Modelling incidence of root rot in picea abies plantations in Southern Sweden

An empirical model is presented to forecast the incidence of root rot at stand level. In addition, the impact of different thinning programmes on the incidence of root rot is evaluated. The model is based on data from 152 permanent forest research plots of pure Picea abies in southern Sweden, within which the incidence of root rot at stump height in thinned trees has been recorded after each thinning since 1950. In total, about 20 000 stumps have been studied. According to simulations with the model, areas previously used as fields or for grazing are particularly susceptible to root rot, while old hardwood sites are less susceptible. Furthermore, simulations with the model imply that the earlier, the harder or more often a stand is thinned, the faster will be the development of root rot.     

Canopy density in stands of Picea abies and Pinus sylvestris after different thinning methods

Altogether 82 plots (261 estimations) of Picea abies (L.) Karst, and 193 plots (360 estimations) of Pinus sylvestris (L.) stands were estimated by a vertical tube. The “crown free projection”, CFP, of stands thinned in three methods with different thinning grades was measured: unthinned, heavily and very heavily thinned, heavily thinned delayed first thinning, extra heavily thinned and thinned from the top. Basal area (m²ha^?1) density (stems ha^?1) and diameter sum (m ha^?1) were plotted against CFP. Basal area was the best practical measure of stand in this study. Generally Scots pine stands have higher CFP and the curves are steeper than in Norway spruce stands. Depending on the grade of thinning, heavily and very heavily thinned spruce stands, delayed first thinning included, have CFP values of 10–15% and stands thinned from the top, 20–40%, compared with 30–80% and 30–60% respectively in pine stands. Extra heavily thinned stands have the highest CFP, 20–80% in spruce and 50–90% in pine stands. The CFP levels after thinning are too high in pine stands for avoidance of sucker and sprout production of aspen and birch. In dense Norway spruce stands thinned from the top or heavily and very heavily thinned, the CFP values are low enough (≤30%) to diminish the production of suckers.     

落叶松枯落针叶水浸液对落叶松和云杉种子的萌发影响

研究了长白落叶松未分解和半分解枯落针叶的水浸液处理对红皮云杉种子和长白落叶松种子萌发的不同生物效应。对于长白落叶松种子萌发来说,长白落叶松半分解和未分解枯落针叶水浸液4.0 g/L浓度的处理效果均为最佳;而对于红皮云杉种子萌发来说,10.0 g/L浓度或0.5～1.0 g/L浓度的处理效果为最佳。长白落叶松枯落针叶水浸液处理对长白落叶松自身种子和对红皮云杉种子萌发的作用均有很大的差异,推测这是长白落叶松枯落针叶水浸液中所含的化感物质和营养物质与长白落叶松和红皮云杉萌发过程中种子产生的不同代谢物质之间不同相互作用的反映。     

Trends of tree growth in Swedish forests 1953–1992: An analysis based on sample trees from the national forest inventory

Average tree height and basal area growth for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) in Sweden were studied as functions of species, age, stand density, location and year of inventory in the period 1953–1992, on the basis of sample tree data from the National Forest Inventory. A highly significant annual increase of both height and basal area growth was found, of the magnitude 0.5–0.8%, during the 40 yr period. Possible reasons for the trend are discussed. The altered way of cutting in the early 1950s, from selective cutting to clear felling and thinning from below, has had a large impact. Also, improved regeneration methods, nitrogen fertilization and ditching have increased growth. The increasing atmospheric deposition of nitrogen is another possible factor.     

祁连山青海云杉林土壤理化指标空间变异性分析

通过对祁连山青海云杉分布带不同土壤剖面（0~40 cm）及不同海拔梯度上（2 500-3 100）土壤的温度、有机质、容重、水分等特征的分析,揭示土壤特性在空间上的变化规律。研究发现土壤温度随剖面深度的增加和海拔梯度的上升,都表现为明显的增大趋势。在0-10 cm,10-20 cm,20-40 cm土层内,土壤有机质含量分别为（135.2±24.6）g/kg、（111.2±14.3）g/kg、（91.7±12.9）g/kg,变异系数分别为18.23%、12.83%、14.10%;土壤有机质含量随土壤深度的增加逐渐降低,随海拔升高逐渐增加;土壤容重在剖面层次上具有明显的增大趋势,在海拔梯度上随海拔升高逐渐减小;土壤水分在0~40 cm土层内随着深度的增加逐渐减小,在海拔梯度上表现为波动变化,无明显的上升或下降趋势。     

多伦县沙地云杉混交林物种多样性研究

以多伦县沙地云杉林3条样带的群落调查数据为基础,研究了沙地云杉混交林的物种组成结构,分析了3个典型群落乔木层、灌木层、草本层的物种多样性。结果表明:沙地云杉混交林植物种类丰富,乔木层、灌木层、草本层共有植物71种,群落垂直结构分层明显;多伦县沙地云杉与白桦混交林物种多样性较丰富,在群落梯度上,群落Ⅰ为52种,群落Ⅱ为45种,群落Ⅲ为47种,物种丰富度指数大小顺序为群落Ⅰ>群落Ⅲ>群落Ⅱ;群落的物种多样性指数变化规律大致相同,均为草本层>灌木层>乔木层;3个典型群落的物种均匀度指数变化规律基本一致,为乔木层最大,灌木层其次,草本层最小。通过对多伦县沙地云杉混交林物种多样性的研究,为加强沙地云杉生物多样性的保护和经营管理提供理论依据。     

Evaluation of regeneration potential of Pinus koraiensis in mixed pine-hardwood forests in the Xiao Xing’an Mountains, China

Large scale harvest of Korean pine(Pinus koraiensis) seeds as a food product in the mixed Korean pine-hardwood forest of northeastern China poses a serious threat to the sustainability and restoration of this endangered regional ecosystem.Seed collection over past decades greatly reduced the seed bank and subsequent seedling and sapling recruitment,and impacting a wide array of granivorous animals that rely on the pine seeds.We surveyed Korean pine seeds,including solid seeds(SS),insect consumed seeds(ICS) and other(animal) consumed(OCS) kernels,of the seed bank(forest floor and the top 10 cm of mineral soil),the seedlings and saplings from 1 m 2 sample plots in five forest types in Liangshui Nature Reserve(LNR) of the southern Xiao Xing’an Mountains in northeastern China to provide accurate information for assessing the Korean pine regeneration potential.The average number of pine seeds in the seed bank were 11.2 seeds/m 2,9.1 seeds/m 2,4.6 seeds/m 2,1.1 seeds/m 2,and 0.2 seeds/m 2 in Korean pine-basswood forest,mixed Korean pine-hardwood forest,mixed conifer-hardwood forest,white birch forests,and oak forests,respectively.In the first three forest types,percentages of SS(potentially viable seeds) were 11.2%,3.5% and 27.8%,respectively.The percentages of ICS(not viable seeds) were consistent at around 35%.The higher but variable percentages of OCS(not viable seeds) indicated high seed predation in these forests.Compared with other studies,we recorded higher percentages of seed damage,probably due to our survey approach and the increased depth of seed bank sampled in our study.Depletion of pine seeds in the seed bank greatly reduced seedling and sapling recruitment.Densities of pine seedlings varied from about 180 trees/ha in the mixed Korean pine-hardwood forest to about 5,400 trees/ha in the mixed conifer-hardwood forests and showed a high degree of spatial variation.Saplings were rare in the mixed Korean pine-hardwood forest,but ranged in the thousands in other forests.Large scale pine seed harvest has seriously threatened the sustainability of the mixed Korean pine-hardwood forest ecosystem.Scaling down the seed harvest or supplemental planting of pine saplings are urgently needed to maintain the health of the existing Korean pine forests and to restore this endangered ecosystem.     

东大河林区青海云杉林健康评价

以2008年青海云杉（Picea classifolia）林样地调查资料为基础,用主成分分析、聚类分析、森林健康综合评价模型的方法,对东大河林区青海云杉林的森林健康状况进行了综合评价,结果表明,反映青海云杉林健康状况的自然环境、群落特征、恢复力、生产力和生产潜力5个方面19个指标,能够初步构建青海云杉林的健康评价指标体系。影响青海云杉林健康状况的主要指标有群落类型、郁闭度、灌木层盖度、林分蓄积量、土壤吸湿水、土壤含水率6个。将13个青海云杉林样地划分为健康、亚健康、不健康3类,健康样地包括7个苔藓-青海云杉林样地,占53.82%;亚健康林包括1个苔藓-青海云杉林样地和3个草类-青海云杉林样地,占30.77%;不健康林包括2个灌木-青海云杉林样地,占15.38%。     

辽东地区不同林型土壤理化性质研究

不同林型内土壤的理化性质存在差异,柞树林内土壤结构疏松,渗透能力强,土壤物理性质最好,其次为红松林,杂木林内最差,10～20 cm土层深度渗透速率仅为0.57 mm.min-1。从化学性质来看,阔叶树种土壤中养分含量较针叶林高,比较而言,柞树林内土壤各养分含量比杂木林内高。作为针叶树种的红松林土壤内,其速效养分含量较其他林型高。     

云杉3种21种源选择研究

摘要：对湖北省宜昌市夷陵区国有樟村坪林场的3个种21个种源5年生（包括苗龄2年）云杉试验林观测数据进行分析,结果表明：成活率和保存率、平均胸径、树高冠幅均表现出欧洲云杉最好,最优良种源是5号和6号种源,其立木单株树高比其它2个种平均树高提高24.7%。