From 1993-1994, a study of Vitellaria paradoxa was carried out. This study involved an in-depth review of biological and ecological information on Vitellatia throughout its range. Stand studies and an analysis of the climate in relation to fire risk. There were also experimental investigations of germination and pollination. All field studies were at the site of the Cocoa Research Institute outstation at Bole. Stand characteristics of Vitellaria (>10 cm dbh) at the 68 kM2 plot of the Cocoa Research Institute's Sheanut Research Station, Bole were examined in two strata distinguished on the basis of distance from the nearest village: >3.0 km and <3.0 km. Regeneration (<10 cm dbh) was assessed and recorded for height, root collar diameter and mode of regeneration. Analysis of variance indicated higher stocking of individuals > 10 cm dbh further from villages but significantly more Vitellaria trees >10 m tall close to villages. Suckers accounted for > 86% of regenerating individuals, and more than 90% of regenerating plants were < 50 cm high. Analysis of climatic data indicated a mean drought index (1990-1994) of 514 ± 61 points. However, the fire danger index never reached an extreme value. The germination response of depulped, cracked and intact seeds of Vitellaria sown under- and outside the canopy of mature Vitellatia trees (> 30 cm dbh), showed a significant association between germination and seed treatment: a higher proportion of depulped than intact seeds germinated. Open pollinated flowers, gave significantly lower fruit set than hand-pollinated flowers. There was no difference, however, in the amount of fruit set achieved with pollen from sources 50 m, 500 m and 1000 m away or from flowers of two different style lengths. It is concluded that fires are adversely affecting the population structure and natural regeneration of stands at Bole, and that low fruit set in Vitellaria is due at least in part, to low vector activity. Suggestions are made for future research on the species.

The basis of scientific forest management in India has been the principle of maximum physical sustained yield of timber and other highvalued products in the interest of posterity. This leads to long rotations, slow turnover of the crop, and slow conversion of existing forest into more productive crops. The needs of the local population have generally been given a lower priority. The community is thus often not in sympathy with the forest departments. This makes the job of protecting and managing the forests as envisaged more difficult. It would therefore be desirable to compare the relative merits of alternative management regimes: maximizing long-term flow of physical product as professed by foresters, maximizing economic efficiency as demanded by neo-classical economists, or maximizing net social value to the current generation, as suggested by modern welfare economists. One framework for such an analysis is afforded by social cost benefit analysis (SCBA). The Little-Mirrlees methodology of SCBA has been used for a study of the teak-bearing forests of North Kanara in Karnataka State, India. Generally, applying economic criteria hastens the liquidation of existing crops, and shortens the optimal rotations of future plantations. Teak plantation as an investment activity is seen to be highly sensitive to the discount rate chosen. This is ultimately a subjective parameter. Hence there is no objective case against long rotations. The social value of maintaining basic needs supplies may, under some conditions, compensate for the loss due to postponement of exploitation of the existing crop. This would support a slow pace of conversion. On the other hand, fuelwood plantations may be more valuable socially than commercial timber crops, thus favouring faster turnover of short rotation smallwood crops in place of timber crops on long rotations. There is thus no inherent social advantage to maximizing physical yield. In conclusion, it is suggested that forestry can serve the interests of posterity better by being more responsive to social needs. On the other hand, economists might make a better contribution to forest management by clearly pointing out the subjective elements in their 'objective' prescriptions.

The economics of two selective logging systems were investigated in Sabah, Malaysia. Both logging systems employed chainsaws and bulldozers to extract timber. Reduced impact logging (RIL) differed from conventional logging (CL) in that it included comprehensive preharvest planning, pre-harvest climber cutting, stock mapping, tree marking, directional felling, and a set of environmentally-friendly skidding guidelines. RIL has been widely recognised as the logging technique to achieve sustainable utilisation of tropical forest. The main objective of this research was to compare the immediate and long term (60 years) economic costs and benefits of RIL with those of conventional logging (CL) practice in terms of timber and nontimber values. The suit of non-timber benefits included carbon, soil, non-timber forest product namely, rattan, water and wildlife values. The study was carried out in Sabah, Malaysia within the Sabah Foundation forest concession. The primary source of data for this research came from a commercial project that was initiated between Innoprise Corporation Sdn Bhd (Malaysia) and the New England Electric Supplies (USA). The RIL project was aimed at reducing logging damage using RIL, hence, increase carbon sequestration potential in forest biomass. The economic analysis comprised two parts, namely (i) an assessment of the logging impacts on the ecological parameters, and (ii) carrying out an economic cost-benefit analysis. Primary data were collected for the timber, carbon, soil values and rattan values using a system of rectangular plots. The water and wildlife values were based on secondary data from published information. To determine the timber harvest for the second cut, a forest growth model (DIPSIM) was adopted for this purpose. Similarly, the potential future carbon in the logged forest was projected using a carbon recovery model (C-REC). The valuation of the timber and non-timber values was based on the market price and opportunity costs techniques. Future costs and benefits were discounted at rates between 2% and 10 % using standard method except where costs and benefits were not derived on annual basis. The findings of this study showed that using RIL to harvest timber had reduced logging damage on the forest vegetation and soils by 50 % compared with CL techniques. Timber production per area logged was comparable with conventionally logged forest, but differed significantly when compared on per management unit basis. There were fewer skid trails and log landings in RIL forest. In addition, soil disturbances was lower on skid trails and log landings, hence, the negative effects of off-site sedimentation was reduced. The lower disturbance in the RIL forest resulted in higher timber stock for timber and non-timber product such as rattan. The timber yield for the second harvest from RIL forest was also higher compared with CL forest. However, RIL was more expensive than CL techniques under some assumptions and constraints. Non-timber benefits other than carbon in the cost-benefit analysis were relatively unimportant. Carbon prices were variable, ranging from negative prices, through prices quite comparable with other results, to very high prices. The study concluded with justifications to relax the RIL harvesting guidelines that were pertinent to the area left unlogged in RIL. There was also a case for exploring alternative logging technologies such as helicopter logging to harvest the unlogged area. These airborne technologies were conceivably costlier than ground based logging system, but the international community could share this burden in a united stand to strive towards sustainable utilisation of tropical forests.

Different methods of estimating the value of recreational areas are discussed with particular attention being given to socioeconomic methods - the survey method and Clawson's method. Aspects of consumer's surplus and aggregating welfare measures have been dealt with. A Clawson method has been applied to empirical data from a forest area in Wales and data from a region in Denmark. In the case from Wales, it was found that 73% of all visitor groups in the sample were on holiday. In addition, for many visitor groups (48%) the visit to the forest area was just one part of the day's outing. Therefore, it was considered necessary to modify the Clawson method. Problems with the weighting of points for the trip demand curve have been given considerable attention. The data from Denmark give rise to consideration of the problem of substitute areas and a classification system was used to select population zones for the Clawson analysis. Different models for the trip demand curve have been tested and the exponential was found to be the most appropriate.

No description available.

No description available.

In view of the Indian Government's growing commitment to forestry, a number of afforestation projects have been implemented. But most projects in developing countries do not conclude as per plan, uncertainty being a major factor. This study undertakes physical, financial, economic and social appraisal of the afforestation programme through case studies of the farm forestry (FF) and the rehabilitation of degraded forest (RDF) components and discusses the conceptual and methodological issues in appraisal of these projects under risk, threat and uncertainty. We have used three different approaches to risk appraisals in the present study. They are: the expected value of NPV through the illicit felling models; the cumulative distribution function comparisons through stochastic efficiency rules; the utility function of the project managers. Physical (logistic and Weibull models), financial and management decision (deterministic and probabilistic models) models developed in the study help in threat appraisal through quantification of physical loss, financial appraisal of its consequences and formulation of a management strategy under the threat of illicit felling. The risk analysis of the FF and the RDF component using Monte Carlo simulation is used to generate probability of return profiles and the results are compared through stochastic efficiency rules. The utility functions of the project managers are used to describe their risk attitude. The study shows that most managers are risk averse and the analysis of their utility functions supports the decreasing absolute risk aversion hypothesis. It emphasizes the need for a risk policy in the Forest Department. The economic appraisal examines the interaction of the FF and the RDF components with the economy rather than the treasury. Illicit felling is accounted for as a benefit to the economy. A 'Shadow pricing approach' is adopted for economic and social appraisals. For the social appraisal, inputs and outputs are estimated in terms of net discounted utility-weighted consumption flows. All the parameters of social and economic appraisal such as the consumption value of unit reinvestment, utility weight for incremental consumption at different consumption levels, social discount rate and economic discount rate are estimated. To study farmers' adoption behaviour, principal component analysis is used to explore significant factors and a logit model is developed after that to estimate probability of adoption. The study indicates that adoption of FF can be explained in an overall framework of evolutionary theory proposed in this study. The evolutionary theory posits that farmer tree growing can be considered as a land use strategy in response to both changing macro and micro factors, many of which relate to characteristics of the farmers, their resource endowments etc. It is concluded that success of projects can be assessed by taking account of the factors influencing the variability in the project outcome and understanding the whole process of people's interaction and participation in the project.

Agroforestry development programmes frequently rely on knowledge from a number of different sources. In particular, there is a growing recognition amongst development professionals of the value of augmenting partial scientific and professional understanding with the detailed knowledge held by local people. Taking advantage of the complementarity of local, scientific and professional knowledge demands the development of effective mechanisms for accessing, recording and evaluating knowledge on specified topics from each of these sources. The research described in this thesis developed a methodology for the acquisition, synthesis and storage of knowledge. The defining feature of the approach is the explicit representation of knowledge. This is achieved through the application of knowledge-based systems techniques. AKT2 (Agroforestry Knowledge Toolkit), a software toolkit developed in Prolog, an artificial intelligence programming language, provides the user with an environment for the creation, storage and exploration of large knowledge bases containing knowledge on a specified topic from a range of sources. The use of diagramming techniques, familiar to ecologists and resource managers through systems analysis, provides an intuitive and robust interface. This knowledge-based system drives incremental knowledge acquisition based on an iterative evaluation of the knowledge bases created. The iterative approach to knowledge acquisition provides a coherent, consistent and comprehensive, and therefore more useful, record of knowledge. Once created, knowledge bases can be maintained and updated as a record of current knowledge. Techniques for the exploration and evaluation of the knowledge base may be useful in : " giving research and extension staff access to a concise and flexible record of the current state of knowledge; " providing a resource and mechanisms for use in planning and prioritising research objectives; and " providing a resource and mechanisms for the generation of extension materials tailored to the needs of particular clients.

No description available.

Air pollution can lead to environmental impacts. Over the past decades there have been some success stories reducing pollutant emission, namely sulphur dioxide (SO2). However, impacts on ecosystems from atmospheric nitrogen (N) pollution are still seen as a major threat for European biodiversity. Across Europe over 70% of Natura 2000 sites are at risk for eutrophication with over 70% of the Natura 2000 area in Europe (EU28( exceeding critical loads for nutrient nitrogen deposition. Agricultural ammonia is a key contributor to the threat to these sites due to the close proximity of agricultural activities and protected sites. Source attribution modelling using an atmospheric transport model showed that agricultural livestock production in the UK is the dominant nitrogen source for N disposition across the UK Natura 2000 network. Nearly 90% of all sites had livestock as their dominant source, contributing 32% of the total nitrogen deposition across the whole network. 76% of all Special Areas of Conservation (SAC) sites exceeded their critical load for nutrient nitrogen, representing 74% of the entire SAC area. The extent of exceedance is also notable with many sites experiencing depositions of >50 kg N/ha/yr over the critical load. the situation for acidity critical load exceedance is less sever, by 51% of sites are still exeeded. Legislation to regulate pollutant emissions to air and protect biodiversity are often not integrated, and there has been no common European approach for determining the impacts of nitrogen deposition on individual Natura sites, or on conservation status. Off-site sources of air pollution present difficulties in assessing and attributing impacts, because deposition can result from local sources (1-2 km), or very far away sources (>1000 kms). Managing nitrogen losses on the farm and improving the efficient use of nitrogen are key components for overall reduction in NH3 emissions. Many nitrogen management options are available to abate ammonia from agricultural activities. On the one hand, technical and management measures include controlling emissions from manure storage and spreading, livestock feeding strategies, and improving housing systems. Trees, on the other hand, are effective scavengers of both gaseous and particulate pollutants from the atmosphere, making tree belts potentially effective landscape features to support ammonia abatement strategies. Using a coupled deposition and turbulence model the recapture efficiency of tree planting around ammonia sources was estimated. Using different canopy structure scenarios, tree depths and differing leaf area density (LAD) and leaf are index (LAI) were adjusted for a main canopy and a backstop canopy. Recapture efficiency for ammonia ranged from 27% (trees planted around housing systems), up to 60% (under-story livestock silvopastoral systems). Practical recapture potential was set at 20% and 40% for housing and silvopastoral systems respectively. Model results from scaling up to national level suggest that tree planting in hot spot areas of ammonia emissions would lead to reduced N deposition on nearby sensitive habitats. Scenarios for on-farm emission control through tree planting showed national reductions in nitrogen deposition to semi-natural areas of 0.14% (0.2 kt N-NHx) to 2.2% (3.15 kt N-NHx). Scenarios mitigating emissions from cattle and pig housing yielded the highest reductions. The afforestation strategy showed national-scale emission reductions of 6% (8.4 kt N-NHx) to 11% (15.7 kt N-NHx) for 25% and 50% afforestation scenarios respectively. Increased capture by the planted trees also generated an added benefit of reducing long-range transport effects, including a decrease in wet deposition of up to 3.7 kt N-NHx (4.6%) and a decrease in export from the UK of up to 8.3 kt N-NHx (6.8%). Agroforestry measures for ammonia abatement were shown to be cost-effective for both planting downwind of housing and in silvopastoral systems, when costs to society were taken into account. Planting trees was also cost-effective from a climate change perspective. Comparing the cost per kg of NH3 abated showed that planting trees is a method of ammonia emission mitigation comparable with other (technical) measures. The costs for planting trees downwind of housing were calculated at €2.6-7.3/kg NH3. Agroforestry for ammonia abatement offers multiple benefits for the farmer and synergistic effects for society as a whole including i) carbon sequestration. ii) visibility screening around housing units, iii) imporved animal welfare for silvopastoral systems, iv) reducing critical load exceedance on protected sites, v) price advantage of 'woodland chick' productions, vi) supporting the Industrial Emission Directive (IED) requirements for emission reduction, vii) supporting national afforestation policies. The results of this work support the notion that in the emerging discussion about the values of ecosystem services and the role of nature-based solution to tackle persistent environmental challenges, tree planting has a large potential in rural and urban environments.