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> NISC Pty Ltd en-US Southern Forests: a Journal of Forest Science 2070-2620 Copyright for articles published in this journal is retained by the journal publisher. Relative performance of coppice versus seedlings of 16 eucalypt taxa over two rotations in northern coastal Zululand, South Africa <p>From the 1980s, <em>Eucalyptus grandis</em> × <em>E. camaldulensis</em> (GC) and <em>E. grandis</em> ×<em> E. urophylla</em> (GU) were planted as alternatives to <em>E. grandis</em> for improved productivity in the Zululand coastal regions of South Africa. Although these hybrid combinations provided a degree of drought and/or disease tolerance together with the ability to regenerate the stand via the management of coppice growth, there was the need to test better-suited species for the drier, northern parts of coastal Zululand. Species, provenances and inter-specific hybrid clones of the genera <em>Eucalyptus</em>, <em>Corymbia, Acacia</em> and <em>Casuarina</em> were tested as alternatives to GC and GU in four site × species trials over one rotation (1996 to 2006). Although <em>E. longirostrata</em>, <em>Corymbia henryi,</em> <em>C. citriodora subsp</em>. <em>variegata</em> and <em>E. argophloia</em> showed promise as alternatives to GC and GU, their coppicing ability remained unknown. To determine this, one of the trials (Palm Ridge) was re-implemented and managed for regeneration via coppice over a second rotation (2R). Coppicing ability, growth and susceptibility to pests and disease data were compared for the 16 species at Palm Ridge over the two successive rotations (1R — planted = 8.9 years; 2R — coppiced = 8.2 years). Except for <em>E. argophloia</em> and one <em>E. camaldulensis</em> provenance, all treatments had equivalent, or improved stem stocking in 2R relative to 1R (trial mean: 1R = 1 174 stems ha<sup>−1</sup>; 2R = 1 288 stems ha<sup>−1</sup>). The two commercial hybrid clones had the highest volumes in both the 1R (GU = 174 m<sup>3</sup> ha<sup>−1</sup>; GC 163 m<sup>3</sup> ha<sup>−1</sup>) and 2R (GU = 149 m<sup>3</sup> ha−1; GC 124 m<sup>3</sup> ha<sup>−1</sup>) rotations. The mean annual volume increments (MAI in m<sup>3</sup> ha<sup>−1</sup> y<sup>−1</sup>) were not significantly different between rotations (1R = 10.74 m<sup>3</sup> ha<sup>−1</sup> y−1; 2R = 9.95 m<sup>3</sup> ha<sup>−1</sup> y<sup>−1</sup>), nor were there any significant rotation × treatment interactions indicating that the treatments performed in a similar manner over both rotations. Although there were differences among provenances within taxa, these were not as great as the differences amongst the taxa tested: GC/GC &gt; C. c<em>itriodora subsp. variegata</em> &gt; <em>E. logirostrata</em> &gt; <em>C. henryi,</em> with <em>E. tereticornis</em>, <em>E. camaldulensis</em>, <em>E. argophloia</em> and <em>E. watsoniana</em> not performing well over both rotations. Despite the higher rainfall recorded over 2R (837 mm y<sup>−1</sup>) relative to 1R (765 mm y<sup>−1</sup>), the incidence of pests and diseases that was not recorded in 1R most likely contributed to the reduced growth of the coppiced trees. Most notable of these were <em>Leptocybe</em> <em>invasa</em> on the GC, <em>E. tereticornis</em> and <em>E. camaldulensis</em> treatments, <em>Botryosphaeria</em> spp. on all but the Corymbia treatments, kino on the Corymbia treatments, and <em>Coniothyrium</em> spp on the GU treatment. Relative to the two commercial hybrid clones (GC and GU), <em>E. longirostrata</em>, and <em>C. henryi</em> were the most promising of the alternative species tested over both rotations (planted and coppiced), with <em>C. citriodora</em> subsp. <em>variegata</em> also showing promise. Although all treatments were affected by pest(s) or disease(s), some of the species showed resistance and provenances within species tolerance, indicating the potential for selection for a reduction in biotic risk.</p> K.M. Little R.A.W. Gardner Copyright (c) 2021-11-11 2021-11-11 83 2 99 110 Wood volume estimation strategies for trees from a Dry Forest/Savannah transition area in Piauí, Brazil <p>Prediction of aboveground wood volume is one of most important stages when conducting a forest inventory and<br>making forest management decisions. This is more difficult for native forest than for plantations given the high<br>variability of the former (trees of different species and age groups). The objective of this work was to evaluate different strategies to estimate aboveground standing tree wood volume (<em>v</em>) using its diameter at breast height (DBH) and total height (<em>h</em>), comparing the use of form factors, volume equations fitted by ordinary least squares and mixed modelling, as well as the options from the literature. To achieve this, 351 trees were scaled during field campaigns, with 158 felled trees and 193 measured using Criterion equipment. The data collected from each scaled tree was: <em>h</em>, DBH, <em>v</em> and identification of the botanical species. We found that the best application of form factors occurred when the trees were divided by diameter classes. However, regression models, regardless of the fitting technique, presented better volume estimates than form factors. Mixed models, with either the species or diameter class as the random variable, provided the lowest errors when estimating tree volume. Thus, we recommend the use of mixed models as the best strategy to estimate volume of standing trees. The following equation can be used to estimate aboveground wood volume for trees from vegetation types similar to the ones of this study:&nbsp; ln(<em>v</em>) = −9.06013 + 1.91756 ln(DBH) + 0.69846 ln(<em>h</em>).</p> Lailla Sabrina Queiroz Nazareno Andressa Ribeiro Mylla Vyctória Coutinho Sousa Cynthia Wanick Vieira Antonio Carlos Ferraz Filho Copyright (c) 2021-11-11 2021-11-11 83 2 111 119 Genetic diversity of improved genotypes of <i>Tectona grandis</i> in the state of Mato Grosso, Brazil <p>Teak (<em>Tectona grandis</em>) is a tree species native to South-east Asia and widely cultivated in Latin America. In Mato Grosso state, Brazil, teak is the second-most planted forest species due to its high productivity resulting from high adaptability to the soil and climate conditions of the region. However, there is little information about the genetic diversity of improved genotypes cultivated in the state. Thus, the objective of this study was to quantify, through ISSR (inter-simple sequence repeat) molecular markers, the genetic diversity of improved teak genotypes used in different plantations in Mato Grosso state. For this, 31 ISSR primers were tested on 113 genotypes separated into nine populations. Six primers were selected to perform the analyses, resulting in 55 amplified loci. All selected primers showed a high polymorphic information content. Considering all genotypes in the Mato Grosso population, the percentage of polymorphic loci (<em>P</em>) was 96.4%, the genetic diversity according to Nei՚s genetic diversity index (<em>H</em>) was 1.96, and according to Shannon՚s information / diversity index (<em>I</em>), it was 0.53. Considering each population individually, <em>P</em> varied from 50.9% to 90.9%, <em>H </em>from 0.21 to 0.33, and I from 0.30 to 0.49. Most of the genetic diversity observed was within populations (86%). Four genetic groups were identified, with a high level of admixture among them. The existence of a considerable genetic diversity within populations indicates the possibility of exploring this variation in genetic improvement programmes. However, the introduction of new genetic materials is recommended to increase the genetic base of this species in Brazil.</p> Mariana de Moura Queiroz Sidney Fernando Caldeira Alexandre Magno Sebbenn Daniele Aparecida Alvarenga Arriel Copyright (c) 2021-11-11 2021-11-11 83 2 120 127 Carbon production from seasonal litterfall in the Brazilian Atlantic Forest <p>Forests play an important role in climate change, acting as a source or sink of carbon. There is, however, a lack of data regarding the carbon production from litterfall in tropical forests. The Atlantic Forest is one of the most distinguished forest types in Brazil, encompassing the Araucaria Forest. In this study, we assessed the seasonal carbon production from litterfall. Data were collected every season from 27 litter traps. Dry matter and carbon fraction were investigated and confronted with meteorological variables. Litterfall components were stratified into Brazilian pine leaves and twigs: broadleaved leaves, twigs, bark, reproductive material, and other material (miscellaneous).<br>The Tukey test indicated significant differences among the carbon fractions for litter components. Seven key species were determinant in litterfall production. Brazilian pine leaves and twigs were the primary carbon source to the forest, followed by leaves and twigs from broadleaved species. Most carbon input from litterfall comes during spring and summer. We concluded that litterfall is a source of carbon and nutrient to the ecosystem. This study contributes to improving the Brazilian national greenhouse inventory and related reports addressed to climate change mitigation.</p> Greyce C.B. Maas Carlos R. Sanquetta Renato Marques Sebastião do A . Machado Mateus N.I. Sanquetta Ana Paula D. Corte Iara M. Barberena Copyright (c) 2021-11-12 2021-11-12 83 2 128 134 Investigating the wood production and adaptability potential of <i>Corymbia</i> hybrid progeny in northern coastal Zululand, South Africa <p>During August 2013, two ‘new’ eucalypt taxa × site interaction trials were established in northern coastal Zululand. The main purpose of these trials was to investigate the commercial forestry potential of a range of <em>Corymbia</em> inter-specific hybrids for the region. Two sites contrasting in mean annual precipitation (850 mm and 1 155 mm respectively) and productivity potential, namely Mfezi (Mtubatuba) and Flatcrown (Kwambonambi), were selected for these trials. The 28 <em>Corymbia</em> hybrid seedlots comprised controlled crosses between <em>C. torelliana</em> and <em>C. citriodora</em> subsp<em> citriodora</em>,<em> C. citriodora</em> subsp <em>variegata</em> and <em>C. henryi</em>. Trees were assessed annually for the presence of pests and diseases and at mid-rotation (48 months) comprehensively measured for growth. By mid-rotation, none of the<em> Corymbia</em> hybrid<br>families showed susceptibility to the suite of insect pests plaguing many of the commercial <em>Eucalyptus</em> hybrid clones in the region. Furthermore, no noteworthy disease infection symptoms were observed in any of the <em>Corymbia</em> or<em> Eucalyptus</em> species and hybrids in the trials. At the drier site of the two (Mfezi), at 24 months following 2 successive dry (&lt;700 mm rainfall) years, trees of some of the <em>Corymbia</em> hybrid families manifested drought stress symptoms in the form of mild to moderate kino exudations from stems and branches. However, by mid-rotation, most of the <em>Corymbia</em> hybrid families in the trial showed excellent tree health, survival and stem volume relative to that of the commercial hybrid controls. At both sites, the seven top-ranking treatments for volume were <em>Corymbia</em> hybrid families. Based on the overall excellent growth performances of several of the <em>Corymbia</em> hybrid families in the two trials, more intensive investigations, for example in the areas of wood properties, vegetative propagation and clonal performance testing, would appear well-warranted.</p> Robin A.W. Gardner David J. Lee Copyright (c) 2021-11-12 2021-11-12 83 2 135 143 Fungicides and an insecticide tested for the control of wattle rust and brown wattle mirid in <i>Acacia mearnsii</i> plantations <p>Black wattle is planted on 110 000 ha in South Africa, and considered economically important for both private and commercial growers. Black wattle is intensively managed, with protection from abiotic and biotic risk factors forming an important component of any management strategy. Of the various pests and diseases, brown wattle mirid and wattle rust have a negative impact on early wattle growth. Although pesticides have been shown to be effective for their management, the opportunity to combine an insecticide and fungicide in the same tank and applied as a mix would reduce operations. In November 2017 four trials were initiated on contrasting black wattle sites in KwaZulu-Natal, South Africa. Azoxystrobin + tebuconazole (Custodia®) were tested at varying rates, timing (November or January) and in combination with cypermethrin (Kemprin®) for the control of the wattle mirid and rust on different site types. Azoxystrobin + difenoconazole (AmistarTop®) were included as a reference standard, and an untreated control for comparative purposes. Tree growth, tree condition and disease/insect expression assessments over one growing season were used to determine optimum treatments. The fungicides and rates at which they were tested were equally effective for the control of wattle rust. Custodia® when applied at either 1.2 or 2 L ha−1 showed similar trends to AmistarTop® (1 L ha−1) in terms of optimum tree performance/condition, together with fewest wattle rust symptoms. Although there were tree performance benefits associated with the curative application of a fungicide after infestation (January 2018), spraying before infestation (November 2017) provided the greatest benefits. Wattle mirid presence in three trials indicated tree performance benefits when controlled with an insecticide. However, greater benefits were obtained when combined with a fungicide for the control of both wattle mirid and rust. Applying the two as a tank mixture would reduce costs without a noticeable impact on the efficacy for either active ingredient.</p> Keith Little Copyright (c) 2021-11-12 2021-11-12 83 2 144 157 Structure, growth and growing space efficiency of <i>Pinus radiata</i> (D. Don) trees as affected by their social position <p>Currently, silvicultural prescriptions such as thinning monospecific stands from above and transitioning from monospecific to mixed-species stands are scrutinised regarding their ability to reduce stress and damage. That the quantity and quality of the trees harvested by intermediate and final cuts will vary depending on the chosen prescription is likely but more or less neglected so far. Here we analyse 60 Pinus radiata (D. Don) trees earmarked for removal from the Jonkershoek thinning experiment at the West Cape, South Africa. The experiment comprises both thinning from above and below allowing for comparison of the structure and growth of dominant and subdominant trees removed at 11 years old. Thinning from above removed mainly dominant trees which were on average 44.3% larger in tree diameter, only 8.5% larger in tree height, but 83% larger in crown projection area and more than 25% tapering than subdominant trees extracted by thinning from below. The courses of diameter growth over age of the dominant trees were degressively asymptotic; those of subdominant trees were S-shaped, due to competitive pressure. The volume growth was exponential in both groups. However, the dominant trees achieved<br>2–3 times higher stem volumes at 10 years of age. Tree structure and growth were highly correlated: the mean annual volume increment showed a Pearson correlation of r = 0.64 with crown length, <em>r</em> = −0.76 with the current ratio of stem slenderness, and <em>r</em> = −0.70 with the competition index by Hegyi. Thus, crown length, slenderness and the competition index were most relevant in explaining tree growth. The analysis of the mode of competition indicated in both groups and in total a sub-proportional increase of stem growth with increasing size. Interestingly, growing space efficiency in terms of mean annual volume growth per crown projection area was similar in both groups.</p> Hans Pretzsch Andreas Rais Deon Malherbe Antonio Ruano Hugo Lambrechts Enno Uhl Ben du Toit Copyright (c) 2021-11-12 2021-11-12 83 2 158 169 Initial growth results comparing first generation F1 and advanced-generation F2 <i>Pinus patula</i> × <i>Pinus tecunumanii</i> interspecific hybrid families <p>The hybrid between <em>Pinus patula</em> and<em> P. tecunumanii</em> low elevation (PPTL) and high elevation (PPTH) sources was developed in the 1990s in South Africa and commercialised during the 2000s in response to high post-establishment mortality of <em>P. patula</em> caused by <em>Fusarium circinatum</em>. The growth and wood properties for these hybrids are also superior to the parental species. This study describes an experiment where F1 hybrid families and F2 advanced hybrid families of the <em>Pinus patula</em> × <em>P. tecunumanii</em> low elevation hybrid were compared in a progeny field experiment. Seed yield and early growth at three years is reported. The early results from this study indicate that there were no significant differences in growth between the F1 and F2 PPTL hybrid and both the F1 and F2 hybrid outperformed the pure P. patula control. These early results should be monitored further to determine if this trend continues. The F2 hybrid offers the opportunity to obtain tolerance of <em>F. circinatum</em> and better growth than P. patula at a much lower cost than that of deployment of the F1 PPTL hybrid.</p> André Nel Juan J. Acosta Gary R. Hodge Copyright (c) 2021-11-12 2021-11-12 83 2 170 176 Predictions of chlorophyll concentrations in the leaves of seedlings of two congeneric tropical trees from RGB digital image components <p>The segmentation of digital images in red, green and blue (RGB) components is a low-cost method for monitoring leaf chlorophyll concentrations and seedling quality. The two congeneric species, <em>Cariniana legalis</em> and <em>C. estrellensis</em>, are distinguished based on differences in bark texture and the colour of their new leaves. We compared indices based on leaf colour segmentation in RGB to predict total chlorophyll concentrations (Chlt) in the leaves of seedlings of these two species. Mature leaves were digitalised in a flatbed scanner and segmented in red (R), green (G) and blue (B). The relationships between the three RGB indices and Chlt were tested. Additionally, we calculated the anthocyanin content-chroma basic (ACcb). The mean value of ACcb was significantly higher in <em>C. legalis</em> than in<em> C. estrellensis</em>, demonstrating a higher anthocyanin concentration in <em>C. legalis l</em>eaves. Based on the highest coefficients of determination (R<sup>2</sup>) and lowest prediction errors (PE), for all indices, the best results were obtained for <em>C. estrellensis</em>. The presence of anthocyanins in the leaves of<em> C. legalis</em> and the limitation of the RGB colour segmentation indices for separating all leaf pigments might be the main causes of the differences in Chlt prediction in the leaves of these two congeneric tree species.</p> Marcelo Schramm Mielke Luciana Santos Lobo Geane Santos da Costa Ana Cristina Schilling Martielly Santana dos Santos Ândrea Carla Dalmolin Copyright (c) 2021-11-12 2021-11-12 83 2 177 184