Proportion Of Bark Research Articles

Influence of the Periodicity of Ground Fires in Middle-Аged Pine Forests on the Combustible Materials Stocks

Significant areas of forest are annually exposed to fires in the Krasnoyarsk Territory. Fires transform forest areas and change the stocks and structure of combustible materials. Information on the dynamics of forest fuel accumulation can serve as a basis for managing the pyrogenic resistance of forest areas. The purpose of the research is to assess the impact of early spring ground fires of different frequencies on the structure and stocks of combustible materials in forests. Experimental fires were carried out in middle-aged mixed-grass-green-moss pine forests in the forest-steppe zone of the Krasnoyarsk Territory. Experimental fires were simulated with different periodicities (annual, with an interval of 2–3 years and a singular one). Regardless of periodicity, the experimental fires led to an increase of combustible materials stocks in 2–3 years after fires. Repeated burnings reduced the stocks of combustible materials close to pre-fire values. The structure of combustible materials has changed, which has led to a decrease in potential flammability of pine forests. The proportion of needles and bark in litter has decreased, and the proportion of cones has increased. Fires led to a redistribution of deadwood classes towards larger diameters. During the research period (2014–2018), the largest reserve of forest fuel loads was noted on the plot with triennial fires (68.2 t ha–1).

Bark Thickness of Forest-forming Species: Modeling and Comparative Analysis

The need to assess the carbon-depositing capacity of a stand, an individual tree and its components is constantly emphasized in the world literature, since mitigation of the effects of climate change has become the highest priority. Since the carbon concentration differs in different tree species and in different components of the tree, including in the stem wood and bark, it is necessary to develop species-specific mathematical models for estimating the proportion of bark in trunks to improve the accuracy of knowledge about the carbon balance of forests. The relationship of bark thickness with both age and diameter of the tree trunk is known, but with respect to its regional variability, the data are contradictory. According to the actual data from 1100 model trees of five forest-forming species, allometric models of a mixed type have been developed. They include as independent variables the age and diameter of the trunk, as well as a binary variable characterising the influence of the growing area itself on the bark thickness of Scots pine, silver birch and Siberian larch, as well as the difference in the thickness of the bark between Siberian spruce and Siberian fir in case of joint growth in mature stands of the taiga zone. At a statistically significant level, it was found that the bark thickness of Scots pine and silver birch trees in the steppe zone is significantly greater compared to the taiga zone, and the bark thickness of Siberian larch trees in the forest-tundra is significantly greater compared to the steppe zone. The bark thickness of Siberian spruce trees is significantly less than that of Siberian fir trees. The ranking of species by bark thickness is included in the paper.

Towards sustainable and recyclable plastic materials: Vanilin-based epoxy bio-composites with spruce bark powder and hydrochar, pioneering green chemistry solutions for shape memory applications

The negative impacts of fossil-based plastic production and its excessive usage are significant and multifaceted, affecting both the planet and humanity in various ways. In this study, a novel approach to developing sustainable and recyclable materials sourced from lignocellulosic biomass is introduced. This methodology involves formulating an epoxy-based resin using diglycidyl ether of vanillin (DGEVA) for curing with dodecenylsuccinic anhydride (DDSA), in presence of significant proportions (5–20 wt%) of either spruce bark (SB) powder or its hydrochar (HTC). Through thermomechanical analyses conducted via Dynamic Mechanical Analysis (DMA), it was ascertained that while the inclusion of SB has minimal impact on material performance, the incorporation of HTC leads to significant improvements. Specifically, a substantial enhancement in storage modulus is observed, increasing from 1.5 GPa to 3.1 GPa, and a rise in the damping factor from 56°C to 61°C. These findings are further corroborated by Scanning Electron Microscopy (SEM) analysis, which demonstrates excellent compatibility between the bioresin matrix and the biofillers. Moreover, this investigation underscores the remarkable mechanical and chemical recycling capabilities of the systems, which are notably improved by the presence of spruce bark or HTC particles, in addition to their inherent shape-memory properties. This approach not only showcases the feasibility of sustainable material development but also highlights the potential for an effective waste utilization in enhancing material properties and reducing the environmental impact.

Nutrient extraction is related to stem diameter distribution, tissue concentration, and yield in an annually harvested Salix coppice

In plantations, nutrient extraction is likely to be higher with shorter rotations. This is because thinner stems have a higher proportion of nutrient-rich bark, and sapwood contains more nutrients than hardwood. Annual willow plantations may extract even more nutrients than long rotation forests. In short rotation forest systems, the diameter of the harvested stems may affect the amount of nutrients exported with the wood. The present study investigated the effect of stem diameter distribution on nutrient extraction and nutrient use efficiency (UE). Two Salix clones were planted at low or high densities, and irrigated or left rainfed. Stems were harvested annually, and three years after planting, N, P, K, and Ca concentrations in small, medium, and big stems were determined, as well as the proportion of each stem diameter class at harvest. N extraction was the highest, followed by Ca, K, and P extraction. Nutrient extraction and nitrogen use efficiency were influenced by the proportion of small, medium, and big stems. The clones showed differences in nutrient concentration and stem diameter distribution, and irrigation increased the proportion of large stems and nitrogen concentration. Although the NUE and PUE were not linearly related to yield, they were related to the distribution of stem diameter and nutrient concentration. Higher yield resulted in higher CaUE and KUE, but the extraction of these nutrients during harvest was fine-tuned by stem diameter distribution and tissue concentration. This highlights the significance of stem diameter distribution in assessing the nutrient costs of wood production for bioenergy.

Bark thickness and related parameters of tree species along an elevation transect leading to treeline in Central Himalaya.

Since treelines are generally fire-free, the trees growing there are expected to have thin bark, unless adaptation to other factors than fire results in the selection of a thick bark. Related to this is also higher proportional investment in inner bark in such an environment of infrequent fire. This study has considered stem bark thickness both in absolute and relative terms and also in the frame of the composition of outer and inner bark components of 20 tree species along an elevation transect (2100-3300m) in high ranges of the Central Himalaya leading to treelines. The study species varied from 2.1 to 16.2mm for total bark thickness and from 1.2 to 18.85% for relative bark thickness. The average absolute total bark thickness across the tree species decreased with elevation from forest to treeline, both when trees of all diameters (10.2 ± 0.84mm for forest and 6.9 ± 1.79mm for treeline) and those of the same stem diameter range (18-20m) were compared (9.10 ± 1.30mm for forest species and 6.38 ± 1.31mm for treeline species). Nevertheless, the treeline bark thickness was similar to those of several forest communities considered to have comparatively thick bark. Like many other biological structures, bark carries out multiple functions; therefore, its thickness could be affected by more than one environmental factor. We suggest that the requirement of mechanical resistance to the snowfall, rainstorms, wind and adaptation to a high sunlight and UV radiations or storage of water, and non-structural carbohydrates could affect total, outer and inner bark thickness. Studies on these aspects in similar ecosystems may help understand the multi-functional attributes of the bark. For trees of comparable sizes (trees with 18-20cm diameter at breast height) treeline species also had lower relative bark thickness (< 6%) than trees of forest below it (> 7%). The median proportion of inner bark of the total bark (70.5%) for our 20 species was more than that for savannas (~ 50%), exposed to frequent fire regime and similar to those of in cool sclerophyllous forests and temperate rain forests where fire return time is > 100years. However, it was lower than the inner bark proportion reported for tropical rain forests. To conclude, in spite of a fire-free environment, the Himalayan treeline and adjoining forest species show mixed bark characters.

Molded Plywood with Proportions of Beech Bark in Adhesive Mixtures: Production on an Industrial Scale.

Molded plywood is used for furniture components such as seats, backrests, or integral seat shells, and it must be durable and harmless to health. Molded plywood is made with urea-formaldehyde (UF) adhesives; therefore, the issue of the fillers used in them is important. The potential of using ground beech (Fagus sylvatica L.) bark as an eco-friendly additive in UF adhesives for molded plywood manufacturing was investigated in this work. Wheat flour was used as a reference filler. The beech bark (BB) level as a filler was 10%, a value verified under laboratory conditions. Nine-layer flat and molded plywood were produced under industrial conditions from beech veneers bonded with a UF adhesive mixture. The mechanical (bending strength and bonding quality) and physical (swelling and absorbency values after 2 and 24 h) properties of the industrially fabricated molded plywood were evaluated and compared with the European standard requirements (EN 310 and EN 314-2). The mechanical properties of the molded plywood with the addition of BB in the adhesive mixture were acceptable and met these standards' requirements. The positive effect of BB in the UF adhesive mixture on a reduction in formaldehyde emissions from the molded plywood was also confirmed. BB, considered to be wood-processing industry waste or a by-product, has significant potential to be used as a filler in UF resins for molded plywood production, providing an environmentally friendly, inexpensive solution for the industrial valorization of bark as a bio-based formaldehyde scavenger.

VARIABILITY OF ANATOMICAL AND MORPHOLOGICAL TRAITS OF PINUS NIGRA AND PINUS SYLVESTRIS SEEDLINGS AFFECTED BY DIFFERENT CONTAINER TYPE

In the paper was analysed the influence of three different container types, used for cultivation of Pinus nigra and Pinus sylvestris seedlings, on dimensions of their anatomical (resin ducts width, resin ducts number, tracheid number, tracheid width, wood rays height) and morphological (height, root collar diameter, sturdiness coefficient) elements, and on proportion of wood, bark and pith, as well. Two-factorial ANOVA showed that container type affects a lot all investigated anatomical traits by both species, but on the other side, these species varied between each other just in terms of tracheid width and wood rays height. Based on descriptive statistics, significantly lower values of all studied anatomical elements were recorded by biodegradable compared to plastic containers. As for P. nigra seedlings, they showed the best anatomical performance in Plantagrah I, while Hiko V-120 SS was the most suitable for P. sylvestris. The highest proportion of pith and bark was recorded in biodegradable container. As for morphological parameters, such as height and root collar diameter, higher values were recorded by plastic containers.

Effects of Environmental and Nutritional Conditions on Mycelium Growth of Three Basidiomycota

In recent decades, an enormous potential of fungal-based products with characteristics equal to, or even outperforming, classic petroleum-derived products has been acknowledged. The production of these new materials uses mycelium, a root-like structure of fungi consisting of a mass of branching, thread-like hyphae. Optimizing the production of mycelium-based materials and fungal growth under technical conditions needs to be further investigated. The main objective of this study was to select fast-growing fungi and identify optimized incubation conditions to obtain a dense mycelium mat in a short time. Further, the influence of the initial substrate characteristics on hyphae expansion was determined. Fungal isolates of Ganoderma lucidum, Pleurotus ostreatus, and Trametes versicolor were cultivated for seven days on substrate mixtures consisting of various proportions of pine bark and cotton fibers. Furthermore, the substrates were mixed with 0, 2, and 5 wt.% calcium carbonate (CaCO3), and the incubator was flushed with 0, 5, and 10 vol.% carbon dioxide (CO2). All samples grew in the dark at 26 °C and a relative humidity of 80%. Evaluation of growth rate shows that cotton fiber-rich substrates performed best for all investigated fungi. Although Pleurotus ostreatus and Trametes versicolor showed comparatively high growth rates of up to 5.4 and 5.3 mm d−1, respectively, mycelium density was thin and transparent. Ganoderma lucidum showed a significantly denser mycelium at a maximum growth rate of 3.3 mm d−1 on a cotton fiber-rich substrate (75 wt.%) without CaCO3 but flushed with 5 vol.% CO2 during incubation.

Variation and Driving Mechanisms of Bark Thickness in Larix gmelinii under Surface Fire Regimes

Bark is vital for woody plants, providing protection, transporting nutrients and water, and storing essential resources. For fire-prone ecosystems, bark thickness is a key adaptive trait conferring fire resistance. Few studies have been conducted on the drivers of variation in bark thickness of the widely distributed Larix gmelinii (Rupr.) Kuzen in the Great Xing’an Mountains region, on the southern edge of East Siberia, where surface fire disturbances are frequent. To elucidate the relationships between variation in bark thickness (inner vs. outer bark) of L. gmelinii and plant size, environmental factors, and co-variation with other fire-tolerance traits, we selected 26 sites to set up plots and carried out a survey and bark sampling. Results showed that stem diameter primarily determines variation in bark thickness, especially outer bark. The proportion of outer bark to total bark increased accordingly as the tree increased in size. We also observed stronger correlated variation in outer bark thickness, tree height, and self-pruning capacity, implying that larger trees have thicker protective outer bark and taller heights with greater self-pruning, mitigating crown fire risks. Environmental factors appear to have a relatively limited effect on changes in bark thickness in L. gmelinii. Mean air temperature, annual precipitation, and total soil nitrogen content had some effect on outer bark thickness, and mean air temperature had some effect on inner bark thickness.

The Effect of Age on the Evolution of the Stem Profile and Heartwood Proportion of Teak Clonal Trees in the Brazilian Amazon

Stem profile modeling is crucial in the forestry sector, particularly for commercially valuable species like teak (Tectona grandis Linn F.), whose value depends on its stem dimensions, heartwood proportion, and age. We proposed a nonlinear mixed-effect model to describe the evolution of the stem and heartwood profiles of clonal teak trees with ages between 4 and 12 years in the Brazilian Amazon. Tapering models were used to estimate the bark, bark-free, and heartwood diameters. Dummy variables were included in each tapering model to estimate each type of diameter and enable compatibility. We used mixed models with age as a random effect in order to improve the accuracy. The Demaerschalk model provided the most accurate and compatible estimates for all three types of stem diameter. Also, age as a random effect significantly improved the model’s accuracy by 7.2%. We observed a progressive increase in the heartwood proportion (14% to 34%) with advancing age, while the proportions of bark (23% to 20%) and sapwood (63% to 45%) showed inverse behavior. The growth rate of the heartwood differed from that of the bark volume, emphasizing the importance of considering the age of heartwood maximization when determining the cutting cycle of the species.

Effect of tip path overlap on ring debarker performance of frozen and unfrozen black spruce logs

ABSTRACT The effect of the tip path overlap on debarking quality of unfrozen and frozen black spruce logs was studied. The power, energy consumption, and torque were also measured for both temperature conditions. The experiment consisted of debarking logs using three overlaps (8, 27, and 43%) at two temperatures (−12°C and +20°C). Debarking quality was evaluated by the proportion of bark remaining on log surfaces and by the amount of wood in bark residues. Log characteristics (dimensions, eccentricity, and knot features), bark/wood shear strength (BWSS), moisture content, and basic densities of sapwood, inner, and outer barks were measured and treated as covariates. Experiments revealed that tip path overlap affects debarking quality for both temperature conditions: the amount of bark remaining on log surfaces decreased, and the proportion of wood in bark residues increased as tip path overlap increased. In addition, the effects of bark/wood shear strength, the proportion of knot area and sapwood, inner and outer barks densities, and moisture content on debarking quality criteria were analyzed. The mean power, energy consumption, and torque increased as the tip path overlap increased. These parameters were also positively affected by the log diameter and BWSS for frozen logs. The results give helpful information to improve debarking quality within the studied range of overlaps, log characteristics, and debarking parameters with efficient energy use.

Quality of the Pellets Obtained with Wood and Cutting Residues of Stone Pine (Pinus pinea L.)

The use of wood and residual biomass from forestry works is a CO2 emission-neutral source of energy that also contributes to reducing the risk of spreading forest fires, especially under Mediterranean climate. The forest stands of stone pine (Pinus pinea L.) occupies about 0.7 million hectares in the Mediterranean basin. In this study, the commercial quality of the pellets manufactured from different types of cutting residues (needles and thin branches, medium branches and bark), as well as wood from trunks and thick branches, was assessed. It was concluded that with the exclusive use of residual biomass it is not possible to obtain pellets of high commercial quality, useful for residential or industrial use. However, the highest quality pellets could be obtained by combining them with stone pine debarked wood, but in a certain proportion that differs depending on the type of residue (around 15% for bark, 30% for medium branches and less than 15% for needles and thin branches). It is recommended to take advantage of both the thick wood (trunk + thick branches) and a proportion of medium branches and bark, while in the case of needles and thinnest branches it would be more convenient to leave them in the forest for their incorporation into the soil, given their high nutrients concentration and their low quality for energetic use. The results found support a greater valorization of the biomass obtained in the stone pine fellings. In the future it will be necessary to study which is the most appropriate logistics of the silvicultural works to be able to conveniently apply the results of this study.

Allocation Patterns and Temporal Dynamics of Chinese Fir Biomass in Hunan Province, China

How trees allocate their biomass among different components has important implications for their survival and growth and ecosystem carbon cycling. Data on the distribution pattern and dynamics of tree biomass are essential for fully exploiting forest carbon sequestration potential and achieving the goal of carbon neutralization. However, there has not been enough research to-date on tree biomass spatial allocation and temporal dynamics in different site qualities at specific tree species scales. This study aimed to evaluate the biomass allocation patterns within tree components of Chinese fir and to examine how they are affected by tree age and site quality. A total of 87 trees were destructively sampled and measured for stem, branch, leaf, bark and root biomass. The biomass proportion difference of tree components in different age stages (8-40 years) was analysed, and the influence process of tree age and site quality on biomass allocation was examined. Our results indicate that the biomass allocation varied with tree age and was also affected by site quality. Stem biomass accounted for the largest proportion of total tree biomass, followed by leaf, root, branch and bark biomass in young forests, and it was followed by root, bark, branch and leaf biomass in other age groups. The biomass proportion of each component all nonlinearly changed with tree age. The proportion of stem biomass increased with increasing tree age, and the biomass proportion of branches and leaves decreased with increasing tree age. The proportion of root biomass first increased and then decreased with tree age, while the bark biomass proportion first decreased and then increased with increasing tree age. Site quality had a positive effect on the biomass proportion of stems but a negative effect on the biomass proportion of branches and bark. The interaction of tree age and site quality also had a significant effect on the proportion of stem biomass as well as root biomass. Therefore, to obtain accurate estimates of Chinese fir forest biomass and carbon stocks, age-specific changes and the influence of site conditions on it need to be considered.

Adhesives free bark panels: An alternative application for a waste material.

The proportion of bark in tree trunks is in the range of ~ 10-20%. This large amount of material is currently mainly considered as a by- or even waste-product by the timber processing industry. Recently, efforts towards the use of bark have been made, e.g. as a raw material to harvest different chemical compounds or as an additive for wood particle boards. Our motivation for this work was to keep the bark in an almost natural state and explore alternative processes and applications for use. The traditional method of de-barking tree trunks by peeling was used to harvest large bark pieces. Two pieces of peeled bark were placed crosswise, with the rhytidom side (outer bark) facing each other. After different conditioning steps, bark pieces were hot pressed to panels without adding adhesives. These experiments on bark samples of different Central European tree species suggest that production of panels with species dependent properties is possible and feasible. This is a step towards producing sustainable panels by using a natural waste material, while retaining its beneficial structure and its natural chemical composition.

Оценка загрязнения древесины и коры дуба 137Cs в зоне отчуждения Чернобыльской атомной электростанции

The results of studying the 137Cs contamination of English oak (Quercus robur L.) trunks in high-aged oak forests in the most radioactive polluted part of the Polesye State Radiation-Ecological Reserve territory located in the evacuation (exclusion) zone of the Chernobyl nuclear power plant are presented. The features of modern surface contamination soil by 137Cs in oak forest stands have been established, the factors that caused them have been identified: removal of research objects from the release site and conditions for deposition of radioactive fallout, as well as vertical redistribution of radionuclide in the soil over the time since the accident. The density of 137Cs soil contamination varies by types of oak forest. The current indicators of 137Cs accumulation in wood, bark and oak trunks, their changes by forest types, the relationship with the density of soil pollution and the distance to the disaster site are determined. A 2-3-fold excess of 137Cs oak bark contamination was found in comparison with wood, which is due to their morpho-physiological characteristics. Over the past 25 years, the wood and bark proportions of the relative contributions to the specific activity of 137Cs of the oak trunks have changed significantly. The decrease in the contribution of the bark to the specific activity of 137Cs in the trunk is due to a slowdown in the entry of radionuclide into it. The 137Cs distribution in oak wood by classes of growth and development of trees by Craft is shown. It was found that the average values of the radionuclide specific activity in standing and lying deadwood are 25-28 % lower than in the wood of living trees. The tendency of decreasing of 137Cs concentration in oak wood from the periphery to the center of the trunk has been confirmed. As of 2021, according to the sanitary standard of the Republic of Belarus for the content of 137Cs 1480 Bq kg-1, harvesting of oak wood could be allowed in 84 % of the surveyed stands, oak trunks with bark - in 72 %. The standard of 740 Bq kg-1 corresponded to oak wood in bark and without bark in 32 % of forest stands.

Модели для оценки биомассы и объема коры деревьев липы мелколистной (Tilia cordata Mill.)

The research is aimed at analyzing variability and developing mathematical models for estimating bark biomass and volume, volume of trunk with bark, and bark proportion of small-leaved linden (Tilia cordata Mill.) trees growing in natural coppice and artificial stands. The models are based on data from 107 and 95 destructively sampled trees in natural coppice and artificial stands, respectively. There were 10 sampling areas per stand type, representing different growth stages. The model trees were sawn into 2-meter sections, the volumes of which with and without bark were calculated using the Huber formula. The total volume of the tree trunk with and without bark is obtained by summing the volumes of all sections and the conical volume of the tree top. The bark volume was the difference between these two parameters. The bark biomass was determined by direct weighing, followed by conversion to absolutely dry mass. The correlations between the dendrometric parameters and the selected tree characteristics were estimated. The effectiveness of 3 regression models using the diameter at breast height (dbh = 1.3 m) and the tree height (h) as independent variables was studied in a comparative aspect. The bark biomass and volume, and the volume of trunk with bark are strongly influenced by these values. This correlation is very weak for the bark volume proportion in natural coppice stands, and insignificant in artificial stands. The bark volume proportion for each tree was calculated as the ratio of the difference between the volume of trunk with and without bark and the volume of trunk with bark. The equation that showed the best statistical characteristics in terms of consistency was chosen in order to predict the bark biomass and volume, the volume of trunks with bark of small-leaved linden trees. These models were estimated using the weighted least squares method taking into account the inherent errors and heteroscedasticity, by assigning each model its weight function separately for natural coppice and artificial stands that differ significantly from each other in morphometric features.

Effect of Tool Tip Radius on ring Debarker Performance

The effects of the tool tip radius on debarking quality of unfrozen and frozen black spruce logs were studied. The power, energy consumption and torque on frozen conditions were also studied. A proto-type one-arm ring debarker was used. The experiment consisted of debarking logs using three tool tip radii (40, 180, and 300 µm) for each temperature (-20°C and +20°C). The rotational and feed speeds, tip overlap, and rake angle were kept constants. Debarking quality was evaluated by two criteria: the proportion of bark remaining on log surfaces and the amount of wood in bark residues (WIB). Log characteristics, used as covariates, ie dimensions, eccentricity, bark thickness, knot features, bark/wood shear strength (BWSS), basic densities and moisture contents of sapwood and bark were measured, as well as total removed material after debarking. The results showed that tool tip radius had a significant effect on debarking quality of frozen and unfrozen logs. The proportion of bark on log surfaces increased and the amount of WIB decreased as tip radius increased. At the same applied radial force, a wider tip radius showed a shallower tip penetration leaving bigger regions of bark on the log surfaces. In contrast, a narrower tip radius showed a deeper tip penetration resulting in important wood fiber tear-out. The bark thickness and inner bark MC also affected debarking quality. The mean power, mean torque, and energy consumption increased as the tip radius decreased. However, this effect will depend on the choice of the applied radial force during debarking. Motor performance was also affected by the total removed material, log diameter, and BWSS. Overall, the results highlight the importance of choosing an adequate combination of tool tip radius and applied radial force to obtain the most profitable debarking quality with an efficient energy consumption.

The Mathematical Modeling of Mechanical Group Debarking in a Barking Drum

The process of wood debarking plays a crucial role in determining the price and quality of the final product. Hence, this work aims to elaborate on a theoretical basis for upgrading wood chips production technology. Consideration should be given to the influence of various debarking parameters when processing wood in barking drums. Such parameters as the number of wood collisions with each other and against a drum body, shear pressure, and others were chosen as equation coefficients to model the wood debarking time and knife sharpening angle. The treatment time is shown to depend on the number of collisions, the diameter of the log and indices that consider filling, the proportion of bark and the thickness, and wood hardness. It was established that the time required to debark the tree using knives is 1.5-3 times lower depending on the temperature of raw materials. Moreover, the process tends to be intensified with increasing knife sharpness.

Investigating the Use Profile of Kigelia africana (Lam.) Benth. through Market Survey in Benin

This research focuses on Kigelia africana in Benin where it is widely used in traditional medicine but receives little attention from researchers. In addition, this species has recently been recorded as threatened in the country. The aim was to gather ethnobotanical knowledge using a printed semi-structured questionnaire to collect data from herbal medicine traders, randomly selected, through a face-to-face discussion. The survey was carried out from January to March 2020. Among 36 questioned herbal traders, 36% of respondents obtained parts of K. africana by purchase in their own markets and by travelling far (3–10 km covered). The same proportion travel very far before buying parts (more than 10 km covered). None mentioned harvesting parts from wild populations. A high proportion of informants (63%) sold fruits and stem bark whereas a relatively low proportion of them (37%) sold fruits, stem bark, and leaves. The stem bark was recorded as most in demand followed by fruits. Respondents mostly confirmed the species scarcity. This species was used to treat 13 diseases and disorders. The stem bark was the most cited in the management of stomach infections and gynecological disorders. Fruits were mainly used in magic rituals and the treatment of stomach infections. Five preparations were recorded whither 54% of traders mentioned bark decoctions and 27% highlighted infusion of fruits in water. Overall, Kigelia africana is an important plant in Beninese ethnomedicine and the harvest and trade of its different parts represent major threats. Therefore, urgent conservation tools and actions are needed.

Reducing peat in substrate mixture formulations for press pots using the Taguchi method

The need to substitute peat in growing media has become an urgent issue. Approximately one-third of European horticultural peat consumption occurs in vegetable production, where seedlings are cultivated in press pots. More research is needed to detect suitable, high-quality peat substitutes that provide the needed nutrient content, malleability and form stability. Mixtures of several raw materials can balance and mitigate negative effects in peat-reduced substrates; however, optimizing those mixtures may require considerable analytical effort. The Taguchi experimental design allows for a reduction of experimental trials as well as a minimization of variance. It therefore can be considered a time- and cost-saving alternative to classic experimental designs for identifying optimal mixtures. For this study, nine peat-reduced substrates (orthogonal array: L9, 34) were created, with different proportions of green compost, bark compost, sawdust and rice husks constituting 50% of these mixtures. Several biochemical, physico-chemical and physical properties were tested to assess the substrate qualities. Green compost affected the salt content, stability and bulk density of the substrates, whereas bark compost influenced nitrogen dynamics and substrate pH-values. With respect to their smaller overall proportions (0–20%), the added fibrous materials positively influenced the density and stability of the press pots. Even though N was immobilized in the peat-reduced substrates, low salinity and pH-values as well as improved stability make them promising for the creation of high-quality press pot substrate mixtures containing less than 50% peat. The “robust” Taguchi design might be a useful tool to evaluate the effects of different mixtures of up to four components with a low sample size effort.