- Email: [email protected]
Transformation of Plantation Forests
Forest Ecology and Management 151 (2001) 1±5
Preface
Transformation of Plantation Forests Papers presented at the IUFRO Conference held in Edinburgh, Scotland, 29 August to 3 September 1999
1. Introduction The establishment of productive plantation forests on marginal agricultural soils has been a major means of restoring forest cover in many parts of the world during the 20th century. Such forests are typically composed of a few pioneer species in uniform evenaged stands. However, the increasing emphasis upon multi-purpose management in recent years as a consequence of the Rio summit in 1992, accentuated through the Montreal and Helsinki Processes, not to mention the international debate upon certi®cation, has resulted in increasing pressure to diversify (`transform') these forests in both species composition and structure. The process of transformation has been pursued for over a century in some parts of central Europe, but it is a more recent development in other parts of the world. Sharing experience in and knowledge of this ®eld among researchers and practitioners from different countries should help to minimise mistakes, to identify key principles and to identify the major gaps in our understanding. The main objective of this conference, held under the auspices of the IUFRO Uneven-Aged Silviculture Project Working Group (Section 1.14.00) was indeed to share such expertise and experience. It was appropriate to hold a conference on Transformation of Plantation Forests in Great Britain because this country had seen a major expansion of its forest area through an afforestation programme carried out from 1920 to 1990 and based largely
upon non-native conifers. As a result, the forest cover now exceeds 2.5 million hectares or 12% of the land area compared with only 4% at the beginning of the 20th century. Opening the conference, David Bills, the Director-General of the British Forestry Commission, said that, if the creation of plantation forests has been the major achievement of the last century in British forestry, then the transformation of these uniform plantations to the diverse forests required to meet the needs of multi-purpose management would be the major challenge confronting British foresters in the 21st century. He said that it was not a question of whether to transform plantation forests, but determining where, when and how best to do it. Echoing these comments in a closing address, Dr. Bob McIntosh, Chief Executive of Forest Enterprise (the management agency of the Forestry Commission) identi®ed a need to have better information upon management costs and other operational aspects associated with transformation. He announced that a number of large-scale demonstration areas would be created in British plantation forests to provide this information. He aimed to use the guidance provided at this conference to inform the establishment and monitoring of these areas. The speci®c aims of the conference were to identify the feasibility of transformation as determined by forest type and environment; to review the costs and benefits provided by unevenaged stands;
0378-1127/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 - 1 1 2 7 ( 0 0 ) 0 0 6 9 1 - 5
2
Preface
to provide information on yield regulation and other techniques in the management of unevenaged and/or irregularly structured stands. The papers included in this Special Issue of Forest Ecology and Management are presented in line with these conference aims under the main headings: ecological aspects of transformation; silviculture of transformation, and quanti®cation of the transformation. 2. Ecological aspects of transformation Malcolm et al. examine the links between the occurrence of natural regeneration and gap size in British conifer forests and the implications for the choice of silvicultural system. They ®nd that the relative shade intolerance of the main species and the oceanic nature of the climate result in a predisposition towards large gap sizes for achieving effective regeneration. Using the ratio of gap diameter to height as a guide, they conclude that the most effective systems in British conditions are likely to be group selection or irregular shelterwood. Aspects of stand development relevant to the occurrence of natural regeneration in plantations of Sitka spruce (Picea sitchensis) in Britain are reported by Hale, Page et al. and Quine. Hale studied the light climate beneath the canopy of stands of different ages using hemispherical photographs. She found that most stands had low gap fractions (a measure of the potential of the canopy to transmit light) as a consequence of a high basal area so that there was insuf®cient light for seedling growth. This ®nding was supported by the work of Page and her colleagues who, while reporting a positive relationship between seedling density and basal area, found that seedling growth was negatively correlated with basal area. Both sets of authors conclude that normal stand densities need to be reduced by up to 25% to provide suitable conditions for advance regeneration. Quine considers the occurrence of natural regeneration within windthrown gaps in ®ve upland Sitka spruce forests. Germinants were more common than seedlings with the upturned rootplate being the favoured regeneration niche. The area of gaps with seedlings was signi®cantly greater than for those without
seedlings, and a minimum gap size for seedling development is proposed. Wetzel and Burgess examine the response of Pinus strobus regeneration in eastern Canada to different intensities of thinning and site disturbance. Two years after treatment, the greatest response was to thinning to one crown spacing between trees with secondary bene®ts from scari®cation and control of woody weeds. Light was found to be the most crucial factor for successful seedling growth compared with soil moisture and temperature. The results indicate that traditional shelterwood management can be modi®ed to produce irregular forests with eastern white pine. The development of an undisturbed Picea abies forest on an island off the coast of Sweden and the implications for management of irregular stands are reported by Svensson and Jeglum. The forest has a patchy, uneven structure characterised by a heterogeneous overstorey and abundant deadwood. They note that variation in height is more useful in describing the variation within the stand compared to more conventional measures of diameter. They propose that crown thinning would mimic gap disturbance and should allow sustained natural regeneration. However, this strategy could increase the risks of windthrow and it is not certain whether the desired regeneration would be obtained. 3. Silviculture of transformation O'Hara identi®es an international trend towards achieving greater naturalness in stand management which is a response to increasing criticism of the lack of variability in even-aged plantations. He argues that there is a danger of responding to this trend solely by favouring the complex stand structures characteristic of single-stem selection forestry. Other intermediate strategies of stand management exist which will increase stand variability such as those based upon seed tree or shelterwood systems. These systems can produce multi-aged stands with irregular diameter distributions and should be easier to introduce in even-aged plantations. The Swiss experience of transforming regular stands to irregular structures is reviewed by Schutz. He notes that even in the Swiss Jura it can take up to a
Preface
century to achieve success. The two main reasons for this are the need to develop adequate light conditions for regeneration and recruitment while avoiding the development of regular two storied stands. An important consideration is the desirability of fostering a limited number of `framework' trees with deep crowns (40±60 trees per hectare) in order to promote differentiation within the stand. If such trees cannot be found or developed through thinning, then it is unrealistic to attempt transformation on the current stand. The history of transformation of conifer forests in central Europe is reviewed by Kenk and Guhne, and illustrated using a range of case studies and longterm trials. Their ®ndings show the lengthy periods required to achieve successful transformation and the in¯uence of different thinning intensities and regeneration periods upon the outcome. For example, in one experiment dating from 1927, a mixed Pinus sylvestris Picea abies stand was transformed into an irregular structure when light thinning and a long regeneration period were used. However, in the same stand, heavy thinning and a short regeneration period produced a more regular structure with a different species composition. Sterba and Zingg discuss the use of harvesting strategies based upon the removal of all trees above a given diameter (`target diameter harvesting') as a means of developing an irregular structure in evenaged Picea abies stands. In particular, they examine the response of the smaller trees to the removal of their larger neighbours. They ®nd a positive growth response in the smaller trees, provided that they have crowns of at least average size, and conclude that target diameter thinning does indeed appear to be an ef®cient method of transformation. 4. Quanti®cation of the transformation Buongiorno argues that successful transformation necessitates the de®ning of target stand structures and their integration with harvesting intensity through the use of a growth model appropriate to the speci®c forest type. The growth model used needs to be able to predict stand development over a long period, accommodating different initial conditions and stand treatments and should contain an adequate representation
3
of natural ingrowth to the stand. Desirable stand states should have their outcomes quanti®ed, even if the management objective is solely ecological. Once a desired stand state has been de®ned, relatively simple harvesting rules can be implemented such as only harvesting those trees which are in excess of the desired distribution. Lahde et al. report results from two experiments examining alternative stand management of irregular forests in southern Finland. Low thinning or selective removal of all trees above a predetermined diameter were compared with single stem selection. Low thinning promoted less variable stands compared with the other two treatments. However, stands treated by selective removal had a reduced volume increment than the other treatments. Spathelf and Durlo consider the application of a transition matrix in modeling the development of a semi-natural forest in Brazil. Despite some limitations in their data, they report that this approach allows both an estimation of growth development under present conditions as well as evaluation of sustainable harvesting strategies for these mixed tropical forests. The approach could be improved by the availability of long-term data sets, allowance for species differences in recruitment, and allowance for differing responses to harvesting. Hagner et al. discuss the use of an economic approach based upon assessment of the potential growth of individual trees as a means of implementing irregular stand management in Swedish boreal forests. This type of management involved greater harvesting and management costs compared to clear-felling, but the improvements in wood quality and the larger tree sizes harvested were suf®cient to offset these disadvantages. Knoke and Plusczyk explore the ®nancial consequences of transforming Picea abies stands to an irregular structure compared with conventional even-aged management using data from southern Germany. They report that transformation involves a reduction in timber volume and a decline in total revenue compared with even-aged management based upon clear-felling. However, because transformation involves harvesting of greater volumes at an earlier age, the net present value of the transformation approach exceeds than from even-aged approach under the conditions tested. In a related paper,
4
Preface
Hanewinkel examines the implications of transforming similar stands to uneven-aged mixed stands of Picea abies and Fagus sylvatica. While the costs of transformation can be substantial, their impact is critically dependant upon the interest rate used to evaluate the alternative options, with the difference being less at higher interest rates. Evaluation of the returns from the irregular stand after transformation is hampered by the lack of an adequate representation of seedling recruitment within the growth simulator used. The implications of transformation for timber quality of Picea abies are considered by Seeling using results from a series of thinning trials. Assuming that transformation will require opening out of stands to develop deeper crowns and favour tree stability, she concludes that this strategy is likely to result in greater ring widths, larger branch diameters, and a higher incidence of compression wood. The combined effect of these factors is likely to result in a loss of sawtimber quality during the period of stand differentiation. Foster considers the need to be able to identify speci®c differences among treatments or changes over time before designing programmes to monitor responses to change in silvicultural practices. Such initial power analysis is essential to determine whether the desired changes can be detected. He illustrates his argument using a case study from a 35,000 ha unit in the northwestern United States, where variable density thinning is being used to accelerate the development of late-successional irregular stands. 5. Summary of ®nal discussion On the morning of the last day of the conference, each participant was asked to list up to ®ve topics for possible discussion in the ®nal session. These lists were combined to provide a shortlist of priority subjects. These included the critical role of thinning in developing variability within stands undergoing transformation; the need to adapt to existing thinning regimes to achieve this goal; the importance of considering irregularity in both the horizontal and the vertical plane;
the role of broadleafs in the transformation of conifer plantations; the usefulness of fostering irregular stands as one way of maintaining key biotypes within plantation forests; the compatibility of irregular silviculture based upon natural regeneration with the increased availability of improved genotypes developed in tree improvement programmes; the possible use of variable spacing as a means of fostering irregularity in plantations from the beginning; improved mechanisms for providing better guidance to forest managers on how to implement transformation; what criteria could be used to determine whether transformation had been achieved and/or the progress being made; the use of adaptive management as a means of developing feedback between researchers and managers during the process of transformation. Acknowledgements The conference organisers are very grateful for the ®nancial support provided by the Universities of Aberdeen and Edinburgh, the Duchy of Cornwall, the Forestry Commission, Shotton Paper, Tilhill Economic Forestry, the Timber Growers Association, and UPM-Kymmene. Without their support, we would not have been able to invite keynote speakers to attend the meeting. We are grateful for all the organisational support provided by members of Forest Research before and during the conference, and particular thanks are due to Colin Edwards, Evelyn Hall and Esther Kerr. Other members of the organising committee were Grace Balfour (Tilhill Economic Forestry), James Simpson (Forestry Commission), Ben Gunneberg (Timber Growers Association), and Louise Page and Gary Clarke (University of Aberdeen). Colin Forsyth (Tilhill Economic Forestry), Paul Hill-Tout (Forestry Commission), Douglas Malcolm (University of Edinburgh). Bob McIntosh (Forest Enterprise) and Len Yull (Timber Growers Association) made an invaluable contribution to the success of the meeting through their skillful chairing of the formal sessions. We thank David Bills for his inspirational opening address and
Preface
Bob McIntosh for his concluding remarks and his readiness to endorse the aspirations of many delegates. We are very grateful to the staff of the Borders District of Forest Enterprise, particularly Malcolm Crosbie and Jeremy Thompson, for their contribution to excellent study visits to Wauchope and Glentress Forests. Douglas Malcolm and John Blyth (Edinburgh University) provided very informative guidance on the afternoon visit to the classic transformation trial in Glentress. The post conference tour was ably hosted by staff of Forest Enterprise districts in Inverness, Fort Augustus and Aberfoyle as well as of Tilhill Economic Forestry in Oban, and of Cawdor and Novar Estates. Finally, we wish to acknowledge the contribution made by all the delegates to this conference in providing such an enjoyable and stimulating event.
5
A.D. Cameron* Department of Forestry, University of Aberdeen 581 King St., Aberdeen AB24 5UA, Scotland, UK W.L. Mason Forest Research, Northern Research Station Roslin Midlothian EH25 9SY, Scotland, UK D.C. Malcolm School of Forestry, University of Edinburgh Darwin Building, May®eld Road Edinburgh EH9 3JU, Scotland, UK *
Corresponding author E-mail address: [email protected] (A.D. Cameron)
Preface
Transformation of Plantation Forests Papers presented at the IUFRO Conference held in Edinburgh, Scotland, 29 August to 3 September 1999
1. Introduction The establishment of productive plantation forests on marginal agricultural soils has been a major means of restoring forest cover in many parts of the world during the 20th century. Such forests are typically composed of a few pioneer species in uniform evenaged stands. However, the increasing emphasis upon multi-purpose management in recent years as a consequence of the Rio summit in 1992, accentuated through the Montreal and Helsinki Processes, not to mention the international debate upon certi®cation, has resulted in increasing pressure to diversify (`transform') these forests in both species composition and structure. The process of transformation has been pursued for over a century in some parts of central Europe, but it is a more recent development in other parts of the world. Sharing experience in and knowledge of this ®eld among researchers and practitioners from different countries should help to minimise mistakes, to identify key principles and to identify the major gaps in our understanding. The main objective of this conference, held under the auspices of the IUFRO Uneven-Aged Silviculture Project Working Group (Section 1.14.00) was indeed to share such expertise and experience. It was appropriate to hold a conference on Transformation of Plantation Forests in Great Britain because this country had seen a major expansion of its forest area through an afforestation programme carried out from 1920 to 1990 and based largely
upon non-native conifers. As a result, the forest cover now exceeds 2.5 million hectares or 12% of the land area compared with only 4% at the beginning of the 20th century. Opening the conference, David Bills, the Director-General of the British Forestry Commission, said that, if the creation of plantation forests has been the major achievement of the last century in British forestry, then the transformation of these uniform plantations to the diverse forests required to meet the needs of multi-purpose management would be the major challenge confronting British foresters in the 21st century. He said that it was not a question of whether to transform plantation forests, but determining where, when and how best to do it. Echoing these comments in a closing address, Dr. Bob McIntosh, Chief Executive of Forest Enterprise (the management agency of the Forestry Commission) identi®ed a need to have better information upon management costs and other operational aspects associated with transformation. He announced that a number of large-scale demonstration areas would be created in British plantation forests to provide this information. He aimed to use the guidance provided at this conference to inform the establishment and monitoring of these areas. The speci®c aims of the conference were to identify the feasibility of transformation as determined by forest type and environment; to review the costs and benefits provided by unevenaged stands;
0378-1127/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 - 1 1 2 7 ( 0 0 ) 0 0 6 9 1 - 5
2
Preface
to provide information on yield regulation and other techniques in the management of unevenaged and/or irregularly structured stands. The papers included in this Special Issue of Forest Ecology and Management are presented in line with these conference aims under the main headings: ecological aspects of transformation; silviculture of transformation, and quanti®cation of the transformation. 2. Ecological aspects of transformation Malcolm et al. examine the links between the occurrence of natural regeneration and gap size in British conifer forests and the implications for the choice of silvicultural system. They ®nd that the relative shade intolerance of the main species and the oceanic nature of the climate result in a predisposition towards large gap sizes for achieving effective regeneration. Using the ratio of gap diameter to height as a guide, they conclude that the most effective systems in British conditions are likely to be group selection or irregular shelterwood. Aspects of stand development relevant to the occurrence of natural regeneration in plantations of Sitka spruce (Picea sitchensis) in Britain are reported by Hale, Page et al. and Quine. Hale studied the light climate beneath the canopy of stands of different ages using hemispherical photographs. She found that most stands had low gap fractions (a measure of the potential of the canopy to transmit light) as a consequence of a high basal area so that there was insuf®cient light for seedling growth. This ®nding was supported by the work of Page and her colleagues who, while reporting a positive relationship between seedling density and basal area, found that seedling growth was negatively correlated with basal area. Both sets of authors conclude that normal stand densities need to be reduced by up to 25% to provide suitable conditions for advance regeneration. Quine considers the occurrence of natural regeneration within windthrown gaps in ®ve upland Sitka spruce forests. Germinants were more common than seedlings with the upturned rootplate being the favoured regeneration niche. The area of gaps with seedlings was signi®cantly greater than for those without
seedlings, and a minimum gap size for seedling development is proposed. Wetzel and Burgess examine the response of Pinus strobus regeneration in eastern Canada to different intensities of thinning and site disturbance. Two years after treatment, the greatest response was to thinning to one crown spacing between trees with secondary bene®ts from scari®cation and control of woody weeds. Light was found to be the most crucial factor for successful seedling growth compared with soil moisture and temperature. The results indicate that traditional shelterwood management can be modi®ed to produce irregular forests with eastern white pine. The development of an undisturbed Picea abies forest on an island off the coast of Sweden and the implications for management of irregular stands are reported by Svensson and Jeglum. The forest has a patchy, uneven structure characterised by a heterogeneous overstorey and abundant deadwood. They note that variation in height is more useful in describing the variation within the stand compared to more conventional measures of diameter. They propose that crown thinning would mimic gap disturbance and should allow sustained natural regeneration. However, this strategy could increase the risks of windthrow and it is not certain whether the desired regeneration would be obtained. 3. Silviculture of transformation O'Hara identi®es an international trend towards achieving greater naturalness in stand management which is a response to increasing criticism of the lack of variability in even-aged plantations. He argues that there is a danger of responding to this trend solely by favouring the complex stand structures characteristic of single-stem selection forestry. Other intermediate strategies of stand management exist which will increase stand variability such as those based upon seed tree or shelterwood systems. These systems can produce multi-aged stands with irregular diameter distributions and should be easier to introduce in even-aged plantations. The Swiss experience of transforming regular stands to irregular structures is reviewed by Schutz. He notes that even in the Swiss Jura it can take up to a
Preface
century to achieve success. The two main reasons for this are the need to develop adequate light conditions for regeneration and recruitment while avoiding the development of regular two storied stands. An important consideration is the desirability of fostering a limited number of `framework' trees with deep crowns (40±60 trees per hectare) in order to promote differentiation within the stand. If such trees cannot be found or developed through thinning, then it is unrealistic to attempt transformation on the current stand. The history of transformation of conifer forests in central Europe is reviewed by Kenk and Guhne, and illustrated using a range of case studies and longterm trials. Their ®ndings show the lengthy periods required to achieve successful transformation and the in¯uence of different thinning intensities and regeneration periods upon the outcome. For example, in one experiment dating from 1927, a mixed Pinus sylvestris Picea abies stand was transformed into an irregular structure when light thinning and a long regeneration period were used. However, in the same stand, heavy thinning and a short regeneration period produced a more regular structure with a different species composition. Sterba and Zingg discuss the use of harvesting strategies based upon the removal of all trees above a given diameter (`target diameter harvesting') as a means of developing an irregular structure in evenaged Picea abies stands. In particular, they examine the response of the smaller trees to the removal of their larger neighbours. They ®nd a positive growth response in the smaller trees, provided that they have crowns of at least average size, and conclude that target diameter thinning does indeed appear to be an ef®cient method of transformation. 4. Quanti®cation of the transformation Buongiorno argues that successful transformation necessitates the de®ning of target stand structures and their integration with harvesting intensity through the use of a growth model appropriate to the speci®c forest type. The growth model used needs to be able to predict stand development over a long period, accommodating different initial conditions and stand treatments and should contain an adequate representation
3
of natural ingrowth to the stand. Desirable stand states should have their outcomes quanti®ed, even if the management objective is solely ecological. Once a desired stand state has been de®ned, relatively simple harvesting rules can be implemented such as only harvesting those trees which are in excess of the desired distribution. Lahde et al. report results from two experiments examining alternative stand management of irregular forests in southern Finland. Low thinning or selective removal of all trees above a predetermined diameter were compared with single stem selection. Low thinning promoted less variable stands compared with the other two treatments. However, stands treated by selective removal had a reduced volume increment than the other treatments. Spathelf and Durlo consider the application of a transition matrix in modeling the development of a semi-natural forest in Brazil. Despite some limitations in their data, they report that this approach allows both an estimation of growth development under present conditions as well as evaluation of sustainable harvesting strategies for these mixed tropical forests. The approach could be improved by the availability of long-term data sets, allowance for species differences in recruitment, and allowance for differing responses to harvesting. Hagner et al. discuss the use of an economic approach based upon assessment of the potential growth of individual trees as a means of implementing irregular stand management in Swedish boreal forests. This type of management involved greater harvesting and management costs compared to clear-felling, but the improvements in wood quality and the larger tree sizes harvested were suf®cient to offset these disadvantages. Knoke and Plusczyk explore the ®nancial consequences of transforming Picea abies stands to an irregular structure compared with conventional even-aged management using data from southern Germany. They report that transformation involves a reduction in timber volume and a decline in total revenue compared with even-aged management based upon clear-felling. However, because transformation involves harvesting of greater volumes at an earlier age, the net present value of the transformation approach exceeds than from even-aged approach under the conditions tested. In a related paper,
4
Preface
Hanewinkel examines the implications of transforming similar stands to uneven-aged mixed stands of Picea abies and Fagus sylvatica. While the costs of transformation can be substantial, their impact is critically dependant upon the interest rate used to evaluate the alternative options, with the difference being less at higher interest rates. Evaluation of the returns from the irregular stand after transformation is hampered by the lack of an adequate representation of seedling recruitment within the growth simulator used. The implications of transformation for timber quality of Picea abies are considered by Seeling using results from a series of thinning trials. Assuming that transformation will require opening out of stands to develop deeper crowns and favour tree stability, she concludes that this strategy is likely to result in greater ring widths, larger branch diameters, and a higher incidence of compression wood. The combined effect of these factors is likely to result in a loss of sawtimber quality during the period of stand differentiation. Foster considers the need to be able to identify speci®c differences among treatments or changes over time before designing programmes to monitor responses to change in silvicultural practices. Such initial power analysis is essential to determine whether the desired changes can be detected. He illustrates his argument using a case study from a 35,000 ha unit in the northwestern United States, where variable density thinning is being used to accelerate the development of late-successional irregular stands. 5. Summary of ®nal discussion On the morning of the last day of the conference, each participant was asked to list up to ®ve topics for possible discussion in the ®nal session. These lists were combined to provide a shortlist of priority subjects. These included the critical role of thinning in developing variability within stands undergoing transformation; the need to adapt to existing thinning regimes to achieve this goal; the importance of considering irregularity in both the horizontal and the vertical plane;
the role of broadleafs in the transformation of conifer plantations; the usefulness of fostering irregular stands as one way of maintaining key biotypes within plantation forests; the compatibility of irregular silviculture based upon natural regeneration with the increased availability of improved genotypes developed in tree improvement programmes; the possible use of variable spacing as a means of fostering irregularity in plantations from the beginning; improved mechanisms for providing better guidance to forest managers on how to implement transformation; what criteria could be used to determine whether transformation had been achieved and/or the progress being made; the use of adaptive management as a means of developing feedback between researchers and managers during the process of transformation. Acknowledgements The conference organisers are very grateful for the ®nancial support provided by the Universities of Aberdeen and Edinburgh, the Duchy of Cornwall, the Forestry Commission, Shotton Paper, Tilhill Economic Forestry, the Timber Growers Association, and UPM-Kymmene. Without their support, we would not have been able to invite keynote speakers to attend the meeting. We are grateful for all the organisational support provided by members of Forest Research before and during the conference, and particular thanks are due to Colin Edwards, Evelyn Hall and Esther Kerr. Other members of the organising committee were Grace Balfour (Tilhill Economic Forestry), James Simpson (Forestry Commission), Ben Gunneberg (Timber Growers Association), and Louise Page and Gary Clarke (University of Aberdeen). Colin Forsyth (Tilhill Economic Forestry), Paul Hill-Tout (Forestry Commission), Douglas Malcolm (University of Edinburgh). Bob McIntosh (Forest Enterprise) and Len Yull (Timber Growers Association) made an invaluable contribution to the success of the meeting through their skillful chairing of the formal sessions. We thank David Bills for his inspirational opening address and
Preface
Bob McIntosh for his concluding remarks and his readiness to endorse the aspirations of many delegates. We are very grateful to the staff of the Borders District of Forest Enterprise, particularly Malcolm Crosbie and Jeremy Thompson, for their contribution to excellent study visits to Wauchope and Glentress Forests. Douglas Malcolm and John Blyth (Edinburgh University) provided very informative guidance on the afternoon visit to the classic transformation trial in Glentress. The post conference tour was ably hosted by staff of Forest Enterprise districts in Inverness, Fort Augustus and Aberfoyle as well as of Tilhill Economic Forestry in Oban, and of Cawdor and Novar Estates. Finally, we wish to acknowledge the contribution made by all the delegates to this conference in providing such an enjoyable and stimulating event.
5
A.D. Cameron* Department of Forestry, University of Aberdeen 581 King St., Aberdeen AB24 5UA, Scotland, UK W.L. Mason Forest Research, Northern Research Station Roslin Midlothian EH25 9SY, Scotland, UK D.C. Malcolm School of Forestry, University of Edinburgh Darwin Building, May®eld Road Edinburgh EH9 3JU, Scotland, UK *
Corresponding author E-mail address: [email protected] (A.D. Cameron)