Pub Date : 1997-03-01DOI: 10.1080/10295925.1997.9631135
N. Eccles, J. Kritzinger, K. Little
SYNOPSIS The objective of this work was to compare several commonly used measures of tree performance in three commercially grown pine species (Pinus patula, P. taeda and P. elliottii) during the first growth season in a weeding experiment. Both tree mortality and above-ground tree biomass measures indicated that there was significant tree suppression by weeds for all three species. Using above-ground biomass as an absolute measure of tree performance it was clear that root collar diameter was far more sensitive to treatment effects than height. A derived index combining both height and root collar diameter was consistently the most closely correlated with above-ground biomass. Leaf: stem ratios were significantly different between the three species, and between different weed regimes.
{"title":"Appropriateness of Non-Destructive Measures of Young Pine Tree Performance in Weeding Experiments","authors":"N. Eccles, J. Kritzinger, K. Little","doi":"10.1080/10295925.1997.9631135","DOIUrl":"https://doi.org/10.1080/10295925.1997.9631135","url":null,"abstract":"SYNOPSIS The objective of this work was to compare several commonly used measures of tree performance in three commercially grown pine species (Pinus patula, P. taeda and P. elliottii) during the first growth season in a weeding experiment. Both tree mortality and above-ground tree biomass measures indicated that there was significant tree suppression by weeds for all three species. Using above-ground biomass as an absolute measure of tree performance it was clear that root collar diameter was far more sensitive to treatment effects than height. A derived index combining both height and root collar diameter was consistently the most closely correlated with above-ground biomass. Leaf: stem ratios were significantly different between the three species, and between different weed regimes.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126301576","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 : 1997-03-01DOI: 10.1080/10295925.1997.9631133
J. Zwolinski
SYNOPSIS Palmer drought models are introduced as an objective measure of monthly moisture conditions and their application for forestry research is discussed. A case-study showed that Palmer Hydrological Drought Index was preferred to Palmer Drought Severity Index for deciding on establishment strategy to prevent excessive post-planting mortality.
{"title":"Palmer Drought Indices and Their Application to Plantation Establishment Strategies","authors":"J. Zwolinski","doi":"10.1080/10295925.1997.9631133","DOIUrl":"https://doi.org/10.1080/10295925.1997.9631133","url":null,"abstract":"SYNOPSIS Palmer drought models are introduced as an objective measure of monthly moisture conditions and their application for forestry research is discussed. A case-study showed that Palmer Hydrological Drought Index was preferred to Palmer Drought Severity Index for deciding on establishment strategy to prevent excessive post-planting mortality.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126375040","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 : 1997-03-01DOI: 10.1080/10295925.1997.9631141
C. Kätsch, B. Bredenkamp
SYNOPSIS Management of information as a production factor is imperative in modern forestry practice. However, development of individual application programmes has resulted in systems which cannot be integrated without excessive effort and expense. It is shown that the route to an integrated information system can be difficult due to the relatively abstract procedure which is required, but a feasible compromise is possible through a multi-phased process-oriented model. As forestry data are exceptionally diverse, the development of information models for the industry must be an integral part of forest research and practice.
{"title":"Towards an information system for forestry","authors":"C. Kätsch, B. Bredenkamp","doi":"10.1080/10295925.1997.9631141","DOIUrl":"https://doi.org/10.1080/10295925.1997.9631141","url":null,"abstract":"SYNOPSIS Management of information as a production factor is imperative in modern forestry practice. However, development of individual application programmes has resulted in systems which cannot be integrated without excessive effort and expense. It is shown that the route to an integrated information system can be difficult due to the relatively abstract procedure which is required, but a feasible compromise is possible through a multi-phased process-oriented model. As forestry data are exceptionally diverse, the development of information models for the industry must be an integral part of forest research and practice.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116976010","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 : 1997-03-01DOI: 10.1080/10295925.1997.9631134
C. Geldenhuys, G. B. V. D. Bussche
SYNOPSIS Podocarpus falcatus, a canopy tree of the mixed evergreen forests in South Africa, is planted in riparian zones in commercial forestry areas. In 1982 provenance trials were initiated to evaluate the performance of 11 provenances in three experimental sites: De Hoek in the northeastern Transvaal; Frankfort in the eastern Transvaal; and Witfontein in the southern Cape. Only five provenances were planted in all three sites. The great variation in fruit and seed mass could not be related to latitudinal or locality differences of origin of the provenances. Germination capacity ranged between 3 and 94%, but the differences were related to periodically unsuitable environmental conditions during fertilisation of the ovule rather than genetic variation. For most provenances the germination rate over time followed the normal pattern of a sharp increase in germination during October, about 50 weeks after sowing. However, seed from the sub tropical Zululand coast germinated after 10 weeks and continued to ge...
{"title":"Performance of Podocarpus falcatus Provenances in South Africa","authors":"C. Geldenhuys, G. B. V. D. Bussche","doi":"10.1080/10295925.1997.9631134","DOIUrl":"https://doi.org/10.1080/10295925.1997.9631134","url":null,"abstract":"SYNOPSIS Podocarpus falcatus, a canopy tree of the mixed evergreen forests in South Africa, is planted in riparian zones in commercial forestry areas. In 1982 provenance trials were initiated to evaluate the performance of 11 provenances in three experimental sites: De Hoek in the northeastern Transvaal; Frankfort in the eastern Transvaal; and Witfontein in the southern Cape. Only five provenances were planted in all three sites. The great variation in fruit and seed mass could not be related to latitudinal or locality differences of origin of the provenances. Germination capacity ranged between 3 and 94%, but the differences were related to periodically unsuitable environmental conditions during fertilisation of the ovule rather than genetic variation. For most provenances the germination rate over time followed the normal pattern of a sharp increase in germination during October, about 50 weeks after sowing. However, seed from the sub tropical Zululand coast germinated after 10 weeks and continued to ge...","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"28 5 Suppl 16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116568205","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 : 1997-03-01DOI: 10.1080/10295925.1997.9631137
W. Burdzik
SYNOPSIS The new South African Timber Design Code, SABS 0163, no longer specifies strength values for laminated products in South Africa. The onus now rests on the manufacturers to determine the strength of their laminated beams. This could lead to unnecessary costs, if every possible size of member has to be either tested or proof loaded. Proof loading at the incorrect level could lead to a large number of members being broken unnecessarily. In this paper the author illustrates that the finger joint strength is one of a number of factors that influences the strength of a laminated beam. These factors are explained and values for them are given. The author describes how, based on the strength of the finger joints, the strength of any possible beam size can be predicted. The author compares theoretical strengths with some test values and shows that there is good correlation between theoretical and test values. This method will help the manufacturers design their members correctly for strength. Costs can be...
{"title":"Finger Joint Strength. A Laminated Beam Strength Predictor","authors":"W. Burdzik","doi":"10.1080/10295925.1997.9631137","DOIUrl":"https://doi.org/10.1080/10295925.1997.9631137","url":null,"abstract":"SYNOPSIS The new South African Timber Design Code, SABS 0163, no longer specifies strength values for laminated products in South Africa. The onus now rests on the manufacturers to determine the strength of their laminated beams. This could lead to unnecessary costs, if every possible size of member has to be either tested or proof loaded. Proof loading at the incorrect level could lead to a large number of members being broken unnecessarily. In this paper the author illustrates that the finger joint strength is one of a number of factors that influences the strength of a laminated beam. These factors are explained and values for them are given. The author describes how, based on the strength of the finger joints, the strength of any possible beam size can be predicted. The author compares theoretical strengths with some test values and shows that there is good correlation between theoretical and test values. This method will help the manufacturers design their members correctly for strength. Costs can be...","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133594558","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 : 1997-03-01DOI: 10.1080/10295925.1997.9631138
A. Seydack
Paper Presented at the meetings of Technical Committee for Forestry, Southern African Development Community (SADC), Forestry Sector. Theme session: Management of Indigenous forests in Southern Africa, Pretoria, 7 May 1996.
{"title":"The Challenge of Indigenous Forest Management: From Information to Implementation","authors":"A. Seydack","doi":"10.1080/10295925.1997.9631138","DOIUrl":"https://doi.org/10.1080/10295925.1997.9631138","url":null,"abstract":"Paper Presented at the meetings of Technical Committee for Forestry, Southern African Development Community (SADC), Forestry Sector. Theme session: Management of Indigenous forests in Southern Africa, Pretoria, 7 May 1996.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"1861 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127458071","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 : 1997-03-01DOI: 10.1080/10295925.1997.9631140
C. Geldenhuys
SYNOPSIS Woodlands covered > 50% of the land area in southern Africa, but only 57% remain today and only 7% occur in protected areas. Mean population density in the region is 17 people/km2 and urbanisation is increasing. In several countries subsistence agriculture is still the main contributor to the GDP. The main challenge in the region is to develop a sustainable contribution to the industry and service sectors of the economy from the woodland resources while improving the conservation status of the vegetation resources. A wide range of timber and non-timber products are harvested from the woodlands, often with no concern for the maintenance of the resource, or to optimise and economise the utilisation of the trees that are felled, or to pursue multiple-use systems. Very few species are utilised, and some of the harvested species are relatively rare, or are over-utilised, and the management systems to not favour their regeneration. Sustained-use management of woodlands require the maintenance of 1) the...
{"title":"Sustainable Harvesting of Timber from Woodlands in Southern Africa: Challenges for the Future","authors":"C. Geldenhuys","doi":"10.1080/10295925.1997.9631140","DOIUrl":"https://doi.org/10.1080/10295925.1997.9631140","url":null,"abstract":"SYNOPSIS Woodlands covered > 50% of the land area in southern Africa, but only 57% remain today and only 7% occur in protected areas. Mean population density in the region is 17 people/km2 and urbanisation is increasing. In several countries subsistence agriculture is still the main contributor to the GDP. The main challenge in the region is to develop a sustainable contribution to the industry and service sectors of the economy from the woodland resources while improving the conservation status of the vegetation resources. A wide range of timber and non-timber products are harvested from the woodlands, often with no concern for the maintenance of the resource, or to optimise and economise the utilisation of the trees that are felled, or to pursue multiple-use systems. Very few species are utilised, and some of the harvested species are relatively rare, or are over-utilised, and the management systems to not favour their regeneration. Sustained-use management of woodlands require the maintenance of 1) the...","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127610773","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 : 1997-03-01DOI: 10.1080/10295925.1997.9631139
K. Olbrich, S. Christie, J. Evans, D. Everard, B. Olbrich, R. Scholes
SYNOPSIS We discuss five issues which we feel will have a major influence on the long term sustainability of the South African forest industry. These are: water, site fertility, labour issues, environmental issues, and national and international market forces. Specifically, we attempt to highlight aspects of our current understanding, and identify gaps in our knowledge. In exploring these issues, our objective is to contribute to the debate on sustainability, provoke discussion, and identify some of the research which is needed to meet the goal of sustainable forest management.
{"title":"Factors Influencing the Long Term Sustainability of the South African Forest Industry","authors":"K. Olbrich, S. Christie, J. Evans, D. Everard, B. Olbrich, R. Scholes","doi":"10.1080/10295925.1997.9631139","DOIUrl":"https://doi.org/10.1080/10295925.1997.9631139","url":null,"abstract":"SYNOPSIS We discuss five issues which we feel will have a major influence on the long term sustainability of the South African forest industry. These are: water, site fertility, labour issues, environmental issues, and national and international market forces. Specifically, we attempt to highlight aspects of our current understanding, and identify gaps in our knowledge. In exploring these issues, our objective is to contribute to the debate on sustainability, provoke discussion, and identify some of the research which is needed to meet the goal of sustainable forest management.","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122609202","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 : 1997-03-01DOI: 10.1080/10295925.1997.9631132
A. Morris
SYNOPSIS Five-year growth data are presented for a blanking trial with a third rotation Pinus patula crop measuring the effects of amount (25% or 50% blanks) and timing (2 and 11 months after first planting) of blanking. The blanking treatments achieved survival levels (range 81–90%) comparable to the control (85%) which was established without blanking. Blanks were generally smaller than originals, contributing mostly below average size trees and increasing overall stand variability. These effects were most pronounced when blanking 11 months rather than two months after planting of originals. Relative to the control, the treatments blanked after two months had comparable stand volumes but the 11 month blanking treatments had significantly reduced stand volume. The pattern of growth response to treatment of both blanks and originals suggests the inferior size of blanks results from competition effects between blanks and originals as well as simply the younger age of blanks. Should the increased proportion...
{"title":"Five-year results from a blanking trial with Pinus patula","authors":"A. Morris","doi":"10.1080/10295925.1997.9631132","DOIUrl":"https://doi.org/10.1080/10295925.1997.9631132","url":null,"abstract":"SYNOPSIS Five-year growth data are presented for a blanking trial with a third rotation Pinus patula crop measuring the effects of amount (25% or 50% blanks) and timing (2 and 11 months after first planting) of blanking. The blanking treatments achieved survival levels (range 81–90%) comparable to the control (85%) which was established without blanking. Blanks were generally smaller than originals, contributing mostly below average size trees and increasing overall stand variability. These effects were most pronounced when blanking 11 months rather than two months after planting of originals. Relative to the control, the treatments blanked after two months had comparable stand volumes but the 11 month blanking treatments had significantly reduced stand volume. The pattern of growth response to treatment of both blanks and originals suggests the inferior size of blanks results from competition effects between blanks and originals as well as simply the younger age of blanks. Should the increased proportion...","PeriodicalId":228456,"journal":{"name":"The Southern African Forestry Journal","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124097894","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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