In this study, a geometric model of a growing forest stand has been explored. The basic relationships considered link stand volume and stand density, diameter at breast height (DBH), mean DBH and mean height. The model provides simple formulas connecting the exponents of all the relationships. Application of the formulas to real forestry data provided a high level of predictions of an exponent from two others measured through regressions from empirical data. The Pinus sylvestris L. data were of a static nature, a collection of individual stands, while the Pseudotsuga menziesii (Mirb.) Franco data were dynamic, representing forest stand development over time. The ability of the model to predict exponents in the empirical data implies, on the one hand, a substantial level of similarity between the model and the forestry data. And, on the other hand, the model gives an example in which parameters of one relationship may be linked to parameters of another. Supposedly this kind of ‘relationship between relationships’ may be observed in forest stands undergoing active growth and competition-induced self-thinning.
A new model for predicting the total tree height for harvested stems from cut-to-length (CTL) harvester data was constructed for Pinus radiata (D.Don) following a conceptual analysis of relative stem profiles, comparisons of candidate models forms and extensive selections of predictor variables. Stem profiles of more than 3000 trees in a taper data set were each processed 6 times through simulated log cutting to generate the data required for this purpose. The CTL simulations not only mimicked but also covered the full range of cutting patterns of nearly 0.45 × 106 stems harvested during both thinning and harvesting operations. The single-equation model was estimated through the multiple-equation generalized method of moments estimator to obtain efficient and consistent parameter estimates in the presence of error correlation and heteroscedasticity that were inherent to the systematic structure of the data. The predictive performances of our new model in its linear and nonlinear form were evaluated through a leave-one-tree-out cross validation process and compared against that of the only such existing model. The evaluations and comparisons were made through benchmarking statistics both globally over the entire data space and locally within specific subdivisions of the data space. These statistics indicated that the nonlinear form of our model was the best and its linear form ranked second. The prediction accuracy of our nonlinear model improved when the total log length represented more than 20% of the total tree height. The poorer performance of the existing model was partly attributed to the high degree of multicollinearity among its predictor variables, which led to highly variable and unstable parameter estimates. Our new model will facilitate and widen the utilization of harvester data far beyond the current limited use for monitoring and reporting log productions in P. radiata plantations. It will also facilitate the estimation of bark thickness and help make harvester data a potential source of taper data to reduce the intensity and cost of the conventional destructive taper sampling in the field. Although developed for P. radiata, the mathematical form of our new model will be applicable to other tree species for which CTL harvester data are routinely captured during thinning and harvesting operations.
The Atlantic Forest is one of the largest and most biodiverse rainforests of South America but anthropogenic activities are drastically changing these landscapes. The invasion of alien or exotic species is one of the greatest threats to biodiversity. There are few studies of invasive species in tropical Brazilian ecosystems. This research examines growth and ecological aspects of Syzygium cumini and Clitoria fairchildiana, two invasive tree species in the Pedra Branca State Park, an Atlantic Forest remnant in southeastern Brazil. Both species were successfully dated, indicating an average age of 58 and 31 years, respectively. A positive relationship between growth and precipitation of the previous growing season suggests an ecological adaptive strategy, which could be facilitating their invasion into the environment. Cumulative growth diameter curves indicate slow and fast growth rates for S. cumini and C. fairchildiana, respectively. Growth release episodes detected in the tree rings indicate increased anthropogenic disturbances over the last 50 years.
The study of plant species abundance distribution (SAD) in natural communities is of considerable importance to understand the processes and ecological rules of community assembly. With the distribution of tree, shrub and herb layers of eight natural communities of Toona ciliata as research targets, three different ecological niche models were used: broken stick model, overlapping niche model and niche preemption model, as well as three statistical models: log-series distribution model, log-normal distribution model and Weibull distribution model, to fit SAD of the different vegetation layers based on data collected. Goodness-of-fit was compared with Chi square test, Kolmogorov–Smirnov (K–S) test and Akaike Information Criterion (AIC). The results show: (1) based on the criteria of the lowest AIC value, Chi square value and K–S value with no significant difference (p > 0.05) between theoretic and observed SADs. The suitability and goodness-of-fit of the broken stick model was the best of three ecological niche models. The log-series distribution model did not accept the fitted results of most vegetation layers and had the lowest goodness-of-fit. The Weibull distribution model had the best goodness-of-fit for SADs. Overall, the statistical SADs performed better than the ecological ones. (2) T. ciliata was the dominant species in all the communities; species richness and diversity of herbs were the highest of the vegetation layers, while the diversities of the tree layers were slightly higher than the shrub layers; there were fewer common species and more rare species in the eight communities. The herb layers had the highest community evenness, followed by the shrub and the tree layers. Due to the complexity and habitat diversity of the different T. ciliata communities, comprehensive analyses of a variety of SADs and tests for optimal models together with management, are practical steps to enhance understanding of ecological processes and mechanisms of T. ciliata communities, to detect disturbances, and to facilitate biodiversity and species conservation.
African teak (Milicia excelsa (Welw.) C.C. Berg) is an endangered multi-use species. Understanding the impact of climate change on the distribution of this species may improve the ability to anticipate or recognize its decline or expansion and to take appropriate conservation measures if necessary. Ecological niche modeling was projected in geographical space to study the current and future distribution of M. excelsa in Bénin. MaxEnt was used to estimate the potential geographic distribution of the species under two Representative Concentration Pathways (RCP). Miroc 5 summaries and two RCP 4.5 and RCP 8.5 scenarios were used as predictor variables for projections of the geographic potential of this species. The performance of the model was assessed by the area under the curve (AUC), true skill statistics (TSS) and partial receiver operating characteristics (Partial ROC). From the results, M. excelsa was more a secondary species in the Guinean climatic zone and part of the Sudanian-Guinean and Sudanian climatic zone. The projections show a significant decrease in suitable habitats for the species from the two RCP scenarios. Only a part of the Guinean climatic zone remained suitable and few protected areas will conserve in situ M. excelsa. For the sustainable conservation of M. excelsa, it is essential to strengthen the protection of sacred forests located in the Guinean climatic zone.
The rapid rate of deforestation in Côte d’Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction. Some reforestation and afforestation has been completed. However, for some species, the numbers of surviving transplants has declined. Hence, it is necessary to develop properly adapted and resilient genotypes that can effectively support the programs of forest restoration. In this context we evaluated the effects of the provenances of seeds and of various treatments on the germination rates and on plant growth of four commercial trees species (Pycnanthus angolensis, Terminalia superba, Mansonia altissima and Pterygota macrocarpa). We analyzed these parameters for seeds of three provenances (Daloa, Akoupé and Daoukro) of four species and for thirty plants aged 6 months per provenance. Time to begin germination and time to reach maximum germination were similar among species, and were not influenced by either treatment or provenance. Untreated seeds and those soaked for 24 and 48 h in water at room temperature yielded the highest germination rates, irrespective of species or provenance. The one exception was P. angolensis, for which no germination was recorded. Within species, some provenances produced higher germination percentages than did others. No clear relationship was computed between the germination rate and the morphometric characteristics of the seeds which varied significantly between provenances. Plant growth and morphological variability also depended greatly on provenance. Genetic factors might be implicated, therefore provenance trials should be undertaken and evaluated. Furthermore, molecular analysis should be undertaken to confirm the implications of genetic factors and allow for genetic selection.
High potential productivity together with short rotation periods have made hybrid aspen an interesting option for wood production on former arable land in Nordic countries. In this study, some of the oldest active experimental plots with hybrid aspen in Sweden were remeasured at 23–30 years of age. A main aim was to assess age and productivity at the time of maximum mean annual volume increment. In addition, the influence of commercial thinning on stand development and differences in genetic gain among clones were investigated. Data from five experiments in southern Sweden were used, including three genetic trials, one demonstration stand with a clone mixture and one stand regenerated from root suckers. The three genetic trials were treated as single plot experiments, subject to a standard thinning program. In the remaining experiments, different thinning strategies were tested in a balanced block design. Volume growth had culminated or was close to maximum at age 25–30 years. Mean annual stem volume increment at culmination was 20–22 m3 ha−1 a−1. Dominant height reached 30–35 m at 28–30 years of age. Mean diameter at breast height was 27–29 cm after 29–30 years in the genetic trials. Clonal ranking based on diameter at age 7–9 years was positively correlated with the ranking at the final measurement in the genetic trials, 20 years later. This indicates that clones can be selected for superior growth based on results from young trials. More intense thinning programs increased the mean diameter compared to light thinning. The study indicates that one or two early and relatively heavy thinnings can promote the development of crop trees, without jeopardizing total volume production during a rotation of 25–30 years.
The rooting capacity of Pinus massoniana is poor, especially for mature trees, and has prevented the development of clonal forestry for P. massoniana. In this study, we varied explant types, subculture times and exogenous hormones for plantlet regeneration and assessed shoots for rooting rate and root number for P. massoniana. Following five repetitive grafts, new shoots from grafts used as explant sources were rejuvenated as observed from juvenile shoot morphology and anatomy, leading to greatly enhanced plant regeneration in comparison to that of mature materials from 26-year-old P. massoniana trees. The rooting capacity of subcultured shoots increased with successive subcultures, reaching a peak at 20 subcultures with 35–40 days per subculture. However, rooting performance was significantly reduced after 30 subcultures. The addition of naphthaleneacetic acid (NAA) plus indoleacetic acid in the medium improved the root number, but the combination of exogenous NAA with paclobutrazol (PBZ) increased rooting rate and root number. We thus greatly improved the rooting capacity of mature P. massoniana trees by optimizing explant types (rejuvenated), subculture times (20 subcultures, 35–40 days per subculture) and addition of NAA + PBZ to the rooting medium. The conditions can be used for efficient plantlet regeneration of P. massoniana.
Tachi-branco (Tachigali vulgaris, L.F.Gomes da Silva & H.C.Lima) is a leguminous tree species native to the Amazon rainforest that has drawn attention for its remarkably fast growth, a required trait for biomass/bioenergy plantations. In evaluations of biomass production and wood properties of T. vulgaris planted in homogeneous plantations at different spacings in the Amazonian state of Pará, Brazil, biomass of 7-year-old trees was quantified for individual trees and the entire population. Wood was also sampled to assess properties relevant to bioenergy applications. The choice for spacing dimension for planting nonclonal T. vulgaris should consider whether the priority is greater productivity per tree, achieved with greater spacings (9.0 m2 and 12.0 m2), or productivity per area, achieved with closer spacings (6.0 m2 and 7.5 m2). Genetic variability of the T. vulgaris seed stand and/or high heritability of wood traits overcame the effect of different spacing on all morphological, physical, chemical and energetic properties of T. vulgaris wood. This species has moderate basic density when cultivated at spacings larger than 6 m2 and net heating value above 7.95 MJ/kg, which is suitable for bioenergy purposes. The high variation in wood properties within tree spacing is strongly indicative of great potential for genetic breeding. The fast growth and the suitable moderate wood basic density confirm the outstanding potential of homogeneous plantations of T. vulgaris for providing wood for bioenergy.
The objective of this research was to improve the growth and biomass of Pterocarpus santalinus L.f. (an endangered leguminous tree) using native microbial symbionts such as arbuscular mycorrhizal fungi and Rhizobium associated with native populations of P. santalinus. The native arbuscular mycorrhizal fungi isolated from P. santalinus soils were identified as (1) Glomus fasciculatum; (2) Glomus geosporum; and Glomus aggregatum. A nitrogen-fixing microbial symbiont was isolated from the root nodules of P. santalinus and identified as Rhizobium aegyptiacum by 16s rRNA gene sequencing. These microbial symbionts were inoculated individually and in combination into P. santalinus seedling roots. After 90 days, growth and biomass had improved compared with uninoculated controls. Shoot and root lengths, number of leaves, stem circumference, number of root nodules, biomass, nutrient uptake and seedling quality index were significantly increased by a combined inoculation of arbuscular mycorrhizal fungi + Rhizobium aegyptiacum. It was concluded that native microbial symbionts positively influenced P. santalinus seedling growth which will be helpful for successful field establishment.
Salix L. (willow) is the largest genus of the family Salicaceae and plays an important role in riparian habitats, wetlands and in shrub tundra. Due to the different implications for the species belonging to this family, it is fundamental to identify molecular tools characterizing relevant clones. A set of six multilocus and multiallelic simple sequence repeat (SSRs) markers are presented, leading to 390 polymorphic fragments considered as single dominant markers and able to discriminate successfully 92 S. alba L. from 24 Salix spp. The polymorphic fragments have been used to perform genetic diversity studies, and to investigate population structures and cluster analysis in a germplasm collection. The results highlight the capability of the six SSRs to be powerful genetic resources in applied forestry research, both to distinguish S. alba clones from Salix spp. and to perform genetic population studies for breeding programs.
Estimating the carbon storage of forests is essential to support climate change mitigation and promote the transition into a low-carbon emission economy. To achieve this goal, voluntary carbon markets (VCMs) are essential. VCMs are promoted by a spontaneous demand, not imposed by binding targets, as the regulated ones. In Italy, only in Veneto and Piedmont Regions (Northern Italy), VCMs through forestry activities were carried out. Valle Camonica District (Northern Italy, Lombardy Region) is ready for a local VCM, but carbon storage of its forests was never estimated. The aim of this work was to estimate the total carbon storage (TCS; t C ha−1) of forest biomass of Valle Camonica District, at the stand level, taking into account: (1) aboveground biomass, (2) belowground biomass, (3) deadwood, and (4) litter. We developed a user-friendly model, based on site-specific primary (measured) data, and we applied it to a dataset of 2019 stands extracted from 45 Forest Management Plans. Preliminary results showed that, in 2016, the TCS achieved 76.02 t C ha−1. The aboveground biomass was the most relevant carbon pool (48.86 t C ha−1; 64.27% of TCS). From 2017 to 2029, through multifunctional forest management, the TCS could increase of 2.48 t C ha−1 (+ 3.26%). In the same period, assuming to convert coppices stands to high forests, an additional TCS of 0.78 t C ha−1 (equal to 2.85 t CO2 ha−1) in the aboveground biomass could be achieved without increasing forest areas. The additional carbon could be certified and exchanged on a VCM, contributing to climate change mitigation at a local level.
To elucidate the dynamics of aluminium (Al), an element potentially toxic and strongly affected by acidification processes, in soils, we selected two regions that were similar in relief, soil types, and vegetation cover but differed markedly in their history of acid precipitation: the Jizerské Mountains (anthropogenically acidified) and the Novohradské Mountains (naturally acidified) in the Czech Republic. The levels of Al forms (exchangeable and organically bound) associated with different environmental impacts were measured and univalent, divalent and trivalent Al species were quantified using HPLC/IC. Exchangeable and organically bound Al concentrations were higher in the anthropogenically acidified area. Only the concentrations of the least-dangerous species, the univalent, in organic soil horizons were similar for both mountains. The concentrations of exchangeable Al forms were correlated with Ca concentrations and with pH in the organic horizon. The known relationship of Al with soil pH was stronger in the mineral horizons. Relationships of exchangeable Al forms concentrations with sulphur concentrations or even more with the sulphur calcium molar ratio were found only in the Jizerské Mountains, not in the Novohradské. Generally, the obtained results support the hypothesis that mechanisms differed between natural and anthropogenic acidification.
This study evaluated boron diffusion from rods made of raw boron minerals, ulexite and colemanite with low water solubility, in comparison with di-sodium octaborate tetrahydrate (DOT). Scots pine (Pinus sylvestris L.) sapwood and heartwood blocks were conditioned to target moisture contents of 30%, 60%, and 90%. The rods were inserted into the blocks through treatment holes and boron diffusion was observed at three assay zones across the blocks after 7, 30, 60 and 90-day-incubation at room temperature. Ethylene glycol was also inserted into the holes to improve boron diffusion. Boron levels increased with increased wood moisture content. With some exceptions, boron in the assay zones did not tend to follow consistent amount gradients with distance from the treatment hole. Boron levels from ulexite rods were higher than those from colemanite rods, with DOT rods with the highest diffusion rates as a result of higher water solubility of DOT than ulexite and colemanite. The results suggest that ulexite-based rods may be useful in the presence of ethylene glycol in sapwood when wood is at high moisture content for extended periods.