Southern Forests: a Journal of Forest Science <p><em>Southern Forests: a Journal of Forest Science</em><span> is one of the leading forestry journals in the Southern Hemisphere. The journal publishes scientific articles in forest science and management of fast-growing, planted or natural forests in the Southern Hemisphere and the tropics. Papers are also encouraged on related disciplines such as environmental aspects of forestry, social forestry, agroforestry, forest engineering and management as well as the goods and services that are derived from forests as a whole. Articles published by the journal are of value to foresters, resource managers and society at large. The journal particularly encourages contributions from South America, Africa and tropical/subtropical Australasia and Asia. Publication of the journal is supported by the Southern African Institute of Forestry.</span></p><p>Read more about this journal <a href="" target="_blank">here</a>. </p> en-US Copyright for articles published in this journal is retained by the journal publisher. (Publishing Manager) (Editorial Office) Wed, 03 Feb 2021 11:47:58 +0000 OJS 60 Current status of technology-use for plantation re-establishment in South Africa <p>Plantation re-establishment is a key component of silviculture as it deals with the creation of a suitable environment when planting or seeding a stand. Re-establishment practices include slash management, site preparation, marking and preparation of a planting position, planting, fertilisation and vegetation management. Over the past decade, there has been a shift towards mechanising re-establishment activities primarily due to labour challenges such as: aging rural workforce; increasing labour costs; high labour turnover; problematic health issues leading to lower productivity; inconsistent work quality by manual labour; and poor ergonomic practices. A survey was conducted to assess and gauge the level of mechanisation within these re-establishment practices in South Africa. Responses to an e-mail questionnaire were received from 43 contractors and 11 grower companies from within the different provinces where commercial forestry is practiced in South Africa. The survey, a first of its kind, was designed and administered following the techniques used in conducting the Forest Engineering technical survey. Descriptive and inferential statistics were used to analyse the data. The results showed that the total area re-planted by respondent contractors and grower companies was ± 36 923 ha–1 per year. The predominant activities conducted prior to planting comprised: burning (78%); marking a planting position using the baseline method (71%); preparation of a planting position using a road pick (57%) and pre-plant chemical weeding with a knapsack (70%). Furthermore, 45% of planting and 77% of blanking operations were carried out manually with a trowel. Post planting activities such as fertilizing and weeding were carried out through manual spot application of fertiliser (61%) and herbicide application with a knapsack (43%). Overall, the results indicated that typical re-establishment activities are still dominated by manual methods. This study is a baseline for future, periodic surveys that can be conducted to analyse trends and identify areas for improvement in re-establishment activities in South Africa.</p> <p><strong>Keywords:</strong> blanking, fertilising, planting, weeding</p> Muedanyi M. Ramantswana, Michal P. Brink, Keith M. Little, Raffaele Spinelli, Paxie W.C. Chirwa Copyright (c) Tue, 02 Feb 2021 00:00:00 +0000 Physical properties of <i>Tectona grandis</i> (Lamiaceae) juvenile wood thermally modified in a closed system <p>This paper reports the first results of the effect of an industrial closed-system thermal modification process on the physical properties of fast-growth teak wood (Tectona grandis L.f.). The wood (juvenile) came from thinning a 15–18-year-old plantation located in Mato Grosso state, Midwest Brazil, broken down into plainsawn battens measuring 25 × 70 × 1 070 mm (radial × tangential × longitudinal). The battens were from material close to the pith which was combined heartwood (≈75%) and sapwood. We sampled untreated and thermally modified battens, which were transformed into specimens for testing. The thermal modification was carried out at 160 °C in an industrial scale reactor, according to the parameters of the TanWood process, which is classified as a closed hygrothermal system. Twelve specimens by treatment (25 × 60 × 50 mm3 — radial × tangential × longitudinal) were conditioned in a climatic chamber set up at 35 °C and the relative humidity (RH) was raised stepwise (31%, 49%, 69% and 81%). Apparent density and equilibrium moisture content of the specimens were measured at every step. The latter was used as an index of wood hygroscopicity. For the statistical analysis, only the results of apparent density and moisture content at 35 °C and 69% RH were compared. At the end of the conditioning, the specimens were saturated in water, followed by oven-drying and then the total swelling (from saturated to oven-dried) was calculated. Thermally modified wood became less dense, less hygroscopic and more dimensionally stable than untreated wood. The apparent density and the equilibrium moisture content of wood were reduced by 20% and 18% respectively. With the continuous increase of RH from 31% to 81%, the thermally modified wood proportionally adsorbed less water than the untreated wood. The radial, tangential and volumetric total swelling were reduced by 25%, 5% and 15% respectively.</p> <p><strong>Keywords</strong>: apparent density, hygroscopicity, TanWood process, total swelling </p> Natália A. Cunha, Tiago A. Gales, Amanda M. Nunes, Glaucileide Ferreira, Thaís M. Brito, Adriano Ribeiro de Mendonça, Djeison C. Batista Copyright (c) Wed, 03 Feb 2021 00:00:00 +0000 Development and testing of volume models for <i>Pinus nigra Arn., Fagus sylvatica L.,</i> and Quercus pubescens Willd.</i> <p>Volume models were developed and tested for Pinus nigra Arn., Fagus sylvatica L., and Quercus pubescens Willd. to accurately predict the woody stem volume at tree level, since despite the economic importance of these species in the Mediterranean type of forests standard models do not apply. Using a total non-destructive sample of 471 trees in mountain forests of northern Greece, two fundamental volume models, the Hohenadl–Krenn and the standard equation were fitted using a generalised least squares (GLS) estimator along with a power function, to regulate the unequal variance and the normality assumption of the residuals. The results showed that both models presented good fitting performance explaining the largest part of stem volume variance and therefore they can be used in operational forest management planning. In addition, the normality assumption of the distribution of the residuals can be satisfied through weighting techniques for reducing the potential heteroscedastic trends during the fitting procedure. The GLS may provide the necessary framework for stem volume model development on an accurate and unbiased basis.</p> <p><strong>Keywords:</strong> forest management; generalized least squares (GLS); Mediterranean mountain region; standing tree volume</p> Dimitrios I. Raptis, Vassiliki Kazana, Angelos Kazaklis, Christos Stamatiou Copyright (c) Wed, 03 Feb 2021 00:00:00 +0000 Mixed-species plantations of <I>Eucalyptus</I> and <I>Acacia mangium</I> increase labile carbon and phosphorus levels in Ferralsol soils in the Cerrado biome, Brazil <p>In order to clarify the effect of mixed planting in the dynamics of phosporus (P), we assessed the fractions of this element in mixed plantings of Eucalyptus urophylla × E. grandis (Urograndis) and Acacia mangium in a tropical soil clay, analysing changes in the fractions of P and examining the correlation of these changes with the fractions of soil organic matter. Pure stands of Urograndis (E) and A. mangium (A) (0A:100E and 100A:0E) and mixed stands of the two species (50A:50E and 37A:66E) were established. The fractionation of P, the granulometric fractionation of organic matter and the labile carbon (POXC) were determined at soil depths of 0–5 and 5–10 cm. Regarding the availability of P, organic parts contributed 34.6% to 38.1% relative to the total P, with the highest percentages being observed for the moderately labile fraction. Highest levels of labile organic P were observed in the mixed plantations. About soil carbon (C), the highest levels of the more labile C fractions were recorded in plantations in which Acacia was present. Mixed plantations were found to show a greater balance between labile P and C fractions. The C fractions warrant particular attention in future studies, notably those related to the emission of greenhouse gases.</p> <p><strong>Keywords</strong>: forest nutrition, fractionation of phosphorus, organic carbon, organic phosphorus</p> Wilbert Valkinir Cabreira, Marcos Gervasio Pereira, Fabiano de Carvalho Balieiro, Eduardo da Silva Matos, Renato de Aragão Ribeiro Rodrigues, Raissa Nascimento dos Santos Copyright (c) Wed, 03 Feb 2021 00:00:00 +0000 Assessing the utility of airborne laser scanning derived indicators for tropical forest management <p>The objective of this study was to evaluate four airborne laser scanning derived indicators for monitoring tropical forest stands at different stages of sustainable management practices. The traditional monitoring routines are inefficient and time consuming due to the limitation of optical sensors in detecting features below the canopy and to the large areas involved in forest management. Nine production units at different logging cycle stage&nbsp; were surveyed using airborne laser scanning. Non-logged sites were also included in the analysis. For each production unit we computed the above-ground biomass, the proportion of road and trails, the number of emergent trees, proportion of clearings and the time after logging. We analysed the effects of time after logging on each indicator using the generalised linear model. The number of emergent trees was not influenced by the time after logging. However, the above-ground biomass, number of canopy gaps and low-density of returns area responded to the time after logging and showed sensibility to monitoring sustainable forest management (SFM) sites.</p> <p><strong>Keywords</strong>: logging, remote sensing, sustainable forest management </p> Vitor Antunes Martins da Costa, Adeliton da Fonseca de Oliveira, Jhonathan Gomes dos Santos, Alex Augusto Abreu Bovo, Danilo Roberti Alves de Almeida, Eric Bastos Gorgens Copyright (c) Wed, 03 Feb 2021 00:00:00 +0000 Mechanisms of drought response in <I>Populus</I> <p>Drought affects plant growth and has become a serious problem worldwide. Populus species have different drought tolerance and sensitivity abilities. In order to evaluate the mechanism of drought stress tolerance in different cultivated Populus species distributed in China, the response to drought in the morphology and physiology of three poplars clones, NL-895, NL-351 and NL-3412 was investigated. The growth, gas exchange capacity, water use efficiency, antioxidant enzyme activity and lipid peroxidation were measured in order to evaluate differences among different genotypes in responses to two watering regimes (80% and 30% of field capacity). Our results indicated that drought stress had serious adverse effects on the seedlings as the biomass, leaf area, nett photosynthetic rate (Pn) and chlorophyll content were decreased while the activities of antioxidative enzymes were increased and the relative electric conductivity and malondialdehyde (MDA) content were enhanced. The results showed Populus possessed an effective self-protective mechanism to relieve the inhibition of growth induced by water deficit through increasing waster use efficiency, adjusting osmotic membrane and decreasing plant growth. These findings deepened our understanding of drought-tolerance mechanism in Populus.</p> <p><strong>Keywords</strong>: gas exchange, osmotic adjustment, protective enzymes, water use efficiency </p> Lita Yi, Bin Li, Helena Korpelainen, Fei Yu, Lihong Wu, Meihua Liu Copyright (c) Wed, 03 Feb 2021 00:00:00 +0000 Growth and modulus of elasticity of pine species and hybrids three years after planting in South Africa <p>Growth data and modulus of elasticity (MOE) of 11 different pine species and hybrids were examined at six sites in three regions in South Africa. Growth traits and three MOE variables were measured at three years of age in order to evaluate whether other potential pine species were more suitable than the current commercial species. There were strong observed species differences for all three MOE variables both within and across the four sites measured for wood properties, with across-site MOE ranging from 3.03 to 6.40 GPa. Green density varied among species, and an assumed constant green density of 1 000 kg m–3 underestimated MOE for species with a very high green density; similarly, for species with a very low green density, MOE was overestimated. Although survival was poor at several sites, the data shows that there are alternative pine species that exhibit comparable growth rates to the current commercial species. For estimating MOE, it is concluded that assuming a constant green density generally<br>does not affect the species ranking, but if the aim is to find the ‘true’ MOE, sampling in the field to determine the appropriate green density is needed.</p> <p><strong>Keywords</strong>: green density, MOE, Pinus, plantations</p> O. Nilsson, G.R. Hodge, L.J. Frampton, W.S. Dvorak, J. Bergh Copyright (c) Tue, 02 Feb 2021 00:00:00 +0000 Screening of ectomycorrhizal and other associated fungi in South African forest nurseries <p>The South African forestry industry covers approximately 1.3 million hectares and is dependent on exotic pine and eucalypt species. Nursery seedlings are not inoculated with ectomycorrhizal (ECM) fungi. This investigation assessed levels of naturally occurring ECM colonisation of Pinus patula seedlings from 10 different South African forestry nurseries using a grid line intersect method. Fungi from colonised roots were identified using morphological characteristics and Illumina sequencing. Colonisation of seedlings in production nurseries was low (2–21%). Morphologically, the ECM fungi Thelophora terrestris, Suillus sibiricus, and the genera Russula and Pseudotomentella were identified. Molecularly, the ECM fungi T. terrestris, Inocybe jacobi and the genus Sphaerosporella, as well as several other ECM-containing families were identified, along with many&nbsp; saprotrophic/ endophytic fungi belonging to genera such as <em>Penicillium, Ramasonia</em> and <em>Talaromyces</em>. As can be seen, a combination of both molecular and morphological identification techniques are needed as neither is able to give a full picture of the species present in isolation. This study reveals an initial insight into the root microbiome community associated with Pinus patula seedlings, which should be taken into account when inoculation with beneficial microbes is considered. It determined that natural ECM fungal root colonisation levels are very low throughout the South African nurseries investigated, indicating the need for ECM fungal inoculation, which can increase seedling growth, viability and resistance to pathogens.</p> <p><strong>Keywords</strong>: ectomycorrhizal fungi; natural colonisation; <em>Pinus patula</em> </p> V Chartier FitzGerald, J. Dames, G. Hawley Copyright (c) Wed, 03 Feb 2021 00:00:00 +0000