Average DBH Research Articles

Škody ohryzem a loupáním ve smrkových porostech: potvrzení posunu do mladších porostů

The increase in wild ungulate population density harms the dynamics of forest ecosystems. Therefore, this study aimed to evaluate the initial degree of damage, as a key factor in the secondary spread of fungal pathogens, and other parameters as a result of bark stripping caused by red deer (Cervus elaphus L.). The research focused on young Norway spruce (Picea abies [L.] Karst.) stands (7–26 years) in a total of 20 permanent research plots at four locations in the Klášterec nad Ohří and Rumburk Forest Service, each with an area of 100 m2 (10 m × 10 m). From the assessment of 783 spruce individuals, it follows that damage by bark stripping in particular stands amounted to 23.4–58.3%. Average circumferential damage ranged between 20.2–32.1% with a trunk wound length of 38.5–77.0 cm. Overall, a significant (p < 0.05) difference in dendrometric parameters (DBH and tree height) was found between undamaged “healthy” trees, and individuals with new and old damage in terms of attractiveness to game. The average DBH of undamaged trees varies between 2.0 and 3.7 cm, which is the size that wildlife prefers for initial damage. The lowest dimension of newly damaged trees starts from a DBH of 1.5 cm, and trees with a DBH > approx. 9 cm were no longer searched for wildlife. Effective hunting management and regulation of the abundance of ungulates to ecologically acceptable levels are the key to the protection of forest stands.

Spatial Distribution Pattern of Response of Quercus Variabilis Plantation to Forest Restoration Thinning in a Semi-Arid Area in China

Plantations are increasing in frequency and extent across the landscape, especially in China, and forest thinning can accelerate the development of late-successional attributes, thereby enhancing plantation stand structural heterogeneity. To quantify the effect of forest restoration thinning on the spatial heterogeneity and the structure of Quercus variabilis plantations, a restoration thinning experiment in a 40-year-old Quercus variabilis plantation by removing trees from the upper canopy level was conducted; two one-hectare sample plots with thinning and a control (i.e., unlogged) were sampled; and geostatistics methods were used to analyze the spatial distribution pattern of the DBH, height, and density of the stand. We found that restoration forest thinning in the Quercus variabilis plantation had a significant impact on the average DBH and tree height of the stand. Meanwhile, the coefficient of variation and structure ratio of the DBH, tree height, and stand density in the thinning plot were larger than those in the control plot. The range and spatial autocorrelation distance of the DBH and stand density in the thinning plot were smaller than those in the control plot, but the fractal dimension showed the opposite trend. The range and spatial autocorrelation distance of tree height in the thinning plot were higher than those in the control plot. These findings suggested that, compared with the control plot, the stereoscopic distribution of the DBH and stand density in the thinning plot fluctuated less and changed gentler, and its spatial continuity was not high but its variation was significant; meanwhile, the stereoscopic distribution of the tree height in the thinning plot was highly fluctuating and changed more significantly, with a strong spatial dependence and strip gradient distribution. Hence, forest restoration thinning could improve the distribution of the DBH and stand density and adjust the spatial heterogeneity of the DBH, tree height, and stand density of Quercus variabilis plantations.

Socioeconomic Disparities in Urban Forest Diversity and Structure in Green Areas of Santiago de Chile.

Urban trees enhance biodiversity, provide ecosystem services, and improve quality of life in cities. Despite their benefits, trees are not distributed equitably, and many cities exhibit a "luxury effect". Given the importance of public green space for providing access to urban tree benefits, we investigated the relationship between socioeconomic level and tree diversity and structure in 60 green areas in Santiago de Chile. Species richness and total tree abundance did not significantly vary among socioeconomic levels; however, a differential effect was found according to species origin. Introduced tree species exhibited similar abundance and species richness across socioeconomic levels, but native tree species were more abundant and richer in higher socioeconomic level areas compared to lower ones. Tree cover was higher in the high and medium socioeconomic level areas than in the low socioeconomic level area. A higher average DBH was found in the medium socioeconomic level area, which may be explained by older neighborhoods and a legacy of the luxury effect. Our findings reveal that socioeconomic groups are associated with differences in tree cover, width, and the number of native species in public green areas. Consequently, urban residents have different provisions of ecosystem services and opportunities to interact with natural heritage. Increasing the amount of tree cover and native species available to vulnerable groups will reduce disparities.

Carbon Storage and Sequestration by Trees in some Urban Public Parks of Jalalabad Afghanistan

‌Urban areas, characterized by rapid development and increasing carbon emissions, have become focal points for climate change mitigation strategies. This research investigates the role of urban trees as crucial components in carbon storage and sequestration, exploring their potential impact on mitigating climate change. The objectives include assessing the efficacy of urban trees in sequestering atmospheric carbon, examining variations in carbon storage across different urban settings, and elucidating the factors influencing the sequestration potential of various tree species. Additionally, the research investigates the indirect impacts of urban tree cover on local climate dynamics, including temperature regulation, air quality improvement, and overall environmental resilience. The anticipated outcomes encompass comprehensive data on the carbon storage and sequestration potential of urban trees, providing insights into the variation of these capacities within different urban contexts. By understanding the relationships between urban trees, carbon sequestration, and climate change, the research aims to inform urban planning, policy formulation, and sustainable development practices. The carbon sequestration of 512 trees belonging to 45 species was estimated. The average carbon content of these trees was 50.391t/tree. The total carbon sequestered by these trees was 120.757t/year. Highest (23709 kg/year) sequestration was observed in Ficus relegiosa and the lowest (50.59 kg/year) in Morus alba. Ficus relegiosa showed the highest average DBH and more carbon sequestration potential, whereas Morus alba showed the minimum carbon sequestration potential. The regression analyses indicated that both DBH and number of trees have a positive relation with carbon sequestration rate of tree species.

Fungal Presence and Changes of Wood Structure in Bark Stripping Wounds Made by Red Deer (Cervus elaphus L.) on Stems of Fraxinus angustifolia (Vahl)

Narrow-leaved ash (Fraxinus angustifolia Vahl), a highly valued European forest tree species, has been severely affected by a large-scale decline, which is most probably driven by a complex of multiple interacting factors including fungi, which contribute to and accelerate this process. Red deer (Cervus elaphus L.) can be considered as one of the contributing factors, as they inflict damage on the stems of young trees by stripping the bark. These wounds not only represent suitable entry points for fungi which can cause tissue necroses and decomposition, they can lead to changes in the wood structure as well. The aims of this research were to analyze chosen parameters of bark stripping wounds in narrow-leaved ash stands, identify fungi present in the tissue exposed by wounding, and inspect the effect of wounding on the wood structure. Bark stripping was observed on ash trees from 2 cm up to 18 cm of DBH and between 0.1 m and 1.9 m of stem height. The most susceptible trees were those with an average DBH of 5 ± 2.5 cm. On most of the ash trees (51%), one-third to two-thirds of the circumference was damaged. In wounded tissue, 174 fungal isolates were found, most of which belonged to known endophytic fungi from the genera Trichoderma, Fusarium, and Clonostachys. It was observed that earlywood cells in the wounding zone had narrower lumens compared to ones in adjacent healthy zone with regard to different trees and stem heights.

A planting optimization strategy to improve the carbon sink benefit for urban green-Taking the communal green of Nanjing Forestry University as an example

This research study identified the communal green at Nanjing Forestry University as an example and focused on the carbon sink benefits of the plant communities. Firstly, the representative plant communities in the communal green were investigated, and the parameters of the plant communities were established so that the carbon sink benefits of each plant community could be quantified. Secondly, by applying correlation analysis to study the influence degree of varied plant community factors on the benefits of carbon sink, it was found that the canopy closure, diameter class structure and tree density showed significant positive correlation; the correlation between community density and daily carbon sequestration per unit area was significant; the correlation between community density and carbon storage per unit area showed none significance; and the correlation between the proportion of trees and shrubs and the carbon sink benefits was of no significance. Thirdly, regression analysis was used to study the curve trends of the carbon sink benefits of the plant communities, from which it was concluded that increasing canopy density, average plant height, average crown width and tree density will improve carbon sink benefits. Increasing the average DBH would achieve positive effects for increasing daily carbon sequestration per unit area only at the early stage of the community growth. The plant community density showed positive effects on the increase of the daily carbon sequestration per unit area within a limited range. Since most regression formulas resulted in S-curves, certain threshold bottlenecks were found existed of improving the carbon sinks benefits by increasing the plant community factors. Finally, the characteristics of plant communities with high carbon sink benefit were summarized to provide theoretical references for forming a planting optimization strategy of urban green.

Community structure and species composition of typical Quercus variabilis natural secondary forest at the northern foothills of the Qinling Mountains, China

We investigated species composition and community structure of a typical Quercus variabilis natural secondary forest in the northern foothills of the Qinling Mountains, within the dynamic monitoring plot of deciduous broad-leaved forest at the Louguantai experimental forest farm in Zhouzhi County, Shaanxi Province. The results showed that there were 3162 individual woody plants with diameter at breast height ≥1 cm in the plot, which were belonged to 42 species, 36 genera, and 25 families. The community genus's areal type was dominated by the temperate component, which accounted for 44.4%, and followed by the tropical component. The community was dominated by several tree species. The top three species with respect to importance value were Q. variabilis, Pinus tabuliformis, and Quercus aliena, with the sum of their importance value being 64.7%. The average DBH of all woody plants was 7.58 cm. The distribution of all individuals and dominant species in the tree layer was approximately normal, with more medium-size individuals. The community structure was stable. The community was poorly renewed, with a trend of population decline. Biodiversity indices varied considerably among different plots, being lower than those of subtropical broad-leaved evergreen forests. There was a significant correlation between community species distribution and environmental factors. Soil and topography explained 42.4% of the variation in community distribution. Altitude and soil alkali hydrolysable nitrogen had a significant effect on community distribution. Altitude, soil total phosphorus, and organic matter content significantly affected the species diversity of Q. variabilis communities. The stronger adaptability of Q. variabilis populations allowed them to become dominant in low-nutrient environments, which limited species diversity in the community.

Effects of Boom-Corridor and Selective Thinnings on Harvester Productivity in Dense Small Diameter Pyrenean Oak (Quercus pyrenaica Willd.) Coppices in Spain

Due to socioeconomic transformations in the 20th century, Quercus pyrenaica Willd. coppices in Spain, as well as other European coppices, have experimented an abandonment and lack of intervention leading to stagnant high density stands with fragile health due to competition. Thinnings are often required to ensure their stability and health, producing forest products such as firewood or biomass, which are key energy sources in a carbon-neutral economy. However, thinnings are seldom performed because they lack economic sustainability due to a low productivity, high costs and low biomass prices. In this study, two thinning methods, selective thinning (ST) and boom-corridor thinning (BCT), were tested carrying out a time study in a high-density small-diameter Q. pyrenaica stand in the León province (Castilla y León, Spain) with a forest harvester base machine, on which an accumulating felling head Bracke C16c was mounted. The residual stands were significantly different regarding the final density (greater in BCT) and the final average DBH (bigger in ST), while thinning intensity (odt·ha-1) was the same. In most work elements, time per tree was not significantly different. BCT showed a significant 48.6% increase in harvester productivity when compared to ST, with averaging 4.43 and 2.99 odt·pmh-1, respectively, due mainly to the average weight per extracted tree, 42% greater in BCT. When considering the common range of unit tree weight, the productivity was 16–23% greater for BCT, far less than observed in the trials. These results show the potential of BCT over ST in the studied conditions, although there is room for improvement. Further studies could include the future evolution of the treated stands and perform a cost analysis.

Morphometric analysis of tree species from the central region of Imperatriz-MA municipality

Urban forestry is essential in urban environments and if poorly planned, ends up affecting its efficiency and the society quality of life, generating conflicts with urban infrastructure. Morphometry allows the growth dynamics of the tree component to be known, predicting the space needed for its development and stability, silvicultural actions and appropriate management in urban environments. In this sense, the objective was to analyze the most common tree species in the central region of the Imperatriz-MA municipality, in terms of their composition and morphometric parameters. Thus, through a census in 228 blocks, all individuals had their dendrometric parameters measured and 2,321 trees, distributed in 69 species and 26 families were counted. Of the total number of individuals, 66% were exotic species and 34% native, with M. tomentosa being the most representative. As for the morphometric parameters, the average total height of the most representative species was 6.2 m, the height of the first bifurcation was 1.2 m, the crown height was 2.1 m, and the average DBH was 0.25 m. The average diameter and the average crown area obtained were 5.37 m and 26.83 m², respectively. As a result, it can be concluded that the Imperatriz forestry can be considered young with recent plantings and also with inadequately managed plants in the adult stage. Azadirachta indica should be progressively replaced by regional native species, with the young tree component managed to provide maximum canopy area and tall forked trunks that occupy less space on the pavement, regardless of their size.

The Identification of the Abundance of European Larch Trees in Polish Forests

The purpose of the study was to identify the abundance of European larch trees in Polish forests, taking into account the size of areas and their location. A dendrometric analysis (volume, age of trees) was performed as a source of knowledge on the availability of the raw material base as a response to the production needs of wood products in Poland. The detailed data were made available in 2023 by the Directorate General of State Forests on the basis of a license specifying the conditions of use of the vector record of the forest numerical map and appraisal description data. European larch trees are in areas all around Poland. They grow throughout the country, with most stands located in the southern and northern parts of Poland. Stands with a dominant share of larch in the species composition (i.e., those that are part of trees stands with a minimum area of 0.1 ha) occupy 44,813 ha and occur in 17,553 stand divisions. The analysis of productivity showed that the average height of larch stands in Poland ranges from 5 m to 45 m. Tree stands are predominately 26–30 m in height. Most stands with trees over 30 m high are located in the RDFS Krosno (over 15% of the entire forest area with larch as the dominant species). European larch stands in Poland are characterized by significant differences in the average DBH. They are correlated with the age of the stands.

Developing Growth and Harvest Prediction Models for Mixed Coniferous and Broad-Leaved Forests at Different Ages

In order to clarify the combined impact of tree species composition, site quality, and stand age on the growth and harvest of mixed forests, the prediction models of average DBH and stand volume for mixed forests were established, respectively. The interval period and tree species composition coefficient (TSCC) were considered as independent variables. These models were then optimized by using the particle swarm optimization algorithm for reparameterization and evaluating their applicability. It was found that after introducing the site quality grade and TSCC, the average stand height prediction model showed a better fitting result. The fit accuracy of the average DBH prediction model and the stand volume prediction model were both improved with the help of the TSCC, mainly because the tree species composition affects the growth rate of the average stand height and average DBH and the maximum growth rate of the stand volume. The degree of the impact can be sorted as Cunninghamia lanceolata > Pinus massoniana > hard broad-leaved tree species (group). Overall, the established growth and harvest prediction models for mixed forests with the interval period and TSCC as independent variables have high fit accuracy and applicability.

Initial growth of four endemic species in degraded peatland revegetation in Ogan Komering Ilir, South Sumatra

Peatland plays an important role as the storage of carbon stocks both in the soil layer and biomass. The value of carbon stocks in peatlands is strongly influenced by the peatland’s quality and potential to produce carbon emissions if the natural conditions are disturbed. Revegetation can improve the quality and land cover compared to natural succession. The success of revegetation can be seen from the survival rate and growth performance of planted species. The purpose of this preliminary study was to see the survival rate and growth of four species of revegetation plants in the burnt peatland area located in Pedamaran, Ogan Komering Ilir, South Sumatra in 2017 and 2021. This study was carried out using quantitative descriptive methods. Results show that the growth performance of four endemic revegetation species was different, reflected by the diameter of breast height (dbh), height, and survival rate. Based on data, pulai (Alstonia pneumatophore) show the best growth performance compared to tembesu (Fragraea fragrans), jelutung (Dyera polyphylla), and balangeran (Shorea balangeran). Pulai showed the highest survival rate (98.61%), with an average dbh growth of 8.31 mm and 75.60 cm in height. Furthermore, all data obtained in this study can be used as basic data for revegetation development to increase growth and survival rate, enhance carbon stocks, and other efforts in climate change mitigation and adaptation.

Stand, plot characteristics, and tree species diversity jointly dominate the recruitment biomass of subtropical forests

Forest dynamics is largely affected by the recruitment of trees. Despite several investigations on forest recruitment biomass (FRB), it is still not well explored how tree species diversity, stand characteristics, climate, and topography regulate FRB. Moreover, there have been limited studies and discussions on FRB in typical subtropical forests in karst areas. We examined the relationship between influencing factors and forest biomass from the perspective of tree recruitment using data from 2334 Chinese National Forest Inventory (CNFI) plots in Guizhou Province. The best predictors within each group were chosen using a stepwise regression model, and the effects of five categories, including tree species diversity, stand factors (e.g., stand density), climatic factors (e.g., mean annual temperature and annual precipitation), topographic factors (e.g., elevation and slope), and plot factors (e.g., canopy density and forest composition) on FRB were determined using structural equation models (SEM). Besides this, the relative importance of each variable among five categories in determining FRB was also quantified by hierarchical partitioning analysis (HPA). Our results indicated that diversity of tree species had the highest relative importance in determining FRB (28.85 %), followed by average DBH (21.06 %), canopy density (10.29 %) based on HPA. While for five categories, stand factors contributed the most to FRB (37.04 %), followed by plot factors (29.01 %), tree species diversity (28.85 %), climatic factors (3.81 %), and topographic factors (1.29 %). Moreover, SEM showed FRB was strongly directly and significantly controlled by tree species diversity (β = 0.63, P < 0.05), while stand factors had a strong direct effect (β = 0.45, P < 0.05) and indirect effect (β = -0.78, P < 0.05). We conclude that niche complementarity is the primary mechanism driving this forest's FRB. Our findings highlight the significance of tree recruitment in maintaining subtropical forests' carbon storage capacity. Furthermore, increasing tree species diversity, particularly by combining conifers and broad-leaved trees, will encourage the recruitment of young trees.

Modeling Productivity and Estimating Costs of Processor Tower Yarder in Shelterwood Cutting of Pine Stand

Cable-based yarding technology has had a long tradition on steep slopes in Europe, and the new implementation of yarding functions in recent decades favored operational efficiency and lower extraction costs. The main goal of this study was to evaluate the performance of the Syncrofalke 3t truck-mounted Processor Tower Yarder (PTY) on steep terrain, in coniferous forests managed with the shelterwood system. In particular, the aim was to determine PTY productivity and costs, with attention to parameters that could increase PTY effectiveness. The study was carried out in the Sredna Gora Mountains, Central Bulgaria, in pure Scots pine stand, with trees of average DBH = 34 cm and height = 22 m. The study was carried out in six corridors with 120 work cycles of tree extraction up the hill, 28° (53%). The mean productivity of PTY was 15.20 m3 per productive machine hour (PMH) and 12.29 m3 per scheduled machine hour (SMH) and was mainly influenced by the productivity of the yarder unit. Under the given conditions, the performance of PTY significantly increased if more than one tree (at least two trees) were attached and extracted per yarder cycle, since the productivity of the processor was approximately twice that of the yarder. The gross costs of the studied PTY were calculated at 297.48 EUR PMH−1 and 16.17 EUR m−3. The variable costs (75%) predominate in the net costs distribution, followed by the fixed costs (15%) and the labor costs (10%). The time, productivity and cost results obtained showed the high efficiency and level of integration of PTY operations in order to achieve economic efficiency of logging in montane pine forest managed in a shelterwood system.

Structure, diversity and spatial distribution pattern of significant tree species in Hefei city

&lt;p&gt;In order to further tap the ecological potential of urban trees, improve the diversity of tree species in urban environment, and promote the sustainable development of urban trees, this paper further analyzes the structure, diversity and spatial distribution law of the prominent tree species in Hefei city on the basis of on–the–spot identification of the prominent trees distributed in the main city. The results show that: 1) 528 significant trees are identified in the three districts, belonging to 40 species, 36 genera and 27 families, with 23 trees evaluated by qualitative index and 505 trees by quantitative index. In quantity distribution, the number of significant trees in the three districts is ranked as Yaohai District&amp;gt; firstringroad City&amp;gt; Government Affairs District. The top four tree species in relative abundance are Platanus acerifolia, Cinnamomum camphora, Ginkgo biloba and Cedar. 2) In terms of the tree age structure, most trees are 20~40 years old, and only 22 trees are over 100 years old; the ratio of evergreen to deciduous tree species is 1: 3, and the ratio of plant to tree is about 7: 18; there are 23 native tree species accounting for 57.50%, but only 171 trees. 3) In terms of area distribution, the average tree height and crown area in Yaohai District are the largest, the average DBH, Shannon–Wiener index and Simpson index in the first–ring city area are the highest, and the species evenness index in Government District is the highest. 4) In terms of site types, most significant trees are distributed in urban streets, residential areas and parks, and only 11.74% of them are distributed in government organizations, schools, public facilities, scenic spots and religious land.&lt;/p&gt;

Genetic analysis distinguished new natural population and old plantations of Cryptomeria japonica

Natural forest is important not only for conserving genetic diversity, but also as a future breeding resource, especially for forestry tree species. Cryptomeria japonica is an important forestry tree species in Japan, but natural populations are limited. We discovered apparently natural C. japonica individuals on Mt Aoba, adjacent to Wakasa Bay in Fukui Prefecture, Japan. The area around Wakasa Bay was an important refugia for this species during the Last Glacial Maximum. To clarify whether these individuals are natural origin or not, we sampled 195 individuals with a diameter at breast height (dbh) greater than 60 cm (with an average dbh of 79 cm), and conducted genetic analyses with 249 SNP and 20 SSR markers. We found two genetic clusters identified as ura-sugi and omote-sugi lineages and the genetic diversity of the sample was similar to known natural populations. The ura-sugi lineage showed a clear correlation between age and dbh, whereas the omote-sugi lineage showed no correlation. The ura-sugi lineage was also genetically very similar to nearby natural populations. Most of the omote-sugi lineage trees were about 100 years old regardless of dbh, and located in one small valley close to a village. The results suggest that the ura-sugi lineage (124 individuals) represents a population of natural origin, whereas the omote-sugi lineage (60 individuals) population was probably planted about 100 years ago using trees of non-local origin. Seven individuals appeared to be hybrids, displaying both ura-sugi and omote-sugi lineages. In situ conservation of the ura-sugi individuals should be a priority, after removing the omote-sugi lineage, in order to conserve the natural genetic resources they represent. Ex-situ conservation strategies should also be implemented to protect the endemic gene pool from gene flow from the many C. japonica plantations in the surrounding area.

High carbon storage and oxygen (O2) release potential of Mahagony (Swietenia macrophylla) woodlot plantation in Bangladesh

Woodlot plantation takes our attention nowadays because of having high wood value, biomass and carbon stock. It also has considerable potential for regulating climate change by sinking CO2. This study investigated the market value of Swietenia macrophyllawoodlots concerning the current carbon trade mechanism, local timber and oxygen value.The carbon-di-oxide equivalence (CO2e) and release oxygen (O2 Release) ranged from 125.5 to 1004.5 Mg/ha (mean 436.3 Mg/ha) and 91.25–730.26 Mg/ha (mean 317.2 Mg/ha), respectively. Form carbon trade, the Swietenia macrophylla woodlots owner will earn 4,285–34,470 BDT/ha (mean 14,900 BDT/ha). It also seemed that the present market value of release oxygen (O2 Release) ranged from 3.2 to 25.5 million BDT/ha (average 11.1 million BDT/ha). However, the study area's average DBH, height, density, and basal area were 18.9 cm, 12.6 m, 1233 stem/ha, and 36.6 m2/ha, respectively. The above-ground biomass, below-ground biomass, and total biomass ranged from 45.9 to 389.7 Mg/ha (mean 166.5 Mg/ha), 22.5–157.7 Mg/ha (mean 71.2 Mg/ha), and 68.4–547.4 Mg/ha (mean 237.7 Mg/ha) correspondingly. Besides, the produced wood volume ranged from 64.95-1225.19 m3/ha (average 481.48 m3/ha). While the price of wood ranged from 0.8 to 15.14 million BDT/ha (mean 5.95 million BDT/ha). However, the above-ground, below-ground, and total carbon ranged 22.97–194.85 Mg/ha (mean 87.27 Mg/ha, 11.23–78.85 Mg/ha (35.61 Mg/ha), and 34.2–273.7 Mg/ha (118.89 Mg/ha) independently.Moreover, our three developed basal area-based allometric models are fit for calculating the carbon stock of Swietenia macrophylla woodlots. This study explores the potentiality of woodlots in Bangladesh. Policymakers should encourage the farmers to create more woodlots that actively participate in climate change mitigation.

The patterns of nearest neighbor trees in a temperate forest

The nearest neighbor trees (NNTs) are essential for reflecting forest structure and spatial heterogeneity in a forest stand. It is not clear whether different tree species have varied patterns of NNTs in a small area due to biological interactions, whether big trees affect the nearest neighbors for diversity and recruitments, or whether a universal linear relationship between the distance of NNTs and their average DBH exists. In this study, the information of NNTs at two plots (each 30 × 100 m) in a temperate mixed broadleaved forest in Southern USA was collected by field survey. Our results indicated that approximately 80% of NNTs were within a distance of 1.5-4.0 m. Tulip poplar, oaks, and hickory trees did not have the same species as NNTs or were very limited. Carolina buckthorn had itself as an NNT but with fewer other species. Sugar maple could serve as the NNT for oaks, hickory and others. The relationships between the distance of an NNT and its cumulative percentage were different among varied species or groups. Overall, for trees and their NNTs, there existed complicated relationships between their sizes (e.g., height and DBH). Big trees might affect NNTs in diversity and recruitment. The suggested linear relationship between tree size and distance was not observed. The results could be helpful to manage forest structure (tree species and NNT) and provide evidence to improve the scaling theory on NNTs.

Dynamic estimates of tree carbon storage and shade in Mediterranean urban areas

To highlight the ecosystem value of trees in the urban environment an EU's funding instrument for the environment and climate action – LIFE Project – was undertaken involving four Mediterranean cities as study cases: Thessaloniki in Greece, Cascais in Portugal, and Perugia and Bologna in Italy. The methodology utilized to evaluate plant carbon storage and shade areas highlighted the usefulness of gathering data about both the current urban green asset in the Project's investigated areas and future potential performances of the same asset to evaluate its efficiency in the forthcoming decades (2030–2050). The lower future potential of some cities for CO2 storage can be attributed to having older 'green assets' in comparison to other municipalities. A projection over the next 30 years on the basis of census results in the 4 studied areas highlighted the potential of some green areas characterised by the presence of efficient carbon storage tree species (high-growing broadleaf plants) while still small in size. &lt;br/&gt;The main objective of this study was to present both the current urban green asset carbon storage potential in the studied areas and also its future potential efficiency. Another aim of the work was to develop tree growth curves in urban areas, not only to estimate tree volumes but also to estimate the present and future shade areas related to woody plants' presence. &lt;br/&gt;With regard to CO2 storage simulation, the research highlighted the potential of green areas in Perugia that present tree species particularly efficient at carbon storage yet still small in size. Conversely, the lowest value presented by the species recorded in Cascais was influenced by the predominance of Cupressus sempervirens and Pinus pinea : two species not particularly efficient and large in size with average DBH values above 50 cm.

Farmers’ Compliance with Standard Silvicultural Practices and its Impact on the Performance of Pinus Spp. Woodlots in Rubanda District, South-Western Uganda

This study investigated farmers’ compliance to standard silvicultural practices and its impacts on the performance of Pinus spp in plantations in Rubanda District, South-western Uganda. A total of 122 pine plantations were randomly selected for intensive assessment. The findings revealed an average spacing of 2.90m, which significantly differs from the standard spacing of 3.0m for pine. Generally, stem density of pine plantations at various age categories such as 8 and 10 years was significantly higher than the recommended. The overall average pruning height of 3.26m as practiced by the farmers was significantly lower than 6.81m, the standard requirement of 50% average tree height (p≤ 0.05). In comparison, there were significant differences in average dbh in the three stem density categories. The increase in stem density caused a corresponding decline in dbh of trees in the pine plantations. Farmers with a pine crop of seven years and above with tree stock above the recommended stem density had incurred an average loss of 70.5m3 per hectare leading to an equivalent financial loss of UGX 3,525,000/= (USD 952.7) per hectare. Therefore, to avoid competition and unnecessary financial loss, adjustment of stem density by thinning as the pine plantation grows is strongly recommended.