processes for the advisory process. The effects of privatization are discussed as well.
Vietnam: contracting for extension training in participatory planning methods.
Authors: Dinh Duc Thuan Dinh Duc Thuan , Nguyen Ba Ngai Nguyen Ba Ngai , Paul B. 
Published: November 2017

Abstract

This chapter deals with the training contract executed during January-December 1997 between the World Food Programme Project 5322 'Smallholder Forestry Development in Five Northeastern Provinces of Vietnam' and the Social Forestry Training Centre at the Vietnam Forestry University. The impact, replicability, and sustainability of the changes that were brought about through the contract are discussed, as well as the lessons learned from the contracting process.
Portugal: contracting for IPM extension by the Association for Viticultural Development in the Douro Valley.
Authors: Cristóvão A. , Alves F. , Koehnen T. 
Published: November 2017

Abstract

This chapter describes the Association for Viticultural Development in the Douro Valley's (ADVID) contracted integrated pest management extension. The impact, sustainability, and replicability of the extension contracts are discussed, as well as the lessons learned from ADVID's experience.
China: from government-driven Group Contracting Extension to farmers' need-oriented contracting extension: the case of Xinyang Prefecture in Henan Province.
Authors: Liu YongGong Liu YongGong 
Published: November 2017

Abstract

This chapter describes the 'Group Contracting Extension' (GCE) system in Xinjiang Prefecture, Henan Province, China. The impacts, sustainability, and replicability of GCE are discussed, as well as the lessons learned from the GCE case.
Finland: a long history of contracting for agricultural extension.
Authors: Riikka Rajalahti Riikka Rajalahti , Eija Pehu Eija Pehu 
Published: November 2017

Abstract

This chapter on contracting for agricultural extension in Finland is comprised of two cases: contracting by the national, although privately based Rural Advisory Centre; and contracting between agribusinesses, the university and growers. The impacts of contracting and the critical factors for the success of extension contracts are discussed.
Latin American sweetener markets: economic reform and regional integration.
Authors: McCoy T. L. 
Published: November 2017

Abstract

This chapter examines the political and economic changes that have taken place in Latin America and the Caribbean (referred to inclusively as Latin America) and their implications for sweetener markets. Particular attention is given to processes of economic reform and regional integration and their consequences. It is concluded that the political and economic changes are all in the direction of opening up the sweetener market to market forces and to greater competition. However, these changes may occur less rapidly and less completely in the sugar industry (given the prominence of the industry and its political clout) than it will in all other agricultural sectors of Latin America.
CARICOM's sugar in the new liberal trade order.
Authors: Northover P. , Thomas C. Y. 
Published: November 2017

Abstract

This chapter first examines the Caribbean Community and Common Market's (CARICOM) reliance on trade preferences. Sugar exports from CARICOM are intimately affected by three special trade agreements: trade with the EU under the Lomé Convention; trade with the USA under the Caribbean Basin Initiative; and trade with Canada under the Caribbean-Canadian agreement (CABRICAN). Next, the implicit transfers that occur in CARICOM through preferential trade agreements (PTAs) are examined. After developing the implications of preferential trade in CARICOM, the factors affecting sugar production there are examined. Based on this examination, the implications of changes in the existing PTAs for the sugar industry in the Caribbean are discussed. The chapter concludes by considering the significance of sugar within CARICOM's economy and the general implications of the future of its sugar production.
The competitive prospects for Cuba's sugar agroindustry.
Authors: Peña Castellanos L. , Alvarez J. 
Published: November 2017

Abstract

This chapter first discusses three main reasons for the crisis in Cuba's sugar agroindustry: the exhaustion of the state's extensive growth model applied to sugarcane agriculture during the 1980s; the negative impact that the demise of the Soviet Union and the socialist countries in Eastern Europe had on the Cuban economy; and the reinforcement of the economic sanctions that have been imposed by the USA on Cuba. It then looks at the process of Cuban economic reform in the sugar agroindustry, examines the sugar production costs in Cuba, and explores how Cuba can recover its competitive position in sugar.
Brazil's domination of the world sugar market.
Authors: Schmitz T. G. , Seale J. L., Jr. , Buzzanell P. J. 
Published: November 2017

Abstract

This chapter first discusses the sugar market in Brazil in terms of: raw and refined sugar; anhydrous and hydrous alcohol; government policies toward sugarcane and the products made from it; and sugar and ethanol prices in Brazil and in the world market. To investigate the potential effects of increasing the alcohol/gasoline blend ratio from 20 to 26%, the next section develops a conceptual model that considers the Brazilian sugarcane market in the context of sugarcane production and prices, refined sugar production and prices, ethanol production and prices, and world market effects. The conceptual model also makes it possible to identify welfare measures for Brazilian and world consumers and producers of sugarcane-based products. Next, an empirical model, based on several measures of supply and demand sensitivities to prices and government policies, is simulated. Ranges for the effects of the increased blend ratio on prices, quantities and welfare are calculated.
Alternative sugar policies for the United States.
Authors: Orden D. 
Published: November 2017

Abstract

This chapter develops a proposal for a sugar cash-out (direct payments) programme in the USA. The first section of the chapter presents arguments for this approach by reviewing the history of reform progress along the cash-out path for other crops, summarizing the economic welfare costs resulting from failure to cash out the sugar programme, and describing past sugar cash-out recommendations. The second section describes alternative cash-out options. The least radical reform would be to simply let the domestic sugar price reach a market-clearing level, given domestic production and US minimum import commitments, while providing domestic producers with direct payments of any difference between the market price and a chosen price support. The third section presents various obstacles to a successful cash out of the sugar policy. These obstacles arise from the transparency of direct payments, from federal budget constraints, from the distributional effects of potential retention of some gains by industrial sweetener users, and from sugar producer and processor opposition.