Dbh Distribution Research Articles

Vegetation Structure and Regeneration Status of Woody Species in Gerba Dima Moist Afromontane Forest of Southwestern Ethiopia: Implications for Conservation

This study assessed vegetation structure and regeneration status of woody species in Gerba Dima forest, southwestern Ethiopia. Ninety sample plots measuring 25 m × 25 m were laid through a stratified random sampling procedure. The studied forest was stratified into three forest strata based on its altitudinal variation. Stratum I was found at an altitudinal range of 1500−1800 m, while strata II and III were located at altitudinal ranges of 1801−2000 m and 2001−2300 m, respectively. All woody plant species with a diameter at breast height (dbh) equal to or larger than 2.5 cm and a height of at least 1.5 m were recorded. Analysis of the structure of the vegetation was conducted using frequency distribution of dbh, height, and importance value (IV). The regeneration pattern of the study species was assessed by employing the total count of seedlings and saplings. The density of woody species in the study area was 1829 individuals ha−1. Basal area of the Gerba Dima forest was 65.05 m2ha−1. Total densities of seedlings, saplings, and trees/shrubs were 4558 ha−1, 2149 ha−1, and 1515 ha−1, respectively. Structural analysis and assessment of the regeneration status of woody species in the Gerba Dima forest showed that the overall ecological condition of the forest was healthy as indicated by inverse J‐curve dbh distribution, which showed a large number of individuals in lower dbh classes. Furthermore, a large number of seedlings and saplings were recorded for most species, in addition to the presence of a sufficient number of matured trees. However, some species exhibited abnormal population structure and abnormal patterns of regeneration characterized by fewer or no individuals in lower dbh, as well as in seedling and sapling stages. It was thus concluded that species with abnormal population structure and regeneration status (e.g., Sapium ellipticum and Trichilia dregeana) require urgent conservation attention.

ARTICLE WOODY SPECIES STRUCTURE AND REGENERATION STATUS IN MEHAL WONZ - ZEGO FOREST, N/ SHEWA ZONE, AMHARA REGIONAL STATE, ETHIOPIA

This study was conducted on Mehalwonze- Zego forest in North Shewa zone, Amhara Regional State, Ethiopia, A Transect sampling method was used to collect vegetation data. Sixty seven(67) plots of 20m × 20m were laied each at 300m intervals and five subplots of 2m × 2m, one in the center and four in the corner of the main plots, were laid for seedling and sapling inventory. Vegetation parameters such as DBH >2.5cm, H ≥2.5m of as well as seedling and sapling density with five sub plots of 2m × 2m. A total of 55 woody species belonging to 51 genera and 38 families were identified. The density of seedlings, saplings and matured woody plants in all of the plots were 1302, 1517 and 905 individuals, respectively. Importance Value Index (IVI) of each species were calculated, based on this value the conservation priority classes was done which indicated that there are woody species that require urgent conservation. The total basal area of the forest was 67.96 m2/ha. DBH and height class distribution of woody spcies confirms that the forest is under a secondary stage of development. Based on the results of regeneration assessment, conservation priority should be given for species with poor regeneration status.

Analysis of Selection-Cutting Silviculture with Thujopsis dolabrata—A Case Study from Japan Compared to German Plenter Forests

(1) Background: In Japan, single-tree selection-cutting silviculture with hiba (Thujopsis dolabrata var. hondai) is a traditional silvicultural system and is well documented. We evaluated an experimental forest regarding past structural dynamics and future development while comparing it to the German multilayer coniferous “Plenterwald/plenter forest”. (2) Methods: Classical growth and yield data were recorded since 1995 from two hiba-mixed species plots, one managed since Matsukawa’s (the founder) times in 1931 and the other unmanaged since 40–50 years before 1931. (3) Results: Clear structural differences appeared, with the managed plot having a reverse J-shaped DBH and tree height distribution curve, and a higher percentage of hiba, also typical for German plenter forests’ intensely multi-storied structure. The unmanaged plot was composed of trees with large stem diameters, even though they were more evenly distributed, together with less admixed species. In both plots, the growing stock increased in the past. While the managed plot’s growing stock in 2019 was 561 m3 ha−1, the unmanaged plot reached 982 m3 ha−1 with large portions accumulated in DBH classes >60 cm. (4) Conclusions: When compared to today’s clearcutting system in Japan, selection silviculture shows advantages and may thus serve as a valuable inspiration for silviculture in Japan as it was with plenter forestry for Germany.

Prediction of Diameter and Height of Rubber from Tree Age

Hevea brasiliensis (rubber) is one of the main economic crops in Sri Lanka which is cultivated primarily for latex production. Rubber tree is also a valuable source of fuel and timber used in wood[1]based industries such as medium density fiberboard manufacturing. Due to high economic value of rubber latex and wood, it is important for the plantation managers to have a reliable mechanism to monitor the growth of those trees in the plantations. Therefore, this study aimed at building mathematical models to predict the tree diameter at breast height (dbh) and total height of rubber with the tree age from the plantation establishment to the uprooting stage. Data collection was done at Halpe and Salawa rubber estates located in the low country wet zone. Dbh and total height measurements were collected from six age classes from 4 to 31 years, at each estate. Twenty trees were measured from each age class totaling to 240 tree measurements. After observing the distribution of both dbh and total height with tree age, two forms of non-linear models, viz., Michaelis-Menten and power-law, were selected for model construction. First, data collected from Halpe and Salawa estates were separately fitted to the selected two model forms and residuals were statistically compared. Since there were no significant differences of the residual values in the two sites for both dbh and height, the data were pooled and re-fitted to the selected models. The quality of the models were determined using both qualitative tests by standard residual distribution and quantitative tests by coefficient of determination, average model bias, mean absolute difference and modelling efficiency. Validation of the finally selected models was done using data reserved at the beginning which were not used for model construction. Finally, Michaelis-Menten models for dbh and height prediction of rubber were selected based on its higher performance than the power-law model.
 Keywords:Hevea brasiliensis, Michaelis-Menten, Allometric model, Modelling efficiency, Residuals
 Acknowledgement: Authors acknowledge the assistance of Pussellawa Plantations Limited

Phytochemical Screening and In-Vitro Antimicrobial Activity of Acacia Brevispica Leave Extract Collected around Haramaya Wereda

There is limited quantitative information with regard to the vegetation structure in South-eastern Ethiopia. This study was therefore carried out to determine the density, DBH, Basal area and height distributions of woody plant species at Jello-Muktar dry afromontane forest. Systematic sampling design was used to collect vegetation data in total of 90 circular sample plots of each 30cm radius. In each plot all woody plants which are ≥2 cm diameter at breast height and height > 1m were identified, measured and recorded. Analysis of Size class distribution was performed for height (100 cm and above) and diameter classes (2 cm and above) and BA of each woody plant species with DBH ≥ 2 cm was computed The study revealed that more than 93% of the individuals had the DBH class distribution of more than 40.01 cm DBH. The DBH class distribution showed an inverted J-shape curve with the presence of more individuals in the lower DBH classes which is an indication of the active regeneration. The basal area in this study ranged from 10.9 m 2 /ha for DBH class 1 to 59.02 m 2 /ha for DBH class 11. The total basal area was found to be 245.65m 2 and there was a J-shape curve relationship between DBH class and basal area class distribution. About 89 % of trees and shrubs had heights of more than 5m tall but only 3.45% the total individuals recorded were more than 30m. The population structure of the entire forest showed higher stem densities in the Lower diameter classes and progressively declining stem densities with increasing Diameter classes. Study of woody plant species population structure is an invaluable strategy for planning management actions and also helps in identifying the status of the forest stand with regard to its rate of disturbance. Hence it is better to manage those parts of forest stands with less number of individuals through enrichment planting of indigenous tree species. Keywords: DBH, basal area, height, DBH class, height class, dry afromontane, woody DOI: 10.7176/JNSR/13-5-03 Publication date: March 31 st 2021

Elaboration of Sustainable Forest Model for Community Forest Management in Nghe An Province, Vietnam

The main trend in sustainable forest management is to use the forests to perfectly accomplish their environmental conservation role parallel with supplying forest products to fulfil communities' requirements. However, forests handed over to the local community are commonly found poor and require driving solutions to make them more stable and productive. The question is how to use the forest in sustainable management. The paper presented the methods for estimating forest products and benefits use based on the so-called sustainable forest model. The sustainable forest model is limited to stem number-diameter distribution ( /DBH distribution), which follows probability density N functions. Meyer function is opted to be used in this research because it can make a rather good simulation of /DBH distribution having the Nshape of decreasing curves. The results showed that the proposed /DBH distribution of the sustainable forest model of group II and III has = N N276 e ; = 164 e (respectively). This forest model will help identify the benefit levels to the community, make suitable and · · -0.096 -0.063 D D N straightforward planning of wood exploitation, and reduce the costs by comparing the number of trees of the researched forests with that of the model.

Modeling in Forestry Using Mixture Models Fitted to Grouped and Ungrouped Data

The creation and maintenance of complex forest structures has become an important forestry objective. Complex forest structures, often expressed in multimodal shapes of tree size/diameter (DBH) distributions, are challenging to model. Mixture probability density functions of two- or three-component gamma, log-normal, and Weibull mixture models offer a solution and can additionally provide insights into forest dynamics. Model parameters can be efficiently estimated with the maximum likelihood (ML) approach using iterative methods such as the Newton-Raphson (NR) algorithm. However, the NR algorithm is sensitive to the choice of initial values and does not always converge. As an alternative, we explored the use of the iterative expectation-maximization (EM) algorithm for estimating parameters of the aforementioned mixture models because it always converges to ML estimators. Since forestry data frequently occur both in grouped (classified) and ungrouped (raw) forms, the EM algorithm was applied to explore the goodness-of-fit of the gamma, log-normal, and Weibull mixture distributions in three sample plots that exhibited irregular, multimodal, highly skewed, and heavy-tailed DBH distributions where some size classes were empty. The EM-based goodness-of-fit was further compared against a nonparametric kernel-based density estimation (NK) model and the recently popularized gamma-shaped mixture (GSM) models using the ungrouped data. In this example application, the EM algorithm provided well-fitting two- or three-component mixture models for all three model families. The number of components of the best-fitting models differed among the three sample plots (but not among model families) and the mixture models of the log-normal and gamma families provided a better fit than the Weibull distribution for grouped and ungrouped data. For ungrouped data, both log-normal and gamma mixture distributions outperformed the GSM model and, with the exception of the multimodal diameter distribution, also the NK model. The EM algorithm appears to be a promising tool for modeling complex forest structures.

Effects of clint on the distribution and leaf phenotypic variation of a dominant plant Lindera communis in Maolan Karst National Natural Reserve, SW China

The heterogeneous habitat plays an important role in the conservation and restoration for rare and endangered plant species. In the karst area, the clints usually cause the soil differentiation of physical and chemical properties, which affect the distribution and adaptation strategy of dominant plant populations. To study the distribution and adaptation strategy of the dominant plants in heterogeneous habitats induced by clints, we investigated the leaf phenotypic variation along the transect from Lindera communis plant to clint (0 cm, 0.1cm-10cm and ≥ 10 cm) within the Maolan Karst National Nature Reserve, Libo County, Guizhou Province, China. The results showed: (1) 483 individuals of L. communis had been recorded, and the trees (DBH≥1cm) were 374 individuals (77.43% of the total). The DBH of biggest L. communis was 10.5cm, which was 6 cm away from the clint. In the 0cm distance group, the tree (mean DBH 2.97±1.71 cm) were 200, and the seedlings and saplings were 29. In the 0.1cm-10cm distance group, the tree (mean DBH 2.75±1.62 cm) were 50, and the seedlings and saplings were 44. In the ≥ 10cm distance group, the tree (mean DBH 2.52±1.29 cm) were 124, and seedlings and saplings were 36. The mean DBH of L. communis individuals was decreased with the increase of the distance between plant and clint. The coefficients of variation of L. communis individuals DBH in each distance group, which indicated that the DBH distribution of this species was uncertain at different groups. (2) The leaf length, width, width/length and thickness of L. communis was 79.71±12.95 mm, 30.17±6.68 mm, 0.38±0.07, 0.24±0.05 mm, respectively. The petiole length and diameter of L. communis was 6.65±1.87 mm and 1.19±0.63 mm, respectively. The coefficient of variation of petiole length increased first and then decreased with the distance from clint increasing. Meanwhile, the variation coefficients of leaf length, leaf width, leaf width/length, leaf thickness and petiole diameter decreased first and then increased with the increase of distance from clint. The distance between the clint and L. communis had significant effect on the leaf length (P < 0.05), and thickness (P < 0.01) and width/length (P < 0.01), and had minor effect on the other leaf traits. The present study highlighted that the clint had a profound influence effect on the distribution and leaf characteristics traits of L. communis. Therefore, we can use the clint as a key node to protect and restore the plant population size.

Understory species diversity, regeneration and recruitment potential of sacred groves in south west Nigeria

Global species extinction rates due to forest conversions are increasing. Ecologists, conservationists and governments have adopted various conservation methods. Sacred grove is one conservation option that has gained attention in recent time. We assessed understory species diversity, regeneration and recruitment potentials of four sacred groves in southwestern Nigeria. Overstory tree species were inventoried in eight 800 m2 temporary sample plots, systematically laid along two transects of 1000 m each. Understory tree species were assessed in 100 m2 plots for saplings and 25 m2 plots for seedlings in all sample plots. Shannon–Wiener diversity index (1.8–3.46 (overstory); 2.65–3.55 (understory)), number of species (32–58 (overstory); 39–78 (understory)) and tree density (309–417 individuals/ha (overstory); 775–1445 individuals/ha (understory)) were comparable and/or higher at the understories than the overstories. Dbh distribution curves showed highest stand density at the lowest class (10–20 cm) and decreased with increasing dbh, indicating good regeneration status and healthy ecosystem. Regeneration was considered good and fair, because in most cases, number of seedlings > saplings > overstory trees or number of seedlings > saplings ≤ overstory trees. The good regeneration status was further confirmed by the good species recruitment in the understory. However, the high influx of people into sacred groves for festivals and rituals, which results in trampling and burning of seedlings, is a threat to the diversity, regeneration and recruitment potentials of the groves. High regeneration and recruitment status maintained in all the sacred groves in this study were achieved using taboos, cultural and traditional methods. These methods could be incorporated in managing forest reserves in Southwestern Nigeria.

Crown bole diameter linear equation for Daniellia oliverii (Rolfe) Hutch and Daviz and its application to stand density control in natural stands

At present, no adequate information on the application of crown-bole diameter model to stand density and stock control for Daniellia oliverii (Rolfe) Hutch and Daviz open grown trees for sustainable forest management in the study area. The species numbers are threatened, because farmers and foresters do not actively plant this tree species. Livestock, fire, and anthropogenic activities are few factors that limit the success of natural regeneration of the species; and is facing regeneration problem. These have led to the species declining in the natural forest areas and the loss of biological values (genetic hereditary). A total of nine blocks as sample plots sizes 100x100 meters were randomly laid. Simple random sampling was used to collect data on tree diameter at breast height (dbh). Dbh was used to estimate crown diameter using a developed simple linear crown-bole diameter model. Based on this finding, dbh distribution was more (42 tree stands) concentrated at the lower diameter class (10 to 30cm) than at the upper diameter class distribution (31 and above). This could be that such tree stands might have been exploited as timber in the ecosystem. Nowadays, trees of smaller dimension are generally logged immediately they are discovered, especially the most economic and desirable species. The status of the tree species was a reversed “J” shaped distribution curve. The reverse ‘J-shape’ diameter distribution indicated healthy recruitment potentials; the lower class diameter tree stands could develop into mature trees and replace the old ones in the future if proper conservation efforts are sustained. Thus, this structure is typical of a natural forest. This finding estimated limiting stocking and stand density required for producing a complete canopy without effect of competition. D. oliverii with diameter 48.7cm would require a stocking of 168 trees per hectare in terms of total occupancy by tree crowns; stand density of 0.00001863m2ha-1 would be needed. Also, tree stands of 80cm dbh would have 73 tree stands limiting stocking, covering a stand density of 0.00005027m2/ha. Linear crown-bole diameter model could simply be used in forest inventory operations for determining the forest stock with less cost and time consuming. More research is needed with a greater variety of site and stand conditions in addition to a greater variety of tree sizes and ages.

Models for diameter distribution and tree height in hybrid aspen plantations in southern Finland

Hybrid aspen ( L. × Michx.) is known with outstanding growth rate and some favourable wood characteristics, but models for stand management have not yet been prepared in northern Europe. This study introduces methods and models to predict tree dimensions, diameter at breast height (dbh) and tree height for a hybrid aspen plantation using data from repeatedly measured permanent sample plots established in clonal plantations in southern Finland. Dbh distributions using parameter recovery method for the Weibull function was used with Näslund’s height curve to model tree heights. According to the goodness-of-fit statistics of Kolmogorov-Smirnov and the Error Index, the arithmetic mean diameter () and basal area-weighted mean diameter () provided more stable parameter recovery for the Weibull distribution than the median diameter () and basal area-weighted median diameter (), while showed the best overall fit. Thus, Näslund’s height curve was modelled using with Lorey’s height (), age, basal area (), and tree dbh (Model 1). Also, Model 2 was tested using all predictors of Model 1 with the number of trees per ha (). All predictors were shown to be significant in both Models, showing slightly different behaviour. Model 1 was sensitive to the mean characteristics, and , while Model 2 was sensitive to stand density, including both and as predictors. Model 1 was considered more reasonable to apply based on our results. Consequently, the parameter recovery method using and Näslund’s models were applicable for predicting tree diameter and height.Populus tremulaP. tremuloidesDDGDMDGMDGDGHGBATPHDGHGBATPHDG

Describing the Structure and Relationship of Height and Diameter in an Old Unmanaged Eucalyptus spp. Plantation

Abstract The aim of this study was to model the height and diameter distributions and the height-diameter relationship in an old unmanaged Eucalyptus stand in southeastern Brazil. The diameter at 1.30 m above soil (DBH) and total height (H) of all 469 trees in the stand were measured. For the DBH-H modeling, besides testing various traditional linear and nonlinear models, the inclusion of diameter class as random effect was also testes. For the DBH and H distributions modeling, seven probability density function were tested. The DBH-H relationship was best represented by the Henriksen’s linear model. Including diameter classes as a random effect did not improve estimates. The three parameters Weibull distribution was the best model to describe the diameter and height in old and unmanaged planting of Eucalyptus. The DBH distribution showed the highest frequency of individuals in lower diametrical classes, influenced by competition, while H had distribution similar to normal.

Woody Species Diversity and Vegetation Structure of Wurg Forest, Southwest Ethiopia

This study was aimed to determine woody species composition, diversity, and vegetation structure and to investigate major threats to Wurg forest, southwest Ethiopia. In order to collect vegetation data, 64 (400 m2) sample plots from eight transect lines were employed. The distances between transect lines and plots were 400 m and 200 m, respectively. DBH of woody species &gt;2.5 cm and the height &gt;2 m were measured and recorded. Voucher specimens were brought to the Ethiopian Biodiversity Institute for identification and deposited there. R program version 12.5.2 software and Microsoft Excel spreadsheet were used to analyze plant community classification and structural analysis, respectively. A total of 76 woody species representing 40 families were recorded. Rubiaceae was the dominant family followed by Asteraceae. The average Shannon–Wiener diversity index (H′) and the average evenness values of Wurg forest were 3.38 and 0.90, respectively. Four plant community types were identified by using the presence/absence values of each species. The total density of woody species with DBH &gt; 2.5 cm was 1745.3 ha−1. The DBH and height class distributions showed an inverted J-shaped pattern, which indicates a good regeneration potential of the forest. The most frequently observed species (92%) was Syzygium guineense, which contributed 46% of the total basal area. The composition of seedling, sapling, and adult trees/shrubs species was 4966.07 ha−1, 3125.78 ha−1, and 1745.27 ha−1, respectively. However, the major threat to the forest was selective cutting of some woody species for various purposes. Therefore, raising local community awareness on conservation and sustainable use of the forest and exploring various alternatives for local communities’ livelihood and promoting private and community plantations are recommendable.

Stocking Density and DBH Distribution of Community Forests in Nepal

There is a growing concern for sustainable forest management globally, and individual countries have been developing national policies and plans for forest management. This is the case in Nepal, but a large area of national forests is still under protection due to lack of people-centric management guidelines. In this study, diameter (DBH) and height were measured for trees, and frequency was recorded for regenerations (sapling and seedling), in concentric circular plots of 8.92 m, 5.64 m and 1 m radius respectively, in 89 plots from two community forests in the Mid-hills of Western Nepal to analyze whether the forests could be used sustainably. Regression analysis and the Mann–Kendall and Sen’s slope coefficient tests were performed to determine the composition and structure of forests in relationship with elevation which largely determines forests' type. It was found that seedling density decreases with increasing elevation, but sapling and tree density do not follow any significant pattern for elevation. The DBH size found to be inversely related to stand density for the two dominant tree species (Shorea robusta and Schima wallichii). In contrast, DBH did not vary significantly with elevation for Pinus roxburghii and Castanopsis indica. The DBH distribution of all trees (26 species) was found to decline consistently with stand age, indicating that the forests are in good condition to manage sustainably by a simple, people-centric and cost-effective regime of thinning and size-based harvesting. Results suggest that forest managers, forest users and policy-makers need to develop and implement user-friendly forest management directives.

조선왕릉 정릉의 역사문화경관림 실태와 관리 방안

The purpose of this study is to understand the actual conditions of historical and cultural landscape forests of Jeongneung Joseon Royal Tomb and to prepare systematic preservation and management plans, and the results of the study are as follows. First, the vegetation is mainly occupied by Quercus 􀁐􀁒􀁑􀁊􀁒􀁏􀁌􀁆􀁄 and is distributed as 􀀴􀁘􀁈􀁕􀁆􀁘􀁖􀀃􀁐􀁒􀁑􀁊􀁒􀁏􀁌􀁆􀁄􀀐􀀶􀁒􀁕􀁅􀁘􀁖􀀃􀁄􀁏􀁑􀁌􀁉􀁒􀁏􀁌􀁄 65.47%, 􀀳􀁌􀁑􀁘􀁖􀀃􀁇􀁈􀁑􀁖􀁌􀃀􀁒􀁕􀁄 11.85%, and 􀀳􀁌􀁑􀁘􀁖􀀃􀁇􀁈􀁑􀁖􀁌􀁉􀁏􀁒􀁕􀁄 afforestation 6.41%. The main vegetation communities are 􀀳􀁌􀁑􀁘􀁖􀀃􀁇􀁈􀁑􀁖􀁌􀁉􀁏􀁒􀁕􀁄, 􀀶􀁒􀁕􀁅􀁘􀁖􀀃􀁄􀁏􀁑􀁌􀁉􀁒􀁏􀁌􀁄, 􀀴􀁘􀁈􀁕􀁆􀁘􀁖􀀃􀁐􀁒􀁑􀁊􀁒􀁏􀁌􀁆􀁄, 􀀳􀁌􀁑􀁘􀁖􀀃􀁇􀁈􀁑􀁖􀁌􀃀􀁒􀁕􀁄 afforestation and Pinus koraiensis afforestation. Second, in Diameter of Basal Height in eight quadrat, the major species were 􀀳􀁌􀁑􀁘􀁖􀀃􀁇􀁈􀁑􀁖􀁌􀃀􀁒􀁕􀁄, Quercus 􀁐􀁒􀁑􀁊􀁒􀁏􀁌􀁆􀁄 and 􀀶􀁒􀁕􀁅􀁘􀁖􀀃􀁄􀁏􀁑􀁌􀁉􀁒􀁏􀁌􀁄 and the maximum distribution of DBH is 15-20cm of 􀀳􀁌􀁑􀁘􀁖􀀃􀁇􀁈􀁑􀁖􀁌􀃀􀁒􀁕􀁄, 10-15cm of 􀀴􀁘􀁈􀁕􀁆􀁘􀁖􀀃􀁐􀁒􀁑􀁊􀁒􀁏􀁌􀁆􀁄 and 5-10cm of 􀀶􀁒􀁕􀁅􀁘􀁖􀀃􀁄􀁏􀁑􀁌􀁉􀁒􀁏􀁌􀁄. Third, the 􀀳􀁌􀁑􀁘􀁖􀀃􀁇􀁈􀁑􀁖􀁌􀃀􀁒􀁕􀁄 forests in the focused management area are dense and very close to 􀀴􀁘􀁈􀁕􀁆􀁘􀁖􀀃􀁐􀁒􀁑􀁊􀁒􀁏􀁌􀁆􀁄􀀐􀀶􀁒􀁕􀁅􀁘􀁖􀀃􀁄􀁏􀁑􀁌􀁉􀁒􀁏􀁌􀁄 so it is disadvantageous for growth and management. Fourth, in order to manage the forests, substitute exotic species such as acacia trees with traditional ones such as pine trees, and plant pine trees so that they can be connected throughout Jeongneung. In areas with dense trees, adequate space is provided for growth. The inclined pine trees around Bonbun are continuously and actively managed. Trees representing visual heterogeneity need to be cleaned up, and the boundary is adjusted to match the existing deciduous tree and the buffer space is secured to around 10 meters. This study is expected to convey important implications to other Joseon royal tombs, which have undergone similar times, and reasonable management measures should be prepared after examining the actual conditions of individual Joseon royal tomb's historical landscape forests.

Effects of Integrated Soil and Water Conservation Practices on Woody Species Diversity, Structure and Regeneration in Southern Ethiopia

Land degradation in the form of soil erosion is <i> one of the most serious problems in the worldwide</i>. Physical and biological soil and water conservation measures implemented by various land rehabilitation program is the best option to address this problem. This study was conducted to evaluate the effect of integrated soil and water conservation (SWC) practices on Woody Species Diversity, Structure and Regeneration in Southern Ethiopia. A total of 60 plots (3 land use*4 transect*5 quadrants), measuring 20 m*20 m each, were established along transect line laid for woody vegetation data collection. Woody species diversity in the study sites were determined using the Shannon (H’) and Simpson diversity index through the analysis of species richness and evenness of species. A total of 28 woody species, belonging to 15 families were identified. The diversity, richness, density and basal area of woody species were significantly higher in closure area with SWC (p<0.05) compared to the value in closure area without SWC and open grazing land. The inverted ’J’ shaped distribution of height and DBH exhibited in closure area with SWC, which has more potential to enhance vegetation regeneration. The findings generally confirmed that area closure with SWC practices was highly improved woody species diversity, structure and regeneration status. Accordingly, to improve the biophysical conditions of degraded hillside areas implementing of area closure with integrated SWC practices is a best option.

Structural characteristics of mixed plantation of pinus massoniana and oak in danjiangkou reservoir area

In this paper, the frequency distribution of DBH and DBH of masson pine and oak trees in mixed forest was simulated by using normal distribution, and the relationship between DBH and tree height was fitted by 11 common curve models. The power model can well simulate the relationship between DBH and tree height.

Structural characteristics of oak plantation in Danjiangkou reservoir area

In this paper, the frequency distribution of DBH and DBH of oak plantation was simulated by using normal distribution, and the relationship between DBH and tree height, DBH and crown area was fitted by 11 common curve models. The relation between DBH and tree height was well simulated by S model and cubic curve model. The relationship between DBH and crown area was simulated by cubic and quadratic models.

Biomass Yield and Fuel Properties of Different Poplar SRC Clones

The goal of the research was to determine the biomass yield and fuel properties of ten different poplar clones. The research was conducted in an experimental plot established in Forest Administration Osijek, Forest Office Darda, in the spring of 2014. The layout of the plot consisted of three repetitions per clone with 40 plants per repetition in spacing 3x1 m. Based on the DBH distribution, in the early spring of 2018, one sample tree of an average DBH per repetition was selected, thus forming a sample of 30 trees. Average survival rate of the investigated trees after four vegetation periods was 74.54 ±13.85% ranging from 52.08% (Koreana) to 91.67% (SV885 and SV490). Average DBH of the sample trees was 8.2 ±1.9 cm, height 9.3 ±1.8 m and root collar diameter 10.7 ±1.9 cm. Moisture content in fresh state (just after the felling) ranged from 51.6% (Hybride 275) to 55.9% (SV885). Bark content averaged 18.4%, from 15.4% (Baldo) to 21.1% (V 609). Average nominal density of the sampled trees amounted to 383.5 ±35.9 kg/m3. Bark ash content was on average ten times higher (6.44 ±0.65%) than wood ash content (0.64 ±0.07%) resulting in average ash content of 1.7 ±0.1% (taking the bark content into account). The clone SV490 showed the highest biomass yield with 15.8 t/ha/year, while the lowest biomass yield was recorded for the clone Hybride 275 with 2.8 t/ha/year. High inter-clonal productivity variation stresses the importance of selection work to find the most appropriate clones with the highest productivity potential for the given area where the poplar SRC plantations are to be established. Due to high initial moisture content, if direct chipping harvesting systems are preferred, wood chips could be efficiently used in CHP (Combined Heat and Power) plants that operate on the principle of biomass gasification (where a gasifier is coupled to a gas engine to produce electric power and heat). In several CHP gasification plants operating in Croatia, wood chips with high initial moisture content (from traditional poplar plantations) are used as a feedstock that has to be pre-dried using the surplus heat. In this respect SRC poplar wood chips could make an ideal feedstock supplement.

Gap dynamics of natural Populus euphratica floodplain forests affected by hydrological alteration along the Tarim River: Implications for restoration of the riparian forests

Due to climate change and excessive human activities, runoff dynamics of the Tarim River in northwest China become more pronounced. Understanding the effects of hydrological alteration on the life strategy and dynamics of the Populus euphratica riparian forests is becoming increasingly important. Forest gaps led by such disturbances change the structure and function of the desert riparian forest ecosystems. However, there is a lack of research on the gap formation and dynamics of this special forest type, for which the main driving force of the gap disturbance has always been unknown. In this study, we investigated several parameters of P. euphratica forest gap, such as gap size, gap age, gap fraction, and gap makers to quantify the gap disturbance regimes in the natural floodplain forests along the Tarim River in arid northwest China. In the middle reaches of the Tarim River, a total number of 263 gap makers and 60 gaps in six 50 m × 50 m plots with a total area of 1.5 hm2 were investigated. The result showed that gap fraction was <5%, and approximately 28.5% of the expanded gaps were from 1.0 to 1.2 in size (ratio of gap diameter to tree height), especially when formed around 1997–2006. The median size of the expanded gap (140.57 m2) in the desert riparian forests was smaller than in tropical forests. P. euphratica was the most abundant gap maker, and its share among gap makers was 12–14 times larger than another species. Furthermore, gap makers contributed to the forest gap size, as shown by a significant correlation between the number of gap makers and the size of expanded gaps, especially those that had been created 50–60 years ago (R2 = 0.455, P < 0.01). The DBH distribution of living trees versus dead trees showed that most P. euphratica mortality occurred in small size classes. However, living trees were equally frequent in large classes, which suggested that large trees were not exclusively injured or died in these P. euphratica stands that were affected by poor habitats, such as water scarcity. We concluded that climate change and anthropogenic activities (increasing water use for irrigation) since the 1970s led to the progressive decrease in water resources at the regional scale and resulted in a higher frequency of forest gaps in the riparian forests along the Tarim River. The results of this study provide useful implications for ecological restoration of P. euphratica to improve sustainable management of desert riparian forests.