Sample Trees Research Articles

Identification of a Novel Geminivirus in Fraxinus rhynchophylla in Korea

Fraxinus rhynchophylla, common name ash, belongs to the family Oleaceae and is found in China, Korea, North America, the Indian subcontinent, and eastern Russia. It has been used as a traditional herbal medicine in Korea and various parts of the world due to its chemical constituents. During a field survey in March 2019, mild vein thickening (almost negligible) was observed in a few ash trees. High-throughput sequencing of libraries of total DNA from ash trees, rolling-circle amplification (RCA), and polymerase chain reaction (PCR) allowed the identification of a Fraxinus symptomless virus. This virus has five confirmed open reading frames along with a possible sixth open reading frame that encodes the movement protein and is almost 2.7 kb in size, with a nonanucleotide and stem loop structure identical to begomoviruses. In terms of its size and structure, this virus strongly resembles begomoviruses, but does not show any significant sequence identity with them. To confirm movement of the virus within the trees, different parts of infected trees were examined, and viral movement was successfully observed. No satellite molecules or DNA B were identified. Two-step PCR confirmed the virion and complementary strands during replication in both freshly collected infected samples of ash tree and Nicotiana benthamiana samples agro-inoculated with infectious clones. This taxon is so distantly grouped from other known geminiviruses that it likely represents a new geminivirus genus.

Effects of a selective thinning on wind loading in a naturally regenerated balsam fir stand

Recent trends in forest management promote the development of stands with a complex structure involving the use of partial cuts of various types. Partial cuts can increase the risk of wind damage but prior research on wind damage has largely focused on simple stand types and new modeling approaches are needed for these more complex stands. The present study looked at how the wind loading distribution in a naturally regenerated balsam fir (Abies balsamea (L.) Mill.) stand is modified by a local selective thinning. Two anemometers placed at canopy height and 2/3 canopy height, and strain gauges attached to the trunks of balsam fir trees allowed us to measure the wind-induced turning moments experienced by a sample of trees. A localized thinning was implemented around 2/3 of the sample trees in the second year of the experiment. Competing trees were removed within a 3.5 m radius of residual trees. Results show a dominant effect of the selective thinning at the tree scale but with an additional effect at the stand scale. The stand scale effect is likely linked to a change in wind profile within the canopy. A distance-independent competition index was useful in explaining the wind load distribution within the stand. Trees experiencing more competition were exposed to the largest increase of turning moment after the selective thinning. This study confirms the potential of competition indices for wind damage modeling in heterogeneous stands.

Simple Allometry To Estimate The Aboveground Tree Biomass For Five Cool-Broadleaved Species Of Bhutan Himalaya

Million tons of carbon was found to be stored in the forest biomass with maximum storage capacity in the broadleaved trees. Developing tree biomass allometric equation being considered fundamental to determine the carbon sequestration potential of tree species. Thus, five broadleaved tree species of Quercus lamellosa, Beilschemidia sikkimensis, Castonopsis hystrix, Persea clerkania and Symplocos sumintia were destructively sampled using Randomized Branch Sampling technique (RBS) to develop allometry for aboveground biomass estimation in cool broadleaved forests in Bhutan. The total of 159 sample trees with minimum 32 trees from each species under different diameter class (5 cm < 90 cm), height class (4 m < 46 m) from four physiographic zones were sampled. The observed total aboveground dry biomass of the trees ranges from 4.12 < 5579.31 kg; 3.62 < 3464.51 kg; 5.99 < 3600.52; 8.89 < 3689.82 kg; kg and 7.08 < 2993.22 kg respectively for above five species. Linear regression was attributed to heteroskedasticity with un-equal distribution of the residual errors. While linearized regression with transformed variables exhibited the best fit line for biomass estimation. Significant prediction of aboveground tree biomass was observed with natural log base transformed linearized power function of DBH -tree height relationships (t (29) = 11.91, 1.63, p ≤ .001) R² = .98) followed by the transformed model of DBH as independent variable (t (30) = 34.31, p ≤ .001) R² = .97). Therefore, the study concluded that, linearized power function with antilog bias correction factor seemed better in predicting aboveground tree biomass of cool broadleaved species in Bhutan

Classification of Typical Tree Species in Laser Point Cloud Based on Deep Learning

We propose the Point Cloud Tree Species Classification Network (PCTSCN) to overcome challenges in classifying tree species from laser data with deep learning methods. The network is mainly composed of two parts: a sampling component in the early stage and a feature extraction component in the later stage. We used geometric sampling to extract regions with local features from the tree contours since these tend to be species-specific. Then we used an improved Farthest Point Sampling method to extract the features from a global perspective. We input the intensity of the tree point cloud as a dimensional feature and spatial information into the neural network and mapped it to higher dimensions for feature extraction. We used the data obtained by Terrestrial Laser Scanning (TLS) and Unmanned Aerial Vehicle Laser Scanning (UAVLS) to conduct tree species classification experiments of white birch and larch. The experimental results showed that in both the TLS and UAVLS datasets, the input tree point cloud density and the highest feature dimensionality of the mapping had an impact on the classification accuracy of the tree species. When the single tree sample obtained by TLS consisted of 1024 points and the highest dimension of the network mapping was 512, the classification accuracy of the trained model reached 96%. For the individual tree samples obtained by UAVLS, which consisted of 2048 points and had the highest dimension of the network mapping of 1024, the classification accuracy of the trained model reached 92%. TLS data tree species classification accuracy of PCTSCN was improved by 2–9% compared with other models using the same point density, amount of data and highest feature dimension. The classification accuracy of tree species obtained by UAVLS was up to 8% higher. We propose PCTSCN to provide a new strategy for the intelligent classification of forest tree species.

Yield estimation of citrus fruit using rapid image processing in natural background

Yield estimation can provide critical information for high-value crop growers. It helps them to plan and coordinate the logistics of harvesting operations. Most existing yield estimation techniques are based on manual sampling and statistical approaches, which are complex, labor-intensive, and time-consuming. In recent years, advances in image processing and the ubiquitous use of autonomous platforms, such as unmanned aerial platforms, have provided an opportunity for faster and more accurate yield estimation techniques for different crops. A new rapid, efficient, and accurate image processing algorithm was proposed in this study. The image segmentation technique was able to separate mature citrus trees and natural background in CIE (Commission International Eclairage) L*a*b* (i.e., Lab) color space. The effect of camera distance to object, affected resolution, and detection accuracy were evaluated and discussed. The results showed that the distance between 1.524 meters (5 feet) and 2.134 meters (7 feet) could provide high detection accuracy. The number of correctly counted fruit reached 91.69% at the average processing time of 1.1 s per picture for 132 pictures. A correlation coefficient (R2) of 0.98 was obtained between the citrus counting algorithm and counting performed through human observation of 66 sample trees. The comparative analysis of the proposed method showed a higher accuracy rate and robustness compared to other similar studies.

DAUR VOLUME OPTIMAL JATI DI HUTAN RAKYAT (STUDI KASUS DI DESA GIRIKARTO, KECAMATAN PANGGANG, KABUPATEN GUNUNG KIDUL

The aim of this research is to define rotation of optimal volume production of teak private smallholder forest. Sample of trees were taken by using purposive sampling method in cutting activity area. Seventy trees have choosen by diameter distribution, healthy and straigh stem. Every sample trees were measured with stem analysis method. Rotation of maximum volume production define by growth curve, mean annual increament (MAI) and current annual increament (CAI) curve. The result show that height youth stage begin 2 until 6 year, diameter youth stage begin 3 until 10 year, volume youth stage begin 4 until 25 year and rotation of maximum volume production is 25 year. 
 Key words: Rotation of optimal volume production, Stem analysis, Growth curve

Kuidas uurida arheoloogilist nahkjalatsit? Kadrioru kogelt leitud nahkjalatsite näitel / How to study archaeological leather footwear? An example of finds from a Kadriorg Cog

In 2015 two shipwrecks were found during construction works for the Tivoli housing development at Kadriorg in Tallinn. These wrecks lay 50 metres from one another. The archaeologists were then faced by a puzzle from the past that different specialists set out to solve. For the purpose of a dendrochronological analysis, samples of wood were taken from both ships (which were given the names the Viljo and the Peeter). The pine trees used to build the Viljo had been cut down after 1487, which makes the wreck the oldest preserved evidence of shipbuilding in this area. Sixteen samples were taken from the Peeter and, apart from one pine tree sample, all of these were oak. Analysis showed that the ship had been built in 1296 AD terminus post quem; the wood had probably grown in eastern Poland, or somewhere further to the east.
 There were approximately 300 footwear fragments among the finds, some of them complete, and requiring further study. The location of footwear fragments can be seen on Photo 1. Photo 2 shows how a footwear item cleared from surface during the excavations looks, and Photo 3 features a footwear item after washing. The first and most important task was to determine which items had sunk with the ship, and which may have been left at the site at a later date. The dating of the artefacts and ship’s timber pointed to the 13th–14th centuries as the focal point of time. This is, however, not sufficient: in order to gain more precise information, it is important to know the development of footwear-making techniques through history; and knowledge of materials is an asset. Out of the registered 82 finds (n.b. several details amongst them belonged to other items), I dated 25 findings as belonging to the end of the 13th and the beginning of the 14th century.
 All the finds are preserved at the Estonian Maritime Museum; the cog Peeter and a selection of the findings are exhibited in the hall of Paks Margareeta tower in Tallinn.
 In my Master’s Thesis, I analysed the techniques, cutting patterns and materials used to make the footwear. The methods and the knowledge needed are laid out in the present article where I describe the documentation of finds MM 15329:222 and MM15329:288.
 Studying archaeological footwear begins at the moment it is cleared from the soil. The task of a calceologist is to identify which footwear fragments belong together, to record the find, to instruct the conservator, and to secure adequate preservation conditions for the find.
 For the purposes of documentation, it helps to be aware of the nature of leather as a material, how it becomes archaeological leather, and which methods should be used for the research. Knowledge of the techniques and their development over time is important for obtaining as accurate information as possible about the date of their manufacture. For recording details, it is necessary to take photos and to make drawings of the fragments using original, or pre-existing, symbols. The drawings must include the stitches used to join details because it is just such information that plays a key role in dating the footwear. Should one wish to reconstruct the footwear, it is worthwhile to compose cutting patterns using, for example, silk paper. The conserved and documented finds should be preserved or exhibited, preferably with the help of 3D support, because this offers a good view of the construction. I hope the article inspires many a reader to look at our everyday footwear differently.
 Keywords: footwear, archaeology, calceology, cogs, leather shoes

First Report of 'Candidatus Phytoplasma ziziphi' in Sweet Potato in China.

Sweet potato (Ipomoea batatas; family Convolvulaceae) is an important food crop and serves as a ground cover in orchards of jujube trees. In August 2020, sweet potatoes growing under jujube trees showed obvious jujube witches' broom phytoplasma disease symptoms in an abandoned jujube orchards in Xinzheng county, Henan province, China (GPS：113°49'56″N， 34°35'54″E). The sweet potato plants were showing symptoms such as small, yellowing leaves and witches' broom. (Figure 1). The incidence of symptomatic sweet potato plants in the orchard (60× 100 m2 ) was about 60%. Leaf samples of sweet potatoes and jujube trees exhibiting disease symptoms were collected to confirm the presence of JWB phytoplasma by PCR. The phytoplasma primers R16mF2/R16mR1 (Gundersen and Lee, 1996) and secAfor1/secArev3 (Hodgetts et al., 2008) were used. Leaf samples of three sweet potato plants and three jujube trees exhibiting disease symptoms were collected to confirm the presence of JWB phytoplasma by PCR. Two healthy sweet potatoes collected from the experimental station at Henan Agricultural University and two healthy, in vitro-grown jujube plantlets were used as negative controls. A JWB-diseased in vitro-grown jujube plantlets was set as the positive control. The total DNA of 3 leaves from each sample was extracted using the Hi-DNA secure Plant Kit (DP350, TianGen, Beijing, China). The phytoplasma amplicon was detected in all leaf samples (Figure 2). The expected 16S rDNA (GenBank accession number MW990090) amplicon is 1,348 bp, and the expected secA (GenBank accession number MZ292648) amplicon is 842 bp. These two fragments were detected in the sweet potato samples (Figure 2a, 2b). The DNA fragment amplified from the diseased sweet potato and the diseased jujube leave samples exhibiting disease symptoms using the 16S rRNA primers was then sequenced (Sangon Biotech, Shanghai, China) and was 100% identical to that of 23 JWB phytoplasma strains through BLAST analysis. The DNA fragment amplified using the secA primers was sequenced and was 100% identical to that of JWB phytoplasma strain ZQ secA gene (GU471770.1). RFLP analysis of the 16S rRNA sequence fragment by the online tool iPhyClassifier (Wei et al., 2007) indicated that the pathogen strain was a member of subgroup 16SrV-B and a 'CandidatusPhytoplasmaziziphi'-related strain. Sweet potato witches' broom disease was reported by Gundersen (1994) and Lee, I. M. (2004). Sweet potato little leaf disease was reported and classified as a phytoplasma in the 16 SrII group (Tairo et al., 2006). According to the evolutionary analysis, the 16S rRNA nucleotide sequences found in sweet potato in this study were quite different from that detected in sweet potato little leaf disease (Figure 2c). Taken together, the results indicated that the phytoplasma associated with sweet potato in the present study is a 'Ca. Phytoplasma ziziphi' strain. To our knowledge, this is the first report of its presence in sweet potato in China.

Energy Stored in Above-Ground Biomass Fractions and Model Trees of the Main Coniferous Woody Plants

The paper considers energy stored in above-ground biomass fractions and in model trees of the main coniferous woody plants (Picea abies (L.) H. Karst., Abies alba Mill., Pinus sylvestris (L.), Larix decidua Mill.), sampled in 22 forest stands selected in different parts of Slovakia. A total of 43 trees were felled, of which there were 12 spruces, 11 firs, 10 pines, and 10 larches. Gross and net calorific values were determined in samples of wood, bark, small-wood, twigs, and needles. Our results show that these values significantly depend on the tree species, biomass fractions, and sampling point on the tree. The energy stored in the model trees calculated on the basis of volume production taken from yield tables increases as follows: spruce < fir < pine < larch. Combustion of tree biomass releases an aliquot amount of a greenhouse gas—CO2, as well as an important plant nutrient, nitrogen—into the atmosphere. The obtained data must be taken into account in the case of the economic utilization of energy stored in the fractions of above-ground tree biomass and in whole trees. The achieved data can be used to assess forest ecosystems in terms of the flow of solar energy, its accumulation in the various components of tree biomass, and the risk of biomass combustion in relation to the release of greenhouse gases.

Characterization of a Novel Emaravirus Affecting Ash Species (Fraxinus spp.) in Europe

We identified a novel virus in diseased European ash (Fraxinus excelsior) and manna ash (F. ornus) trees exhibiting chlorotic ringspots, mottle and leaf deformation such as curling and shoestring symptoms. High-throughput sequencing (HTS, Illumina RNASeq) of total RNA isolated from diseased leaf material in combination with RT-PCR-based amplification techniques and Sanger sequencing determined five complete genome segments, each encoding a single open reading frame. Sequence analyses of RNA1–RNA5 revealed a genome organization typical for emaraviruses, i.e., (i) conserved and complementary terminal 5′ and 3′ termini of each genome segment (ii) proteins showing significant homologies to the RNA-dependent RNA polymerase (RdRP) encoded by RNA1, the glycoprotein precursor (GPP) encoded by RNA2, the viral nucleocapsid protein (N, RNA3), the movement protein (MP, RNA4), and a protein of 26 kDA (P26, RNA5) highly similar to proteins of unknown function encoded by other emaraviruses. Furthermore, we identified spherical particles (double-membrane bodies, DMB) of different sizes (70–80 nm in diameter) which are typical for emaraviruses exclusively in virus-infected leaf tissue exhibiting mottle and leaf deformation. Sequence comparison and phylogenetic analyses confirmed the identified novel virus as a new member of the genus Emaravirus. We established a species-specific RT-PCR detection protocol and could associate the observed disease symptoms with the infection of the novel emaravirus in F. excelsior and F. ornus. Therefore, we propose the name ash shoestring-associated emaravirus (ASaV). Investigation of ASaV-infected sample trees originating from different locations in Switzerland, Germany, Italy and Sweden provided a wide geographical distribution of the virus in affected ash species. To our knowledge, this is the first confirmation of an emaravirus affecting ash tree species with shoestring symptoms of leaves in Europe.

Volume, biomass, carbon sequestration and potential of desert lands’ afforestation irrigated by wastewater on examples of three species

A study was conducted on three species (Khaya senegalensis, Corymbia citriodora and Casuarina equisetifolia) planted in desert lands of Egypt and irrigated with basic treated municipal wastewater. Every single tree is permanently drip irrigated and at the same time fertilised by the nutrient-rich wastewater. Trees of different classes of the diameter at breast height (eight for each species) were felled to determine the form factor and stem volume, as well as the biomass and carbon sequestration of stem, crown and root of the individual trees. In addition, a scenario for the development of un-thinned stands from ages 5 to 35 years was constructed. The age of the sample trees at felling was: 128, 66 and 82 months for K. senegalensis, C. citriodora and C. equisetifolia, respectively. The vigorous sampled trees had a stem volume of 0.289, 0.162 and 0.229 m3 and an aboveground and belowground biomass of 451, 161 and 264 kg for K. senegalensis, C. citriodora and C. equisetifolia, respectively. Results of the scenario showed an unexpectedly high growth rate of afforestation in desert lands using municipal wastewater. At the age of 25, the stem volume for all three species exceeds 398 m3/ha. At the same age of 25 years, K. senegalensis, C. citriodora and C. equisetifolia sequester 1131, 1068 and 860 CO2 t/ha, respectively. Afforestation in desert areas presents a unique situation in forestry, as growth is stimulated by sufficient sunlight, water and nutrients. Competition for water and nutrients is strongly diminished. Self-thinning of stands under such conditions is expected to be much slower than in rain-fed plantation forests. On the other hand, tree maturity span is curtailed. This opens new possibilities for different forest management and practices towards resilient forest-based mitigation of climate change. For its unexpected role as an effective mitigation measure, afforestation in desert lands should be encouraged and further research conducted.

Variation of Triterpenic Acids in 12 Wild Syzygium formosum and Anti-Inflammation Activity on Human Keratinocyte HaCaT.

Syzygium formosum (Wall.) Masam leaf is known as a Vietnamese traditional herbal medicine used to treat atopic dermatitis and stomach ulcers. Recently, its potent anti-allergic effects were reported with possible active compounds analysis. Here, we collected S. formosum leaves from 12 wild trees and compared compositions of triterpenic acids (TA) with Centella asiatica. Anti-inflammatory activities of S. formosum leaf extract (SFLE) was compared with C. asiatica extract (CAE) using human keratinocyte, HaCaT. In this study, up to seven TAs were identified in SFLE, while only madecassic and asiatic acids were detected in the CAE. Total TA content varied among SFLE, but asiatic, corosolic, and betulinic acids were the major components. Surprisingly, wild tree sample 12 (S12) contained total TA of 27.2 mg/g dry-leaves that was 5-fold greater than that in the C. asiatica sample, and S4 had the highest content of asiatic acid (12.6 mg/g dry-leaves) that accounted for 50% of the total TA. S4 and S12 showed more than 3-fold higher anti-oxidative power than the CAE. In the UVB irradiation model, S4 and S12 (5 μg/mL) strongly repressed mRNA levels of pro-inflammatory cytokines (IL-1β, IL-6, and IL-8) and COX-2, while the CAE at the same condition showed moderate or weak repression. The difference in anti-inflammation effects between the SFLE and the CAE was also confirmed by protein quantifications. Taken together, SFLE has great potentials as a new cosmeceutical ingredient with a higher amount of skin-active phytochemicals.

GACM: A Graph Attention Capsule Model for the Registration of TLS Point Clouds in the Urban Scene

Point cloud registration is the foundation and key step for many vital applications, such as digital city, autonomous driving, passive positioning, and navigation. The difference of spatial objects and the structure complexity of object surfaces are the main challenges for the registration problem. In this paper, we propose a graph attention capsule model (named as GACM) for the efficient registration of terrestrial laser scanning (TLS) point cloud in the urban scene, which fuses graph attention convolution and a three-dimensional (3D) capsule network to extract local point cloud features and obtain 3D feature descriptors. These descriptors can take into account the differences of spatial structure and point density in objects and make the spatial features of ground objects more prominent. During the training progress, we used both matched points and non-matched points to train the model. In the test process of the registration, the points in the neighborhood of each keypoint were sent to the trained network, in order to obtain feature descriptors and calculate the rotation and translation matrix after constructing a K-dimensional (KD) tree and random sample consensus (RANSAC) algorithm. Experiments show that the proposed method achieves more efficient registration results and higher robustness than other frontier registration methods in the pairwise registration of point clouds.

Assessment of foliar dusts metals burden as indicators of heavy metals contamination in Kano metropolis, Nigeria

ABSTRACT Plants have been used as biological filters by taking advantage of their capacity to remove dust and heavy metals from the air, which make them effective biomonitors to detect the presence of these metals even at trace levels. The present study was aimed to assess the levels of heavy metal in foliar dust of some selected urban trees along the roadside in Sauna Kawaji, Magwan, Kwanar Ganduje, and Nassarawa GRA of Kano Metropolis. From each sample site, leaf samples of neem trees (Azadirachta indica) were randomly collected along the roadside. The leaves were processed, digested and analysed by atomic absorption spectrometry. From the results, site variation showed that Zinc, Manganese, and Cadmium had the highest levels of 0.019, 0.137 and 0.0039 mg/L at Magwan and Kwanar Ganduje, respectively. In the evening hours, zinc, manganese and cadmium had the highest levels of 0.022, 0.140, and 0.002 mg/L at Magwan, Sauna Kawaji and Kwanar Ganduje, respectively. However, lead was not detected in all samples. Manganese was found to be the highest from all sampling sites, while cadmium had the least. However, the levels of the analysed metals were below the permissible limits of WHO and EPA. Therefore, foliar dust contained heavy metals in relative amount, which might be a cause of concern for environmental issues and could serve in environmental monitoring.

Fruit detection and load estimation of an orange orchard using the YOLO models through simple approaches in different imaging and illumination conditions

Fruit load estimation is an essential step toward Precision Agriculture (PA) as it helps growers more accurately predict market planning, worker planning, purchase of appropriate equipment and so on. Reliable and accurate estimation of fruit yield in an orchard with hundreds of trees needs automatic methods. In recent years, Deep Learning (DL) has been studied widely and applied in various fields of agriculture. Accordingly, the YOLO detection models were applied to detect and count ripe Dezful native orange in an orchard in southwestern Iran. The models were adapted through transfer learning and trained by Google Colaboratory in the RGB images to detect and count orange fruits. Models performance and accuracy of yield estimation for an orchard with 1115 trees were examined. The process was conducted in 3 steps, including training and testing the different versions of the YOLO models by creating an image dataset of orange trees in different illumination conditions, evaluating the models on 100 sample trees, and finally extracting the yield variation map of the orchard after detecting and counting the oranges on images taken from all the trees in the orchard. The precision, recall, F1-score and mAP of the YOLO-V4 as the best model for orange detection over the test images were 91.23%, 92.8%, 92%, and 90.8%, respectively. The overall performance of the models in nighttime and daytime imaging was not significantly different. The YOLO-V4 model was chosen to use for yield estimation in the orchard. The promising results show that the YOLO models can effectively provide researchers and agricultural activists with a simple and practical method for detecting and estimating the yield of orange fruits in an orchard. Significant differences were observed in yield estimation for two-side and four-side imaging. Accordingly, a combined imaging method including two-side and four-side imaging was proposed for thin and dense canopy, respectively. The map of fruit yield changes showed the spatial distribution of tree yield with a +9.19% error.

Morphological variation in the interspecific hybrid of Acacia (Acacia mangium × A. auriculiformis)

Acacia hybrid is an interspecific hybrid resulting from crossing between Acacia mangium and A. auriculiformis either naturally or artificially. This study aimed to determine the morphological variation of artificial Acacia hybrid, obtained by full-diallel control crossing. Observed sample trees were clones at the clonal test, established in 2011 in Wonogiri, Central Java. Tree samples were taken by selecting clones categorized into the superior, intermediate, and inferior clones based on their growth at one year of age, with three different clones in each category. Parameters to be observed were morphological characters including quantitative (tree height, diameter breast height, bole length, phyllode length and phyllode width) and qualitative (stem form, stem straightness, bark type, bark color, phyllode shape, phyllode apex shape, conspicuousness of the main vein, and petiole color). The data quantitative and qualitative were then scored and analyzed using NCSS series 12 software for cluster analysis. The results showed that morphological characters of Acacia hybrid clones varied across the tree categories. Furthermore, the dendrogram showed that the characters of Acacia hybrid grouped into two clusters: Cluster A dominated by superior and most intermediate clones, and Cluster B dominated by inferior clones. The study result implies the use of morphological characters of Acacia hybrid to select the hybrid vigor in a breeding program.

Characterization of bronze leaf disease in western Canadian aspen and poplar trees

Aspen and poplar trees are important horticultural plants grown in Canada for aesthetic, commercial woodlot and windbreak applications. Bronze leaf is a destructive disease in Populus spp. and is caused by the fungal pathogen Apioplagiostoma populi Barr. This pathogen is often difficult to isolate and confirm from infected plant tissues and has been mainly identified by disease symptoms and morphological characteristics of A. populi when fruiting bodies form on infected leaves or branches. Affected leaves and branches typically become necrotic and bronze in colour. Air-borne spores and nursery shipments containing infected plants play an important role in the efficient movement of the pathogen. In this study, bronze leaf disease samples from symptomatic trees in Canada were examined microscopically for A. populi perithecia and asci. Pathogen-specific genomic sequences were identified for the development of sensitive stringent diagnostics that indicated branches and petioles were the most effective tissues for detecting A. populi. Leaf samples from symptomatic trees were collected in Canada and examined for perithecia to microscopically characterize A. populi asci and ascospores. Disease associated DNA sequences of the internal transcribed spacer (ITS) 5.8S region of the nuclear ribosomal, β-tubulin 2, and translation elongation factor-1-γ chain, were isolated from perithecia and symptomatic tree samples. Morphological and molecular biological data from this study characterized the relationship and epidemiology of A. populi and enabled the development of rapid diagnostic methods that restrict the extent of further losses in amenity and commercial plantings of aspen and poplar.

FORM FACTORS AND VOLUME MODELS FOR ESTIMATING TREE BOLE VOLUME OF MAHOGANY AT COMMUNITY FORESTS IN CENTRAL JAVA

Form factors and volume models are often be used in the estimation of tree volumes. However, a few studies have developed and evaluated the accuracy of form factors and volume models for estimating tree volumes of community forests. This study aimed to formulate form factors and volume models and assess their prediction accuracy for estimating tree bole volumes of mahogany at community forests in Central Java. This study used 120 sample trees with diameters of 6–38 cm to formulate artificial and absolute form factors and to develop tree bole volume models. These form factors coupled with bole height and total height were used in simple volume equations. Regression analyses were used to develop volume models using the diameter and total height as predictors. The simple volume equations and volume models' prediction accuracy was evaluated using a cross-validation dataset and independent dataset (30 sample trees). The artificial form factor (0.68 ± 0.11) of mahogany, which was higher than the absolute form factor (0.46 ± 0.09), provided accurate estimates of tree bole volumes when it was used with the bole height instead of the total height. The volume model that uses diameter and total height produced the most accurate estimates, while the volume model that uses diameter alone provided the most practical yet reliable tool for estimating tree bole volumes of mahogany. The results of this study are useful for improving community forest management.

FORM FACTORS AND VOLUME MODELS FOR ESTIMATING TREE BOLE VOLUME OF MAHOGANY AT COMMUNITY FORESTS IN CENTRAL JAVA

Form factors and volume models are often be used in the estimation of tree volumes. However, a few studies have developed and evaluated the accuracy of form factors and volume models for estimating tree volumes of community forests. This study aimed to formulate form factors and volume models and assess their prediction accuracy for estimating tree bole volumes of mahogany at community forests in Central Java. This study used 120 sample trees with diameters of 6–38 cm to formulate artificial and absolute form factors and to develop tree bole volume models. These form factors coupled with bole height and total height were used in simple volume equations. Regression analyses were used to develop volume models using the diameter and total height as predictors. The simple volume equations and volume models' prediction accuracy was evaluated using a cross-validation dataset and independent dataset (30 sample trees). The artificial form factor (0.68 ± 0.11) of mahogany, which was higher than the absolute form factor (0.46 ± 0.09), provided accurate estimates of tree bole volumes when it was used with the bole height instead of the total height. The volume model that uses diameter and total height produced the most accurate estimates, while the volume model that uses diameter alone provided the most practical yet reliable tool for estimating tree bole volumes of mahogany. The results of this study are useful for improving community forest management.

Flood-Rings Production Modulated by River Regulation in Eastern Boreal Canada.

In northeastern boreal Canada, the long-term perspective on spring flooding is hampered by the absence of long gage records. Changes in the tree-ring anatomy of periodically flooded trees have allowed the reconstruction of historical floods in unregulated hydrological systems. In regulated rivers, the study of flood rings could recover past flood history, assuming that the effects of hydrological regulation on their production can be understood. This study analyzes the effect of regulation on the flood-ring occurrence (visual intensity and relative frequency) and on ring widths in Fraxinus nigra trees growing at five sites distributed along the Driftwood River floodplain. Driftwood River was regulated by a dam in 1917 that was replaced at the same location in 1953. Ring width revealed little, to no evidence, of the impact of river regulation, in contrast to the flood rings. Prior to 1917, high relative frequencies of well-defined flood rings were recorded during known flood years, as indicated by significant correlations with reconstructed spring discharge of the nearby Harricana River. After the construction and the replacement of the dam, relative frequencies of flood rings and their intensities gradually decreased. Flood-ring relative frequencies after 1917, and particularly after 1953, were mostly composed of weakly defined (less distinct) flood rings with some corresponding to known flood years and others likely reflecting dam management. The strength of the correlations with the instrumental Harricana River discharge also gradually decrease starting after 1917. Compared with upper floodplain trees, shoreline trees at each site recorded flood rings less frequently following the construction of the first but especially of the second dam, indicating that water level regulation limited flooding in the floodplains. Compared with the downstream site to the dam, the upstream ones recorded significantly more flood rings in the postdam period, reemphasizing the importance of considering the position of the site along with the river continuum and site conditions in relation to flood exposure. The results demonstrated that sampling trees in multiple riparian stands and along with various hydrological contexts at a far distance of the dams could help disentangle the flooding signal from the dam management signal.