陕南栎类资源现状调查

安康、汉中地区栎林面积91.67万ha,蓄积5102万m~3,占整个有林地面积、蓄积的40～50％。在陕南生态平衡、工农业生产中起着极为重要的作用。现有栎林分布不均,可利用性差,中、幼龄林分比重大,质量不高,生产力低;连续多年超伐,森林蓄积大幅度减少。应采取果断措施,制止当前在栎林资源利用中的失控行为,压缩对栎林的消耗;大力造林和改造次生林,扩大栎林资源面积,提高林分质量;节约资源提高资源利用效益,从根本上缓解栎林供需矛盾。     

喜马拉雅山西部Askot野生动物保护区内粗木质残体沿山高度分布格局与现状

在印度Askot野生动物保护区Goriganga流域的3个分水岭(Charigad,Dogarhigad和upper Gosigad)内,沿着海拔高度900～2600m设置5条曲线调查样带(样带A、B、C、D和E),调查了粗木质残体的分布格局和状况.海拔高度每升高100 m设置一块1 hm2的样地.结果表明,不同演替阶段的粗木质残体百分比贡献率按降低顺序排列依次是:枯立木--相位Ⅰ>相位Ⅱ>相位Ⅳ>相位Ⅲ;而原木-相位Ⅲ>相位Ⅱ>相位Ⅳ.调查样带A内喜马拉雅长叶松(Pinus roxburghii)林内枯立木密度在1500m处较高,调查样带B通麦栎(Quercus lanata)林的枯立木密度在2300米处较高(10个/hm2).喜马拉雅长叶松林的枯立木和原木总获得量为13.9 t,其中枯立木和原木分别占41%和59%;而通麦栎林枯立木和原木总量仅为5.6 t,枯立木和原木分别占60%和40%.此外,粗木质残体的存在,有利于为当地生长的兰花营造良好的生长环境.在喜马拉雅长叶松林中等高度区域内,高密度的枯立木和原木导致该区内物种丰富度较低,地被物密度也较低.这主要是由于该区光线充足、土壤水分含量低,只有优势种才能占领这样生境.     

Belowground competition in a broad-leaved temperate mixed forest: pattern analysis and experiments in a four-species stand

We investigated fine root biomass and distribution patterns in a species-rich temperate Carpinus–Quercus–Fagus–Tilia forest and searched for experimental evidence of symmetry or asymmetry in belowground competition. We conducted extensive root coring and applied the recently introduced in situ-root growth chamber technique for quantifying fine root growth under experimentally altered intra- and interspecific root neighbourhoods in the intact stand. In 75% of all soil cores, fine roots of more than two tree species were present indicating a broad overlap of the root systems of neighbouring trees. Quercus trees had more than ten times less fine root biomass in relation to aboveground biomass or productivity (stem growth) and a much higher leaf area index/root area index ratio than Carpinus, Fagus and Tilia trees. The root growth chamber experiments indicated a high belowground competitive ability of Fagus in interspecific interactions, but a low one of Quercus. We conclude that (1) interspecific root competition is ubiquitous in this mixed stand, (2) root competition between trees can be clearly asymmetric, and (3) tree species may be ranked according to their belowground competitive ability. Fagus was found to be the most successful species in belowground competition which matches with its superiority in aboveground competition in this forest community.     

High-pruning of European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.): work efficiency for target pruning as a function of tree species,pruning height,branch characteristics,pole saw type and operator

The objective of this study was to establish an operational model of productive work time per tree (work efficiency) for high-pruning of young European beech and pedunculate oak depending on tree species, pruning height, branch characteristics, pole saw type and operator. The final model included all of these independent variables with branch characteristics specified in terms of number of live branches and cross-sectional area of the thickest branch at the cut. Work time increased with increasing values of each of the three numeric variables. For a given pruning height the size of the largest branch was for all practical purposes more influential than the number of live branches. Beech took 28% longer to prune than oak. The German Ergo-Schnitt saw was 21% slower than the Japanese Silky Hayauchi saw. The variation in worker performance within our study was larger than that attributed to tree species and pruning equipment.     

Effects of dietary Persian oak (Quercus brantii var. persica) fruit extract on survival,growth performance,haematological and immunological parameters in rainbow trout,Oncorhynchus mykiss,fingerlings

The aim of study was to evaluate the effects of jaft (internal layer of oak fruit) extract on growth, haematological and immunological parameters in rainbow trout fingerlings. A total of 360 fish (average weight 6.25 g, total length 7.75 cm) were randomly distributed in 12 fibreglass tanks (stocking density: 1.04 g L^?1) with flow rate of 8 L min^?1. The ethanolic extraction of jaft was taken, and, then, a basal diet was supplemented with 0 (control), 0.5, 1 and 2 g kg^?1 to formulate four experimental diets. After 8 weeks, blood sampling was performed for haematological and immunological parameters. While immunological parameters such as IgM and lysozyme showed their lowest level in control group, their highest amounts appeared in 2 g kg^?1 group. C3, C4 and alternative complement activity increased in fish fed 2 g kg^?1 extract compared to control (P ? 0.05). Haematological parameters such as white blood cell, red blood cell, haemoglobin and haematocrit were enhanced in experimental groups (P ? 0.05). Survival and growth indices did not show significant changes in experimental treatments (P ? 0.05). Results indicated feeding rainbow trout with Persian oak extract at 0.5, 1.0 and 2.0 g kg^?1 levels significantly enhance the immunological parameters.     

Genetic variation of pedunculate oak (Quercus robur L.) in the urban woodlands of Helsinki

We present a genetic profile of pedunculate oak (Quercus robur L.) in three woodlands of the Helsinki region. We genotyped all mature trees and samples of seedlings to evaluate patterns of genetic variation and gene flow, and evaluate the long-term stability and natural regeneration of these stands. Although five microsatellite loci showed no significant differences in heterozygosity between generations in most locations, significant (p?per se does not interfere with gene flow over the distances represented here. Based on our findings, a minimal-maintenance program reliant upon natural regeneration of oak in the public parks of Helsinki seems plausible.     

Establishment and growth of oak (Quercus alba, Quercus prinus) seedlings in burned and fire-excluded upland forests on the Cumberland Plateau

Recurrent problems with regeneration of oaks (Quercus spp.) have been documented across a wide range of ecosystems. In oak-dominated forests of the central and Appalachian hardwood regions of the United States, a lack of competitive oak regeneration has been tied, in part, to fire suppression in these landscapes, and managers throughout the region are using prescribed fire to address this concern. To examine fire effects on oak regeneration, researchers have generally relied on inventories or population studies of existing seedlings. These studies are valuable but do not permit examination of the role of fire in enhancing the establishment and growth of new oak seedlings stemming from oak mast events. In this study, white (Quercus alba) and chestnut oak (Quercus prinus) acorn mast crops serendipitously occurred in year three (fall 2005) of a landscape-scale prescribed fire experiment. We examined establishment, survival, height and diameter of new seedlings on sites on the Cumberland Plateau in eastern Kentucky. Treatments were fire exclusion, a single prescribed fire (1x-burn; 2003), and repeated prescribed fire (3x-burn; 2003, 2004, and after acorn drop in 2006), all conducted in late spring. Initial densities of newly established chestnut and white oak seedlings were statistically similar across treatments (P = 0.42), despite fires on the 3x-burn site having occurred after acorns were on the ground. Oak seedling density was significantly predicted by oak basal area on all sites (R² = 0.12–0.46), except for chestnut oak on fire-excluded sites (R² = 0.04). Litter depth was less on 3x-burn sites compared to 1x-burn and fire-excluded sites, whereas canopy openness was greater on both burn treatments compared to fire-excluded sites. Seedling mortality was generally higher on fire-excluded sites compared to burn sites, especially for white oak. Oak seedling mortality in the first two growing seasons was significantly predicted by initial litter depth and open sky, with greater litter depth and lower percent open sky leading to higher mortality. In the third growing season none of the measured variables predicted chestnut oak seedling survival; for white oak, percent open sky remained a significant predictor of mortality. Initially, seedlings on the fire-excluded sites had similar height but smaller diameter; after three growing seasons there were few differences in seedling height or diameter among treatments. Our findings suggest a potential role for prescribed fire in establishing forest floor and light conditions that may enhance the success of new oak germinants, although different responses among species may suggest the need to target management for individual oak species.     

山西省古稀柞树资源的调查

壳斗科栎属树种统称为柞树,山西省有许多的柞树资源。调查了与柞蚕有紧密关联的8个树种14个不同地点22株古稀树木,介绍了这些树木的遗存及生长情况。     

蒙古栎种群种子雨与地表种子库

对黑龙江省帽儿山地区平均年龄为22a和30a的天然蒙古栎种群的种子雨和地表种子库进行了研究。结果表明:该地区蒙古栎种群种子雨一般从8月下旬开始下落到9月下旬结束,种子雨下落强度不均匀,存在高峰期;不同年龄蒙古栎种群的种子雨强度不同,22a和30a蒙古栎种群的种子雨强度分别为11粒/m2和30粒/m2;不同时期下落的蒙古栎种子质量存在差异,中、前期下落的种子发芽率高,千粒质量大,种子质量好;蒙古栎种群地表种子库损耗的主要因素是虫害和动物取食。     

宝天曼栎类天然次生林乔木层种间联结性研究

在对宝天曼地区乔木层树种的RA、RD、RF及IV分析的基础上,根据2×2联列表,运用联结系数、共同出现百分率、点相关系数以及卡方值分别测定了栎类天然次生林26个主要树木种群间的联结关系。结果表明,锐齿栎的重要值最大,短柄枹树和化香次之,为其主要伴生树种;26个树种间总体呈现不显著的负联结的关系,正联结和无联结关系的种对较少;锐齿栎和其它树种间存在负联结关系,其中与栓皮栎、短柄枹树、茅栗的负联结性极显著。西北林学院学报24卷