从热带到温带 横断山地森林的垂直景观

<正>寒温性针叶林寒温性针叶林是横断山区分布面积最多的森林植被类型,由适应寒冷潮湿气候的云杉、冷杉、红杉(落叶松)等树种构成,主要分布在海拔3000米~4000米的亚高山带。图为在四川稻城亚丁"三神峰"之一的夏诺多吉峰映衬下的落叶松森林景观。     

峨眉冷杉群团状造林的初步研究

我省川西高山林区人工更新工作,通过反复的生产实践和科学试验,总结出了冷杉、云杉“宽带、大穴、丛植”的更新技术,提高了人工更新的保存率,受到许多营林单位普遍重视.但丛植更新尚存在着林分密度大,丛内株距短,林木间竞争剧烈,如抚育间伐不及时,则会影响林木的生长.因此,在研究冷杉、云杉生长特性和自然分布规律的基础上,川南森工局于1965年开始,进行群团状造林的试验.     

金沟岭林场过伐林更新幼苗空间结构分析

对吉林省汪清县金沟岭林场过伐林的更新幼苗株数及其分布格局进行了研究.结果表明:研究林分更新幼苗株数分布呈倒"J"型,主要树种更新幼苗株数由多到少依次为色木、冷杉、云杉和椴树,其它树种更新幼苗株数均较少;色木、冷杉和云杉的更新幼苗株数均随幼苗等级的增大而减少,椴树的更新幼苗株数随幼苗等级的增大而增多,红松、榆树和水曲柳株数变化没有规律;逆函数、三次函数、二次函数、复合函数,幂函数、生长函数、指数函数和逻辑函数均符合林分株数分布规律;分布格局采用方差均值比率法和4种聚集度指标法共同检验,结果表明林分及其主要树种更新幼苗的分布格局均为聚集分布,云杉和冷杉聚集强度居前两位.     

关于白龙江林区云杉人工更新技术的探索

白龙江属亚高山针叶林区,森林的自然分布具明显垂直带谱,从下到上依次为针阔混交林藓类箭竹针叶林,杜鹃冷杉林,高山灌丛及高山草甸。树种以冷杉、云杉为主,冷杉占总蓄积量的54.7%,云杉占20.7%,随着森林的开发利用,大面积的云杉(以 Picea asperata 为主)人工更新始于1961年。近两年,对云杉人工林进行了一次调查,本文根据部分调查资料整理并进行粗浅分析,以供商榷。一、人工林生育情况林区云杉更新的主要范围是海拔2000～3300米,现有成效面积四十余万亩,有的已郁闭形成稳定群落。由于立地条件和经营措施的差别,群落形态结构相异,有的长势弱,林相参差不齐,有的展现速生趋势,为天然林所莫及。以沙滩林场20年生(包括苗令,下同)为例:海拔2800米以下,一般树高5米胸径6厘米左右,而集约经营的树高达7.57米,胸径10.5厘米,均提高约三分之一。     

迭部林区中华松针蚧生物学特性与试验防治研究

迭部县地处甘肃省甘南藏族自治州东南部,总面积5108平方公里,境内森林资源丰富,森林覆盖率58%。按中国植被区划,迭部林区属于青藏高原东南部山地寒温性针叶林岷山峡谷山地落叶阔叶林云冷杉林区。     

论云冷杉林分的合理择伐强度

论述了云冷杉林分的采伐强度。分析了云冷杉林木枯死及风倒、风折的原因。提出云杉冷林分择伐强度应为伐前蓄积量的20-25％是可行的。     

川西亚高山暗针叶林叶面积指数的季节动态与空间变异特征

应用Li-cor LAI-2000植物冠层分析仪,研究生长季节川西亚高山暗针叶林叶面积指数(LAI)的时间动态, 比较4种岷江冷杉林分LAI的差异性,分析LAI与海拔和坡向之间的关系,探讨林分尺度和小流域尺度上LAI的空间变异性.结果表明:川西亚高山暗针叶林小流域LAI的季节动态变化规律明显,为单峰曲线,峰值(5.82±1.32)出现在8月中旬;4种岷江冷杉林LAI平均值为5.44±0.83,不同林分之间LAI差异极显著(p＜0.001),LAI顺序为:藓类-箭竹-岷江冷杉林＞草类-箭竹-岷江冷杉林＞草类-杜鹃-岷江冷杉林＞藓类-杜鹃-岷江冷杉林;随着海拔升高,LAI先增加,后减小,转折点出现在海拔3 000 m处,LAI(y)与海拔(x)之间的回归方程为:y= -22.408 6 0.019 6x-0.000 003 360 1x2 (R2 = 0.999 6, p＜0.001, n=12);半阴坡LAI(5.51±0.91)比半阳坡(5.36±0.72)大,差异显著(p＜0.05);林分尺度上的LAI变异系数(10.02%～12.22%)约是小流域尺度上的(19.79%～22.80%)1/2,随着海拔升高,其变化比较复杂,3 800 m处最大(23.09%),3 500 m处最小(7.64%),且半阴坡(16.58%)＞半阳坡(13.44%).     

金沟岭林场云冷杉林空间分布格局及更新研究

用距离方法(T-square)研究金沟岭林场主要森林类型云冷杉林的空间分布格局,经检验,2个云冷杉林分的林木空间分布格局分别为集聚分布和随机分布.其中2002年择伐的林分还没有得到恢复,因此呈集聚分布;而1988年择伐的林分已恢复了原始林的特征,其空间格局呈随机分布.由调查的更新数据可以清晰看出,研究林分更新状况很好.     

青海不同林分土壤微生物群落结构(PLFA)

【目的】研究青海省7种林分类型土壤微生物群落组成的变化规律,从微生物的角度为该区森林土壤资源的科学管理与评价以及林分结构调整和生态系统更新、恢复与重建提供科学依据。【方法】利用常规实验室分析和磷脂脂肪酸(phospholipid fatty acids,PLFAs)分析法对青海省云杉、白桦、落叶松和山杨组成的7种不同林分类型(大通青海云杉天然林A、大通白桦次生林B、湟中白桦青海云杉天然混交林C、乐都落叶松白桦天然混交林D、民和山杨人工林E、循化山杨白桦次生林F、尖扎青海云杉天然林G)表层土壤(0~20 cm)的土壤理化特征和微生物量及微生物群落结构的组成进行分析,并探索土壤微生物各菌群与土壤理化特性间的相关性。【结果】研究区不同林分类型土壤中共检测到17种PLFA生物标记,且PLFA生物标记的种类不尽相同,在A和B林分种类最多,而G林分种类最少;7种林分类型土壤中含量最高的PLFA生物标记是16:0,最丰富的脂肪酸种类是饱和脂肪酸;土壤微生物PLFA总量表现为B林分最高,G最低;细菌PLFA含量总体表现为阔叶林最高、针阔混交林其次,针叶林最低,真菌的PLFA含量明显表现为阔叶林混交林针叶林,且细菌的分布量显著大于真菌;7种林分类型土壤微生物多样性指数Simpson指数和Shannon-Wiener指数在F和G林分中显著小于其他类型,而McIntosh指数表现为A,B和D显著大于其他处理;主成分分析表明广义细菌和革兰氏阳性菌是土壤微生物群落类群的主要成分;冗余分析表明pH值、土壤含水量和细根生物量对土壤微生物群落的影响最大,其次为土壤有机碳含量、土壤密度和凋落物现存量。【结论】不同林分类型土壤微生物群落特征及其影响因子存在显著差异,在管理和利用森林生态系统时应考虑土壤微生物群落的变化特征,以便制定出合理的森林管理利用措施。     

西南林区冷杉复层林生长的研究(摘要)

1、本项研究对云南西北部潍西沙马公林区长苞冷杉(Abies georgei)及四川西部岷江林区柔毛冷杉(Abies faxoniana)两种复层林设置标准地共36块,先是确定其林型,并对其土壤、植物、更新情况、生长情况进行调查研究,随即从各项测树因子分析不同林层及不同世代林木生长的规律。2、关于林型及土壤调查,系根据林业部综合队原有的基础加以鉴定,并区别各个标准地所属林分不同的性质。     

Short-term effects of nitrogen deposition on soil respiration components in two alpine coniferous forests,southeastern Tibetan Plateau

Nitrogen (N) deposition to alpine forest ecosystems is increasing gradually, yet previous studies have seldom reported the effects of N inputs on soil CO2 flux in these ecosystems. Evaluating the effects of soil respiration on N addition is of great significance for understanding soil carbon (C) budgets along N gradients in forest ecosystems. In this study, four levels of N (0, 50, 100, 150 kg N ha^-1 a^-1) were added to soil in a Picea baifouriana and an Abies georgei natural forest on the Tibetan Plateau to investigate the effect of the N inputs on soil respiration. N addition stimulated total soil respiration (Rt) and its components including heterotrophic respiration (Rh) and autotrophic respiration (Ra);however, the promoted effects declined with an increase in N application in two coniferous forests. Soil respiration rate was a little greater in the spruce forest (1.05 μmol CO2 m^-2 s^-1) than that in the fir forest (0.97 μmol CO2 m^-2 s^-1). A repeated measures ANOVA indicated that N fertilization had significant effects on Rt and its components in the spruce forest and Rt in the fir forest, but had no obvious effect on Rh or Ra in the fir forest. Rt and its components had significant exponential relationships with soil temperature in both forests. N addition also increased temperature sensitivity (Q10) of Rt and its components in the two coniferous forests, but the promotion declined as N in put increased. Important, soil moisture had great effects on Rt and its components in the spruce forest (P<0.05), but no obvious impacts were observed in the fir forest (P>0.05). Following N fertilization, Ra was significantly and positively related to fine root biomass, while Rh was related to soil enzymatic activities in both forests. The mechanisms underlying the effect of simulated N deposition on soil respiration and its components in this study may help in forecasting C cycling in alpine forests under future levels of reactive N deposition.     

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.     

三峡库区主要森林类型的林分蓄积生长预测

正利用林分生长收获模型预测林分生长收获量是森林经营和管理的重要手段。早在200年前欧洲学者就编制了林分产量表,根据林分年龄预测林分产量。20世纪70年代随着计算机的普及,科学家们开始研究林分生长和产量预测模型系统,80年代后趋于成熟[1]。林分水平的生长和产量预测模型是采     

Carbon stocks and soil respiration rates during deforestation, grassland use and subsequent Norway spruce afforestation in the Southern Alps, Italy

Changes in carbon stocks during deforestation, reforestation and afforestation play an important role in the global carbon cycle. Cultivation of forest lands leads to substantial losses in both biomass and soil carbon, whereas forest regrowth is considered to be a significant carbon sink. We examined below- and aboveground carbon stocks along a chronosequence of Norway spruce (Picea abies (L.) Karst.) stands (0-62 years old) regenerating on abandoned meadows in the Southern Alps. A 130-year-old mixed coniferous Norway spruce-white fir (Abies alba Mill.) forest, managed by selection cutting, was used as an undisturbed control. Deforestation about 260 years ago led to carbon losses of 53 Mg C ha(-1) from the organic layer and 12 Mg C ha(-1) from the upper mineral horizons (Ah, E). During the next 200 years of grassland use, the new Ah horizon sequestered 29 Mg C ha(-1). After the abandonment of these meadows, carbon stocks in tree stems increased exponentially during natural forest succession, levelling off at about 190 Mg C ha(-1) in the 62-year-old Norway spruce and the 130-year-old Norway spruce-white fir stands. In contrast, carbon stocks in the organic soil layer increased linearly with stand age. During the first 62 years, carbon accumulated at a rate of 0.36 Mg C ha(-1) year(-1) in the organic soil layer. No clear trend with stand age was observed for the carbon stocks in the Ah horizon. Soil respiration rates were similar for all forest stands independently of organic layer thickness or carbon stocks, but the highest rates were observed in the cultivated meadow. Thus, increasing litter inputs by forest vegetation compared with the meadow, and constantly low decomposition rates of coniferous litter were probably responsible for continuous soil carbon sequestration during forest succession. Carbon accumulation in woody biomass seemed to slow down after 60 to 80 years, but continued in the organic soil layer. We conclude that, under present climatic conditions, forest soils act as more persistent carbon sinks than vegetation that will be harvested, releasing the carbon sequestered during tree growth.     

Larval performances and life cycle completion of the Siberian moth, <Emphasis Type="Italic">Dendrolimus sibiricus</Emphasis> (Lepidoptera: Lasiocampidae), on potential host plants in Europe: a laboratory study on potted trees

The Siberian moth, Dendrolimus sibiricus, Tschtv. is the most harmful defoliator of coniferous forests in North Asia. The pest has already spread over the Urals and continues moving westwards. Recently, it has been recommended for quarantine in member countries by European and Mediterranean Plant Protection Organization (EPPO). The performances of the pest on coniferous species planted in Europe were assessed on a range of potted trees corresponding to the spectrum of economically important conifers in the EU: European larch Larix decidua, Norway spruce Picea abies, Scots pine Pinus sylvestris, European black pine Pinus nigra, and the North American species: Douglas fir Pseudotsuga menziesii and grand fir Abies grandis. Larvae showed a potential to survive and complete the development on all these host tree species. Favorable hosts were grand fir, European larch, and Douglas fir that allowed higher survival, better larval development, and as a result, yielded heavier pupae and adult moths with higher longevity. Black pine was a poor host but, however, could still support larval and pupal development. Norway spruce and Scots pine had an intermediate behavior. If accidentally introduced to Europe, the Siberian moth may become especially damaging in forest stands predominated by European larch and by the North American firs. Norway spruce and especially the two-needle pines will be less prone to intensive defoliation by this species. The fact that the pest may damage the range of economically important coniferous species should be taken into account in the pest risk assessment for Europe and also for North America where the Siberian moth occurrence is considered likely.     

冰雪灾害后生态公益林乔木层物种结构变化

于2008年冰雪灾害后在福建省宁化县水茜乡生态公益林内常绿阔叶林、针阔混交林代表地段设置固定样地,探讨封育对冰雪灾害后的次生幼龄林乔木物种结构的变化。结果表明:经5 a封育,乔木层物种丰富度指数明显增加,自然恢复为以壳斗科、山茶科、樟科、杉科、安息香科等物种为建群种或共建种的次生常绿阔叶林、针阔混交林。随着封育的延续,针阔混交林往常绿阔叶林方向发展,使林分形成一个稳定的顶级森林群落。     

Variation in the incidence and severity of drought crack in three conifer species in North East Scotland

The incidence of longitudinal drought cracks in coniferous trees may increase as a consequence of climate change. While larger diameter trees are more prone to splitting, it is unclear why only some of the larger trees within the same stand typically suffer damage. Matched pairs of trees of the same size with and without cracks were studied in two adjacent pole-stage mixed stands of Sitka spruce/grand fir (Picea sitchensis/Abies grandis) and Sitka spruce/noble fir (Picea sitchensis/Abies procera) located in North-East Scotland. A range of attributes were measured on 15 damaged and undamaged trees of each species. Length and position of cracks on stems were also recorded, and annual ring width and latewood percentage measured on cores. Noble fir had significantly longer cracks and these were located higher in the stem than the other species. Fewer cracks formed on east-facing side of stems in all species suggesting that prevailing westerly winds may place greater tensile forces on the damaged sides of stems. A higher proportion of latewood (associated with higher tangential shrinkage) was found in the firs and may explain the greater incidence of cracking on grand and noble fir stems (13% and 16%, respectively) in comparison with Sitka spruce (3%).     

北亚热带不同森林群落类型的生物多样性研究

北亚热带地区的人工针叶纯林可以通过抚育间伐或者封山育林等措施大大加快其向着该地区的顶级群落方向演替。该地区几种典型群落的乔木层生物多样性指数大小依次为：针阔混交林〉〉常绿阔叶纯林〉马尾松纯林（郁0.5）〉马尾松纯林（CK组）〉杉木纯林（修枝）〉杉木纯林（间伐10%）;灌木层生物多样性指数大小排序为：马尾松纯林（CK组）〉杉木纯林（间伐10%）〉杉木纯林（修枝）〉常绿阔叶纯林〉马尾松纯林（郁0.5）〉针阔混交林。     

川西米亚罗林区云冷杉林健康状况评价

采用目标法和专家咨询法,建立一套结构由目标层、准则层和指标层组成的森林群落健康评价指标体系,其中准则层包括群落结构完整性、林分稳定性、林分生长状况3个方面,指标层包括郁闭度、下木总盖度、建群种平均胸径等9个指标.以森林小班为评价单元,对四川省阿坝州川西林业局301林场云、冷杉林进行森林群落健康状况评价.结果显示:301林场健康林分占有比例最小,其中健康云杉林面积占云杉林面积的13.82%,健康冷杉林面积占冷杉林面积的1.46%.亚健康林分比例最大,亚健康云杉林面积占云杉林面积的83.46%,亚健康冷杉林面积占冷杉林面积的76.03%.不健康林分比例也比较小,不健康云杉林面积占云杉林面积的2.71%,不健康冷杉林面积占冷杉林面积的22.51%.最后初步分析造成目前这种森林群落健康状况的主要原因.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.