Tree Diameter Research Articles

基于人机交互智能树干涂白装置的设计与实验研究

Tree whitewash has the functions of parasite prevention and cold protection and is therefore commonly used in the maintenance and management of trees. At present, tree whitewash mainly relies on manual operation, which has the problems of low efficiency, poor quality, and uneven distribution of the whitewash agent. To address this issue, this study developed a smart tree whitewash device based on human–computer interaction. The device was controlled mainly by a programmable logic controller (PLC). Once the trunk information collected by sensors was received by the PLC, it would control the up and down motions of the ball screw to manipulate the mechanical arm for whitewash. In addition, a Mitsubishi GT12 touch screen was adopted to facilitate system operation. Subsequently, a whitewash experiment was performed on poplar trunks with lengths of 10–35 cm using three different whitewash devices, i.e., a backpack sprayer, a semi-automatic tree sprayer, and the proposed smart tree whitewash device; the efficiency and the amount of whitewash agents used were compared. The results suggested that as the tree diameter at breast height increased, the amount of required whitewash agent elevated accordingly. In this case, the time required by the backpack sprayer and the semiautomatic tree sprayer to complete the job both increased, whereas that required by the smart tree whitewash device remained almost identical. In terms of work efficiency, the time required by the smart whitewash device to whitewash a tree was 109.89 s, which was approximately 1/2 of the time required by the backpack sprayer or 2/3 of that required by the semiautomatic tree spraying device. Meanwhile, the amount of whitewash agent required by the smart whitewash device to whitewash a tree was 140.23 g, which was approximately 0.46 of the amount required by the backpack sprayer or 0.74 of that required by the semiautomatic tree spraying device. Therefore, it was concluded that the proposed smart tree whitewash device could not only improve the work efficiency of tree whitewash but also greatly reduce the amount of whitewash agent required, thereby decreasing the cost and minimising environmental pollution. This study provides theoretical guidance and technical support for future research on smart tree whitewash devices.

Distribution and Carbon Sequestration Potential of Cola laurifolia Mast.: A Dominant Native Riparian Species along Permanent Rivers in Sub-Saharan Africa

The continuously increasing interest in carbon market call for adequate approaches to assess and monitor the growth and carbon of tree species. Species-specific models for estimating aboveground biomass (AGB) are the accurate means of quantifying species’ carbon pools. This study aimed at developing allometric equation for Cola laurifolia Mast., a dominant and multi-purpose riparian species along the Mouhoun River in Burkina Faso. The study first used a destructive sampling approach on thirty trees individuals of different diameter classes after collecting their dendrometric data. Explanatory parameters used to build the models were tree diameter at breast height (Dbh), basal diameter at 20 cm (D20), height (H), and mean crown diameter (MCd). Model development involved looking at different forms of models and different compartments of the tree (leaves, branches, stems and total above ground biomass). Subsequently, field inventory data were collected in protected and communal areas along three zones of the Mouhoun river (upstream, midstream and downstream) to assess and compare the carbon stock in the different areas and also characterize their population (assessment of regeneration status of the species). The results showed that the log-log linear model was the best-fitted form for the three tree compartments (i.e., leaf, branch, stem) and the total AGB, and incorporated Dbh and H as predictors. The total AGB model was more accurate with the highest goodness of fit (high R2) low residual standard error (RSE) (R²=0.92; RSE=0.28) as compared to the three component models. Nevertheless, all the allometric equations established for the prediction of leaves, stem, branches and total aboveground biomass were statically significant (p≤0.0001). The study also showed that the population structure of the species reflects a low regeneration potential along the studied river zones (i.e., upstream, intermediate and downstream zones), calling for initiatives to address the issue. The carbon stock was found to be 56.40 kg C tree-1 and 9.24 Mg C. ha-1. The density of C. laurifolia was higher in downstream zone, and consequently the carbon stock was higher in these areas. The study also compared the outputs from existing generalized allometric models to our newly developed specific-equation and found that they overestimate or underestimate the carbon stock of C. laurifolia. The results confirm the value of species-specific model which therefore calls for more effort to develop such models for all dominant species for greater accuracy in AGB estimations at scale.

Infinite WARM graphs III: strong reinforcement regime

We study a reinforcement process on graphs G of bounded degree. The model involves a parameter α > 0 governing the strength of reinforcement, and Poisson clock rates λ v at the vertices v of the graph. When the Poisson clock at a vertex v rings, one of the edges incident to it is reinforced, with edge e being chosen with probability proportional to its current count (counts start from 1) raised to the power α. The main problem in such models is to describe the (random) subgraph , consisting of edges that are reinforced infinitely often. In this paper, we focus on the finite connected components of in the strong reinforcement regime (α > 1) with clock rates that are uniformly bounded above. We show here that when α is sufficiently large, all connected components of are trees. When the firing rates λ v are constant, we show that all components are trees of diameter at most 3 when α is sufficiently large, and that there are infinitely many phase transitions as . For example, on the triangular lattice, increasingly large (odd) cycles appear as (while on the square lattice no finite component of contains a cycle for any α > 1). Increasingly long paths and other structures appear in both lattices when taking . In the special case where and α > 1, all connected components of are finite and we show that the possible cluster sizes are non-monotone in α. We also present several open problems.

Effectiveness of forest density reduction treatments for increasing drought resistance of ponderosa pine growth.

As the climate changes, it is increasingly important to understand how forests will respond to drought and how forest management can influence those outcomes. In many forests that have become unnaturally dense, "restoration treatments," which decrease stand density using fire and/or mechanical thinning, are generally associated with reduced mortality during drought. However, the effects of such treatments on tree growth during drought are less clear. Previous studies have yielded apparently contradictory results, which may stem from differences in underlying aridity or drought intensity across studies. To address this uncertainty, we studied the growth of ponderosa pine (Pinus ponderosa) in paired treated and untreated areas before and during the extreme California drought of 2012-2016. Our study spanned gradients in climate and tree size and found that density reduction treatments could completely ameliorate drought-driven declines in growth under some contexts, specifically in more mesic areas and in medium-sized trees (i.e., normal annual precipitation > ca. 1100 mm and tree diameter at breast height < ca. 65 cm). Treatments were much less effective in ameliorating drought-associated growth declines in the most water-limited sites and largest trees, consistent with underlying ecophysiology. In medium-sized trees and wetter sites, growth of trees in untreated stands decreased by more than 15% during drought, while treatment-associated increases in growth of 25% or more persisted during the drought. Trees that ultimately died due to drought showed greater growth reductions during drought relative to trees that survived. Our results suggest that density reduction treatments can increase tree resistance to water stress, and they highlight an important pathway for treatments to influence carbon sequestration and other ecosystem services beyond mitigating tree mortality.

A new approach to project stand tables

Recent research studies have shown that an integrated system can be constructed to provide future predictions when the inputs are from plot summary, a tree list, or a diameter distribution. The current study addresses the missing link, allowing this integrated system to also accept inputs from a stand table. In this study, different existing techniques were employed to process data in stand table format. Trees in each diameter class were modeled with a truncated Weibull distribution. A tree list was generated by dividing each diameter class into 0.2-cm sub-classes, the midpoint diameter of which represented diameter of an individual tree. Projecting the stand table was equivalent to growing trees in the tree list. Future tree survival and diameter growth were predicted by use of an individual-tree model, which was derived from a whole-stand model. This new method outperformed three existing stand table projection models, based on two error indices.

Increasing stand stature weakens the positive effects of tree richness and structural imbalance on aboveground biomass in temperate forests: The stand stature hypothesis

Irrespective of whether niche complementarity or selection effects enhance aboveground biomass (AGB) due to tree diversity in natural forests, these effects are confounding due to the roles of tree structural imbalance (i.e., either individual tree height or diameter inequality). Here, we hypothesize that increasing stand stature weakens the positive effects of tree richness and structural imbalance on AGB (i.e., we term ‘the stand stature hypothesis’). Using data from 365 plots of natural temperate forest of the Karakoram mountains in the Gilgit-Baltistan region of Pakistan, we tested several piecewise structural equation models (pSEMs) to disentangle the relative impacts of topographic elevation, stand density and tree richness or structural imbalance on AGB across short-statured (mean tree height < 15 m at stand level) and tall-statured (height ≥ 15 m) forests, and across species mixture (i.e., dominated by either single- or multi-species). We found that tree richness and structural imbalance had significant positive effects on AGB in short-statured (β = 0.30 to 0.33, P < 0.001) as compared to tall-statured (β = 0.02 to −0.06, P = 0.635 to 0.088) stands, irrespective of species mixture. In contrast, tree structural imbalance (β = -0.11 to −0.12, P = 0.015 to < 0.001) rather than tree richness (β = 0.01, P = 0.949) declined AGB in multi-species tall-statured stands but these effects were positive (β = 0.01 to 0.32, P = 0.866 to < 0.001) in single-species stands. Meanwhile, increasing topographic elevation declined AGB (β = -0.09 to −0.42, P = 0.151 to < 0.001). We show that increasing stand stature declines the positive effects of tree richness and structural imbalance on AGB, irrespective of the ubiquitous positive influence of stand density on AGB (i.e., the stand stature effect). Thus, we suggest that tall-statured and short-statured forests should be treated separately during the work plan of forest management and biodiversity conservation.

The Development of a Set of Novel Low Cost and Data Processing-Free Measuring Instruments for Tree Diameter at Breast Height and Tree Position

In current forestry investigation studies, the research hotspots have tended to concentrate on ascertaining the precision of certain tree parameters. This has resulted in an augmented intricacy of the technique in terms of algorithms and observation instruments. The complexity of the technology and the cost of the equipment make it impossible to use for large-scale forest surveys, for example, a national forest inventory (NFI). The aim of our study was to design a new type of low-cost measuring method that could be utilized in a NFI and in developing countries. Meanwhile, the newly designed method was expected to be able to output certain forest measurement factors without necessitating data processing by NFI field investigators. Based on these objectives, we developed a measuring method that included hardware comprised of two tools. The first tool was an electronic measuring tape that contained a microcontroller unit (MCU) and could automatically record and collaborate with other equipment via wireless protocols. The second tool was a tree stem position mapper that utilized our own designed mechanisms. The results showed that the tree DBH measurements exhibited a 0.05 cm (0.20%) bias and a 0.36 cm (1.45%) root mean square error (RMSE), and the biases on the x-axis and the y-axis of the tree position estimations were −15.92–9.92 cm and −25.90–10.88 cm, respectively, accompanied by corresponding RMSEs of 15.27–29.40 cm and 14.49–34.68 cm. Moreover, an efficiency test determined that the average measurement time per tree was 20.34 s, thus, demonstrating a marked improvement in speed by nearly one-fold compared to the conventional method. Meanwhile, this measurement kit costs less than 150 Euros and is economically suitable for large-scale applications. We posit that our method has the potential to serve as a standard tool in a Chinese NFI and in developing countries in the future.

Variability of activity concentrations and radial distributions of 137Cs and 90Sr in trunk wood of Scots pine and Silver birch

This study analyzes the variability of 137Cs and 90Sr concentrations in wood and their radial distributions in the trunks of Scots pine and Silver birch trees in the small uniformly contaminated forest stands in the Chornobyl Exclusion Zone. Concentrations of both radionuclides follow a lognormal distribution with a large scatter of values measured in the trees within the stands (GSD ranges from 1.6 to 2.0). No correlation was found between the concentrations of the two radionuclides measured in individual trees, or between their concentrations and tree diameter. The average 137Cs and 90Sr Tag were 8.4 × 10−4 m2 kg−1 and 8.8 × 10−3 m2 kg−1 for pine, respectively, and 9.3 × 10−4 m2 kg−1 and 1.1 × 10−2 m2 kg−1 for birch, indicating a much higher availability of 90Sr for uptake by the studied species. For 137Cs, the Tag values are within the range recommended by the IAEA Handbook (IAEA, 2010), while the values for 90Sr exceed the recommended range for birch and are close to its upper value for pine.The highest concentrations of 137Cs in pine at the height of 1.3 m were measured in the youngest sapwood rings; they were lower in the rest of the sapwood and decreased further in the heartwood, but remained relatively high even in annual rings that were the heartwood at the time of deposition, suggesting sapwood-to-heartwood translocation of the radionuclide by diffusion and/or ray transport. In contrast, 90Sr concentrations increased through the sapwood from the trunk periphery in pine trees up to 80 years old and remained stable through the sapwood in older trees (except for higher concentrations in the young annual rings), but dropped to zero in physiologically inactive heartwood tissues. In most birch trees, regardless of age, 137Cs concentrations demonstrated an increasing trend from the trunk periphery towards the pith, while concentrations of 90Sr were relatively stable in the whole trunk except in the oldest annual rings, where they increased sharply, likely indicating active transport of the radionuclide to senescing tissues.

Morphological characterization of papaya accessions in Jember through multivariate analysis

This study aimed to select the most informative morphological descriptors in characterizing and distinguishing papaya accessions in Jember. The multivariate analysis was used to i) determine the closeness between the papaya accessions collected based on morphology descriptors and ii) define a list of sufficient minimum descriptors to distinguish papaya accessions in Jember. Five quantitative and fifteen qualitative descriptors were used in evaluating 23 accessions. The data collected through quantitative descriptors were analyzed by the means of PCA­biplot analysis and qualitative descriptors were analyzed using entropy level. Statistical analysis was carried out by R studio software using two packages, i.e. biotools and factoextra packages. Based on the research results, the first two principal components of the PCA­biplot representation of 23 accessions were able to evaluate 67.18% of the total variability. The accessions located in KAL­SUK, GUM­PUR 1, and GUM­PUR 2 had similarities in tree diameter and width of mature leaf characters, while KAL­PLA, MUM­SUM 1, LED­SLA, MUM­LEN 1, SUM­RO 2, and SUM­JAM accessions shared similarities in the length of mature leaf, petiole, and peduncle. The minimum descriptors that could be used to characterize papaya plant accessions in Jember were two quantitative descriptors (tree diameter and length of mature leaf) and three qualitative descriptors (general shape of mature leaf teeth, height to first fruit, and stem color). The combination of quantitative­qualitative descriptors allowed the simple and rapid characterization of papaya accession. In addition, it could reduce costs and labor without losing information in the characterization of papaya plants.

Spatial variability of dendrometric parameters in a native tree Mabea fistulifera Mart. and its relationship with soil physical properties

Mabea fistulifera Mart. (common name: canudo-de-pito) belongs to the Euphorbiaceae family and is a native tree species in Brazil showing a high potential to recover degraded lands. This study aimed to evaluate the distribution and spatial correlation between the dendrometric parameters of the M. fistulifera plants and the physical attributes of the soil through geostatistics. The study was carried out at the Paulista State University (UNESP), in the city of Selvíria, MS, Brazil, in a typical dystrophic Red Oxisol with a clayey texture. The following properties were analyzed: for soil, penetration resistance, gravimetric moisture, particle density, and, for plants, circumference and diameter at breast height (measured at 130 cm above the ground), tree height, and total volume of the tree. An experiment grid was introduced with 35 sample points spaced 13 m x 13 m. Two soil samples were taken at each point, at 0.00 - 0.10 m and 0.10 - 0.20 m depth. Descriptive data analysis and spatial dependence analysis were carried out through semivariogram adjustments and kriging maps. The dendrometric properties of the species M. fistulifera and the soil gravimetric moisture content showed spatial dependence. The spherical semivariogram model best explained the spatial structure of circumference at breast height, diameter at breast height, tree volume, and soil gravimetric moisture. There was an emphasis on the correlation between the total volume of the tree as a function of the diameter at breast height, showing a moderate spatial dependence. Furthermore, the tree diameter at breast height proved to be a good indicator for determining the total height of the M. fistulifera tree.

Tree dieback, woody plant diversity, and ecosystem driven by topography in semi-arid mountain forests: Implication for ecosystem management

Mountain landscapes are highly heterogeneous due to topography, notably positions along slope and slope shapes, which control ecosystem mechanisms. We hypothesized that tree dieback is controlled by topography, selecting productive and less diverse communities in lower slopes, and stress-resistant and more diverse communities on upper slopes. Understanding how this heterogeneity drives vegetation patterns should provide benchmarks for ecosystem management of mountain forest dominated by Quercus brantii. Woody communities were sampled along convex vs concave topography (i.e., ridge vs talweg), and with measurements of tree dieback severity, environmental variables (litter depth, soil quality, rock outcrop), stand structure (canopy cover, mistletoe infestation, tree diameter and height, diameter and height differentiations, oaks' number from sprout-clumps or seed-origin), and biodiversity. Slope position was the most significant driver that affected all variables, excepted evenness. Dieback severity was higher on slope shoulders and summits, and lower in lower slopes where trees were the most productive: taller, larger, more homogeneous, and mostly seed-origin. Catena shape affected the diversity and dieback severity, both higher in talwegs, but had no effect on environmental variables and little on stand structure. Outputs indicate that the higher diversity of woody plants is on upper slopes supporting stress-resistant community associated with more severe dieback and mistletoe infection probably because frugivore birds attracted by the shrubs’ fruits. Semi-arid forest management must consider the shaped-slope ecosystem heterogeneity by preserving ridges that are more susceptible to tree dieback, and naturally support biodiversity. Restoration measures on lower fertile slopes could be carried out by oak planting or seedlings under the cover of shrubs to counter dieback effects and environmental stresses. In addition, forestry measures can be taken in lower positions for the conversion of coppice to high oak forest to potentially consider a moderate forestry.

Species Diversity, Structure, and Regeneration Status of Woody Plants in Saleda Yohans Church Forest, South Wollo, Ethiopia.

The study was conducted to determine woody plant species composition, structure, and regeneration status in Saleda Yohans Church forest, South Wollo Zone, Ethiopia. Five transect lines oriented to north-south directions at a distance of about 500 m were laid down along transects across the forest. Fifty main plots of 20 m × 20 m were laid for tree/shrub data collection. Within each main plot, 5 small quadrats of 5 m × 5 m were laid in the corners and centre for the collection of seedling and sapling data of woody species. All vegetation data within the plots were counted and recorded. Tree height and diameters at the breast height of plants were also measured and estimated. Moreover, frequency, basal area, diversity, evenness, and other vegetation data were analyzed. The result showed that this Church forest is composed of 50 woody plant species distributed in 31 families. The Shannon-Wiener diversity index and evenness values of the forest were found to be 3.82 and 0.84, respectively. Lamiaceae was the dominant family followed by Fabaceae in their species composition. The density of trees/shrubs, saplings, and seedlings was 625, 650, and 935 ha-1, respectively. Based on the result, the entire vegetation of Saleda Yohans Church forest is in good regeneration status. In conclusion, although this Church forest appears to be in a good regeneration status, its species richness is low compared to a similar study of some other vegetation. Therefore, attention should be given to the rehabilitation of this forest.

Effects of Successive Planting of Eucalyptus Plantations on Tree Growth and Soil Quality

The ultra-short-cycle successive planting of Eucalyptus plantations has caused environmental and social problems, and changing the rotation cycle is a very good option to solve this issue. However, the effects of successive planting on Eucalyptus growth and soil quality after changing the cultivation period are unclear. This study evaluated the effects of successive Eucalyptus planting on growth, soil nutrients, and bacterial and fungal community structure with an eight-year cultivation period. Eucalyptus plantations with different succession generations (first, second and third generation) were selected, and tree height and diameter at breast height were measured. Ten indicators of soil nutrients in different soil layers (0–20 cm and 20–40 cm) were measured, and soil bacteria and fungi were sequenced in high throughput. Results show that there is an upward trend in tree growth after three successive generations, reaching the highest timber yield in the third-generation plantation. Soil nutrients also showed changes, in the 0–20 cm soil layer, with decreased TN, NH4+-N, NO3−-N and AK and increased AP, particularly for OM and TP content. In the 20–40 cm soil layer, the content of NH4+-N and NO3−-N increased slightly and the soil’s OM, TP, and TK content increased significantly. The diversity of bacterial and fungal communities in different soil layers increased significantly, and the community structure composition changed. Bacterial and fungal community structures were mainly driven by pH, NH4+-N, TP and AP factors and by OM, NH4+-N, TP and TK factors, respectively. Thus, successive plantings of Eucalyptus plantations with a cultivation period of eight years is conducive to the growth of trees. Some nutrients of the soil were returned, and the soil microbial diversity increased. Successive planting has brought efficiency and economic benefits while maintaining the soil’s fertility.

Sustainable use of forests

Sustainable use of forests

Remote sensing in mapping biodiversity – A case study of epiphytic lichen communities

In boreal forests, European aspen (Populus tremula L.) is a keystone species that hosts a variety of accompanying species including epiphytic lichens. Forest management actions have led to a decrease in aspen abundance and subsequent loss of suitable habitats of epiphytic lichens. In this study, we evaluate the environmental responses of epiphytic lichen species richness and community composition on aspen, focusing on the potential of remote sensing by combined hyperspectral imaging and airborne laser scanning to identify suitable habitats for epiphytic lichens. We measured different substrate and habitat parameters in the field (e.g., aspen diameter and bark pH) and by remote sensing (e.g., mean canopy height and tree species composition of the surrounding forest) in the study area in Southern Finland that includes protected and non-protected forest. We used linear regression and the Hierarchical Model of Species Communities (HMSC) to compare how the different parameters explain and predict lichen species richness and community composition, respectively. We show that coarse predictions of epiphytic lichen community composition can be made using parameters extracted from remote sensing data. Estimated mean canopy height, tree density, dominant tree species and tree species diversity of the stand predicted the species community on aspens slightly better than field parameters. Remote sensing variables calculated over a larger area (30 m radius) always outperformed the same variables calculated over a smaller area (10 m radius) in predicting community composition, highlighting the cost-efficiency of remote sensing compared to covering a similar area with on-ground measurements. These results are encouraging for the prospects of using remote sensing data to direct field inventories and to map potential high-biodiversity habitats. Aspen bark pH was the only parameter affecting species richness regardless of whether the forest was protected or not, whereas, interestingly, the effects of tree diameter, height and furrow depth were only significant in protected areas. Our results also underline the importance of protected areas, since they hosted a higher tree-specific number of epiphytic lichen species, and red listed species, than non-protected areas.

Diameter Growth of Silver Fir (Abies alba Mill.), Scots Pine (Pinus sylvestris L.), and Black Pine (Pinus nigra Arnold) in Central European Forests: Findings from Slovenia

The main objectives of the study were to (1) determine the response of the diameter growth of silver fir, Scots pine, and black pine in Central European seminatural forests to tree, stand, and environmental factors and (2) test for differences in their growth rate on different soils. Based on 26,291 permanent sampling plots (500 m² each), we developed a linear mixed-effects model of the diameter increment for each of these tree species. The models explained 32%–47% of the total diameter increment variability. The models differ in the set of predictors. All models suggested a non-linear effect of tree diameter on diameter increment. Nine predictors were common to all three models (stand basal area, quadratic mean diameter, basal area of overtopping trees, the proportion of beech in the stand volume, inclination, elevation, mean annual temperature, mean diurnal range, and soil unit), and six predictors were specific for one or two models (tree diameter, logarithm of tree diameter, proportion of other broadleaves, site productivity, rockiness, eastness index). Tree diameter was the most important variable for fir growth, while climatic variables explained most of the variability in pine diameter growth. The soil unit contributed from 5.3% to 7.5% to the explained diameter increment variability. Although the developed models are only locally accurate and cannot be used outside the study area without validation, the model predictions can be compared to those in other stand growth simulators and other geographical regions.

Phenotyping of individual apple tree in modern orchard with novel smartphone-based heterogeneous binocular vision and YOLOv5s

Phenotyping plays a significant role in the breeding of apple tree. However, existing researches mainly relied on instruments, such as LiDAR, RGB-D camera or UAV (unmanned aerial vehicle) embedded with depth sensor, etc., which requires additional costs for users and also inconvenient. Therefore, a novel method of smartphone-based heterogeneous binocular vision was developed to fulfill low-cost automated phenotyping for apple tree. In this study, a pair of cameras on multi-camera smartphone was selected to obtain heterogeneous binocular camera. After that, a so-called virtual focal method was developed to generate standard binocular images from heterogeneous binocular images of smartphone. A well-known YOLOv5s object detection model was trained on a four-class dataset to detect fruits, grafts, trunks and whole trees. Then, the model was simplified to fit the deployment on smartphone. Finally, five phenotypes (trunk diameter, ground diameter, tree height, fruit vertical diameter, and fruit horizontal diameter) of individual apple tree were obtained by pinhole camera model and standard binocular vision. After evaluation of phenotyping manually and by smartphone, our method shows MAPE (mean average percentage error) ranging from 6.00 % to 13.73 % for the five phenotypes. Compared with the existing studies, our method has reached a close or even better phenotyping accuracy with only a smartphone. As more and more smartphones have multi-camera, our method is probably the lowest cost phenotyping method for most of the potential users. Results indicated that the approach could be utilized to phenotyping of apple tree.

Genetic markers and tree properties predicting wood biorefining potential in aspen (Populus tremula) bioenergy feedstock

BackgroundWood represents the majority of the biomass on land and constitutes a renewable source of biofuels and other bioproducts. However, wood is recalcitrant to bioconversion, raising a need for feedstock improvement in production of, for instance, biofuels. We investigated the properties of wood that affect bioconversion, as well as the underlying genetics, to help identify superior tree feedstocks for biorefining.ResultsWe recorded 65 wood-related and growth traits in a population of 113 natural aspen genotypes from Sweden (https://doi.org/10.5061/dryad.gtht76hrd). These traits included three growth and field performance traits, 20 traits for wood chemical composition, 17 traits for wood anatomy and structure, and 25 wood saccharification traits as indicators of bioconversion potential. Glucose release after saccharification with acidic pretreatment correlated positively with tree stem height and diameter and the carbohydrate content of the wood, and negatively with the content of lignin and the hemicellulose sugar units. Most of these traits displayed extensive natural variation within the aspen population and high broad-sense heritability, supporting their potential in genetic improvement of feedstocks towards improved bioconversion. Finally, a genome-wide association study (GWAS) revealed 13 genetic loci for saccharification yield (on a whole-tree-biomass basis), with six of them intersecting with associations for either height or stem diameter of the trees.ConclusionsThe simple growth traits of stem height and diameter were identified as good predictors of wood saccharification yield in aspen trees. GWAS elucidated the underlying genetics, revealing putative genetic markers for bioconversion of bioenergy tree feedstocks.

Tree Biomass and Leaf Area Allometric Relations for Betula pendula Roth Based on Samplings in the Western Carpathians.

Biomass allometric relations are necessary for precise estimations of biomass forest stocks, as well as for the quantification of carbon sequestered by forest cover. Therefore, we attempted to create allometric models of total biomass in young silver birch (Betula pendula Roth) trees and their main components, i.e., leaves, branches, stem under bark, bark, and roots. The models were based on data from 180 sample trees with ages up to 15 years originating from natural regeneration at eight sites in the Western Carpathians (Slovakia). Sample trees represented individuals with stem base diameters (diameter D0) from about 4.0 to 113.0 mm and tree heights between 0.4 to 10.7 m. Each tree component was dried to constant mass and weighed. Moreover, subsamples of leaves (15 pieces of each tree) were scanned, dried, and weighed. Thus, we also obtained data for deriving a model expressing total leaf area at the tree level. The allometric models were in the form of regression relations using diameter D0 or tree height as predictors. The models, for instance, showed that while the total tree biomass of birches with a D0 of 50 mm (and a tree height of 4.06 m) was about 1653 g, the total tree biomass of those with a D0 of 100 mm (tree height 6.79 m) reached as much as 8501 g. Modeled total leaf areas for the trees with the above-mentioned dimensions were 2.37 m2 and 8.54 m2, respectively. The results prove that diameter D0 was a better predictor than tree height for both models of tree component biomass and total leaf area. Furthermore, we found that the contribution of individual tree components to total biomass changed with tree size. Specifically, while shares of leaves and roots decreased, those of all other components, especially stems with bark, increased. The derived allometric relations may be implemented for the calculation of biomass stock in birch-dominant or birch-admixed stands in the Western Carpathians or in other European regions, especially where no species- and region-specific models are available.

Mangrove community structure on Kapo-Kapo Island, Mandeh Region, Pesisir Selatan Regency

This study aimed to analyze the structure of the mangrove community including the identification of species, density, frequency, dominance, important value index, and mangrove basal area on Kapo-Kapo Island, Mandeh Region, Pesisir Selatan Regency. Mangrove community structure data collection was carried out by direct observation, starting with data collection and identification of species, number of individuals and diameter of mangrove tree. In collecting data on the structure of the mangrove community, water quality measurements were also carried out pH, salinity, temperature and looking at the substrate of the mangrove. Based on the results of the study, identified species of mangrove in Kapo-Kapo Island, Mandeh Region, Pesisir Selatan Regency, namely R. apiculata, S. casseolaris, and L. littorea. The average values of KR, FR, DR and INP on tree-level mangroves at R. apiculata were 97.00%, 65.00%, 93.02%, and 255.03%. S. casseolaris 1.82%, 28.33%, 6.14%, and 36.29%. L. littorea 1.18%, 6.67%, 0.84%, and 8.68%. The species R. apiculata had the highest Important Value Index from the tree level of the most dominating species on each transect.Keywords: Kapo-Kapo Island; mangrove; structure of the mangrove community