Pub Date : 2021-10-02DOI: 10.2989/20702620.2021.2000326
E. R. Konzen, Natália Saudade de Aguiar, M. Navroski, C. S. Mota, L. Miranda, Regiane Abjaud Estopa, Erasmo Luis Tonett, Mariane de Oliveira Pereira
Eucalypts are economically important worldwide, being largely propagated by clonal means, that is, frequently achieved by mini-cuttings. Regional climatic conditions, however, interfere with this strategy. Southern Brazil, especially in higher altitudes, has a considerable number of cloudy and cold days annually. It is a challenge for clonal propagation, even for cold-tolerant species such as Eucalyptus benthami and E. dunnii. The supplementation with artificial light has proved to be effective for improving growth in agricultural crops, but little work has been done with trees. Here we conducted a set of experiments for producing mini-cuttings of two commercial clones of E. benthamii and one clone of E. dunnii under the supplementation with artificial light, using red/far-red (660:730 nm) and red/blue (660:450 nm) light emitting diodes (LED), in comparison to a control (sunlight only). The supplementation with red/far-red and red/blue light increased the production of mini-cuttings in colder months, but more consistently positive impacts were observed with red/far-red lamps. The shoots produced under red/far-red light were more elongated and implicated in higher leaf canopy coverage. Overall, this work is a first step aimed at improving clonal propagation systems of E. benthamii and E. dunnii through mini-cuttings supplemented with artificial light.
{"title":"Artificial light improves productivity of mini-cuttings in a clonal minigarden of Eucalyptus benthamii and E. dunnii","authors":"E. R. Konzen, Natália Saudade de Aguiar, M. Navroski, C. S. Mota, L. Miranda, Regiane Abjaud Estopa, Erasmo Luis Tonett, Mariane de Oliveira Pereira","doi":"10.2989/20702620.2021.2000326","DOIUrl":"https://doi.org/10.2989/20702620.2021.2000326","url":null,"abstract":"Eucalypts are economically important worldwide, being largely propagated by clonal means, that is, frequently achieved by mini-cuttings. Regional climatic conditions, however, interfere with this strategy. Southern Brazil, especially in higher altitudes, has a considerable number of cloudy and cold days annually. It is a challenge for clonal propagation, even for cold-tolerant species such as Eucalyptus benthami and E. dunnii. The supplementation with artificial light has proved to be effective for improving growth in agricultural crops, but little work has been done with trees. Here we conducted a set of experiments for producing mini-cuttings of two commercial clones of E. benthamii and one clone of E. dunnii under the supplementation with artificial light, using red/far-red (660:730 nm) and red/blue (660:450 nm) light emitting diodes (LED), in comparison to a control (sunlight only). The supplementation with red/far-red and red/blue light increased the production of mini-cuttings in colder months, but more consistently positive impacts were observed with red/far-red lamps. The shoots produced under red/far-red light were more elongated and implicated in higher leaf canopy coverage. Overall, this work is a first step aimed at improving clonal propagation systems of E. benthamii and E. dunnii through mini-cuttings supplemented with artificial light.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87387815","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 : 2021-10-02DOI: 10.2989/20702620.2021.1978825
Lorena Oliveira Barbosa, César Augusto Guimarães Finger, Emanuel Arnoni Costa, O. Campoe, C. Schons
Crown variables are used in growth and production models to increase the accuracy of estimates. These variables are costly and difficult to measure, mainly in dense native forests such as mixed ombrophilous forests (MOF), where Araucaria angustifolia is the predominant species. Thus, this study aimed to evaluate the effect of qualitative and quantitative variables to describe the vigour of the crown, competition and growth of A. angustifolia in Southern Brazil MOF. We selected trees in the MOF area and measured circumference at breast height (CBH) and total height (h). For the crowns, a ranking of values was established in the variables: Crown Shape (CS), Vertical crown Shape (VS), Distance between Branches (DB), Sociological Position (SP), percentage of Green Leaves (GL) and Crown Size (CZ). Periodic Annual Increment in basal area (PAIg) and a Competition Index (CI) were calculated. We used principal component analysis (PCA) and Hierarchical Cluster Analysis (HCA) to describe and classify the sampled trees. Two groups were generated: i) dominant and codominant trees, with higher growth, better vigour and better crown quality; and ii) suppressed trees with low vigour, consequently low increment and worse crown quality. The CI, when based only on diameter information, was inadequate to describe the competitive status of the trees, so information about crowns was necessary. Qualitative crowns variables are important to classify the vigour, current level of competition and to understand the different trends in A. angustifolia growth.
{"title":"Using crown characterisation variables as indicators of the vigour, competition and growth of Brazilian pine","authors":"Lorena Oliveira Barbosa, César Augusto Guimarães Finger, Emanuel Arnoni Costa, O. Campoe, C. Schons","doi":"10.2989/20702620.2021.1978825","DOIUrl":"https://doi.org/10.2989/20702620.2021.1978825","url":null,"abstract":"Crown variables are used in growth and production models to increase the accuracy of estimates. These variables are costly and difficult to measure, mainly in dense native forests such as mixed ombrophilous forests (MOF), where Araucaria angustifolia is the predominant species. Thus, this study aimed to evaluate the effect of qualitative and quantitative variables to describe the vigour of the crown, competition and growth of A. angustifolia in Southern Brazil MOF. We selected trees in the MOF area and measured circumference at breast height (CBH) and total height (h). For the crowns, a ranking of values was established in the variables: Crown Shape (CS), Vertical crown Shape (VS), Distance between Branches (DB), Sociological Position (SP), percentage of Green Leaves (GL) and Crown Size (CZ). Periodic Annual Increment in basal area (PAIg) and a Competition Index (CI) were calculated. We used principal component analysis (PCA) and Hierarchical Cluster Analysis (HCA) to describe and classify the sampled trees. Two groups were generated: i) dominant and codominant trees, with higher growth, better vigour and better crown quality; and ii) suppressed trees with low vigour, consequently low increment and worse crown quality. The CI, when based only on diameter information, was inadequate to describe the competitive status of the trees, so information about crowns was necessary. Qualitative crowns variables are important to classify the vigour, current level of competition and to understand the different trends in A. angustifolia growth.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73965443","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 : 2021-10-02DOI: 10.2989/20702620.2021.1994341
Jonas Massuque, Kelly Iapuque Rodrigues de Sousa, P. F. Trugilho
Fibres and vessels represent the largest proportion of anatomical elements in hardwood tree species. They exert significant effects on various properties of the wood, which, consequently, have several implications for the use of the wood. However, the effect of these elements on wood combustion behaviour is still poorly analysed in the literature. The present study aimed to evaluate the effect of fibre and vessel biometry on wood combustibility. The length, width and cell wall thickness of fibre, diameter of the lumen, and length and width of vessels were measured from five native Miombo tree species in Mozambique, namely Brachystegia boehmii Taub., Brachystegia spiciformis Benth., Julbernardia globiflora (Benth.) Troupin, Parinari curatellifolia Planch. ex Benth. and Uapaca kirkiana Müll. Arg. The fibre quality index and cell wall thickness were determined based on fibre biometry. The flexibility coefficient and the wall fraction are inversely proportional indices and individually affected most of the combustion parameters. Wood ignition is driven by large lumen diameter and flexibility in fibres. In addition, cell wall thickness and a larger wall fraction increase wood combustion.
{"title":"Effect of fibre and vessel biometry on wood combustibility of native Miombo tree species","authors":"Jonas Massuque, Kelly Iapuque Rodrigues de Sousa, P. F. Trugilho","doi":"10.2989/20702620.2021.1994341","DOIUrl":"https://doi.org/10.2989/20702620.2021.1994341","url":null,"abstract":"Fibres and vessels represent the largest proportion of anatomical elements in hardwood tree species. They exert significant effects on various properties of the wood, which, consequently, have several implications for the use of the wood. However, the effect of these elements on wood combustion behaviour is still poorly analysed in the literature. The present study aimed to evaluate the effect of fibre and vessel biometry on wood combustibility. The length, width and cell wall thickness of fibre, diameter of the lumen, and length and width of vessels were measured from five native Miombo tree species in Mozambique, namely Brachystegia boehmii Taub., Brachystegia spiciformis Benth., Julbernardia globiflora (Benth.) Troupin, Parinari curatellifolia Planch. ex Benth. and Uapaca kirkiana Müll. Arg. The fibre quality index and cell wall thickness were determined based on fibre biometry. The flexibility coefficient and the wall fraction are inversely proportional indices and individually affected most of the combustion parameters. Wood ignition is driven by large lumen diameter and flexibility in fibres. In addition, cell wall thickness and a larger wall fraction increase wood combustion.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79627519","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 : 2021-10-02DOI: 10.2989/20702620.2021.1987177
Rafael Keret, M. Nakhooda, N. Jones, P. Hills
Globally the demand for forestry resources is booming, and consequently innovative approaches to cultivate valuable hardwoods, such as eucalypts, are crucial. Although micropropagation offers a means to clonally propagate desirable cultivars, this technique is often variety-specific for eucalypts. Thus, recalcitrant genotypes are often excluded from micropropagation programmes as development requires large investments of time, money and expertise. In this study, a minimal maintenance medium was developed to reduce subculturing frequency (∼8 days) and to evaluate each micropropagation stage independently. Furthermore, a generic protocol for use across different varieties was developed by assessing the in vitro performance of three different Eucalyptus grandis x Eucalyptus nitens varieties (varieties 1–3) across various treatments. The purpose of this protocol was to ease the in vitro establishment of novel eucalypt varieties by providing a foundation for future protocol optimisation. During multiplication, medium containing 0.5 mg l−1 meta-topolin with 0.1 mg l−1 of indole acetic acid (IAA) induced the highest bud proliferation and shoot elongation for varieties 1 (59.1 ± 2.9; 1.2 cm ± 0.08), 2 (62.3 ± 2.7; 1.5 cm ± 0.09) and 3 (58.1 ± 3; 1.2 cm ± 0.07). Following multiplication, the rooting treatment that achieved the most consistent rooting percentages among varieties 1 (33.4%), 2 (43.5%) and 3 (34.3%) incorporated 0.029 mg l−1 of racemic-GR24 with 0.5 mg l−1 of IAA. Additionally, root vigour was assessed by measuring the root number and length, which varied considerably based on the variety and treatment in question. Overall, variety 2 was the most amenable to plant growth regulators and upon further investigation was found to possess equal expression levels of the auxin transporters PIN1 and AUX1. Conversely, the other varieties displayed unequal ratios of these transporters. Considering that auxins are principal media components, these expression profiles may serve as markers to identify eucalypt cultivars amenable to micropropagation.
{"title":"Optimisation of micropropagation protocols for temperate eucalypt hybrids in South Africa, with a focus on auxin transport proteins","authors":"Rafael Keret, M. Nakhooda, N. Jones, P. Hills","doi":"10.2989/20702620.2021.1987177","DOIUrl":"https://doi.org/10.2989/20702620.2021.1987177","url":null,"abstract":"Globally the demand for forestry resources is booming, and consequently innovative approaches to cultivate valuable hardwoods, such as eucalypts, are crucial. Although micropropagation offers a means to clonally propagate desirable cultivars, this technique is often variety-specific for eucalypts. Thus, recalcitrant genotypes are often excluded from micropropagation programmes as development requires large investments of time, money and expertise. In this study, a minimal maintenance medium was developed to reduce subculturing frequency (∼8 days) and to evaluate each micropropagation stage independently. Furthermore, a generic protocol for use across different varieties was developed by assessing the in vitro performance of three different Eucalyptus grandis x Eucalyptus nitens varieties (varieties 1–3) across various treatments. The purpose of this protocol was to ease the in vitro establishment of novel eucalypt varieties by providing a foundation for future protocol optimisation. During multiplication, medium containing 0.5 mg l−1 meta-topolin with 0.1 mg l−1 of indole acetic acid (IAA) induced the highest bud proliferation and shoot elongation for varieties 1 (59.1 ± 2.9; 1.2 cm ± 0.08), 2 (62.3 ± 2.7; 1.5 cm ± 0.09) and 3 (58.1 ± 3; 1.2 cm ± 0.07). Following multiplication, the rooting treatment that achieved the most consistent rooting percentages among varieties 1 (33.4%), 2 (43.5%) and 3 (34.3%) incorporated 0.029 mg l−1 of racemic-GR24 with 0.5 mg l−1 of IAA. Additionally, root vigour was assessed by measuring the root number and length, which varied considerably based on the variety and treatment in question. Overall, variety 2 was the most amenable to plant growth regulators and upon further investigation was found to possess equal expression levels of the auxin transporters PIN1 and AUX1. Conversely, the other varieties displayed unequal ratios of these transporters. Considering that auxins are principal media components, these expression profiles may serve as markers to identify eucalypt cultivars amenable to micropropagation.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86475513","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 : 2021-10-02DOI: 10.2989/20702620.2021.1994342
S. Gonçalves, N. Fiedler, J. Silva, Gilson Fernandes Da Silva, Mayra Luiza Marques Da Silva, L. Minette, Daniel Pena Pereira, D. Lopes, Evandro Ferreira da Silva, A. H. C. Ramalho, Jeangelis Silva Santos, Marcelo Otone Aguiar, José de Oliveira Melo Neto, Renisson Neponuceno de Araújo Filho
The productivity of wood harvesting operations is one of the main viability indicators of the forestry enterprise, which is directly influenced by land, population, and operational planning characteristics. The variables that affect the productivity of harvesting machines are particularly difficult to measure and have complex relationships, making it challenging to predict the productivity of operations. This study generated a model using machine learning (ML) techniques to estimate harvesting productivity in Eucalyptus plantations in southeastern Brazil. The input variables for modelling harvesting productivity were the average individual tree volumes, wood volume in the stand, cutting age, spacing, operator experience, and the management regime. The database was randomly divided into training (70%) and validation (30%) datasets. Boosted, artificial neural network (ANN), and adaptive network-based fuzzy inference system (ANFIS) techniques were used to fit the model and were evaluated through statistics and graphical analysis of the residues. The configurations selected for training and validation to estimate harvester productivity resulted in correlation coefficient values greater than 0.9, and root-mean-square error (RMSE) percentages less than 12.41, indicating a strong correlation and high accuracy between the estimates and the observed values. The boosted technique yielded the best results, with correlation coefficients of 0.98 and 0.97, and RMSE percentages of 6.15 and 6.65 in training and validation, respectively. The worst performance for estimating harvesting productivity was obtained using the ANFIS technique. ML techniques were efficient in modelling the productivity of mechanised forest cutting with a harvesting model.
{"title":"Machine learning techniques to estimate mechanised forest cutting productivity","authors":"S. Gonçalves, N. Fiedler, J. Silva, Gilson Fernandes Da Silva, Mayra Luiza Marques Da Silva, L. Minette, Daniel Pena Pereira, D. Lopes, Evandro Ferreira da Silva, A. H. C. Ramalho, Jeangelis Silva Santos, Marcelo Otone Aguiar, José de Oliveira Melo Neto, Renisson Neponuceno de Araújo Filho","doi":"10.2989/20702620.2021.1994342","DOIUrl":"https://doi.org/10.2989/20702620.2021.1994342","url":null,"abstract":"The productivity of wood harvesting operations is one of the main viability indicators of the forestry enterprise, which is directly influenced by land, population, and operational planning characteristics. The variables that affect the productivity of harvesting machines are particularly difficult to measure and have complex relationships, making it challenging to predict the productivity of operations. This study generated a model using machine learning (ML) techniques to estimate harvesting productivity in Eucalyptus plantations in southeastern Brazil. The input variables for modelling harvesting productivity were the average individual tree volumes, wood volume in the stand, cutting age, spacing, operator experience, and the management regime. The database was randomly divided into training (70%) and validation (30%) datasets. Boosted, artificial neural network (ANN), and adaptive network-based fuzzy inference system (ANFIS) techniques were used to fit the model and were evaluated through statistics and graphical analysis of the residues. The configurations selected for training and validation to estimate harvester productivity resulted in correlation coefficient values greater than 0.9, and root-mean-square error (RMSE) percentages less than 12.41, indicating a strong correlation and high accuracy between the estimates and the observed values. The boosted technique yielded the best results, with correlation coefficients of 0.98 and 0.97, and RMSE percentages of 6.15 and 6.65 in training and validation, respectively. The worst performance for estimating harvesting productivity was obtained using the ANFIS technique. ML techniques were efficient in modelling the productivity of mechanised forest cutting with a harvesting model.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81486358","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 : 2021-10-02DOI: 10.2989/20702620.2021.1994340
Cristiane Carla Benin, Danielle de Moraes Lúcio, L. F. Watzlawick, V. A. de Lima
This study aimed to evaluate the properties of Eucalyptus benthamii wood for bioenergy purposes. Trees were sampled in five diametric classes and used to evaluate properties of the wood according to three ages (5, 6 and 7 years) in three regions of E. benthamii production in Parana state, southern Brazil. The basic density, proximate analysis, gross calorific value and net calorific value, and energy density were determined. For evaluation of the energy properties, 27 composite samples were used, which represented tree classes of minimum, medium and maximum diameter. The variables were statistically analysed under the effect of tree age and region. Basic density was positively affected by age, and this effect was reflected in energy density of the wood. The interaction of Region 1 with trees of age seven years identified the best conditions for biomass energy production from this source. As there were no significant differences in the immediate chemical analysis and the calorific value for either factor evaluated, we suggest that plantation managers could reduce the cutting cycle without compromising the energy efficiency of these forests.
{"title":"Energy properties of Eucalyptus benthamii wood based on tree age and region in Guarapuava, Paraná state, Brazil","authors":"Cristiane Carla Benin, Danielle de Moraes Lúcio, L. F. Watzlawick, V. A. de Lima","doi":"10.2989/20702620.2021.1994340","DOIUrl":"https://doi.org/10.2989/20702620.2021.1994340","url":null,"abstract":"This study aimed to evaluate the properties of Eucalyptus benthamii wood for bioenergy purposes. Trees were sampled in five diametric classes and used to evaluate properties of the wood according to three ages (5, 6 and 7 years) in three regions of E. benthamii production in Parana state, southern Brazil. The basic density, proximate analysis, gross calorific value and net calorific value, and energy density were determined. For evaluation of the energy properties, 27 composite samples were used, which represented tree classes of minimum, medium and maximum diameter. The variables were statistically analysed under the effect of tree age and region. Basic density was positively affected by age, and this effect was reflected in energy density of the wood. The interaction of Region 1 with trees of age seven years identified the best conditions for biomass energy production from this source. As there were no significant differences in the immediate chemical analysis and the calorific value for either factor evaluated, we suggest that plantation managers could reduce the cutting cycle without compromising the energy efficiency of these forests.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80226699","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 : 2021-07-03DOI: 10.2989/20702620.2021.1944394
A. Chichinye, C. Geldenhuys, P. Chirwa
The persistence niche (studied through different modes regeneration) of three key species (Baikiaea plurijuga (Harms), Guibourtia coleosperma (Benth.) J. Leonard and Pterocarpus angolensis) (DC) under five different disturbance regimes (eight years after cessation of disturbance) was studied in the Baikiaea–Guibourtia–Pterocarpus woodlands of north-western Zimbabwe. The disturbance regimes were: protected area (no disturbance); timber concession area (timber harvesting); pole and firewood harvesting sites; abandoned crop fields (after clearing for agriculture); and burnt sites (fire disturbance). Influence of stump diameter and height on regeneration factors was investigated. For each disturbance regime, six main plots (100 m × 100 m) each were systematically laid out (20 m apart) to assess regeneration. In each main plot, 10 m wide transects (5 m apart) were surveyed for seedlings and saplings of the target species (at least 100 plants of each species), resulting in 7 transects per main plot, 42 transects in each study site and 210 transects in total. Number of seedlings with or without a rootstock (i.e., just grown from seed) was recorded. Diameter of stumps was measured at the cut surface. Shoot height was measured from their origin. Each target species was associated with mode of regeneration (χ² = 27 642, P < 0.001). Most plants regenerated from root suckers. Regeneration mode is dependent on disturbance regime (B. plurijuga χ² = 225.66, p < 0.001; G. coleosperma χ² = 158.62, p < 0.001; and P. angolensis χ² = 144.01, p < 0.001). Stump diameter negatively influenced number of sprouts for B. plurijuga and P. angolensis, but positively influenced sprout height for all species. Stump height positively influenced sprout height for G. coleosperma and P. angolensis. The study therefore concludes that disturbances are necessary in facilitating sprouting and growth of suppressed shoots. Stump height and diameter influence the ability of stumps to regrow vegetatively through sprouting. Weak relationships between stump diameter/height and coppice density and shoot height suggest that there are other factors that affect vegetative regrowth through coppicing.
{"title":"Disturbance impacts on the persistence niche of key species in the Baikiaea–Guibourtia–Pterocarpus woodlands of north-western Zimbabwe","authors":"A. Chichinye, C. Geldenhuys, P. Chirwa","doi":"10.2989/20702620.2021.1944394","DOIUrl":"https://doi.org/10.2989/20702620.2021.1944394","url":null,"abstract":"The persistence niche (studied through different modes regeneration) of three key species (Baikiaea plurijuga (Harms), Guibourtia coleosperma (Benth.) J. Leonard and Pterocarpus angolensis) (DC) under five different disturbance regimes (eight years after cessation of disturbance) was studied in the Baikiaea–Guibourtia–Pterocarpus woodlands of north-western Zimbabwe. The disturbance regimes were: protected area (no disturbance); timber concession area (timber harvesting); pole and firewood harvesting sites; abandoned crop fields (after clearing for agriculture); and burnt sites (fire disturbance). Influence of stump diameter and height on regeneration factors was investigated. For each disturbance regime, six main plots (100 m × 100 m) each were systematically laid out (20 m apart) to assess regeneration. In each main plot, 10 m wide transects (5 m apart) were surveyed for seedlings and saplings of the target species (at least 100 plants of each species), resulting in 7 transects per main plot, 42 transects in each study site and 210 transects in total. Number of seedlings with or without a rootstock (i.e., just grown from seed) was recorded. Diameter of stumps was measured at the cut surface. Shoot height was measured from their origin. Each target species was associated with mode of regeneration (χ² = 27 642, P < 0.001). Most plants regenerated from root suckers. Regeneration mode is dependent on disturbance regime (B. plurijuga χ² = 225.66, p < 0.001; G. coleosperma χ² = 158.62, p < 0.001; and P. angolensis χ² = 144.01, p < 0.001). Stump diameter negatively influenced number of sprouts for B. plurijuga and P. angolensis, but positively influenced sprout height for all species. Stump height positively influenced sprout height for G. coleosperma and P. angolensis. The study therefore concludes that disturbances are necessary in facilitating sprouting and growth of suppressed shoots. Stump height and diameter influence the ability of stumps to regrow vegetatively through sprouting. Weak relationships between stump diameter/height and coppice density and shoot height suggest that there are other factors that affect vegetative regrowth through coppicing.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81303866","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 : 2021-07-03DOI: 10.2989/20702620.2021.1944395
C. Gevers, B. Slippers, I. Germishuizen, Gudrun Dittrich-Schrӧder, B. Hurley
Leptocybe invasa is an invasive gall wasp and pest of Eucalyptus trees, which has become widely distributed in Africa, Asia, Europe and the Americas. Several other wasp species have been found to co-occur in L. invasa-induced galls. In South Africa, this includes an introduced biological control agent, Selitrichodes neseri; two known, accidentally introduced parasitoids, Megastigmus zebrinus and Quadrastichus mendeli; and M. pretorianensis, whose role in the gall is uncertain. In addition to the gall associates, a second lineage of L. invasa or cryptic species was discovered in South Africa in 2015. To determine the distribution and prevalence of these species across South Africa, a national monitoring scheme was initiated. Galled Eucalyptus material was collected at infested sites and emerging adults were collected and identified. Morphology, DNA barcoding and polymerase chain reaction (PCR) Restriction Fragment Length Polymorphism analyses were used to differentiate between the species and lineages. Results from the first two sampling periods indicated that L. invasa lineage A has spread throughout South Africa while lineage B had a more limited distribution in the country. Subsequent samples recorded the further spread of L. invasa Lineage B, which now occurs in all provinces sampled. The Leptocybe lineages were found to co-occur on individual trees, increasing the potential for admixture. From the Eucalyptus genotypes sampled, there was no indication of differences in host association between the Leptocybe lineages. Selitrichodes neseri, M. zebrinus and M. pretorianensis were present throughout South Africa and emerged from trees that contained both Leptocybe lineages, but their frequency varied with site. This study will inform future distribution of parasitoids as well as monitoring of potential changes in plant host resistance, admixture and parasitoid resistance in future.
{"title":"The distribution and diversity of Leptocybe invasa (Hymenoptera: Eulophidae) and its gall associates in South Africa","authors":"C. Gevers, B. Slippers, I. Germishuizen, Gudrun Dittrich-Schrӧder, B. Hurley","doi":"10.2989/20702620.2021.1944395","DOIUrl":"https://doi.org/10.2989/20702620.2021.1944395","url":null,"abstract":"Leptocybe invasa is an invasive gall wasp and pest of Eucalyptus trees, which has become widely distributed in Africa, Asia, Europe and the Americas. Several other wasp species have been found to co-occur in L. invasa-induced galls. In South Africa, this includes an introduced biological control agent, Selitrichodes neseri; two known, accidentally introduced parasitoids, Megastigmus zebrinus and Quadrastichus mendeli; and M. pretorianensis, whose role in the gall is uncertain. In addition to the gall associates, a second lineage of L. invasa or cryptic species was discovered in South Africa in 2015. To determine the distribution and prevalence of these species across South Africa, a national monitoring scheme was initiated. Galled Eucalyptus material was collected at infested sites and emerging adults were collected and identified. Morphology, DNA barcoding and polymerase chain reaction (PCR) Restriction Fragment Length Polymorphism analyses were used to differentiate between the species and lineages. Results from the first two sampling periods indicated that L. invasa lineage A has spread throughout South Africa while lineage B had a more limited distribution in the country. Subsequent samples recorded the further spread of L. invasa Lineage B, which now occurs in all provinces sampled. The Leptocybe lineages were found to co-occur on individual trees, increasing the potential for admixture. From the Eucalyptus genotypes sampled, there was no indication of differences in host association between the Leptocybe lineages. Selitrichodes neseri, M. zebrinus and M. pretorianensis were present throughout South Africa and emerged from trees that contained both Leptocybe lineages, but their frequency varied with site. This study will inform future distribution of parasitoids as well as monitoring of potential changes in plant host resistance, admixture and parasitoid resistance in future.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87452415","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 : 2021-07-03DOI: 10.2989/20702620.2021.1936686
Brandon Giddey, J. Baard, Lufuno M. Vhengani, T. Kraaij
Recently two large wildfires (around the towns of Knysna in 2017 and George in 2018) jointly burnt over 80 000 ha in the southern Cape, South Africa. Here, patches of closed-canopy Afrotemperate forest occur within a matrix of fire-prone (native) fynbos shrublands or adjacent to commercial plantations of invasive alien Pinus trees (a transformed state). We compared the distances that fire penetrated into forest margins adjacent to fynbos to those adjacent to plantations. Furthermore, we used a satellite-derived index of fire severity, the differenced Normalised Burn Ratio (dNBR), to compare fire severity in forest margins adjacent to fynbos to those adjacent to plantations. Results were inconsistent between the two fires. In the Knysna fire, no significant difference was noted in fire penetration into forest, while forest margins adjacent to plantations burnt at significantly lower severity than those adjacent to fynbos. In the George fire, penetration into and fire severity in forest margins adjacent to plantations were significantly greater than in those adjacent to fynbos. Not only were fire severity and penetration in forest margins with plantations adjacent dissimilar between the George and Knysna fires, but variability in fire severity was greater in forest margins with plantation adjacent than in those with fynbos adjacent. Our study provides evidence that fire severity in forest margins is associated with the adjacent vegetation type and that plantations potentially expose forests to greater variability in fire severity and extent than the forest may experience under natural conditions. Other important factors that may affect the severity and extent of burn in forest margins are forest patch size and topographical position, the nature of the ecotone between forest and the adjacent vegetation, and the fuel load and structure of the adjacent vegetation which varies considerably in relation to stand age and management practices in plantations.
{"title":"The effect of adjacent vegetation on fire severity in Afrotemperate forest along the southern Cape coast of South Africa","authors":"Brandon Giddey, J. Baard, Lufuno M. Vhengani, T. Kraaij","doi":"10.2989/20702620.2021.1936686","DOIUrl":"https://doi.org/10.2989/20702620.2021.1936686","url":null,"abstract":"Recently two large wildfires (around the towns of Knysna in 2017 and George in 2018) jointly burnt over 80 000 ha in the southern Cape, South Africa. Here, patches of closed-canopy Afrotemperate forest occur within a matrix of fire-prone (native) fynbos shrublands or adjacent to commercial plantations of invasive alien Pinus trees (a transformed state). We compared the distances that fire penetrated into forest margins adjacent to fynbos to those adjacent to plantations. Furthermore, we used a satellite-derived index of fire severity, the differenced Normalised Burn Ratio (dNBR), to compare fire severity in forest margins adjacent to fynbos to those adjacent to plantations. Results were inconsistent between the two fires. In the Knysna fire, no significant difference was noted in fire penetration into forest, while forest margins adjacent to plantations burnt at significantly lower severity than those adjacent to fynbos. In the George fire, penetration into and fire severity in forest margins adjacent to plantations were significantly greater than in those adjacent to fynbos. Not only were fire severity and penetration in forest margins with plantations adjacent dissimilar between the George and Knysna fires, but variability in fire severity was greater in forest margins with plantation adjacent than in those with fynbos adjacent. Our study provides evidence that fire severity in forest margins is associated with the adjacent vegetation type and that plantations potentially expose forests to greater variability in fire severity and extent than the forest may experience under natural conditions. Other important factors that may affect the severity and extent of burn in forest margins are forest patch size and topographical position, the nature of the ecotone between forest and the adjacent vegetation, and the fuel load and structure of the adjacent vegetation which varies considerably in relation to stand age and management practices in plantations.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80179178","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 : 2021-07-03DOI: 10.2989/20702620.2021.1960218
M. Wondafrash, B. Slippers, B. A. Asfaw, I. A. Makowe, Herbert Jenya, S. Bush, I. Kayumba, Alphonsine Nambazimana, Simon van der Lingen, B. Hurley
Eucalypt forestry in sub-Saharan Africa is challenged by non-native eucalypt-feeding insects. In recent studies, six invasive eucalypt insect pests, namely Blastopsylla occidentalis, Glycaspis brimblecombei, Gonipterus sp.n.2, Leptocybe invasa, Thaumastocoris peregrinus and Ophelimus maskelli were confirmed present in sub-Saharan Africa. We investigated the diversity and distribution of natural enemies of these pests in six countries in the region. Plant parts (leaves, petioles and stem) infested with the insect pests were sampled from multiple sites in each country. The emerged natural enemies were identified using morphological characteristics and DNA sequence data. Nine species of natural enemies were confirmed present in the surveyed countries, namely Anaphes nitens, Closterocerus chamaeleon, Megastigmus sp., M. pretorianensis, Psyllaephagus blastopsyllae, P. bliteus, Quadrastichus mendeli, Selitrichodes kryceri and S. neseri. No natural enemies were found in Ghana and Sierra Leone despite the presence of L. invasa in both of those countries. Interestingly, most of these natural enemies were unintentionally introduced into the surveyed countries. Results of this study showed that both insect pests and natural enemies introduced into one country are likely to affect many other countries in the region. These findings call for a more coordinated approach to the management of plantation pests in the region.
{"title":"Tracing the distribution of natural enemies of non-native invasive eucalypt insect pests in sub-Saharan Africa","authors":"M. Wondafrash, B. Slippers, B. A. Asfaw, I. A. Makowe, Herbert Jenya, S. Bush, I. Kayumba, Alphonsine Nambazimana, Simon van der Lingen, B. Hurley","doi":"10.2989/20702620.2021.1960218","DOIUrl":"https://doi.org/10.2989/20702620.2021.1960218","url":null,"abstract":"Eucalypt forestry in sub-Saharan Africa is challenged by non-native eucalypt-feeding insects. In recent studies, six invasive eucalypt insect pests, namely Blastopsylla occidentalis, Glycaspis brimblecombei, Gonipterus sp.n.2, Leptocybe invasa, Thaumastocoris peregrinus and Ophelimus maskelli were confirmed present in sub-Saharan Africa. We investigated the diversity and distribution of natural enemies of these pests in six countries in the region. Plant parts (leaves, petioles and stem) infested with the insect pests were sampled from multiple sites in each country. The emerged natural enemies were identified using morphological characteristics and DNA sequence data. Nine species of natural enemies were confirmed present in the surveyed countries, namely Anaphes nitens, Closterocerus chamaeleon, Megastigmus sp., M. pretorianensis, Psyllaephagus blastopsyllae, P. bliteus, Quadrastichus mendeli, Selitrichodes kryceri and S. neseri. No natural enemies were found in Ghana and Sierra Leone despite the presence of L. invasa in both of those countries. Interestingly, most of these natural enemies were unintentionally introduced into the surveyed countries. Results of this study showed that both insect pests and natural enemies introduced into one country are likely to affect many other countries in the region. These findings call for a more coordinated approach to the management of plantation pests in the region.","PeriodicalId":21939,"journal":{"name":"Southern Forests: a Journal of Forest Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83786004","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：