Leaf distribution in large trees and stands of the floodplain forest in southern Moravia

Vertical distributions of leaf dry mass (M(d)) and leaf area (A(f)) were related to relative irradiance (I(r); I(r) above the stand = 1) in closed-canopy, old-growth stands of the floodplain forest in southern Moravia composed largely of Quercus, Fraxinus and Tilia species. Foliage area and mass at any given canopy height were converted to solar equivalent leaf area (A(s)) and mass (M(s)) by multiplying actual values at a given level in the canopy by the relative irradiance at that position. Stand leaf area index (LAI) was 5 (7 including shrub and herb layer), and solar equivalent parameters reached about 25% of that amount. In all species, vertical profiles of both relative irradiance and leaf dry mass to area ratio (LMA) were sigmoidal and the two variables were linearly related. The dominant, upper canopy species had a larger proportion of solar equivalent foliage than suppressed understory species. For individual trees of all species, the upper canopy had a larger proportion of solar equivalent foliage than the lower canopy. Light compensation points at both the leaf and whole-tree level were defined according to leaf or tree position, size and structure. I conclude that optimization of A(s) for forest stands may be used as a basis for determining thinning schedules and evaluating tree survival after damage to tree crowns by various factors.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.     

杉木纯林改混交林阔叶树种的选择

为了可持续利用选出多种杉木纯林改造的阔叶树种的人工复层林的经营模式 ,在杉木纯林间伐后采用多种更新改造阔叶树的随机设计试验。调查分析表明 ,树种间的造林效果达到显著、极显著的差异 ,米老排为效果最佳树种 ,其次为光皮桦、火力楠、细柄阿丁枫 ,初步认为桤木不适宜作为改造树种     

Radial variation of wood properties in Neolamarckia cadamba trees from an East Java community forest

Radial variations in wood properties, cell morphologies and cell proportions were investigated for nine 4-year-old Neolamarckia cadamba trees planted in a community forest in East Java, Indonesia. The relationships between stem diameter and wood properties, cell morphologies or cell proportions were determined to ascertain the effects of stem diameter on these properties. In the radial variations, almost all of the wood properties, cell morphol- ogies and cell proportion in N. cadamba were changed at around 4 to 6 cm distance from the pith, except for fibre diameter, and the proportion of fibre and axial parenchyma. For trees with larger stem diameter, the vessel diameter was also found to increase. In addition, the ray parenchyma and cell wall proportions in trees with larger stem diameter were lower than those in trees with smaller stem diameter. However, the wood properties obtained from the larger stem diameter trees did not always show lower values. The wood properties in N. cadamba were correlated to fibre wall thickness and vessel diameter.     

林木遗传图谱构建研究概述

林木遗传图谱构建研究是进入90年代以来林木遗传研究领域中进展最快且影响较大的领域之一。构建林木遗传图谱是对林木在分子水平上进行系统研究的基础工作，有重要的理论价值和潜在的应用价值。由于林木复杂的生物学特性，林木的遗传图谱构建一直被视为作图研究的难区，90年代初，由美国北卡州立大学发表的首张林木的遗传图谱曾引起较大的轰动和反响，经过10a来的发展，林木遗传图谱构建研究取得很大的进展。该文就林木遗传图谱构建的基本原理、作图方法和作图过程及近几年来林木作图和图谱应用研究的最新进展进行了综述。     

Accumulation of airborne fluorides in forest trees and vegetation

The accumulation of fluoride in natural vegetation exposed to emissions from five aluminium smelter plants in Norway was studied during the years 1990–93. About 2000 leaf, bark and twig samples of 60 plant species, collected mostly during the growing season, were analysed. Rowan (Sorbus aucuparia) was widespread and common in the areas studied, and was used as a reference species. Fluoride concentrations in monthly samples of rowan leaves were linearly related to fluoride exposure (average fluoride concentration in ambient air × days since leaf emergence). The accumulation coefficient for rowan was estimated to be 1.7 m³/g dry wt. day. Most other species had values between 0.3 and 1.5; the median for all species was 0.8. The fern Dryopteris filix-mas was exceptional, containing on average three times greater fluoride concentrations man rowan. High background levels indicated that soil uptake contributed significantly to the fluoride accumulation in this species. The fluoride concentrations in bark and shoots of trees were mostly low compared with leaves, but the bark of Betula pendula and B. pubescens had very high concentrations.     

马尾松林分内套种肉桂的试验分析

肉桂是樟科的亚热带常绿植物 ,其全身是宝 ,根、枝、皮、花、果均可入药 ;叶可提取桂油 ,是现代医药、化工与食品工业的重要原料。而且肉桂具有生长快、周期短、效益高、用途广的优良特性。随着人民生活水平的提高 ,人们对肉桂的需求日益增加 ,市场供需矛盾十分突出。因此 ,漳州市已把发展肉桂作为加快农村脱贫致富、振兴山区经济的重点项目之一。由于福建肉桂造林成活率低 ,严重限制肉桂人工造林的发展 ,再加上近几年闽南地区大力开展山地综合开发 ,在立地条件较好、交通方便的宜林地都已开发种植了速生丰产用材林、果树林和竹林 ,肉桂开发…     

Control of the first flowering in forest trees 1

Precocious flowering provides opportunities to shorten a breeding cycle. A tree may flower for the first time when sufficient crown development has occurred and there are enough meristems to support both vegetative and reproductive buds. Precocious flowering can be promoted through the use of cultural techniques, such as photoperiod, accelerated growth, gibberellins and water stress. The length of the juvenile phase is dependent on genetic and environmental variables that affect achievement of a minimum size, and is positively correlated with the height of the plants within a family. Selection pressure can be applied successfully to the precocious flowering character, and crossed or inbred lines of precocious flowering progeny can be developed. Various levels and amounts of genetic control have been implicated in the control of precocious flowering.     

利用根癌农杆菌转化木本植物的研究进展

本文着重论述了近年来国内外利用根癌农杆菌介导法转化林木的研究进展。简述了获得转基因林木的应用现状,并将国内外林木转基因工作给以概括,提出了转化过程中存在的问题,并对这一转化方法的应用前景进行了展望。     

Transpiration and forest structure in relation to soil waterlogging in a Hawaiian montane cloud forest

Transpiration, leaf characteristics and forest structure in Metrosideros polymorpha Gaud. stands growing in East Maui, Hawaii were investigated to assess physiological limitations associated with flooding as a mechanism of reduced canopy leaf area in waterlogged sites. Whole-tree sap flow, stomatal conductance, microclimate, soil oxidation-reduction potential, stand basal area and leaf area index (LAI) were measured on moderately sloped, drained sites with closed canopies (90%) and on level, waterlogged sites with open canopies (50-60%). The LAI was measured with a new technique based on enlarged photographs of individual tree crowns and allometric relationships. Sap flow was scaled to the stand level by multiplying basal area-normalized sap flow by stand basal area. Level sites had lower soil redox potentials, lower mean stand basal area, lower LAI, and a higher degree of soil avoidance by roots than sloped sites. Foliar nutrients and leaf mass per area (LMA) in M. polymorpha were similar between level and sloped sites. Stomatal conductance was similar for M. polymorpha saplings on both sites, but decreased with increasing tree height (r(2) = 0.72; P < 0.001). Stand transpiration estimates ranged from 79 to 89% of potential evapotranspiration (PET) for sloped sites and from 28 to 51% of PET for level sites. Stand transpiration estimates were strongly correlated with LAI (r(2) = 0.96; P < 0.001). Whole-tree transpiration was lower at level sites with waterlogged soils, but was similar or higher for trees on level sites when normalized by leaf area. Trees on level sites had a smaller leaf area per stem diameter than trees on sloped sites, suggesting that soil oxygen deficiency may reduce leaf area. However, transpiration per unit leaf area did not vary substantially, so leaf-level physiological behavior was conserved, regardless of differences in tree leaf area.     

Root parameters of forest trees as sensitive indicators of acidifying pollutants: a review of research of Japanese forest trees

The root parameters of forest trees can be indicators of a changing environment. We summarize the results of root studies with regard to the effects of acidifying pollutants, especially soil acidification and aluminum toxicity, on various root parameters of Japanese forest trees under experimentally controlled conditions. All root parameters such as biomass, morphology, nutritional status, and physiology can be regarded as indicators, because, under laboratory conditions, root responses occur prior to the responses in the aboveground parts. However, considering the conditions of forest sites, the nutritional status and physiological changes are better indicators of soil acidification and Al stress than the biomass and morphological response. The currently available data suggest that the most important indicator is the Ca/Al molar ratio in roots of Japanese tree species. In order to predict and detect the initial effects of soil acidification, we postulate that the specific root response to the Ca/Al molar ratio of tree roots should be considered as a parameter for use in long-term forest monitoring sites.     

林木根际土壤研究进展

林木根际是土壤水分和矿物质进入根系参与生物循环的场所。林木根系和土壤养分之间的相互作用和关系一直是该领域研究的热点之一。文章主要综述了20世纪90年代以来关于林木根际土壤的研究状况,内容包括:林木根际土壤的研究方法,林木根际土壤的pH值、养分状况和生物化学特性等方面。     

Evidence for the adaptive significance of allozymes in forest trees

Positive correlations between allozyme heterozygosity and fitness measures, primarily growth and fecundity, have been reported for a number of forest tree species. Because the amount of variation in growth explained by allozyme genotype is usually on the order of only a few percent, there has been little effort made towards using electrophoretic screening of allozymes as a tool in early selection on seedlings in production nurseries. We review the progress made in studies of heterozygosity in forest trees, focusing on how recent studies have utilized careful experimental design to allow testing of hypotheses as to the causative nature of the heterozygosity-fitness phenomena. We discuss evidence suggesting a deleterious nature for rare allozyme alleles, and present a case of apparent balancing selection across life history stages acting to maintain rare alleles in Pinus taeda. We also review the apparently common trend in natural stands toward increasing heterozygosity over time, and suggest how gains might be made through artificial selection based on allozyme survey data.     

Genetic diversity—seeing the forest through the trees

Forest trees, populations, races, species, and taxonomic groups above the species level display rich variation in biochemical markers. The variation stems from inherited modifications that trace back in time, through converging ancestries, towards common progenitors. Past movements of continents, mountain building events, and climate changes isolated forest populations one from another and provided critical challenges to the lineages that survived to the present day. A wealth of molecular variants in forest trees characterize these widely-distributed, large, long-lived, outbreeding, organisms. Forest trees have an abundance of rare variants and over one third of all the alleles (different forms of one gene) occur only rarely ( < 2% frequency) in a few trees of a species sample. Those rare alleles may either represent new variation or persistent forms of genes that have low adaptive value under present conditions. From another perspective, however, the largest share of genetic variation in forest trees is due to the presence of multiple alleles found at intermediate frequencies for only a small percentage of all the genes, and those alleles are commonly widespread throughout species areas. These common alleles may mark genes that track historical events in lineages or mark genes with adaptive significance in present populations. Evidence from enzyme studies supports the conclusion that highly comparable functional genes are common to different forest taxa. Future research will be toward understanding the phenotypic expression of particular genes and revealing the relative importance of genetic variants to adaptation and growth.     

生物防火适宜树种的综合评定

采用静风篝火法测定树种抗燃时间，作为生物防火适宜树种的主要选择因子；同时，结合树种的适生性，生物学、造林学特性以及经济性状进行综合评定。结果表明：红花油茶、油茶抗火性能良好，木荷、青冈、苦槠抗火性能中等，在生物防火工程中可根据不同立地条件加以选择利用。     

Biochemical and molecular genetic markers in biosystematic studies of forest trees

Biochemical and molecular markers have proven to be powerful tools for discerning biosystematic, biogeographic, and phylogenetic relationships. Biosystematic information can be important for guiding traditional breeding programs, gene transfer, interspecific hybridization, and gene conservation. A phylogenetic framework is usually necessary, but frequently ignored, for making valid statistical tests in studies of adaptive evolution. Several studies have indicated a strong correlation between biochemical races and traits important to growth and adaptation, suggesting that evolutionary legacy may affect genetic architecture of fitness traits — with consequences for seed transfer, breeding strategies, and tolerance of climate change. A number of methods for phylogenetic analysis exist, but differ in their assumptions. Use of an inappropriate method — such as a method that assumes constant rates of evolution when rates in fact vary — can lead to incorrect phylogenies. Because of their complexity, phylogenetic topologies are often difficult to determine unambiguously; estimates of statistical confidence should therefore accompany phylogenetic trees if they are to be regarded as providing new knowledge, or strong confirmation, of relationships. Molecular genetic markers are more expensive than biochemical markers such as allozymes and terpenes, but they provide increased accuracy and expanded scope of biosystematic inference, and facilitate statistical analyses of phylogenetic trees.Abbreviations BMGMs biochemical and molecular genetic markers - cpDNA chloroplast DNA - OTU operational taxonomic unit - rbcL chloroplast gene encoding ribulose 1,5-bisphosphate carboxylase large subunit - rbcS nuclear gene encoding ribulose 1,5-bisphosphate carboxylase small subunit - rDNA ribosomal DNA - RFLP restriction fragment length polymorphism - UPGMA unweighted pair group method of clustering using averages This is paper 2708 of the Forest Research Laboratory, Oregon State University.     

Responses of deciduous forest trees to severe drought in Central Europe

In 2003, Central Europe experienced the warmest summer on record combined with unusually low precipitation. We studied plant water relations and phenology in a 100-year- old mixed deciduous forest on a slope (no ground water table) near Basel using the Swiss Canopy Crane (SCC). The drought lasted from early June to mid September. We studied five deciduous tree species; half of the individuals were exposed to elevated CO(2) concentration ([CO(2)]) (530 ppm) using a free-air, atmospheric CO(2)-enrichment system. In late July, after the first eight weeks of drought, mean predawn leaf water potential about 30 m above ground was -0.9 MPa across all trees, dropping to a mean of -1.5 MPa in mid-August when the top 1 m of the soil profile had no plant accessible moisture. Mean stomatal conductance and rates of maximum net photosynthesis decreased considerably in mid-August across all species. However, daily peak values of sap flow remained surprisingly constant over the whole period in Quercus petraea (Matt.) Liebl., and decreased to only about half of the early summer maxima in Fagus sylvatica L. and Carpinus betulus L. (stomatal down- regulation of flux). Although we detected no differences in most parameters between CO(2)-treated and control trees, predawn leaf water potential tended to be less negative in trees exposed to elevated [CO(2)]. Leaf longevity was greater in 2003 compared with the previous years, but the seasonal increase in stem basal area reached only about 75% of that in previous years. Our data suggest that the investigated tree species, particularly Q. petraea, did not experience severe water stress. However, an increased frequency of such exceptionally dry summers may have a more serious impact than a single event and would give Q. petraea a competitive advantage in the long run.     

人工林林木竞争数量指标的对比研究

选取5种竞争指标，建立人工落叶松林木胸径、树高和冠长与各竞争指标间的相关关系。对比发现，竞争指标CI、RCI、RC1、RC2随胸径的增大呈指数减小。鉴于此，选取5个经验方程进行建模，结果显示，对于胸径和CI、RCI、RC1、RC2间的关系用双曲线和幂函数方程拟合较为适宜。这一研究结果可作为单木生长模型建立的基础，同时，有助于提高人们对竞争指标的认识。     

Instant trees: Using giant vegetative stakes in tropical forest restoration

Remnant trees have been widely reported to facilitate tropical forest recovery, however, few restoration strategies can mimic the role such trees play in their absence. This study evaluated the establishment success and growth of planting oversized vegetative ‘stakes’ (>4 m tall) of three species: Ficus pertusa (Moraceae), Bursera simaruba (Burseraceae), and Erythrina poeppigiana (Fabaceae) at three different sites in southern Costa Rica. I found high establishment rates for all species (range 67–100%) with no mortality for Erythrina. This result was coupled with a rapid development of canopy area over 1 yr for Erythrina (7.69 ± 0.86 m²) and Bursera (1.82 ± 0.86 m²), but not Ficus (0.23 ± 0.04 m²). Similar results are reported for height. The study presents an important new addition to the growing body of literature on the use of stakes in tropical restoration, where, oversized stakes may be planted as solitary individuals in restoration sites to mimic the role played by remnant trees in forest recovery.