长江上游地区林业生态建设与治理模式(续)

2　高山峡谷区长江上游高山峡谷主要分布于青藏高原东南缘 ,包括金沙江、雅砻江、大渡河、岷江等流域的上游地区 ,总面积约 2 9.9万ｋｍ2 。本区山高坡陡、冬寒夏凉 ,森林类型及组成多样 ,为西南最大的原始林区 ,也是我国珍稀动植物资源最丰富的地区之一 ,森林类型以云杉属、冷     

云南玉龙山亚高山针叶林天然更新的研究

本文主要研究了玉龙山亚高山针叶林(3000—3800米)的天然更新。调查分析了坡向、坡度、乔木郁闭度、下木覆盖度、枯枝落叶层厚度与天然更新的关系。2.在不同树种的林冠下,天然更新有其一定的共同规律。同时,由于各树种特性的不同,显示出某些差异。总的来看,乔木郁闭度中等、下木稀疏、缓坡以及枯枝落叶层厚度在5厘米以下,最有利于高山针叶林天然更新。但不同树种要求不同的坡向,云杉宜于阳坡,冷杉宜于阴坡,混交林则宜于半阳坡。3.当高山针叶林被火烧后,原来林内耐荫的植物不见了,迹地上代之而起的是耐早喜光的种类,山杨、桦木和柳逐渐生长起来。在阳性树种的庇荫下,才又有耐荫针叶树种出现,开始漫长的演替过程。4.就玉龙山的调查研究,提出对滇西北高山针叶林的开发意见。该林区应在发挥森林效益的前提下,制订合理的经营方针。     

开化县森林植被演替特征与景观优化改造分析

对开化县常绿阔叶林、针叶林、常绿落叶阔叶混交林3种不同自然森林植被类型进行演替过程分析研究。结果表明,常绿阔叶林是该地森林植被自然演替的主要发展方向;常绿阔叶林、针叶林、常绿落叶阔叶混交林分别代表了森林植被不同演替类型与动态。结合森林群落类型和生境的异质性、群落树种组成与结构、演替阶段和演替趋势,根据森林植被景观的优美性、多样性等需求,对开化县主要通道两侧的森林植被确定了7类15种目标的森林植被景观改造方案,提出了森林景观优化"主景树种+地带性树种+伴生景观树种"的树种选择模式与营建技术。     

也谈云冷杉的天然更新

森林更新的特点是森林群落长期自然选择的结果。林冠下天然更新能力的强弱,影响着森林植物群落结构的格局和演替趋势。云冷杉林分林冠下的天然更新有其自身的独特规律性。一、调查地区调查地区为云南省迪庆藏族自治州中甸县的尼汝和三坝林区,位于哈巴雪山东侧。属滇西北横断山高山峡谷区,最高海拔5000米,最低1600米,一般海拔3000米以_匕绝对高差     

祁连山排露沟流域中山带青海云杉林生长与海拔梯度上环境因子的关系

选择分布在祁连山排露沟流域中山带（海拔2900～3300 m）分布的青海云杉林为研究对象,研究了其生长与海拔梯度上环境因子的关系。研究结果表明：（1）青海云杉胸径和树高大小从郁闭林2900 m 到高山林线3300 m 处的变化规律表明,青海云杉生长在海拔3200 m 以上受到环境胁迫作用明显;青海云杉更新苗和非更新苗密度在海拔梯度上的变化规律也证实了这一点;（2）随海拔梯度的增加,青海云杉林地年降水量递增率平均值为19.94 mm/100 m;年均气温递减率大小为-0.67℃/100 m,青海云杉生长最低气温为-1.72℃;热量条件在一定程度上抑制了海拔3200 m 以上青海云杉的生长;（3）土壤剖面年均温度沿海拔高度的增加不断减小,而土壤含水量不断增加;土壤有机质、全氮和有效氮含量随海拔梯度的增加其含量也不断增加;土壤全磷、有效磷、全钾和有效钾含量随海拔梯度的增加没有明显的变化规律;不同海拔土壤酸碱性呈碱性;青海云杉林地有机质和全氮含量丰富,但是随海拔梯度增加土壤温度降低使得有效养分供应不足;（4）方差分析表明,海拔梯度影响下的环境因子对不同海拔青海云杉生长的影响大小顺序为：土壤化学性质（10.261）＞气象因子（7.900）＞土壤物理性质（2.535）,林地土壤化学性质是影响林木生长的最关键因子。上述研究结果有望为祁连山森林培育和保护管理提供理论参考和数据支持,也为干旱、半干旱区亚高寒山地森林植被对环境变化响应机制提供理论依据。     

小兴安岭地区退化林修复经营技术

通过对小兴安岭地区2种退化林地类型的实地调查,分析可知该地区退化林是由于过伐后缺乏人工经营形成的天然次生林,恢复策略主要为人工更新、人工促进天然更新以及天然更新相结合,其中以人工更新为主.红松针叶林更新演替退化类型适宜造林树种为红松(Pinus koraiensis),造林株行距为3 m×3 m;云杉针阔混交林更新演替...     

戴云山黄山松林森林群落类型分类及环境梯度解释

该研究运用数量生态学方法,揭示戴云山自然保护区黄山松林森林群落类型、分布规律及其与环境的对应关系。结果表明:(1)TWINSPAN将该研究区86块样地分成34个群落类型,可归为常绿阔叶林、针阔混交林、针叶林和灌丛4个植被类型,能够较好揭示该区群落的间断性和交互性;(2)戴云山保护区内海拔小于1 500 m左右主要是形成以罗浮栲林(Form.Daphniphyllum calycinum)、青冈林(Form. Acer davidii)、甜槠+木荷(Form. Castanopsis eyrei+Schima superba)、黄山松+木荷(Form. Pinus taiwanensis+Schima superba)、黄山松+甜槠(Form.Pinus taiwanensis+Castanopsis eyrei)、马尾松林(Form. Pinus massoniana)、黄山松林(Form. Pinus taiwanensis)等11个群系的镶嵌格局,整个群落处于未成熟的发展阶段,多为共有种群落。同一海拔形成不同演替阶段的植物群落,演替具有多阶段性;(3)CCA排序结果较好地反映出群落分布格局与环境梯度的关系,环境因子海拔梯度、土壤含水量、土壤有机质和p H是影响该区森林群落分布,形成不同植被类型的主要因子。     

川西亚高山森林不同恢复阶段生长季蒸腾特征

【目的】定量揭示我国川西亚高山地区不同恢复阶段森林的蒸腾耗水特征,为当地森林恢复树种选择、水源涵养功能提升与低效林改造等提供科学参考。【方法】选择川西亚高山地区植被恢复系列中无论是林龄、类型还是面积都具有典型代表性的岷江冷杉老龄原始林、红桦次生林和粗枝云杉人工林作为研究对象,利用热扩散技术监测生长季树木蒸腾量;利用林分边材面积进行尺度上推,估算林分冠层蒸腾耗水量。基于机器学习技术(随机森林回归算法)估算整个生长季(5—10月)的林分冠层蒸腾耗水量。【结果】各森林类型平均日冠层蒸腾量表现为粗枝云杉林红桦林岷江冷杉林;在整个生长季观测到的粗枝云杉林、红桦林和岷江冷杉林日最大冠层蒸腾量分别为3. 17、2. 08和1. 69 mm;基于多气象因素,随机森林回归算法可有效估算森林蒸腾耗水量;整个生长季的林分冠层蒸腾总量估算结果表现为粗枝云杉林(314. 1 mm)红桦林(199. 3 mm)岷江冷杉林(125. 5 mm)。【结论】处在演替早期的红桦次生林冠层蒸腾耗水量明显高于处于演替晚期的岷江冷杉原始林;人工林蒸腾耗水量明显高于天然林(岷江冷杉原始林和红桦次生林),因此可将森林蒸腾耗水特征作为研究区森林恢复度的评价指标。该区大量营造的粗枝云杉人工林已步入中龄林阶段,高蒸腾特征可能会对流域产水量构成压力,建议进行抚育性结构调整。通过综合分析多项研究结果,本文提出一个"森林水分利用生态演替"假说:伴随着亚高山森林植被自然恢复进程(正向演替),林地蒸腾耗水量趋于减少,地带性演替顶级群落亚高山暗针叶林具有最低蒸腾耗水特征。这个假说可作为川西亚高山区区域水文平衡维持和植被结构调整的参照体系。     

广西猫儿山典型植被林冠结构比较研究

运用LAI-2000冠层分析仪对广西猫儿山3种典型森林植被进行叶面积指数测定,对比3种典型森林植被叶面积空间分布以及其水平空间分布的均匀性。结果表明,(1)杉木林、木荷林和毛竹林叶面积指数水平分布由内向外逐渐减小,叶面积指数与距林冠投影中心距离呈二次函数关系;(2)杉木林叶分布的最大值在树冠顶部,从上到下叶面积指数逐渐下降;而木荷林从上层到下层叶面积指数呈增加的趋势;(3)杉木林的冠层在水平空间分布的均匀性要好于其他2种林型,毛竹林分布均匀性最差。本研究对揭示不同林型叶面积在森林植被中的空间格局,探究林冠结构和水文过程的关系,具有重要的理论和实践意义。     

大兴安岭东部林区岭南天然次生林经营方式研究

对天然次生林顺行演替采取的经营措施的效果进行分析,结果表明:对过伐林实行封山育林,对火烧迹地实行天然更新,其森林演替效果显著.对过渡阶段的次生林实行抚育间伐效果进行分析,结果表明:间密留稀的抚育方式可以促进树木生长量的提高,有利于森林的顺行演替;采阔留针的作业方式造成土壤肥不足,森林生长速度减慢,森林结构不合理,森林质量下降.不同森林类型的养分流研究结果表明,阔叶树较落叶松纯林更有利于增加土壤肥力,保护森林生产力;阔叶树凋落物的分解速率大大高于针叶树,加速了树木生长和森林演替速度.藉于研究结果,对确定合理的天然次生林经营方式提出了建议.     

The response of ground vegetation to structural change during forest conversion in the southern Black Forest

The aim of this study is to investigate the effects of forest conversion on forest floor vegetation. ‘Ecological’ forest conversion, as defined by an interdisciplinary southern Black Forest project group, describes the transformation of even-aged spruce (Picea abies L. H. Karst.) stands to structured continuous cover forests consisting of spruce (Picea abies), silver fir (Abies alba Mill.) and beech (Fagus sylvatica L.). In order to analyse the conversion process, four conversion stages were defined in a conceptual forest development model. Four forest districts deemed to be representative of the southern Black Forest region were selected for the study. The ground vegetation was initially classified independently from the stand structures. Subsequently, the relationship between stand structures, as determined by development stage, and ground vegetation was analysed. It was revealed that forest conversion modified the ground vegetation. The main factors influencing ground vegetation were the influence of broadleaves, predominately beech (F. sylvatica), on the canopy composition and litter coverage on the one hand; and the canopy coverage of spruce, the proportion of needle litter and the associated light penetration on the other. The prevalence of moss and vascular plant species preferring acidic sites found in spruce forests decreased during the transition process, whereas, species requiring a moderate base supply increased in abundance. The continuous cover forest representing the final stage of conversion increasingly contained a mixture of ground vegetation species normally associated exclusively with either conifer or deciduous forest. Due to the fact that there is an associated ground vegetation specific to the different stages of forest conversion in stands dominated by Norway spruce or European beech and a mixture in the latest conversion stages, large-scale forest conversion should be avoided in favour of management promoting a diversity of silvicultural goals and treatments in neighbouring stands. Only a variety of treatments ensures the maintenance of floristic diversity in the long-term.     

青海云杉林不同结构特征对天然更新的影响

通过对不同结构青海云杉林天然更新情况的调查分析,结果表明:不同生境条件下青海云杉林的树种组成、林分结构、生长状况和更新状况都有较大的差别;青海云杉的径级和高度决定着青海云杉林内不同树木个体间的竞争和分异状况,决定着不同高度级内的株数分布比例;青海云杉纯林中林分结构单一,更新良好;青海云杉+白桦混交林林分结构复杂,更新不良;青海云杉纯林下,拥有丰富的云杉种源,云杉种子饱满,保存云杉幼树数量多且生长状况好,能维持云杉种群的更新连续性和相对稳定性;林冠郁闭度为0.4时,更新情况最好;当郁闭度为0.7时,更新情况差。     

秦岭山地云杉林结构特征与更新动态的研究

云杉 (ＰｉｃｅａａｓｐｅｒａｔａＭａｓｔ.)林是秦岭林区高中山地带的顶极群落类型之一 ,由于其蓄积量高、材质优良 ,亦为秦岭林区开发利用最早的森林类型 (张仰渠 ,1 988)。陕西省云杉天然林面积日渐稀少 ,且资源分散 ,因此恢复云杉林在高山地带特有的防护作用 ,是秦岭林区一个重要的研究课题。本文根据对该林区天然云杉林、择伐更新林及皆伐迹地更新林的调查对比分析 ,研究了云杉林的结构特征及其更新动态 ,以期为探索该区云杉林的恢复途径及扩大这一树种资源提供科学依据。1　研究区概况及方法1 1　研究区概况　该研究在陕西省宝鸡市…     

Snow disturbances in secondary Norway spruce forests in Central Europe: Regression modeling and its implications for forest management

Snow is an important ecological factor limiting vegetation distribution, growth, and regeneration, and the importance of snow in the latitudes of Central Europe is expected to increase in the future. We assessed snow damage to secondary spruce stands (not of native provenance therefore not adapted to local conditions) in a mountainous region of 14500 ha in Central Europe (Moravian-Silesian Beskids, Czech Republic). We used neural networks-based regression modeling to study the relationship between stand and environmental parameters and four types of snow damage (top tree, crown, and stem breakage, and uprooting) that occurred during heavy snowfalls in winter 2005/2006 and 2009. Almost 40000 trees were sampled in 345 plots after each of these two events.The results suggest that parameters that can be controlled by forest management (mainly stand density and taper) were not closely associated with spruce forest resistance to snow damage. Investigated snow damage types were primarily related to the developmental stage of the stand, as indicated by stand volume, age, height, and diameter. Damage in 2009, which was caused by shorter-lasting and lower snow loads than the damage in 2005/2006, was also associated with elevation and snow depth. The response of snow damage to all stand development-related variables was clearly unimodal.We infer that forest management can reduce snow damage to secondary spruce forests in Central Europe only to a limited extent, especially under heavy snow loads. This conclusion is supported by the heavy snows that have frequently fallen on forests in Central Europe in the past and the projected increase in winter precipitation in mid- and northern latitudes; thereby increasing snow damage to forest in the future. Therefore, managers of such spruce forests should not specifically consider forest resistance to snow damage but should apply general practices that maintain forest health and productivity.     

岷江上游不同森林类型土壤有机碳含量及密度特征

本文研究了岷江上游云杉人工林、紫果冷杉人工林、岷江冷杉人工幼龄林、高山栎天然次生林4种森林类型土壤有机碳含量及密度。结果表明:4种森林类型不同土层有机碳含量和有机碳密度均差异显著,都随土层深度增加而逐渐减小,且土壤有机碳集中分布在表层土(0~20 cm)中;4种森林类型土壤有机碳含量从高到低排序为:云杉人工林(5.896 g.kg-1)紫果冷杉人工林(5.479 g.kg-1)高山栎天然次生林(5.019 g.kg-1)岷江冷杉人工幼龄林(2.245 g.kg-1);土壤有机碳密度从高到低为:云杉人工林(0.03541 kg.m-2)高山栎天然次生林(0.03134 kg.m-2)紫果冷杉人工林(0.02474 kg.m-2)岷江冷杉人工幼龄林(0.01573 kg.m-2)。说明林分起源、树种组成、植物根系、地表枯落物和人类活动等因素影响着土壤有机碳含量及碳密度。     

Post-1935 changes in forest vegetation of Grand Canyon National Park, Arizona, USA: Part 2—Mixed conifer, spruce-fir, and quaking aspen forests

This study examined changes in never-harvested mixed conifer (MCF), spruce-fir (SFF), and quaking aspen forests (QAF) in Grand Canyon National Park (GCNP), Arizona, USA based on repeat sampling of two sets of vegetation study plots, one originally sampled in 1935 and the other in 1984. The 1935 plots are the earliest-known, sample-intensive, quantitative documentation of forest vegetation over a Southwest USA landscape. Findings documented that previously described increases in densities and basal areas attributed to fire exclusion were followed by decreases in 1935-2004 and 1984-2005. Decreases in MCF were attributable primarily to quaking aspen (Populus tremuloides) and white fir (Abies concolor), but there were differences between dry-mesic and moist-mesic MCF subtypes. Decreases in SFF were attributable to quaking aspen, spruce (Picea engelmannii + Picea pungens), and subalpine fir (Abies lasiocarpa). Decreases in QAF resulted from the loss of quaking aspen during succession. Changes in ponderosa pine forest (PPF) are described in a parallel paper (Vankat, J.L., 2011. Post-1935 changes in forest vegetation of Grand Canyon National Park, Arizona, USA: part 1 - ponderosa pine forest. Forest Ecology and Management 261, 309-325). Graphical synthesis of historical and modern MCF data sets for GCNP indicated tree densities and basal areas increased from the late 19th to the mid 20th century and then decreased to the 21st century. Changes began earlier, occurred more rapidly, and/or were larger at higher elevation. Plot data showed that basal area decreased earlier and/or more rapidly than density and that decreases from 1935 to 2004 resulted in convergence among MCF, SFF, and PPF. If GCNP coniferous forests are trending toward conditions present before fire exclusion, this implies density and basal area were more similar among these forests in the late 19th century than in 1935. Changes in MCF and SFF can be placed in a general framework of forest accretion, inflection, and recession in which increases in tree density and basal area are followed by an inflection point and decreases. Accretion was triggered by the exogenous factor of fire exclusion, and inflection and recession apparently were driven by the endogenous factor of density-dependent mortality combined with exogenous factors such as climate. Although the decreases in density and basal area could be unique to GCNP, it is likely that the historical study plots provided a unique opportunity to quantitatively determine forest trends since 1935. This documentation of post-1935 decreases in MCF and SFF densities and basal areas indicates a shift in perspective on Southwestern forests is needed.     

Artificial regeneration of Korean spruce in northeast China

Korean spruce (Picea koraiensis Nakai) has been included as a Chinese regeneration species since the 1960′s. In the 1970′s it became one of the four most important species in the northeast forest region of China. Korean spruce is a timber species with a wide range of adaptation, high survival rate, and few diseases or pests. Studies of 30-year trials show that the regeneration of korean spruce is successful and has a prospective future.     

Long-term influence of fire and harvesting on boreal forest age structure and forest composition in eastern Québec

In boreal forests, historical variations in the area disturbed by natural disturbances or harvesting have rarely been compared. We measured temporal and spatial variations in areas affected by severe fires and clearcutting throughout the 20th century in a 57, 332 km² section of the eastern Canadian boreal forest. We examined the effects of these disturbances on spatio-temporal variations in the abundance of forests >60 years. Natural variability for the abundance of forests >60 years was estimated from simulations of natural disturbance regimes. We also measured compositional and structural differences between three categories of stands originating from relatively recent disturbances (∼50 years; clearcutting, fires, and clearcutting followed by fires), and one category of stands that were undisturbed for at least 200 years. At the regional level, we observed that forests >60 years gradually became scarcer throughout the 20th century due to a gradual expansion of harvested areas, an effect most pronounced in the southern part of the region, where mature and old forest abundance was clearly outside the range of natural variability at the end of the studied period. At the stand level, forest composition and structure differed between stand-origin categories: clearcutting-origin stands contained more balsam fir (Abies balsamea), fire-origin stands more black spruce (Picea mariana), and fire/clearcutting-origin stands more hardwoods (Betula papyrifera and Populus tremuloides). Overall, we estimate that strict forest management targets based on natural disturbance regimes will be difficult to achieve in eastern North-American boreal forests, most notably because contemporary disturbance rates, including both clearcutting and fire, have gradually become higher than the fire rates observed during the preindustrial period.     

Long-term spruce forest continuity – a challenge for a sustainable Scandinavian forestry

Macroscopic charcoal and pollen analysis were used to study the disturbance history and development of a boreal Norway spruce (Picea abies (L.) Karst.) forest landscape in southeastern Norway. The sites studied were natural forests and the charcoal records showed no evidence of fire disturbance that could have broken the continuity in the spruce forests that were established ca. 1700 years ago. Consequently, true spruce forest ecosystem continuity was documented on a landscape level. However, fire disturbed the mixed pine-deciduous forest ecosystems that preceded the present spruce forests, suggesting a shift from fire-prone, to fire-free forest ecosystems.It is argued that the studied forest landscape has the potential to be an important natural reference for future forestry, that would be required to mimic natural forest dynamics to be biologically sustainable. A stereotypic promiscuous use of fire in the regeneration phase may cause serious damages in forest ecosystems that have developed without the impact of fire disturbance.     

Availability of standing trees for large cavity-nesting birds in the eastern boreal forest of Québec,Canada

Large cavity-nesting birds depend on large-diameter trees for suitable nest sites. The increased spatial extent of commercial timber harvesting is modifying forest structure across the land base and may thus compromise the availability of large trees at the landscape scale. In this study, our objectives were to (1) characterize the availability of large living and dead trees in old-growth stands dominated by different tree species and surficial deposits that encompass the range of natural cover types of eastern Québec's boreal forest; (2) analyze the distribution of trees among decay-classes; and (3) compare the availability of large trees in unharvested, remnant, and harvested stands for the entire range of decay-classes. A total of 116 line transects were distributed across unharvested forests, remnant linear forests, and cutblocks in cutover areas. Unharvested forest stands (black spruce [Picea mariana], balsam fir [Abies balsamea]–black spruce, balsam fir–white spruce [Picea glauca] and balsam fir) reflected a gradient of balsam fir dominance. The remnant forests selected were isolated for 5–15 years. Analyses were performed at two diameter cut-off values. Trees with DBH ≥20 cm were considered for availability of total trees whereas trees with DBH ≥30 cm were considered for availability of large trees. Forest stands comprised high proportions of standing dead trees (33% of all stems, 8% were large dead stems). Availability of total and large standing trees increased with the dominance of balsam fir in stands. Forest stands located on thick surficial deposits showed higher densities of large dead trees for every stand type suggesting a higher productivity on those sites. Availability of stems according to decay-classes showed a dome-shaped distribution with higher densities of snags in intermediate decay stages. However, for large stems, black spruce stands showed a significantly lower availability that was consistent across all decay-classes. In linear remnant forests, pure balsam fir stands were absent. Remnant stands thus showed a much lower availability in large trees when compared with unharvested balsam fir stands. Clearcuts had the lowest densities of dead trees across sampled stands. Current even-aged management practices clearly affect availability and recruitment of large trees, therefore forest-dwelling wildlife relying on these structures for breeding is likely to be affected by large-scale harvesting in coniferous boreal forests.