Distribution pattern of entry holes of the tree-killing bark beetle Polygraphus proximus

Bark beetles attack their hosts at uniform intervals to avoid intraspecific competition in the phloem. Bark texture and phloem thickness also affect bark beetle attacks, and the bark characteristics are not spatially homogeneous; therefore, the distribution patterns of entry holes can demonstrate an aggregated distribution. Polygraphus proximus Blandford (Coleoptera: Scolytinae) is a non-aggressive phloephagous bark beetle that feeds on Far Eastern firs. They have caused mass mortality in Russia and Japan. However, the distribution pattern of entry holes of P. proximus and spatial relationships with bark characteristics have not been studied. Thus, we investigated the distribution pattern of entry holes of P. proximus. The distribution of entry holes was significantly uniform in most cases. As the attack density increased, an aggregated distribution pattern within a short distance (< 4.0 cm) was observed. The rough bark had a significantly higher number of entry holes than the remaining bark. The distribution pattern of entry holes demonstrated a significantly aggregated spatial association with rough bark. Finally, rough bark around knots had significantly thicker phloem than the remaining barks. These suggest that P. proximus may preferentially attack rough bark to reproduce in the thicker phloem under a rough bark surface.

Distinctness, Uniformity and Stability (DUS) Characterization of Neolamarckia Cadamba Genetic Resources

Neolamarckia cadamba (Kadam) genetic resources were characterised Distinctness, Uniformity and Stability (DUS) traits based on International Union for the Protection of New Varieties of Plants12 guidelines. Twenty-five clones of kadam were characterised based on the morphological characters of leaf and bark with 12 descriptors. Among these 12 descriptors, 9 were qualitative traits viz., leaf shape, Leaf base shape, apex shape, leaf margin, leaf venation, base symmetry, Waxiness in upper side of leaf, bark colour and bark texture and 3 were quantitative characters viz., leaf length, leaf breath, leaf petiole length. The study exhibited significant variations among the genetic resources investigated for various DUS traits, which could act as reference traits for developing variety to protect the genetic resources through Intellectual Property Rights.

INDIVIDUAL TREE SPECIES CLASSIFICATION BASED ON TERRESTRIAL LASER SCANNING USING CURVATURE ESTIMATION AND CONVOLUTIONAL NEURAL NETWORK

<p><strong>Abstract.</strong> In this paper, we propose a new method for specifying individual tree species based on depth and curvature image creation from point cloud captured by terrestrial laser scanner and Convolutional Neural Network (CNN). Given a point cloud of an individual tree, the proposed method first extracts the subset of points corresponding to a trunk at breast-height. Then branches and leaves are removed from the extracted points by RANSAC -based circle fitting, and the depth image is created by globally fitting a cubic polynomial surface to the remaining trunk points. Furthermore, principal curvatures are estimated at each scanned point by locally fitting a quadratic surface to its neighbouring points. Depth images clearly capture the bark texture involved by its split and tear-off, but its computation is unstable and may fail to acquire bark shape in the resulting images. In contrast, curvature estimation enables stable computation of surface concavity and convexity, and thus it can well represent local geometry of bark texture in the curvature images. In comparison to the depth image, the curvature image enables accurate classification for slanted trees with many branches and leaves. We also evaluated the effectiveness of a multi-modal approach for species classification in which depth and curvature images are analysed together using CNN and support vector machine. We verified the superior performance of our proposed method for point cloud of Japanese cedar and cypress trees.</p>

Host affinity and vertical distribution of epiphytic orchids in a montane cloud forest in southern Mexico

<p class="Standard1"><strong>Background</strong>: The host´s structural characteristics provide diverse microhabitats that influence the distribution patterns of the epiphytes at different vertical zones and among tree species.</p><p class="Standard1"><strong>Hypotheses</strong>: Epiphytic orchids have preference for larger host trees and with non-exfoliating rough bark, while the limiting hosts will be those of smaller size and smooth and exfoliating bark, and there will be fewer individuals in the upper canopy of the host trees because the micro-environmental conditions are more stressful compared to the middle and lower parts of the host trees.</p><p class="Standard1"><strong>Methods</strong>: The host preferences and vertical distribution<strong> </strong>of the epiphytic orchids were analyzed in 20 montane cloud forest fragments. In each fragment, two transects of 2 × 50 m were drawn, and the trees with a diameter at a breast height ≥ 20 cm were recorded. In each tree, basal area was quantified and bark texture was characterized. In each tree and vertical zone, the orchid species present were identified and quantified.</p><p><strong>Results</strong>: Orchid distribution patterns vary between vertical zones and host tree species, and the richness is related to host size and bark texture. The highest species richness and number of epiphytic orchid’s individuals were recorded in host trees with fissured bark and larger size. The distribution of orchids in the host was not homogeneous nor was it related to any particular host species. However, five trees species were considered as host preferred, while five tree species were limiting hosts. The highest richness was recorded in vertical zone II and the lowest in zones I and V.</p><p class="Standard1"><strong>Conclusions</strong>: Larger trees contain greater richness of epiphytic orchids, because they offer better conditions for their establishment, provide a great diversity of microhabitats, greater time and area for epiphytic colonization events. The texture of the bark is a relevant factor in the host preference, and in the hosts with smooth bark, the presence of epiphytic orchids depends on the accumulation of organic matter.</p>

Are neotropical predictors of forest epiphyte–host relationships consistent in Indonesia?

Epiphytes represent keystone resources for many arthropod and vertebrate species, however their ecology remains poorly explored, especially within the palaeotropics. Several recent studies have examined relationships between epiphyte richness and characteristics of local habitats, although these have all focused on neotropical forests. Here, we aim to determine whether predictors of neotropical epiphyte richness are consistent at a palaeotropical site. A total of 44 host trees (dbh range 25–288 cm) were sampled at two study sites on Buton Island, Indonesia. For each tree, epiphyte richness and seven variables relating to characteristics of the host tree and surrounding habitats were recorded: site (a proxy value for disturbance level and water availability), host above-ground biomass (agb), altitude, bark texture, exposure, emergence and crown area. Gaussian GLM analyses indicated that the percentage deviance explained in epiphyte richness per host was greatest for agb (20.9%), crown area (19.6%) and site (15.5%); similar to previous findings from the neotropics. Results therefore suggest that high epiphyte diversity within palaeotropical forests is most likely to be found in large tracts of undisturbed forest, supporting large, broad-crowned trees.