Southern Forests: a Journal of Forest Science

Evaluating resistance drilling and NIR spectroscopy for quantifying wood quality of young eucalypts grown in Guangxi province in southern China

2024-06-25T13:34:53+00:00

Cost-effective, non-destructive means of estimating wood properties of eucalypts grown in Guangxi, China, were evaluated using near infrared (NIR) spectroscopy and resistance drilling. For this evaluation, wood samples for NIR analysis and resistance drill measurements were collected from 581 trees, representing eight plantation Eucalyptus taxa across five sites. The near infra-red (NIR) spectra collected from the 581 wood samples were analysed using existing calibrations for kraft pulp yield, cellulose content, hot water extractives and Klason lignin. These spectra and calibrations were effective in predicting over 60% of the variance in total carbohydrates and over 80% of the extractives and lignin values from independent laboratory analysis of a subset of 100 samples. Resistance drilling combined with software developed for processing the drill data proved to be a quick, low cost and effective means of quantifying wood density (as amplitude of the drill torque), stem diameter and bark thickness.

Variation in survival, growth and stem straightness in Eucalyptus urophylla provenances in the Southern Highlands region of Tanzania

2024-06-25T13:46:11+00:00

Lack of quality planting materials has significantly limited productivity and quality of commercial forestry plantations in Tanzania. A provenance/progeny trial of Eucalyptus urophylla was established to test performance in order to select the best planting materials for future plantation activities. A complete randomised block design was used whereby 30 families from 8 provenances within 6 replications were tested. At 13 years tree survival, growth (diameter at breast height and height) and stem straightness were assessed. The results indicate that there were highly significant differences (p < 0.05) among provenances and families in survival, height, breast height diameter (DBH) and stem straightness. The overall survival ranged from 79.0% to 96.2%; height ranged between 24.9 and 32.5 m; and DBH ranged from 18.7 to 24.5 cm. Overall, results from this study show that provenances Alassannaru, Elun kirpas, Nesunhuhun and Nakana ulam have better growth performance and stem form than others. These results provide valuable information on the growth performance of different provenances and families of E. urophylla. The provenances and families selected with best performance can be used in developing improved seeds for plantation establishment and/or selection of plus trees for vegetative propagation as candidate clones for a clonal testing programme in Tanzania.

Growth and adaptability of provenances and progenies of Pinus maximinoi H.E.Moore in northern Mozambique

2024-06-25T13:53:05+00:00

The aim of this study was to evaluate the growth and adaptability of Pinus maximinoi provenances and progenies and to estimate the genetic variation that could be exploited in feature improvement (e.g. breeding studies). Data from this study are from a 12-year P. maximinoi trial established by the Florestas do Niassa Lda, (an afforestation company), with four provenances and nineteen progenies, in the Chimbonila district, northern Mozambique. The field trial was set up in a randomised block design with four repetitions and six plant linear plots. At two, four and eight years of age, performance in total height, diameter at breast height (DBH) and survival were analysed. The results at eight years of age showed no significant variation between provenances for all variables analysed. Our selection criteria detected 45% of the best performing progenies mostly from Yuscaran and San Jeronimo. Most of the nine progenies classified as best, based on predicted additive genetic effect and genetic gain, belonged to Yuscaran and Tatumbla. On the other hand, most of the progenies at the level of the 17 best-classified individuals were from San Jeronimo, which we suggest can be used for future breeding projects in northern Mozambique.

Biomass production and nutritional efficiency in short rotation eucalypt clone plantations for energy in north-east Brazil

2024-06-25T13:59:26+00:00

Selecting adapted hybrids with greater efficiency in the use and return of nutrients is essential to ensure the success of forestry activities. Although topics on the nutritional sustainability of eucalypt biomass harvesting have frequently been discussed, few studies have focused on short rotation eucalypt clonal plantations (aimed at energy production), especially in conditions of nutrient scarcity and water limitations in Brazil. Therefore, our objective was to evaluate the nutritional efficiency and sustainability (for nitrogen (N), phosphorus (P) and potassium (K)) of six eucalypt clones in short rotation cultivation in the north-east of Brazil, considering different harvesting scenarios and using the Eucalyptus urophylla species as a reference, which is traditionally planted in the study region. Direct quantification of the biomass of 21 trees of each clone was carried out at 5 years of age. The clones did not affect the accumulation of total biomass (on average, 199.9 Mg ha⁻¹). The 1296 and 1355 clones provided lower biomass export and greater nutritional efficiency, favouring an increase in the potential number of rotations (PNR) for P and a reduction in the N removal rate (RR). However, the VM58 clone showed higher biomass export and lower PNR. Thus, clones 1296 and 1355 are more favourable, while clone VM58 is less favourable to nutritional sustainability under the studied conditions. Nitrogen and K may cause productivity limitations in future rotations in whole-tree harvesting systems. Adopting more conservationist harvesting systems with removing only the stemwood or stemwood with bark can optimise the potential of clones, minimise the need to add fertilisers and ensure maintenance of the site’s productivity.

Carbon storage in a dry Miombo woodland area in Tanzania

2024-06-25T14:12:44+00:00

A persistent need exists, both politically and academically, for knowledge on carbon storage and sequestration potentials of forest ecosystems and their contributions to the global carbon balance. This study assessed carbon stocks of a 6 065 ha dry Miombo woodland site in Iringa Rural district, Tanzania. The carbon stock for each of the six pools: trees, shrubs, deadwood, herbaceous vegetation (grass and herbs), surface litter and soil were estimated. Assuming a 50% carbon share of biomass, the results showed that the aboveground carbon stocks were: 24.71 Mg C ha⁻¹ for trees; 10.88 Mg C ha⁻¹ for shrubs; 0.54 Mg C ha⁻¹ for deadwood; 0.58 Mg C ha⁻¹ for herbaceous vegetation; and 2.47 Mg C ha−1 for surface litter. Soil carbon was estimated separately for two depth ranges: 0–15 cm and 15–30 cm below the surface. These soil strata contributed 21.24 Mg C ha⁻¹ and 8.22 Mg C ha⁻¹ respectively. The total carbon (C) stock of the six pools was 68.64 Mg C ha⁻¹. Considering the vast area covered by dry Miombo woodlands in Tanzania and in 10 other countries in south-eastern Africa, the carbon stock of these ecosystems is clearly tremendous, underscoring the importance of conserving them.

Effect of invasive species on forest composition in tropical dry forest: a case study of invasion by Gliricidia sepium

2024-06-25T14:19:12+00:00

Ecological concerns caused by biological invasion have been considered an inevitable threat to global sustainability. The superior competitive ability of invasive plant species (IPS) has an impact on vegetation composition and loss of native flora. Recognising IPS at an early stage would significantly contribute to controlling invasive plants, protecting biodiversity and formulating appropriate strategies. Most of the studies available on invasive plants are descriptive and largely confined to non-woody species. The present study focused on the alien Gliricidia sepium, a tree species, to determine the invasive potential of its distribution in tropical dry deciduous forests of Central India. Forty square plots (25 × 25 m) were laid out at each uninvaded and invaded forest to enumerate phytosociological attributes to determine the impact of G. sepium on vegetation composition and community structure. Higher density (37.2 individuals ha−1), basal area (6.32 m2 ha−1) and importance value index (95.8) contributed by G. sepium clearly showed the suppression of seedlings, saplings and trees of native forest species at the invaded sites in terms of species richness, cover and other attributes as compared to at the uninvaded sites. Further, other invasive attributes such as higher seed production, dieback phenomenon, higher coppicing power and higher growth rate as observed during the study clearly affirmed the early speculation that the species might be invasive. The species has a strong potential to spread vigorously and may gradually become invasive throughout the country as already reported from various parts of India. In the present study area, G. sepium was introduced due to restoration and plantation programmes and our findings indicate its negative impact on the native vegetation. Thus, we strongly recommend the avoidance of this species for both plantation and restoration programmes, especially for Indian forests. The study helps in early recognition and rapid monitoring of G. sepium to control its spread throughout the country.

Identification of main variables in forest management for recovery of endemic species habitat in burned areas of southern Chile

2024-06-25T14:23:12+00:00

Wildfires are among the most serious disturbances that affect forest biodiversity, damaging both flora and fauna. In some burned areas, vegetation recovery is a long and complex process that requires the support of restorative actions. This study evaluated changes in forest structural features after a fire that affect habitat suitability for Rhinocryptids, an endemic group of bird species that are indicators of biodiversity in the temperate forests of South America. The study area was the Malleco National Reserve, Chile, where the main ecosystems are temperate forests. Four species from the Rhinocryptidae family of birds were used as bioindicator species. This group of species is endemic to temperate forests in South America. After fires occurred in 2002 and 2015, affecting temperate forests dominated by several Nothofagus species, two field inventories were carried out in 2016 and 2018. These inventories recorded the presence of Rhinocryptids and some forests structural features. Differences between the two stages of forest regeneration were assessed using statistical tests (T-test and Wilcoxon–Mann–Whitney test) and a classification model was proposed to determine the presence of Rhinocryptidae species. The statistical analysis of forest structural features showed that the variables more relevant in the habitat recuperation are vertical stratification (p-value < 0.001) and understory cover (p-value = 0.053). The trained decision tree to predict the presence of Rhinocryptidae species had an accuracy of 65.22%. This model showed that the coexistence of more than one Rhinocryptidae species occurs when vertical stratification is not mono-stratified and the density is lower than 335 trees ha⁻¹. Our results can help forest managers to consider