This study has combined laboratory and greenhouse based experiments using sitka-spruce seedlings, with field studies to examine the effects by heavy metals upon tree growth. Water culture techniques were used to determine the upper critical tissue concentrations for cadmium, copper, lead, nickel and zinc ions: these being the lowest concentrations at which shoot yields were affected. Concentrations of these heavy metals in the soil and foliage at the South Wales forestry sites were found to be elevated with respect to a control site in Mid Wales (Tywi). A comparison of these foliar levels with the critical tissue concentrations showed several sites to be at risk to nickel toxicity (Burton et al 1983). The interactive effects of heavy metals, studied by means of factorial experiments in water culture, did not reveal any synergistic or antagonistic reductions in the yields of the seedlings. However, the interactive effects of these metals were found, in some cases to be additive. Several sites had foliar levels of cadmium and lead which approached their upper critical tissue concentrations. The effects upon tree growth may be even greater at these sites. These experiments also showed that heavy metals can influence the uptake into the shoots and roots of other heavy metals and nutrients. The field situations were more closely modelled using greenhouse experiments with seedlings grown in a typical forestry soil with added heavy metals. Effects upon the growth of the seedlings, as measured by yields of shoots and roots and root lengths, were demonstrated. At soil concentrations of cadmium and lead which were similar to those found at the forestry sites, there were disturbances in the root-mycorrhizal associations indicating that tree growth may also be indirectly affected by the heavy metals in the soil.

These studies on indigenous ecological knowledge were carried out as a case study of the sustainability of miang tea gardens in hill evergreen forest at a remote village setting in the highlands of northern Thailand. The study focused on the miang tea farmers' knowledge associated with decision making criteria in managing their gardens as an agroforestry system. Knowledge was investigated relating to how farmers presently manage their garden ecosystems and the underlying biodiversity of the plants and the interactions occurring between tea trees and biotic components. These were forest trees, ground flora and cattle in relation to microclimate and processes of water and nutrient cycling, soil erosion and plant succession. The knowledge acquired from key informants was evaluated in terms of its representativeness of the knowledge of the community as a whole and the extent to which it was complementary or contradictory to scientific knowledge. The extent to which indigenous and scientific knowledge could be usefully combined was investigated. The indigenous knowledge was collected from interviewing a small number of key informants who were representative of the target popUlation and who were people knowledgeable about the ecology of the gardens. The elicited information was recorded and accessed using knowledge-based system techniques. An indigenous knowledge base was created in terms of diagrams, hierarchies and text statements and stored in a durable, accessible and transparent form. The research demonstrated that the indigenous ecological knowledge collected from key informants was explanatory, predictive and of technical relevance. It was also representative of most of the farmers in the community. The combination of indigenous and scientific knowledge provided a more powerful resource for improving the sustainability of the tea garden ecosystem than using either knowledge system alone but required further quantification for solid management recommendations to be formulated. The knowledge elicited had a useful role to play in furthering scientific understanding about the ecosystem and suggested new lines of research that may be more appropriate for promoting incremental change to miang tea production systems than extending conventional technology packages involving tea monoculture.

No description available.

No description available.

The existing cost-benefit methods addressed to the developing countries are based on the premises of a growth strategy or its variants. They are, therefore, unsuitable to evaluate projects in the context of a basic needs strategy. This thesis attempts to formulate a methodology suitable to analyse the impact of projects on basic needs fulfilment. A pre-requisite for the application of the methodology - basic needs analysis - is the identification of a basic needs basket and the corresponding basic needs income. Analysis of projects then involves the construction of a goods balance sheet and an income balance sheet. " The goods balance sheet highlights the effect of projects on the social stock of basic goods. Social value of inputs and outputs is derived from the market prices using goods-specific and use-specific conversion factors. The value of the conversion factors varies from 0 to 1, the extreme values representing luxuries and essentials respectively. ) , Product mix considerations are thus taken into account in the'goods balance sheet.; (The effects on basic needs income resulting from projects are measured by the income balance sheet. J -=ý Income changes above the basic needs level are given a social weight of 0, whereas changes at or below this level are attributed a weight of 1. Thus, income distributional considerations are directly incorporated into the analysis. Opportunity costs of funds and resources are based on the forgone basic needs benefits from their alternative uses. Aggregation of costs and benefits over time is carried out without resorting to discounting. At the final stage, the two balance sheets are aggregated using weights which reflect the relative priority given to the objectives of basic goods production and basic needs income generation. The usefulness of the methodology is demonstrated by applying it to a forest land use problem in the tropics.

Different modifications, namely hexanolylation, acetylation, thennal modification and silylation by trimethoxy vinyl silane (VTMS,) and by 'Y-methacryloxy propyl silane (TMPS) were applied to impart decay resistance to Corsican pine sapwood, which is a non-durable wood. The possible mechanisms by which the modifications impart decay resistance to the wood were also investigated. The silanes applied in this study showed completely different reactivity so that the vinyl group of VTMS remained un-reacted and the vinyl group of TMPS reacted (but its sHanol was not very reactive). The decay resistance of the modified woods were assessed by soft rot, brown rot and white rot fungal tests. The decay resistance against basidiomycetes and soft rot fungi was improved by all the wood modifications applied in this study, but the wood treated with methanolic solutions of the silanes did not show complete decay resistance against brown rot fungi. The failure of the silanes to impart complete protection of wood against brown rot fungus (c. puteana) was attributed to the restriction of the silanes in penetrating into the cell wall. In the soft rot tests, VTMS modified stakes showed high decay resistance but TMPS modified wood showed a moderate decay resistance. This was attributed to the uneven distribution of TMPS in wood. An industrially acceptable treatment method (by using aqueous solutions of silane instead of methanolic solutions and pressure treatment instead of vacuum treatments was established). The perfonnance of the silane treated wood was assessed by field tests. The method worked well with TMPS (the wood showed significant decay resistance in the test) but it didn not work with VTMS. Since both anhydrides (hexanoic and acetic anhydride) used in this study, showed nearly the same perfonnance against C. puteana and soft rot fungi, it was concluded that the improvement in decay resistance against the brown rot fungi and soft rot depends on the WPGonly. Heat treatment above 200°C was recognised to be an effective treatment in improving the decay resistance of wood. It was shown that heat treatment temperature plays a more important role in the improvement of decay resistance than the treatment time. Heat treatment at 250°C for 2 hours, imparted complete decay resistance to the wood against basidiomycetes and soft rot. No significant difference between decay resistance of heated wood post-extracted and heated wood without any extraction against basidiomycet and soft rot fungi was obtained, suggesting that extractable fungicidal is not the reason for the improved decay resistance. In addition to the decay tests, dimensional stability, pore cell wall pore accessibility and hygroscopicity of the modified wood were also studied to find the mechanism by which the modification imparts decay resistance to the wood. It was suggested that hexanoylation and acetylation reduces hygroscopicity so that not enough water is available for the diffusion of brown rot degrading agents into the cell wall, while lignin substitution might be the main reason for the improved decay resistance against white rot fungi. For heated wood, a good correlation between a reduction in FSP and WL due to decay was obtained. Thus, it was suggested that a reduction in the hygroscopicity of wood could be the main reason for the improved decay resistance. By using the Hailwood Horrobin model it was shown that a reduction in poly-molecular adsorption of heated wood is the main reason for the reduced hygroscopicity. Since good correlation between an increase in the lignin content and a reduction in the poly-molecular sorption was obtained, a reduction in the hygroscopicity of heated wood was suggested to be due to a reduction in the swelling of the wood cell wall in which micro fibrils were placed in a matrix of condensed lignin and the hemicellulose residue, rather than a reduction in the hydroxyl groups of wood. Lignin modification is thought to be the main reason for the reduced hygroscopicity.

A vegetation survey in four regions (Deltaic, Dry, Hilly and Plain) in Bangladesh was conducted with reference to marginal (> 0.02 - 0.08 ha), small (> 0.08 - 0.14 ha), medium (>0.14 - 0.20 ha) and large (> 0.20 ha) farm categories. Eighty homegardens (five from each farm category in each of the four regions) were assessed in terms of structure, species composition and diversity of the perennial species. Ordination of floristic data from the 80 homegardens showed a distinction between the Dry and the other regions due to a combination of lower species richness in the Dry region homegardens and several species exclusive to the regions. Floristic differences led to less marked but nevertheless important differences among the other regions, also. Most species were planted in the border of the homegardens irrespective of farm size and region. Food and fruit producing species dominated near the living quarter and working areas and small plots of annual vegetables and crops separated this part of the garden from the more distant parts favoured for timber species. Six vertical strata were recognised with higher plant density and species richness recorded in the lower three (< 7 m). In total ninety two perennial species were recorded for the set of 80 homegardens surveyed. From gardens in the Deltaic region 67 species were recorded. Corresponding figures were 56 for the Plain region, 54 for the Hilly region and 46 for the Dry region. Diversity was highest among food and fruit producing species, followed by the timber species. Indigenous management techniques in homegardens were investigated using different PRA methods. Farmers' used all sorts of planting materials to regenerate homegardens plants. Homegarden provided more than three quarters of the required planting materials. Mother trees were selected for fruit species only. Farmers practised simple cultural operations (weeding and pruning) which were rarely intensive. The fertility of homegardens was maintained naturally from leaf litter, faeces of animals, kitchen waste and the mud of fish ponds. There was a clear separation of tasks between men and women for homegarden management. Farmers spent only 5-12 % of their labour and 4-7.5% of their active time in homegarden management. Farmers have considerable knowledge about mother tree selection, silvicultural protection, as well as about positive and negative interactions. Farmers' had more knowledge about above-ground interaction than below-ground interactions. Women are more knowledgeable than men in many management aspects of homegardens, but their access to various resources is limited. Farmers are very much aware of different functional aspects of homegardens, but due to the lack of good planting materials, funds and extension supports do not utilise their full awareness and knowledge of these matters for homegarden development.

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.