Pub Date : 1999-07-01DOI: 10.1080/10295925.1999.9631221
J. Zwolinski, B. Bredenkamp
Monthly height growth of Pinus radiata D. Don seedlings after planting was monitored in two locations in the Western Cape Province of South Africa over a period of two years. Two stages in seedling development were defined and modelled with mathematical functions: (i) an acclimatisation stage when relative height growth rate (RGRHT) showed a simple linear increasing trend after planting, and (ii) a post-acclimatisation stage when RGRHT followed a decreasing trend. The acclimatisation period was defined as the time between planting and intersection of the two regressions. This method may prove useful for evaluation of regeneration procedures at operational level.
在南非西开普省的两个地点对辐射松(Pinus radiata D. Don)幼苗种植后的月高生长情况进行了为期两年的监测。本文定义了幼苗发育的两个阶段，并用数学函数建立了模型:(i)驯化阶段，相对高生长率(RGRHT)在种植后呈简单的线性增长趋势;(ii)驯化后阶段，RGRHT呈下降趋势。驯化期定义为种植和两个回归交点之间的时间。这种方法可能被证明对业务层面的再生程序的评价是有用的。
{"title":"Definition of post-planting acclimatisation of Pinus radiata through relative height growth rate","authors":"J. Zwolinski, B. Bredenkamp","doi":"10.1080/10295925.1999.9631221","DOIUrl":"https://doi.org/10.1080/10295925.1999.9631221","url":null,"abstract":"Monthly height growth of Pinus radiata D. Don seedlings after planting was monitored in two locations in the Western Cape Province of South Africa over a period of two years. Two stages in seedling development were defined and modelled with mathematical functions: (i) an acclimatisation stage when relative height growth rate (RGRHT) showed a simple linear increasing trend after planting, and (ii) a post-acclimatisation stage when RGRHT followed a decreasing trend. The acclimatisation period was defined as the time between planting and intersection of the two regressions. This method may prove useful for evaluation of regeneration procedures at operational level.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132007193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-07-01DOI: 10.1080/10295925.1999.9631224
S. Taylor, M. Perrin
The provisioning of stem guards at first planting is a widespread silvicultural practice in the UK, where it is perceived to reduce tree mortality from browse damage and enhance early growth. The adoption of this practice in South Africa has been slow. Here we present evidence to show that the use of stem guards in Pinus patula plantations is primarily beneficial, however as the young tree outgrows the height of the stem guards or the guard degrades, these benefits subside. We conclude that stem guards offer neither permanent protection nor a permanent growth advantage in the case of Pinus patula. We do, however, suggest that guards may be beneficial where the tree species has more economic worth at maturity or to protect the early growth of trees in conservation areas.
{"title":"The efficacy of stem guards in protecting Pinus patula seedlings in KwaZulu-Natal Midlands, South Africa","authors":"S. Taylor, M. Perrin","doi":"10.1080/10295925.1999.9631224","DOIUrl":"https://doi.org/10.1080/10295925.1999.9631224","url":null,"abstract":"The provisioning of stem guards at first planting is a widespread silvicultural practice in the UK, where it is perceived to reduce tree mortality from browse damage and enhance early growth. The adoption of this practice in South Africa has been slow. Here we present evidence to show that the use of stem guards in Pinus patula plantations is primarily beneficial, however as the young tree outgrows the height of the stem guards or the guard degrades, these benefits subside. We conclude that stem guards offer neither permanent protection nor a permanent growth advantage in the case of Pinus patula. We do, however, suggest that guards may be beneficial where the tree species has more economic worth at maturity or to protect the early growth of trees in conservation areas.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125147378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-07-01DOI: 10.1080/10295925.1999.9631227
C. Clarke
There is considerable scope for more efficient use of resources (including water) in the South African pulp and paper industry through manipulation of the raw material. The possibility of increasing the quantity of pulp that is produced per hectare of land (fibre production) is investigated for the following: • the use of alternative raw materials to wood • more efficient use of the present wood resource • tree breeding to genetically improve the wood Alternative fibre sources for the pulp industry such as kenaf, sisal and hemp have been identified in laboratory investigations. None, however, have been found to produce significantly greater quantities of pulp fibre than wood. The most effective means of improving fibre production in the short term is shown to be through fibre classification and separation in the processing unit and, where practically possible, through clonal forestry in the field. In the longer term, tree breeding is expected to provide the greatest improvement.
{"title":"Prospects for producing more pulp fibre per hectare in South Africa","authors":"C. Clarke","doi":"10.1080/10295925.1999.9631227","DOIUrl":"https://doi.org/10.1080/10295925.1999.9631227","url":null,"abstract":"There is considerable scope for more efficient use of resources (including water) in the South African pulp and paper industry through manipulation of the raw material. The possibility of increasing the quantity of pulp that is produced per hectare of land (fibre production) is investigated for the following: • the use of alternative raw materials to wood • more efficient use of the present wood resource • tree breeding to genetically improve the wood Alternative fibre sources for the pulp industry such as kenaf, sisal and hemp have been identified in laboratory investigations. None, however, have been found to produce significantly greater quantities of pulp fibre than wood. The most effective means of improving fibre production in the short term is shown to be through fibre classification and separation in the processing unit and, where practically possible, through clonal forestry in the field. In the longer term, tree breeding is expected to provide the greatest improvement.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127370906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-01DOI: 10.1080/10295925.1999.9631210
F. Ellis, A. V. Laar
Foliage nutrient content of 3 to 6-year old Eucalyptus species/provenances (E. camaldulensis, E. globulus and E. grandis x E. tereticornis) were analysed for eleven elements over a four-year period. The trial was planted on three sites, adjacent to each other, all deep acidic sands with an annual rainfall of about 400 mm along the Cape West Coast. With the exception of the elements Ca, Na and Cu, highly significant differences between species means occurred. The elements K, Na, Mn and Cu showed highly significant differences between sites, with Na values constantly higher in each year on the site closest to the ocean and lowest on the site furthest away. The very high Na values in foliage was ascribed to uptake of Na deposited by water or wind from the sea and the high levels might be toxic for sensitive species. Differences between year means were highly significant for all elements analysed but there was no indication that a decline occurred over the years. Except for Fe, Ca, Mn and B, which appeared to...
对3 ~ 6年生桉树种源(camaldulensis、globulus和grandis x tereticornis)叶片营养成分进行了为期4年的11种元素分析。试验种植在三个地点，彼此相邻，都是深酸性砂，年降雨量约为400毫米沿着西海岸角。除Ca、Na和Cu元素外，物种间存在极显著差异。K、Na、Mn和Cu元素在不同站点间差异显著，近海洋站点的Na值逐年升高，远海洋站点的Na值逐年降低。叶片中的高钠值归因于海水或海风对钠的吸收，高水平的钠可能对敏感物种有毒。对所有分析的要素而言，年份平均值之间的差异非常显著，但没有迹象表明年份之间出现了下降。除了Fe, Ca, Mn和B，它们似乎…
{"title":"Nutrient levels of three Eucalyptus species provenances, measured over four seasons in a trial along the sandy, dry, Cape West Coast of South Africa","authors":"F. Ellis, A. V. Laar","doi":"10.1080/10295925.1999.9631210","DOIUrl":"https://doi.org/10.1080/10295925.1999.9631210","url":null,"abstract":"Foliage nutrient content of 3 to 6-year old Eucalyptus species/provenances (E. camaldulensis, E. globulus and E. grandis x E. tereticornis) were analysed for eleven elements over a four-year period. The trial was planted on three sites, adjacent to each other, all deep acidic sands with an annual rainfall of about 400 mm along the Cape West Coast. With the exception of the elements Ca, Na and Cu, highly significant differences between species means occurred. The elements K, Na, Mn and Cu showed highly significant differences between sites, with Na values constantly higher in each year on the site closest to the ocean and lowest on the site furthest away. The very high Na values in foliage was ascribed to uptake of Na deposited by water or wind from the sea and the high levels might be toxic for sensitive species. Differences between year means were highly significant for all elements analysed but there was no indication that a decline occurred over the years. Except for Fe, Ca, Mn and B, which appeared to...","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128686881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-01DOI: 10.1080/10295925.1999.9631211
A. Gildenhuys
{"title":"The National Water Bill, 1998 Why change was needed and the provisions of the bill","authors":"A. Gildenhuys","doi":"10.1080/10295925.1999.9631211","DOIUrl":"https://doi.org/10.1080/10295925.1999.9631211","url":null,"abstract":"","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123880660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-01DOI: 10.1080/10295925.1999.9631212
E. Nambiar
We face many challenges in managing land for economic and environmental well-being. Among these, the conceptualisation and practice of sustainability, including sustainable forest management is the most complex. Further development of plantation and farm forestry are the only ways through which the increasing mismatch between wood supply and demand can be met. Apart from this, plantation forests are playing a key role in ameliorating a broad range of environmental problems including degradation in agricultural land. Multiple values, diverse expectations, the need to achieve high production, and economic realities of managing a commercially-driven land use system, all impact on the pursuit of sustainability in forestry. The characteristics and processes governing individual elements of sustainability (e.g. productivity) change dynamically so that there is seldom an immutable reference point for the achievement of sustainability. Productivity of many managed forests is increasing over the long term, a tribu...
{"title":"Pursuit of Sustainable Plantation Forestry","authors":"E. Nambiar","doi":"10.1080/10295925.1999.9631212","DOIUrl":"https://doi.org/10.1080/10295925.1999.9631212","url":null,"abstract":"We face many challenges in managing land for economic and environmental well-being. Among these, the conceptualisation and practice of sustainability, including sustainable forest management is the most complex. Further development of plantation and farm forestry are the only ways through which the increasing mismatch between wood supply and demand can be met. Apart from this, plantation forests are playing a key role in ameliorating a broad range of environmental problems including degradation in agricultural land. Multiple values, diverse expectations, the need to achieve high production, and economic realities of managing a commercially-driven land use system, all impact on the pursuit of sustainability in forestry. The characteristics and processes governing individual elements of sustainability (e.g. productivity) change dynamically so that there is seldom an immutable reference point for the achievement of sustainability. Productivity of many managed forests is increasing over the long term, a tribu...","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114932485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-01DOI: 10.1080/10295925.1999.9631213
Julian Evans
Sustainability of wood production from plantations is an important aspect of the whole sustainability issue confronting forestry. Research monitoring growth over three rotations of subtropical pine plantations in the Usutu Forest, Swaziland shows no evidence of decline in yield neither where the same species has been used nor where a switch to another has been made. In the case of changing species from one rotation to the next some benefits may have accrued leading to improved wood yield as species are better matched with site.
{"title":"Sustainability of plantation forestry: impact of species change and successive rotations of pine in the Usutu Forest, Swaziland","authors":"Julian Evans","doi":"10.1080/10295925.1999.9631213","DOIUrl":"https://doi.org/10.1080/10295925.1999.9631213","url":null,"abstract":"Sustainability of wood production from plantations is an important aspect of the whole sustainability issue confronting forestry. Research monitoring growth over three rotations of subtropical pine plantations in the Usutu Forest, Swaziland shows no evidence of decline in yield neither where the same species has been used nor where a switch to another has been made. In the case of changing species from one rotation to the next some benefits may have accrued leading to improved wood yield as species are better matched with site.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117230419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-01DOI: 10.1080/10295925.1999.9631207
R. Hassan
Conventional measures of national income and capital formation underestimate the contribution of industrial plantations to gross domestic product and do not account for the social costs or benefits of their environmental impacts. The present study adopted an environmental accounting approach to establish an improved measure of the sector's contribution to value added and to correct for the omitted social values of water abstraction and carbon sink externalities of plantations. The net economic benefit from carbon storage functions was found to be about half the economic costs of water reduction by plantations. However, the study indicated that plantation forestry contributes marginally to the carbon cycle and hence holds low potential as an instrument for balancing carbon budgets in the country. Measures for reducing CO2 emissions at source sectors may prove more effective alternatives in managing carbon budgets in South Africa.
{"title":"Correcting measures of national income for environmental values: The case of water abstraction and carbon sink externalities of industrial plantations in South Africa","authors":"R. Hassan","doi":"10.1080/10295925.1999.9631207","DOIUrl":"https://doi.org/10.1080/10295925.1999.9631207","url":null,"abstract":"Conventional measures of national income and capital formation underestimate the contribution of industrial plantations to gross domestic product and do not account for the social costs or benefits of their environmental impacts. The present study adopted an environmental accounting approach to establish an improved measure of the sector's contribution to value added and to correct for the omitted social values of water abstraction and carbon sink externalities of plantations. The net economic benefit from carbon storage functions was found to be about half the economic costs of water reduction by plantations. However, the study indicated that plantation forestry contributes marginally to the carbon cycle and hence holds low potential as an instrument for balancing carbon budgets in the country. Measures for reducing CO2 emissions at source sectors may prove more effective alternatives in managing carbon budgets in South Africa.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131933514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-03-01DOI: 10.1080/10295925.1999.9631208
K. Eerikäinen, D. Mabvurira, J. Saramäki
Three types of taper estimation methods for Eucalyptus cloeziana were applied and compared by using Zambian and Zimbabwean plantation data. The methods are: (1) Schumacher's taper equation, (2) diameter prediction method and (3) polynomial taper curve. The Schumacher's taper equation method uses volume equations to derive taper functions, while the diameter prediction method uses underbark diameters at different relative heights of the stem to describe the tree form. The polynomial taper curve method uses a high degree polynomial equation based on relative diameters and heights along the tree stem to describe the taper. Linear and non-linear regression techniques were used to estimate parameters for these methods. Method 3 was the most reliable, followed by Method 2, while the Schumacher's taper equation method was found to be the least reliable. The polynomial taper curve method also provided the best estimates for a regional model developed from the combined Zambian and Zimbabwean data. It is recommende...
{"title":"Alternative Taper Curve Estimation Methods for Eucalyptus cloeziana (F. Muell.)","authors":"K. Eerikäinen, D. Mabvurira, J. Saramäki","doi":"10.1080/10295925.1999.9631208","DOIUrl":"https://doi.org/10.1080/10295925.1999.9631208","url":null,"abstract":"Three types of taper estimation methods for Eucalyptus cloeziana were applied and compared by using Zambian and Zimbabwean plantation data. The methods are: (1) Schumacher's taper equation, (2) diameter prediction method and (3) polynomial taper curve. The Schumacher's taper equation method uses volume equations to derive taper functions, while the diameter prediction method uses underbark diameters at different relative heights of the stem to describe the tree form. The polynomial taper curve method uses a high degree polynomial equation based on relative diameters and heights along the tree stem to describe the taper. Linear and non-linear regression techniques were used to estimate parameters for these methods. Method 3 was the most reliable, followed by Method 2, while the Schumacher's taper equation method was found to be the least reliable. The polynomial taper curve method also provided the best estimates for a regional model developed from the combined Zambian and Zimbabwean data. It is recommende...","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115130168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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