Trembling Aspen Height-Age Models for British Columbia

Trembling aspen (Populus tremuloides), a common hardwood species in the interior of British Columbia, Canada is becoming an increasingly important timber crop species, especially in the northeast corner of the province. Better growth and yield information for aspen is required to manage this species properly. Height-age models for estimating site height and site index are provided in this paper. One-hundred and thirty-five stem analysis plots were established in six biogeoclimatic zones. Three trees in the 0.04 ha plots were selected and stem analysed, and ecological data were collected at each plot. The stem analysis data were split into a model calibration and test data set. Two models were fit to the calibration data: a base model and an extended model that is calibrated for the six biogeoclimatic zones. Both models adequately estimate the height of trembling aspen in British Columbia. The base model was compared to two models for aspen in Alberta, which showed that there were no large differences in the height growth of aspen, except on lower productivity sites.Nigh et al "Trembling aspen height-age models for British Columbia." Northwest Science. 2002; 76(3): 202-21

Using U-Net-Like Deep Convolutional Neural Networks for Precise Tree Recognition in Very High Resolution RGB (Red, Green, Blue) Satellite Images

Very high resolution satellite imageries provide an excellent foundation for precise mapping of plant communities and even single plants. We aim to perform individual tree recognition on the basis of very high resolution RGB (red, green, blue) satellite images using deep learning approaches for northern temperate mixed forests in the Primorsky Region of the Russian Far East. We used a pansharpened satellite RGB image by GeoEye-1 with a spatial resolution of 0.46 m/pixel, obtained in late April 2019. We parametrized the standard U-Net convolutional neural network (CNN) and trained it in manually delineated satellite images to solve the satellite image segmentation problem. For comparison purposes, we also applied standard pixel-based classification algorithms, such as random forest, k-nearest neighbor classifier, naive Bayes classifier, and quadratic discrimination. Pattern-specific features based on grey level co-occurrence matrices (GLCM) were computed to improve the recognition ability of standard machine learning methods. The U-Net-like CNN allowed us to obtain precise recognition of Mongolian poplar (Populus suaveolens Fisch. ex Loudon s.l.) and evergreen coniferous trees (Abies holophylla Maxim., Pinus koraiensis Siebold & Zucc.). We were able to distinguish species belonging to either poplar or coniferous groups but were unable to separate species within the same group (i.e. A. holophylla and P. koraiensis were not distinguishable). The accuracy of recognition was estimated by several metrics and exceeded values obtained for standard machine learning approaches. In contrast to pixel-based recognition algorithms, the U-Net-like CNN does not lead to an increase in false-positive decisions when facing green-colored objects that are similar to trees. By means of U-Net-like CNN, we obtained a mean accuracy score of up to 0.96 in our computational experiments. The U-Net-like CNN recognizes tree crowns not as a set of pixels with known RGB intensities but as spatial objects with a specific geometry and pattern. This CNN’s specific feature excludes misclassifications related to objects of similar colors as objects of interest. We highlight that utilization of satellite images obtained within the suitable phenological season is of high importance for successful tree recognition. The suitability of the phenological season is conceptualized as a group of conditions providing highlighting objects of interest over other components of vegetation cover. In our case, the use of satellite images captured in mid-spring allowed us to recognize evergreen fir and pine trees as the first class of objects (“conifers”) and poplars as the second class, which were in a leafless state among other deciduous tree species

Impact of Patial Releases in Mixed Korean Pine-Broadleaved Stands on the Natural Regeneration Processes

С использованием дендрохронологического анализа выявлены периоды частичных распадов древостоев кедровых лесов Южного и Среднего Сихотэ-Алиня на двух постоянных пробных площадях. Показано, что распады происходят одновременно на обеих площадях с интервалами около 40 лет и вызывают ускорение роста деревьев всех пологов. Периодическое улучшение условий приводит к ступенчатому развитию деревьев, когда быстрый рост чередуется с угнетением.Using dendrochronological analysis we restored disturbance history of mixed Korean pine-broadleaved stands in the South and Middle Sikhote-Alin mountain range on two permanent sample plots. Results of the analysis showed that partial releases occurred in stands history simultaneously on both plots, with intervals of about 40 years, and growth release revealed for trees in all layers. The periodical enhance in environmental conditions leads to stepped development of trees, i.e. periods of fast growth alternate with long suppressions

Impact of Patial Releases in Mixed Korean Pine-Broadleaved Stands on the Natural Regeneration Processes

С использованием дендрохронологического анализа выявлены периоды частичных распадов древостоев кедровых лесов Южного и Среднего Сихотэ-Алиня на двух постоянных пробных площадях. Показано, что распады происходят одновременно на обеих площадях с интервалами около 40 лет и вызывают ускорение роста деревьев всех пологов. Периодическое улучшение условий приводит к ступенчатому развитию деревьев, когда быстрый рост чередуется с угнетением.Using dendrochronological analysis we restored disturbance history of mixed Korean pine-broadleaved stands in the South and Middle Sikhote-Alin mountain range on two permanent sample plots. Results of the analysis showed that partial releases occurred in stands history simultaneously on both plots, with intervals of about 40 years, and growth release revealed for trees in all layers. The periodical enhance in environmental conditions leads to stepped development of trees, i.e. periods of fast growth alternate with long suppressions

Merger of Betula tatewakiana (Betulaceae) from northern Japan with northeast Asian B. ovalifolia based on ploidy level

It has been controversial whether Betula tatewakiana, a dwarf birch distributed in Hokkaido of northern Japan, is an endemic species or a synonym of B. ovalifolia broadly distributed in northeast Asia. The endemic hypothesis is based on the idea that B. tatewakiana is diploid while B. ovalifolia is tetraploid and that they are separated based on the ploidy level; however, no chromosome data have actually been published before. Resolving the taxonomic problem is crucial also in judging the conservation priority of B. tatewakiana in a global perspective. Our chromosome observation revealed that B. tatewakiana is tetraploid as well as B. ovalifolia. We also conducted morphological observations and clarified that B. tatewakiana is morphologically identical to B. ovalifolia in white hairs and dense resinous glands respectively on adaxial and abaxial leaf surfaces, in which they differ from closely related species in the same section Fruticosae. We conclude that the hypothesis that B. tatewakiana is a Hokkaido endemic based on the ploidy level is not supported and that B. tatewakiana should be merged with B. ovalifolia

Molecular and cytological evidences denied the immediate-hybrid hypothesis for Saxifraga yuparensis (sect. Bronchiales, Saxifragaceae) endemic to Mt. Yubari in Hokkaido, northern Japan

An alpine plant Saxifraga yuparensis is endemic to a scree consisting of greenschist of Mt. Yubari in Hokkaido, Japan and it has been proposed as an immediate hybrid derived from two species of the same section Bronchiales based on morphological intermediacy: namely S. nishidae, a diploid species endemic to a nearby cliff composed of greenschist and tetraploid S rebunshirensis comparatively broadly distributed in Japan and Russian Far East. Saxifraga yuparensis is red-listed and it is crucial for conservation planning to clarify whether this is an immediate hybrid and lacks a unique gene pool. The immediate-hybrid hypothesis was tested by molecular and cytological data. In nuclear ribosomal and chloroplast DNA trees based on maximum parsimony and Bayesian criteria, S. yuparensis and S. rebunshirensis formed a Glade with several other congeners while S. nishidae formed another distinct Glade. Genome-wide SNP data clearly separated these three species in principal coordinate space, placing S. yuparensis not in-between of S. rebunshirensis and S. nishidae. Chromosome observation indicated that S. yuparensis is tetraploid, not triploid directly derived from diploid-tetraploid crossing. Additionally, observation of herbarium specimens revealed that leaf apex shape of S. yuparensis fell within the variation of S. rebunshirensis. These results indicate that S. yuparensis is not an immediate hybrid of S. rebunshirensis and S. nishidae but a distinct lineage and an extremely narrow endemic species, that deserves for intensive conservation