Flavanol binding of nuclei from tree species

Light microscopy was used to examine the nuclei of five tree species with respect to the presence of flavanols. Flavanols develop a blue colouration in the presence of a special p-dimethylaminocinnamaldehyde (DMACA) reagent that enables those nuclei loaded with flavanols to be recognized. Staining of the nuclei was most pronounced in both Tsuga canadensis and Taxus baccata, variable in Metasequoia glyptostroboides, faint in Coffea arabica and minimal in Prunus avium. HPLC analysis showed that the five species contained substantial amounts of different flavanols such as catechin, epicatechin and proanthocyanidins. Quantitatively, total flavanols were quite different among the species. The nuclei themselves, as studied in Tsuga seed wings, were found to contain mainly catechin, much lower amounts of epicatechin and traces of proanthocyanidins. Blue-coloured nuclei located centrally in small cells were often found to maximally occupy up to 90% of a cells radius, and the surrounding small rim of cytoplasm was visibly free of flavanols. A survey of 34 gymnosperm and angiosperm species indicated that the first group has much higher nuclear binding capacities for flavanols than the second group.Abbreviations DMACA p-Dimethylaminocinnamaldehyde Communicated by W. Barz     

Disk formation in retinal cones of Tupaia belangeri (Scandentia)

Existing hypotheses on the mode of disk formation in the photoreceptor cells of mammals appear to be incompatible: (1) plasma membranes of adjacent evaginations form a disk which, subsequently, is internalized by a disk rim; (2) pinocytotic vesicles are pinched off from the plasma membrane and fuse into a larger vesicle, which flattens and forms a disk. We have studied the development of the cone outer segment and the disk formation in Tupaia belangeri by transmission electron microscopy. During the first two postnatal weeks, the distal part of the single cilium, which is inserted apically on the inner segment, becomes balloon-shaped. Apical to the axoneme, it contains tubular and vesicular material, which, most probably, has been detached from the axonemal microtubules. These tubules and vesicles do not contribute to disks. The balloon-shaped expansion, later retained as the ciliary backbone, establishes the contact with the pigment epithelium. Formation of disks, from the 12-day-old Tupaia onwards, occurs between adjacent evaginations at the outer segment base. The initial disk rims are “hooked” to the ciliary axonemal microtubules. The axonemal microtubules are involved in the initiation and in the alignment of the disks. Disk rim formation and, thus, internalization of disks proceeds from the base to the apex of the outer segment, that is, from the younger to the older disks. In the adult Tupaia, an uneven progression of disk rim formation on both sides of the axoneme is found among consecutive disks. The seemingly incompatible hypotheses on the mode of disk formation reflect a heterochrony of the internalization of membranes and of the disk formation among different mammals and, possibly, between cones and rods. Received: 24 July 1997 / Accepted: 10 September 1997     

辽河三角洲盐碱地防护林体系建设技术研究

辽河三角洲盐碱地上造林、土壤改良及营林工程技术试验结果表明,在土壤含盐量０．３％以下的干渠上应栽植辽宁杨、中林４６号杨、群众杨;结合土壤改良措施,在土壤含盐量０．４％左右的海堤上栽植刺槐、河南白榆,在含盐量为０．５２～０．７３％油田道路两侧则栽植绒毛白蜡;在土壤含盐量为０．９％左右的拦海防潮堤上,栽植中国柽柳．     

Differences in climate-growth relationships between two tree species that co-occur in a seasonally dry tropical forest in Northeastern Brazil

Seasonally dry tropical forests are an important global climate regulator and represent one of main drivers of carbon sink dynamics. However, projections of climate change suggest future productivity losses and negative impacts on forest functioning. Understanding the interaction between climate variability and tree growth responses between species with different growth strategies represents a crucial challenge to forecast ecosystem functioning in the future. Here we used tree ring chronology to evaluate changes in growth and climate sensitivity of two tropical tree species that co-occur in a seasonally dry tropical forest in Brazil: Cedrela odorata and Ceiba glaziovii. Using Pearson correlations and linear regressions we explored how growth variability is correlated with local (precipitation, temperature) and global (ocean temperature and El Niño Southern Oscillation - ENSO) climatic factors. Tree growth was closely related with precipitation in C. odorata (r = 0.59) and C. glaziovii (0.24). Differences were found at monthly level, which C. odorata showing greater sensitivity in the beginning of rainy season. The South Atlantic Temperature was positively correlated with C. odorata, while ENSO was negatively correlated. Our results showed a dominant effect of precipitation on tree growth and suggest that are different growth strategies among species, which C. odorata being the most sensitive to drought and C. glaziovii more adapted with parenchyma in trunk. Therefore, C. odorata is probably more vulnerable to the deleterious effects of future climate change than C. glaziovii. Our findings highlight the importance of understanding the climate sensitivity of different seasonally dry tropical forest species, which is critical to predicting carbon dynamics in tropical regions. These also reveal that differences in sensitivity must be considered when prioritizing conservation measures for seasonally dry tropical forests.     

Three-dimensional distribution of mass movement signals in disturbed Picea abies (L.) Karst.

Dendrogeomorphologic approaches enable annual absolute dating of various potentially hazardous geomorphic processes. This study tested the dating precision of three commonly used dendrogeomorphic approaches used for the extraction of geomorphic signals from the tree ring series of disturbed trees. The first approach is based on the onset of reaction wood occurrence, and the other two approaches are based on the detection of abrupt changes in tree ring eccentricity. Nine 165 cm long stems of maximally 27 year old Norway spruces (Picea abies (L.) Karst.) growing on unstable slope affected by mass movement events of known age were analysed. Several sampling directions on stems were analysed to reveal the best sampling strategy for each tested approach. The relationships between stem curvature and the dating precision of the approaches were also analysed. The results of dating precision showed crucial differences between the tested approaches. Tree stem curvature did not influence dating precision. Overall, we concluded that the approaches based on eccentric increments are less precise than those based on reaction wood analysis when juvenile P. abies trees that grow on landslide slope are sampled. The importance of this study is in providing new insight into dating precision by analysing the whole tree stems of trees influenced by mass movements. This is unique since the approaches based on eccentricity increments have not been previously tested in such a detail.     

Method for detecting tree ring boundary in conifers and broadleaf trees using Mask R-CNN and linear interpolation

As tree rings can reveal various information regarding climate and environmental factors, increasing research is being conducted on them. Although tree ring analysis software such as Windendro has been applied, research on the development of analysis software using image preprocessing algorithms and deep learning is recently being attempted as computer vision technology. In this study, Mask R-CNN and linear interpolation were applied from images collected using a smartphone (SM-G973, Samsung, Suwon) and a scanner (CanoScan 9000F, Canon, Otaku) to propose an effective method for detecting tree ring boundaries. Pitch pine (Pinus rigida), Korean pine (Pinus koraiensis), white birch (Betula platyphylla), and cork oak (Quercus variabilis) were selected as tree species. Of the 300 images, 240 were classified as training data and 60 as validation data. As a result of learning, smartphones detected 86.0 % (381 ring boundaries) of the rings in pitch pine, 82.1 % (367 ring boundaries) in Korean pine, 84.7 % (309 ring boundaries) in white birch, and 78.7 % (318 ring boundaries) in cork oak. The scanner detected 93.2 % (413 ring boundaries) of the rings in pitch pine, 90.8 % (405 ring boundaries) in Korean pine, 88.2 % (322 ring boundaries) in white birch, and 89.4 % (361 ring boundaries) in cork oak. In particular, the smartphone showed satisfactory results of 84.7 % and 78.7 % for detecting tree ring boundaries of white birch and cork oak, where the boundaries of the rings were unclear. In the annual growth analysis results, both smartphones and scanners were statistically insignificant, and there was no difference compared with those of Windendro. Therefore, Mask R-CNN might be an effective approach for tree ring boundary detection as it showed satisfactory results, even with smartphones. In addition, although there was distortion in cases where images were acquired with a circular lens, there was no statistically significant difference from Windendro results. Thus, Mask R-CNN and linear interpolation can be used for tree ring boundary detection and growth measurement.     

分布区西缘油松种群的生长特征

 在青海省互助北山林场和贵德东山林场的油松林内分别设置6个和5个样方,对分布区西缘的天然油松种群的生长特征进行了生态学研究。结果表明,两地的油松种群均为复层异龄结构;树高与胸径的关系揭示东山的油松种群其生长能力仅为北山的一半;种群内个体的树高直径比与个体的大小呈负相关,表明个体生长对被压的生态适应;两地个体的直径生长过程也差异很大,即东山油松的直径生长随年龄的增长呈下降趋势,而北山呈上升趋势或变化很小。上述差异导致两地的生产力差异很大：北山可望获得200t／ha的生物量,而东山仅约为100t/ha,但两地的生物量密度差异不大,为7一11t／ha．m,利用生物量密度与总胸高断面积之间的线性关系,可以建立良好的推算种群地上部生物量的方法。本文还对天然油松的种群密度与平均个体重之间的关系作了讨论。     

Tree decline in southeastern Australia: Nitrate reductase activity and indications of unbalanced nutrition in Eucalyptus ovata (Labill.) and E. camphora (R.T. Baker) communities at Yellingbo,Victoria

The decline of riparian Eucalyptus camphora/E. ovata stands is examined in relation to an increase in nitrogen availability and to rising salinity in low-lying areas. There are several indications that declining stands are abnormally rich in N: (i) Nitrogen availability in declining stands was greater than that recorded in other Australian forests, was dominated by nitrification and was extremely variable. (ii) Nitrate concentrations in free soil water from declining forest on a dry site were many times those in the corresponding healthy forest. (iii) N/Mg ratios in foliage of declining trees on drier sites were at the extreme end of the recorded range and similar to those found in eucalypt plantations on agricultural soils. In addition, sites where the overstorey eucalypts are declining have been invaded by a variety of herbaceous weeds, most of which display characteristics of nitrophilous plants, e.g. nitrate reductase activity was greater in herbaceous weeds than in native overstorey or understory species in declining stands of E. camphora/E. ovata and was directly related to the concentration of nitrogen in foliage. These observations are consistent with recent suggestions that forest ecosystems may become N-saturated.     

城市环境中树木年轮的变异及其与工业发展的关系

通过对污染敏感树种油松年轮宽度和元素含量的变异与沈阳工业发展的相关分析。追溯和重建沈阳地区的生态环境变迁史,揭示城市环境质量与树木年轮变异之间的相关规律。结果表明,在城市污染条件下,树木年轮宽度和微量元素含量均发生了明显的变异,而且这些变异与沈阳工业发展显著相关．