Tree Dimensions Research Articles

Modeling Height–Diameter Relationships for Mixed-Species Plantations of Fraxinus mandshurica Rupr. and Larix olgensis Henry in Northeastern China

The mixture of tree species has gradually become the focus of forest research, especially native species mixing. Mixed-species plantations of Manchurian ash (Fraxinus mandshurica Rupr.) and Changbai larch (Larix olgensis Henry) have successfully been cultivated in Northeast China. Height–diameter (H–D) models were found to be effective in designing the silvicultural planning for mixed-species plantations. Thus, this study aimed to develop a new system of H–D models for juvenile ash and larch mixed-species plantations, based on competition information and tree and stand attributes. The leave-one-out cross-validation was utilized for model validation. The result showed that the H–D relationship was affected not only by the tree attributes (i.e., tree size and competition information) but also by stand characteristics, such as site quality and species proportion of basal area. The best model explained more than 80% and 85% variation of the tree height of ash and larch, respectively. Moreover, model validation also confirmed the high accuracy of the newly developed model’s predictions. We also found that, in terms of total tree height, ash in middle rows were higher than those in side rows, while larch in the middle rows were higher in the early growth period but then became lower than those in the side rows, as the diameter increased. The newly established H–D models would be useful for forestry inventory practice and have the potential to aid decisions in mixed-species plantations of ash and larch.

Generalized model for plantation production of Eucalyptus grandis and hybrids for genotype-site-management applications

The use of process-based modelling of wood production in forest plantation has increased in recent decades amongst researchers and forest companies. Although, such models are used by several plantation researchers and managers, improved options and sensitivity to soil characteristics, genotype, and management options are desirable. A new generation of forest productivity modelling needs to extend previous capabilities and incorporate modern software engineering technologies. Our objective was to develop and evaluate an Agricultural Production Systems sIMulator (APSIM) Next Generation model for simulating the growth of Eucalyptus grandis and hybrids with or of E. globulus and E. urophyylla. The model simulates stem, canopy and root development, resource capture and use (light, water, N), and C and N allocation as mediated by climate, soil, genotype physiological characteristics and management. Tree dimensions (stem diameter, height, volume) are calculated as empirical functions of above-ground biomass. Datasets used for model calibration or independent evaluation were from diverse conditions in Australia (5 sites) and Brazil (13 sites), and at several of these sites there were treatments for fertilizer, irrigation or genotype. For the calibration and evaluation datasets, model performance was very good for above-ground biomass (Nash Sutcliffe Efficiency, NSE = 0.96 and 0.84 respectively). Notwithstanding this general performance, and as an example, local calibration improved performance in one of the independent test datasets, suggesting that applications of the model for specific sites or clones may benefit from parameterization to local conditions. Simulation of management for weed cover, N fertilizer and genotype are also demonstrated. As the model performed well and has high flexibility, it warrants consideration by forest plantation managers and researchers for knowledge synthesis and operational productivity predictions of Eucalyptus and other plantation genotypes.

Estimation of aboveground biomass using aerial photogrammetry from unmanned aerial vehicle in teak (Tectona grandis) plantation in Thailand

Abstract. Rinnamang S, Sirirueang K, Supavetch S, Meunpong P. 2020. Estimation of aboveground biomass using aerial photogrammetry from unmanned aerial vehicles in teak (Tectona grandis) plantation in Thailand. Biodiversitas 21: 2369-2376. Thailand is one of the best teak planting locations in the world. Teak is one of the most species planting and a significant source of high-value timber in Thailand. For plantation management, biomass is one of the important factors while determining the production of a plantation and also for sustainable forest management. Unmanned Aerial Vehicles (UAV) have the ability to produce 3D RGB digital images which can be used to study the plantation characteristics. This study aimed to use aerial images and photogrammetry techniques derived from unmanned aerial vehicles (UAV) to estimate teak biomass in Thong Pha Phum plantation, Kanchanaburi Province, Thailand. We conducted our study on 15-and 36-year-old teak stands, and compared the tree dimension between data obtained from field measurement and that from aerial images and photogrammetry techniques. In the 15-year-old stand, the average tree height estimated from the UAV and ground-truthing were 12.34 and 13.06 m, respectively. In the 36-year-old stand, the average tree height from the UAV and ground-truthing were 28.87 and 29.39 m, respectively. We found that in both stands, the difference between data generated from the UAV and ground-truthing data was not significant (p-value = 0.07 and 0.306, respectively). There was also a strong correspondence between tree height estimated from the UAV and that measured on the ground which is indicated by the high R2 (i.e. 0.70 and 0.64 for the 15-and 36-year-old stands, respectively). Using UAV generated data, the total biomass of 15-and 36-year-old stands was estimated to be around 42.07 t ha-1 and 67.13 t ha-1, respectively. The overall results suggest that UAV can be used as an effective tool to survey and monitor stand’s productivity in teak plantation.

Respon Fisiologi Mindi (Melia azedarach L.) dan Kedelai (Glycine max (L.) Merrill) dalam Agroforestri Secara Organik

Mindi is one of commercial tree species for its timber. Sustainable management of mindi community forest can be obtained by inter-planting the trees with agricultural crop such as soybean. This study aimed to analyze physiological respond of mindi and soybean, which were planted in an organic agroforestry system. The research was done in Conservation Unit for Medicinal Plants at Cikabayan, Bogor Agricultural University (IPB). The first study was about the growth of mindi saplings in monoculture and agroforestry systems (with soybean). The experiment used completely randomized design (CRD). The second study was about the growth of soybean in monoculture and agroforestry systems (with mindi), and used split-plot design. The result show that nutrient uptake of N, P, and K in agroforestry system was higher than in monoculture. The increase of nutrient content in agroforestry system led to the higher increase of growth dimensions of mindi tree than the ones in monoculture. The content of soybean chlorophyll planted in agroforestry system was higher than the ones in monoculture. Soybean in agroforestry system had higher nutrient uptake of N, P, and K compared to the ones in monoculture. Soybean productivity in monoculture system showed higher result than the ones in agroforestry.
 Keywords: chlorophyll, monoculture, root, tree dimension, varieties

Estructura espacial de los bosques mixtos e irregulares en el estado de Durango

El propósito de este trabajo fue describir la estructura espacial e investigar las interacciones o correlaciones espaciales entre algunas características de árboles en bosques mixtos e irregulares en el estado de Durango. Se usó la localización horizontal y ciertos atributos de los individuos arbóreos de 446 sitios permanentes de investigación forestal y de suelos. La distribución espacial, así como la interacción entre grupos de especies se determinaron con el empleo de estadísticos de segundo orden como la función K de Ripley en sus formas normalizadas univariada L(r) y bivariada L12(r). La asociación dimensional de los árboles se evaluó con el uso de la función de correlación de marcas Kmm(r). Estas herramientas estadísticas permitieron determinar que la estructura espacial de los boques estudiados es de naturaleza compleja y dependiente de la escala de evaluación con que se analice. A distancias menores de 2 m domina una distribución espacial aleatoria del arbolado, mientras que a distancias mayores de 2 m predomina el agrupamiento. Por otra parte, en la mayoría de los sitios no se observaron interacciones o mezclas significativas en la distribución de los árboles de Pinus y Quercus, lo cual indica que la regeneración y la silvicultura siguen un patrón aleatorio. El análisis de la interacción espacial entre los tamaños de los diámetros de los árboles significa la existencia de un patrón de distribución espacial independiente, en el que los individuos de diferentes diámetros están mezclados de manera aleatoria dentro de los sitios de muestreo.

Estimation of Forest Growing Stock Volume with UAV Laser Scanning Data: Can It Be Done without Field Data?

Laser scanning data from unmanned aerial vehicles (UAV-LS) offer new opportunities to estimate forest growing stock volume ( V ) exclusively based on the UAV-LS data. We propose a method to measure tree attributes and using these measurements to estimate V without the use of field data for calibration. The method consists of five steps: i) Using UAV-LS data, tree crowns are automatically identified and segmented wall-to-wall. ii) From all detected tree crowns, a sample is taken where diameter at breast height (DBH) can be recorded reliably as determined by visual assessment in the UAV-LS data. iii) Another sample of crowns is taken where tree species were identifiable from UAV image data. iv) DBH and tree species models are fit using the samples and applied to all detected tree crowns. v) Single tree volumes are predicted with existing allometric models using predicted species and DBH, and height directly obtained from UAV-LS. The method was applied to a Riegl-VUX data set with an average density of 1130 points m−2 and 3 cm orthomosaic acquired over an 8.8 ha managed boreal forest. The volumes of the identified trees were aggregated to estimate plot-, stand-, and forest-level volumes which were validated using 58 independently measured field plots. The root-mean-square deviance ( R M S D % ) decreased when increasing the spatial scale from the plot (32.2%) to stand (27.1%) and forest level (3.5%). The accuracy of the UAV-LS estimates varied given forest structure and was highest in open pine stands and lowest in dense birch or spruce stands. On the forest level, the estimates based on UAV-LS data were well within the 95% confidence interval of the intense field survey estimate, and both estimates had a similar precision. While the results are encouraging for further use of UAV-LS in the context of fully airborne forest inventories, future studies should confirm our findings in a variety of forest types and conditions.

Under-canopy UAV laser scanning for accurate forest field measurements

Surveying and robotic technologies are converging, offering great potential for robotic-assisted data collection and support for labour intensive surveying activities. From a forest monitoring perspective, there are several technological and operational aspects to address concerning under-canopy flying unmanned airborne vehicles (UAV). To demonstrate this emerging technology, we investigated tree detection and stem curve estimation using laser scanning data obtained with an under-canopy flying UAV. To this end, we mounted a Kaarta Stencil-1 laser scanner with an integrated simultaneous localization and mapping (SLAM) system on board an UAV that was manually piloted with the help of video goggles receiving a live video feed from the onboard camera of the UAV. Using the under-canopy flying UAV, we collected SLAM-corrected point cloud data in a boreal forest on two 32 m × 32 m test sites that were characterized as sparse (n = 42 trees) and obstructed (n = 43 trees), respectively. Novel data processing algorithms were applied for the point clouds in order to detect the stems of individual trees and to extract their stem curves and diameters at breast height (DBH). The estimated tree attributes were compared against highly accurate field reference data that was acquired semi-manually with a multi-scan terrestrial laser scanner (TLS). The proposed method succeeded in detecting 93% of the stems in the sparse plot and 84% of the stems in the obstructed plot. In the sparse plot, the DBH and stem curve estimates had a root-mean-squared error (RMSE) of 0.60 cm (2.2%) and 1.2 cm (5.0%), respectively, whereas the corresponding values for the obstructed plot were 0.92 cm (3.1%) and 1.4 cm (5.2%). By combining the stem curves extracted from the under-canopy UAV laser scanning data with tree heights derived from above-canopy UAV laser scanning data, we computed stem volumes for the detected trees with a relative RMSE of 10.1% in both plots. Thus, the combination of under-canopy and above-canopy UAV laser scanning allowed us to extract the stem volumes with an accuracy comparable to the past best studies based on TLS in boreal forest conditions. Since the stems of several spruces located on the test sites suffered from severe occlusion and could not be detected with the stem-based method, we developed a separate work flow capable of detecting trees with occluded stems. The proposed work flow enabled us to detect 98% of trees in the sparse plot and 93% of the trees in the obstructed plot with a 100% correction level in both plots. A key benefit provided by the under-canopy UAV laser scanner is the short period of time required for data collection, currently demonstrated to be much faster than the time required for field measurements and TLS. The quality of the measurements acquired with the under-canopy flying UAV combined with the demonstrated efficiency indicates operational potential for supporting fast and accurate forest resource inventories.

Attitudes toward Plants: Comparing the Impact of Instruction through Writing & through a Botanical Garden Trip

We designed and implemented two instructional approaches to plant education, with the intention of supporting positive attitudes toward plants among sixth-grade students (11–13 years old). In one instructional approach, students prepared a book about plants that have interesting characteristics. In the other approach, students visited a botanical garden. The purpose of the study was to compare the effects of these approaches on students' attitudes toward plants. A matched-pairs experimental design was used in the research. A total of 56 students (28 in each group) participated in the study. Data were gathered by using the Plant Attitude Questionnaire. This instrument consisted of 28 items using a five-point Likert scale and included four dimensions of attitudes toward plants: importance, urban trees, interest, and utilization. Our results indicate that instruction via writing a book about plants with interesting characteristics is a good way to support students' positive attitudes toward plants; this approach was especially effective in the dimensions of interest and utilization. The botanical garden trip was also effective, though in a more limited way, in supporting students' positive attitudes toward plants; this approach was most effective in the dimension of urban trees.

Quantitative and qualitative approaches to assess tree vigor and stand health in dry pine forests

Despite a critical need to evaluate effectiveness of forest treatments in improving stand health, practitioners lack quantitative, repeatable metrics to assess tree vigor and stand health. We evaluated canopy and whole tree attributes of ponderosa pine (Pinus ponderosa Dougl. Ex Laws) related to carbon balance, water balance, and susceptibility to insects and pathogens in dry, pine-dominated forest stands during a multi-year drought, an environmental challenge to stand resilience. Metrics of trees in two unmanaged, and seven treated forested stands, in both uplands and lowlands to develop the quantitative approach. Whole tree and crown attributes including needle length and color, branchlet length and diameter, needle retention (needle ages and retention within ages), and frequency of insects, fungi, and abiotic needle damage were statistically selected to assess tree vigor. Cluster analysis of vigor attributes revealed that trees responded or persisted independently within a forest treatment; forest treatments did not necessarily yield similar tree responses within a stand. A rapid, qualitative assessment was developed to rank trees as low, average, and above-average vigor. To demonstrate an application of our approach, trees were ranked annually over six years in most stands, as well as in a stand where the prescription was adjusted due to the evaluation. The proportion of trees in the three tree vigor ranks differed, suggesting differing levels of stand health. Quantitative metrics and qualitative ranking of tree vigor could assist in selecting trees to be retained to meet specific management objectives, to evaluate treatment implementation, and to monitor post-treatment changes in stand health.

Twenty-Five Years after Stand Thinning and Repeated Fertilization in Lodgepole Pine Forest: Implications for Tree Growth, Stand Structure, and Carbon Sequestration

Silvicultural practices such as pre-commercial thinning (PCT) and repeated fertilization have been used successfully around the world to increase forest biomass for conventional wood products, biofuels, and carbon sequestration. Two complementary studies were designed to test the hypotheses (H) that large-scale PCT and PCT with repeated fertilization of young (13–17 years old) lodgepole pine (Pinus contorta var. latifolia) stands, at 25 years after the onset of treatments, would enhance (H1) productivity and structural features (diameter and height growth, crown volume and dimensions) of crop trees; (H2) merchantable volume of crop trees, (H3) abundance of understory conifer, herb and shrub layers, and (H4) carbon storage (sequestration) of all layers. Results are from two studies in south-central British Columbia, Canada. The PCT study had three densities: 500, 1000, and 2000 stems/ha, an unthinned, and old-growth stand replicated at three areas. The PCT-FERT study had four densities: 250, 500, 1000, and 2000 stems/ha with and without a repeated fertilization treatment, and an unthinned-unfertilized stand, replicated at two areas. Heavily thinned (≤1000 stems/ha) and fertilized stands generally had larger mean diameters and crown dimensions than lightly thinned or unfertilized stands, whereas mean heights of crop trees remained relatively unaffected, and hence partial support for H1. Despite differences in stand density (4- and 8-fold) of original crop trees, ingress of intermediate crop trees over the 25 years changed density dramatically. There was no support for H2, as mean merchantable volume of total crop trees was similar across stand densities owing to ingress, and was also similar in fertilized and unfertilized stands. In stands thinned to ≤500 trees/ha, there is an anticipated increase in crop tree density of 2.2 to 4.3 times over 25 years compared with the original post-thinning densities. Mean abundance of understory conifers was generally similar among stands owing to successional development towards canopy closure, whereas herbs and shrubs persisted only in canopy gaps in heavily thinned stands, thereby providing no support for H3. Mean carbon storage was similar across densities in both studies with ingress contributing a considerable amount to carbon sequestration at the lower densities. Fertilization increased (1.4 times) mean carbon storage significantly among total crop trees, total conifers, and the grand total of all layers, thereby providing partial support for H4. Thus, much of the potential above-ground carbon storage lost by thinning was restored in the heavily thinned stands at 25 years post-treatment.

Variabilidad espacial de Swietenia macrophylla en sistema agroforestal de la Amazonia brasileña

La caracterización del comportamiento de la variación espacial de atributos dendrométricos de especies tropicales en sistemas agroforestales es importante para su manejo y, en ese sentido, la geoestadística se destaca por utilizar técnicas capaces de caracterizar esa variación. Se utilizaron métodos geoestadísticos para evaluar y mapear la variabilidad espacial del diámetro a 1.3 m del nivel del suelo (dap), de la altura comercial (hc) y del volumen comercial (vc) de árboles de Swietenia macrophylla King, plantadas en un sistema agroforestal en la Amazonia brasileña. El muestreo de campo se realizó con base en una cuadrícula de 50 m × 50 m, que resultó en 36 puntos sistemáticos. En cada punto, se instaló una parcela circular de 500 m2 para medir el dap y la hc. El vc fue estimado con la ecuación mejor ajustada a los datos de cubicación de 108 árboles. Luego se modelaron los patrones de distribución espacial de las variables por medio de la geoestadística y se utilizó kriging ordinario para generar mapas con predicciones e incertidumbres de las variables. El modelo de Schumacher-Hall resultó en la mejor ecuación para estimar el vc y la cuadrícula sistemática utilizada mostró ser eficiente para detectar los patrones espaciales de esas variables. Los modelos de semivariogramas ajustados demostraron la fuerte dependencia espacial del dap, de la hc y del vc, lo que permitió hacer interpolaciones precisas, generando resultados de validación cruzada sin tendencia, principalmente para vc que presentó el modelo teórico mejor ajustado.

Changes of Technosol properties and vegetation structure along a chronosequence of dredged sediment deposition in areas with alluvial gold mining in Colombia

PurposeAlluvial gold mining leaves a vast amount of dredged sediment that covers the natural soil, destroys riparian ecosystems, and impacts riverbeds and valleys. In Colombia, more than 80,000 ha are covered by dredged sediment. Technosols developed from such deposits undergo strong transformations during the early stages of formation due to the diverse nature of the constituents. The aims of this study are (i) to investigate changes in soil morphological and physicochemical properties at early stages of pedogenesis, (ii) to estimate the variability of size structure distribution of the new plant cover as affected by the time period since establishment and deposit type, and (iii) to determine which soil parameters correlate best with the size structure distribution of vegetation.Materials and methodsSoil characterization through morphological and physicochemical analysis was conducted on Technosols developed from gravel and sandy deposits of different ages (0–12 years). A vegetation survey was conducted to measure tree dimensions and identify the most common species. Data were analyzed using non-parametric tests to avoid the loss of information due to data smoothing.Results and discussionThe studied Technosols are subject to processes similar to those occurring in natural parent materials such as mineral transformations, changes in redox conditions, organic matter accumulation in the topsoil, and a rapid differentiation of horizons. However, the Technosols in our study sites show an unusually fast development not often observed in natural soils, with drastic changes observed at very early stages of formation. Gravel deposits offer more favorable conditions for plant growth, and marked changes in pedogenic processes can be observed compared with sandy deposits, which are reflected in changes of chemical properties.ConclusionsFactors such as the technology used for mining and the continuous deposition of dredged sediments in a cumulative way during the exploitation period, as well as the disturbances after deposition, result in a high diversity of constituents and high heterogeneity of dredged sediment deposits. Gravel and sand deposits, originated from the same sections of the river and after similar separation processes for ore extraction, undergo divergent pedogenic processes at different rates, which could be explained by a remarkable effect of particle size distribution. For vegetation establishment, the selection of tree species should be based on their capacity for nutrient pumping through deep rooting to sequester carbon and to adapt morphologically to heterogeneity in nutrient availability by growing roots in nutrient-rich zones.

Decision Tree Based Interference Recognition for Fog Enabled IOT Architecture

The cyber-attacks nowadays are becoming more and more erudite causing challenges in distinguishing them and confining. These attacks affect the sensitized information’s of the network by penetrating into the network and behaving normally. The paper devises a system for such interference recognition in the internet of things architecture that is aided by the FOG. The proposed system is a combination of variety of classifiers that are founded on the decision tree as well as the rule centered conceptions. The system put forth involves the JRip and the REP tree algorithm to utilize the features of the data set as input and distinguishes between the benign and the malicious traffic in the network and includes an decision forest that is improved with the penalizing attributes of the previous trees in the final stage to classify the traffic in the network utilizing the initial data set as well as the outputs of the classifiers that were engaged in the former stages. The proffered system was examined using the dataset such BOT-Internet of things and the CICIDS2017 to evince its competence in terms of rate of false alarm, detection, and accuracy. The attained results proved that the performance of the proposed system was better compared to the exiting methodologies to recognize the interference.

Heritage Trees in Macau: Relationships Among Biomass Structure, Age, and Ecosystem Services

Older trees in good health are expected to provide more ecosystem services and equivalent economic values due to their large size. The relationship of tree dimensions, respective tree height, crown area, diameter at breast height (dbh), and total leaf area vis-a-vis age were studied for 790 heritage trees ≥ 100 years old in Macau; 50 genera and 63 species were represented. Seven out of ten common genera showed no significant increase for all tested parameters except increase of dbh with age. Other factors, such as condition and geometry of growing spaces, controlled the performance of heritage trees, as well as the realization of their biological potential size, with implications on the provision of ecosystem services. The effects of these heritage trees on air-quality improvement and gross carbon sequestration were quantified by the i-Tree Eco model. Overall, 806.8 kg of air pollutants were removed annually, with benefits valued at US $8,091. The heritage trees stored 3,041 t carbon in total and sequestered 842 kg carbon/yr, equivalent to US $601 in annual benefits. The values were much higher than ordinary urban forest trees. Ten common heritage tree genera were ranked by their capacities for air quality improvement, carbon storage, and sequestration. The findings can serve as a decision tool for heritage tree management and conservation and to estimate potential ecosystem services of established trees

The Role of Vegetation in the Morphological Decoding of Lisbon (Portugal)

In the academic context, especially in the fields of architecture, landscape architecture, and urbanism, urban form studies are assumed to be a vehicle for reflection on the built and unbuilt city. This essay aims to challenge the most common and stabilized morphological approaches in the city reading process, invoking vegetation and its role as an element of urban composition that is recurrently left out of it. Methodologically, this work uses the city of Lisbon to carry out a morphological characterization of different homogeneous areas based on a decomposition process of urban systems and elements. The article focuses on the reading of the public component of three homogeneous areas in Lisbon—Alfama, Avenidas and Alvalade—and specifically on the role of urban greenery as a systemic element of the formal or informal composition of the city. Through an initial systematization process reflects upon the formal attributes of vegetation and trees in particular, this research may contribute not only to the development of the discipline of urban morphology applied to the city of Lisbon but also to the acknowledgment of urban greenery as a contributor to the creation of specific, unique, and unrepeatable spaces within urban landscapes.

The fractal geometry of bronchial trees differs by strain in mice.

Fractal biological structures are pervasive throughout the plant and animal kingdoms, with the mammalian lung being a quintessential example. The lung airway and vascular trees are generated during embryogenesis from a small set of building codes similar to Turing mechanisms that create robust trees ideally suited to their functions. Whereas the blood flow pattern generated by these fractal trees has been shown to be genetically determined, the geometry of the trees has not. We explored a newly established repository providing high-resolution bronchial trees from the four most commonly studied laboratory mice (B6C3F1, BALB/c, C57BL/6 and CD-1). The data fit a fractal model well for all animals with the fractal dimensions ranging from 1.54 to 1.67, indicating that the conducting airway of mice can be considered a self-similar and space-filling structure. We determined that the fractal dimensions of these airway trees differed by strain but not sex, reinforcing the concept that airway branching patterns are encoded within the DNA. The observations also highlight that future study design and interpretations may need to consider differences in airway geometry between mouse strains.NEW & NOTEWORTHY Similar to larger mammals such as humans, the geometries of the bronchial tree in mice are fractal structures that have repeating patterns from the trachea to the terminal branches. The airway geometries of the four most commonly studied mice are different and need to be considered when comparing results that employ different mouse strains. This variability in mouse airway geometries should be incorporated into computer models exploring toxicology and aerosol deposition in mouse models.

PENGARUH UMUR TANAMAN TERHADAP DIMENSI POHON SENGON (Paraserianthes falcataria. L) PADA KETINGGIAN TEMPAT TUMBUH YANG BERBEDA

Sengon (Paraserianthes falcataria) can grow from beach to 1600 m sal. The influence of P. falcataria growth cannot be studied because the growth and development of a species is determined by genetic factors (G), environmental factors (E), and interactions between environmental and genetic factors (G + E). The objects of studies is the effect of plant age and altitude of the growing place against the dimension of P.falcataria and obtain the age of plant and altitude that produce the best tree dimension. The research method used experiments using Split Plot with two factors. The main plot factor is the height of the P. falcataria growing site. Results of studies were an interaction between the heights of the place with the age of P.falcaria plants against the volume of P. falcataria. The interaction of the total height and diameter based on the altitude of 825 m sal and the age of P. Falcatia 9 years produced the highest volume of P. falcataria with age of 7 years.

Sawlog quality and tree dimensions of Scots pine 34 years after artificial moose browsing damage

Moose ( L.) browsing causes severe damage in Scots pine ( L.) seedling stands. The effects of this damage on the quality of sawlogs were studied in a long-term controlled experiment. This article reports the stem size and external quality characteristics of Scots pine stems 34 years after artificial moose browsing damage. Damaging the trees by clipping the main stem at the seedling stage reduced the diameter, height, and tree volume of the trees at the end of the experiment. The tree growth reduction was dependent on the severity of clipping. The differences between the damaged and the control trees were more obvious in diameter than in height at the time of final felling. Stem form defects and vertical branches were the most typical externally detectable defects caused by clipping. Defects in the butt logs were detected in 71–89% of the damaged trees, depending on the clipping treatment severity. The stronger the clipping treatment, the more likely the stem form was defected and the more commonly were vertical branches and crooks detected in the stems. The results indicate that both tree dimensions and stem quality suffer from moose browsing. The findings of this controlled experiment more likely underestimate than overestimate the damage in comparison to real moose browsing. Further analyses are required to assess the effects of browsing damage on the internal quality of sawlogs and subsequent economic outcomes.Alces alcesPinus sylvestris

Metric Dimension of Skeletal Trees of Unicyclic Graphs

The smallest subset M ⊂ V of a graph G = (V, E) such that for any pair u, v ∈ V there exists at least one vertex t ∈ M with dG(t, v) 6= dG(t, u), is called a metric basis of G, and its cardinality |M| is called the metric dimension of G and denoted by dim(G). Since it is known that finding the metric dimension of a graph is NP-hard problem, finding the metric dimension of a graph is usually carried out in certain directions such as description of graph classes for which the metric dimension can be found in polynomial time and calculation of the metric dimension of certain, well-known families of graphs (such as grid graphs, wheels, etc.). One of these areas of research deals with characterization of graph families having a constant metric dimension. In particular, it has been proven that a graph has the metric dimension 1 if and only if it is a path. It is also known that metric dimensions of the cycle Cn, the complete graph Kn and the complete bipartite graph Ks,t are equal to 2, n − 1 and s + t − 2, respectively. Another area of research on the metric bases of graphs is the finding the metric dimension of graphs obtained by operations on graphs whose metric bases are known. In this paper, we present the relationship between a unicyclic graph (a graph with exactly one cycle) with metric dimension 2 and the metric dimension of its spanning trees. Since the corresponding spanning trees for a graph are determined ambiguously, depending on the method of deleting the edge to obtain such a tree, its metric dimension may also change. The present paper describes conditions under which a spanning tree of a unicyclic graph G with dim(G) = 2 has the metric dimension from 1 to 4.

INFLUENCE OF FERTILIZATION ON GROWTH OF YOUNG CHESTNUT TREES (Castanea sativa MILL.) MANAGED FOR WOOD PRODUCTION

ABSTRACT In Portugal, chestnut wood demand has increased in the last decades. Since chestnut plantations are usually established in low fertility soils, addition of N, P and K as fertilizers usually have a benefic effect in increasing wood productivity. The study aims to evaluate the effects of fertilization on growth of chestnut tree (Castanea sativa Mill.) cultivated for wood purposes. An experimental essay was established in a 3-year old chestnut tree stand with a planting spacing of 3.5 × 3.0 m. Four treatments were applied to randomized blocks with three repetitions: control (C), addition of phosphorus (P), addition of phosphorus and potassium (PK) and addition of nitrogen, phosphorus, and potassium (NPK). The chemical properties of the soil and the concentration of nutrients in the leaves were evaluated after the treatment, and measurements of tree diameter and stem height were made for a monitoring period of 4 years. Treatments did not affect soil properties or leaf nutrient concentrations. On the counterpart, the effect of the fertilizers was noticed for tree dimensions and growth. Gains of NPK in relation to the control were observed for the height variable, over the years. Seven years after application of the treatments, differences were also noticed for the diameter and the volume index variables. The NPK treatment has presented a significant effect on tree growth compared to the control, with noticeable gains in the stem height.