首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Uneven-aged management of conifer plantations is proposed as a way to increase the value of these forests for the conservation of bird diversity. To test this assumption, we compared the impact of four common silvicultural systems on bird communities, defined by cutblock size (large in even-aged silvicultural systems/smaller in uneven-aged silvicultural systems) and tree species composition (spruce/beech) in the Belgian Ardenne where beech forests have been replaced by spruce plantations. The abundances of bird species were surveyed in young, medium-aged and mature stands in 3–5 forests per silvicultural system (66 plots in all). The effect of silvicultural systems on bird species richness, abundance and composition were analysed both at the plot and at the silvicultural system levels. In plots of a given age, beech stands were richer in species. The composition of bird species at the plot level was explained by stand age and tree composition, but weakly so by stand evenness. For the silvicultural systems, bird species richness was significantly higher in even-aged and in beech forests, and bird species composition depended on the silvicultural system. This study emphasises the importance of maintaining native beech stands for birds and suggests that uneven-aged management of conifer plantations does not provide a valuable improvement of bird diversity comparatively with even-aged systems.  相似文献   

2.
A preliminary analysis was made of growth trends in two silver fir forests in the Apennines in central Italy. The forests are closely located but were managed differently in the past. The aim was to verify the climatic variation over time, the influence of extreme events on radial growth and the role of silvicultural systems in defining growth response. The two forests have distinct structures due to differing past silvicultural management. The Camaldoli Forest, containing one-storeyed, evenaged, pure silver fir stands, was essentially managed in the past for wood production and featured high plantation density, low to moderate thinning, and clear cutting every 80–100 years. The La Verna Forest includes multi-layered, unevenaged stands that are mixed in with beech and other broadleaves. Increment cores were collected from aged dominant and healthy trees in the two forests. Climatic data were taken from the Camaldoli station and covers the period 1885–1994. All the analysed dendroecological parameters displayed similar patterns and indicated suitable site conditions for the silver fir. Silvicultural systems played an important role in defining growth pattern and rate. In the evenaged system there were higher growth rates and a greater number of pointer years, whereas there were lower growth rates and long, homogeneous development stages in the semi-natural conditions of La Verna. A rising growth trend recorded in the last three decades in both series could be explained by the consistent extension of the growing season due to a significant increase of mean spring and autumn temperatures. No correlation was found with precipitation while significant correlations were found between tree ring growth and February, April and August temperatures. Preliminary results indicated that the silvicultural system does not bias, but just enhances the ability of the species to record the effects of disturbing factors.  相似文献   

3.
4.
黄土高原主要森林类型自然性的灰色关联度分析   总被引:2,自引:0,他引:2  
为了解陕西黄土高原子午岭林区主要森林类型的自然性,以油松林、辽东栎林、白桦林、山杨林和侧柏林等5种森林类型为研究对象,通过0-1型变量聚类,较为客观地提出了森林群落各个演替阶段的植物组成,并计算出了各自的群落顶极适应值;采用层次分析的方法,得到群落特征指标权重,然后利用灰色关联分析方法,得到了各个森林群落的灰色关联度。研究结果表明,黄土高原不同森林类型的群落顶极适应值由大到小依次为辽东栎林(Quercus wutaishanica)8.37,油松林(Pinus tabulaefomis)8.16,山杨林(Populus davidiana)7.89,侧柏林(Platycladus orientalis)6.88,白桦林(Betula platyphylla)6.87;关联度由大到小依次为油松林1.143、辽东栎林1.085、侧柏林0.893、白桦林0.849、山杨林0.789。油松林和辽东栎林的灰色关联度较高,是这一地区较为稳定的理想森林类型,侧柏林和白桦林的关联度居中,山杨林最小。辽东栎林和油松林属于该地区的顶极和亚顶极群落类型,白桦林和侧柏林属于演替过渡类型,山杨林为演替阶段较低的森林类型。用灰色关联度的方法能够定量地分析森林群落的自然性,研究结果对森林近自然经营、林分改造有一定的应用价值和科学意义。  相似文献   

5.
Artificial drainage (ditching) is widely used to increase timber yield in northern forests. When the drainage systems are maintained, their environmental impacts are likely to accumulate over time and along accompanying management, notably after logging when new forest develops on decayed peat. Our study provides the first comprehensive documentation of long-term ditching impacts on terrestrial and arboreal biodiversity by comparing natural alder swamps and second-generation drained forests that have evolved from such swamps in Estonia. We explored species composition of four potentially drainage-sensitive taxonomic groups (vascular plants, bryophytes, lichens, and snails), abundance of species of conservation concern, and their relationships with stand structure in two-ha plots representing four management types (ranging from old growth to clearcut). We found that drainage affected plot-scale species richness only weakly but it profoundly changed assemblage composition. Bryophytes and lichens were the taxonomic groups that were most sensitive both to drainage and timber-harvesting; in closed stands they responded to changed microhabitat structure, notably impoverished tree diversity and dead-wood supply. As a result, natural old-growth plots were the most species-rich and hosted several specific species of conservation concern. Because the most influential structural changes are slow, drainage impacts may be long hidden. The results also indicated that even very old drained stands do not provide quality habitats for old-growth species of drier forest types. However, drained forests hosted many threatened species that were less site type specific, including early-successional vascular plants and snails on clearcuts and retention cuts, and bryophytes and lichens of successional and old forests. We conclude that three types of specific science-based management tools are needed to mitigate ditching effects on forest biodiversity: (i) silvicultural techniques to maintain stand structural complexity; (ii) context-dependent spatial analysis and planning of drained landscapes; and (iii) lists of focal species to monitor and guide ditching practices.  相似文献   

6.
Understanding the main factors driving bryophyte communities in forests is a worthwhile research area as it provides a framework within which to evaluate effective management options. Previous studies elucidated the role of forest structure, substrate, and climate, but their effect in a wide environmental context encompassing several types of forests is still unclear. The aim of this study was to assess the effect of climate, stand structure, substrates (tree trunks, deadwood, forest floor), and different forest types for species richness, species composition, and cover of bryophytes. Seven different types of Alpine forests dominated by spruce, larch-stone pine, silver-fir, Scots pine, oak, beech, and alder were selected. Bryophytes were sampled on tree trunks, deadwood, and forest floor. The importance of forest type, substrate, climate, and forest structure was determined by variance partitioning. Species richness and species composition were best explained by substrate (respectively 13% and 11%) and by forest type (respectively 13% and 11%). The bryophyte cover was primarily explained by the forest type (24%), and to a lesser extent by the climatic factors and stand structure. Overall, these results suggest that in this region ecologically based forest management might focus their efforts in protecting all the forest types and associated substrates. This means that forests of less economic value should also be preserved, and that acceptable silvicultural options should pay attention to the naturally available substrates. Too often, deadwood availability was a limiting substrate for bryophytes.  相似文献   

7.
In subtropical rainforest in eastern Australia, changes in the diversity of trees were compared under natural conditions and eight silvicultural regimes over 35 years. In the treated plots basal area remaining after logging ranged from 12 to 58 m^{2}/ha. In three control plots richness differed little over this period. In the eight treated plots richness per plot generally declined after intervention and then gradually increased to greater than original diversity. After logging there was a reduction in richness per plot and an increase in species richness per stem in all but the lightest selective treatments. The change in species diversity was related to the intensity of the logging, however the time taken for species richness to return to pre-logging levels was similar in all silvicultural treatments and was not effected by the intensity of treatment. These results suggest that light selective logging in these forests mainly affects dominant species. The return to high diversity after only a short time under all silvicultural regimes suggests that sustainability and the manipulation of species composition for desired management outcomes is possible.  相似文献   

8.
格氏栲天然林与人工林枯枝落叶层碳库及养分库   总被引:30,自引:4,他引:26  
通过对福建三明格氏栲天然林及在其采伐迹地上营造的 33年生格氏栲人工林和杉木人工林枯枝落叶层现存量与季节动态、C库及养分库的研究表明 ,格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层现存量分别为 8.99t· hm- 2 、7.5 6t· hm- 2 和 4 .81t· hm- 2 ;枯枝落叶层中叶占现存量的比例分别为 6 4 .96 %、6 1.38%和 38.0 5 % ,枝占比例分别为 31.5 9%、37.83%和 4 2 .6 2 %。格氏栲天然林与人工林枯枝落叶层现存量最大值均出现在春季 ,而杉木人工林枯枝落叶层现存量最大值出现在夏季。格氏栲天然林枯枝落叶层 C贮量为 4 .0 2 t· hm- 2 ,分别是格氏栲人工林和杉木人工林的 1.2 2倍和 1.77倍 ;格氏栲天然林和人工林枯枝落叶层 C库与杉木人工林的差异均达到显著水平 (P<0 .0 5 )。格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层养分贮量分别为 138.4 2 kg· hm- 2 、113.5 6 kg· hm- 2 和 72 .39kg· hm- 2 ;除 Mg外 ,格氏栲天然林枯枝落叶层中各种养分贮量均最高。与人工林相比 ,天然林枯枝落叶层现存量、C和养分贮量均最大。枯枝落叶层对林地长期生产力维持具有重要作用。  相似文献   

9.
格氏栲天然林与人工林细根生物量、季节动态及净生产力   总被引:59,自引:14,他引:59  
通过对福建三明格氏栲天然林及在其采伐迹地上营造的33年生格氏栲人工林和杉木人工林细根分布、季节动态与净生产力进行的为期3a(1999~2001)的研究,结果表明,格氏栲天然林、格氏栲和杉木人工林活细根生物量分别为4.944t/hm2、3.198t/hm2和1.485t/hm2,死细根生物量分别为3.563t/hm2、2.749t/hm2和1.287t/hm2;死细根生物量占总细根生物量的比例分别为41.9%、46.2%和46.4%;<0.5mm细根生物量占总细根生物量的比例分别为31.2%、29.4%和69.9%。3种林分活细根生物量和死细根生物量季节间差异显著(P<0.05),但年份间差异则不显著(P>0.05);活细根生物量最大值均出现在3月份,最小值一般出现在5~7月份或11~翌年1月份间。0~10cm表土层格氏栲天然林活细根生物量高达295.65g/m2,分别是格氏栲人工林和杉木人工林的2.4倍和8.1倍;该层格氏栲天然林活细根生物量占全部活细根生物量的59.8%,均高于格氏栲人工林(39.07%)和杉木人工林(24.51%)。格氏栲天然林、格氏栲人工林和杉木人工林细根分解1a后的干重损失率分别为68.34%~80.13%、63.51%~77.95%和47.69%~60.78%;年均分解量分别为8.747、5.143和2.503t/hm2;死亡量分别为8.632、5.148和2.492t/hm2;年均净生产量分别为8.797、5.425和2.513t/hm2,年周转速率分别为1.78、1  相似文献   

10.
Silvicultural practices are traditionally aimed at increasing forest profits; however, recent approaches to forest conservation have broadened to include nature-based silviculture for regenerating forests. In southern Ontario (Canada), originally dominated by deciduous forests, conifer plantations were established on abandoned agricultural sites. Currently, there is an increasing interest to convert these conifer stands to a state that mimics the original deciduous forest. We investigated arthropod abundance, species richness of carabid beetles, and abundance of arthropod assemblages (trophic and prey groups) under five silvicultural treatments conducted to regenerate deciduous forests (the natural forest type) from the old conifer plantations. The treatments included: (1) uniform canopy removal; (2) uniform canopy removal and understory removal; (3) group canopy removal; (4) group canopy removal and understory removal; and (5) untreated control plots (relatively pure red pine). Insects were sampled annually using sweepnets and pitfall traps. Results revealed treatment effects on the abundance of Coleoptera, Heteroptera, herbivores, and small arthropods (<3 mm) caught in sweepnet samples, where plots subjected to group shelterwood removal and understory removal supported higher abundances than the control plots. There was no treatment effect on the abundance of other arthropod groups or on the species richness and abundance of carabid beetles. The silvicultural treatments used to encourage natural regeneration did not seem to affect arthropod food availability for insectivorous vertebrates. Thus, the type of silvicultural strategy used to convert pine plantations to a stage that mimics the natural deciduous forests had little overall impact on arthropods.  相似文献   

11.
Khatouri  M. 《Plant Ecology》1992,(1):77-82
The coppice method is the silvicultural system commonly applied to Quercus ilex (holm oak) forests for the production of firewood and charcoal. Although the holm oak is the species that covers the largest area in Morocco (1400 000 hectares), little is known about its growth and yield. The objective of this study is to quantify the stand growth and yield of young coppice holm oak stands in the Tafferete forest in the eastern part of the Middle Atlas (Morocco).Equations relating dominant height to age, and basal area, volume, and number of trees to dominant height were developed and used to derive young holm oak coppice yield estimates.The growth and yield information developed in this study may have a greater utility in defining cultural measures that should be applied in the early stage of holm-oak coppice stands.  相似文献   

12.
1 A variety of silvicultural techniques have been suggested for managing forest defoliating insects. The objectives focus on minimizing defoliation or minimizing damage from defoliation. 2 The theoretical foundations of many approaches have been built upon observation and correlation, and very little reliable empirical evidence exists to support the objectives of silvicultural manipulations. Existing experimental data have yielded inconsistent results. 3 We review the conceptual framework and underlying assumptions of the major silvicultural approaches recommended or in use in North America. 4 Well‐designed, long‐term studies are needed to clarify the effect of silviculture on defoliators and their effect on forests.  相似文献   

13.
Greece, as part of the Mediterranean Basin, is projected to be among the most vulnerable countries to climate change. It is therefore quite urgent to adapt forest management to the changing climate in order to enhance biodiversity and to enable the conservation of healthy and productive forests. In the framework of the project LIFE+ AdaptFor (www.life-adaptfor.gr), an effort was made to understand the ecological responses and the vulnerability of forest ecosystems in the face of climate change; the overall aim of the project is the development and implementation of appropriate adaptation strategies. Four study areas were selected where changes in vegetation, quite likely attributed to climate change, have already been observed (dieback of Scots pine and Greek fir, intrusion of conifers in broadleaved forests). To investigate the synergism of climatic parameters’ alterations in the development of the occurring phenomena, time series of temperature and precipitation for the period 1950–2009 were produced and parameters of forest status were investigated, including mapping of vegetation changes through remote sensing. The findings support the hypothesis that climate change has an impact on forest health; the dieback of tree species can be attributed to outbreaks of pathogens (fungi and insects) which are associated with climatic parameters. However, the intrusion of conifer species into broadleaved forests showed no direct connection to climatic parameters, something that needs to be further investigated. In all cases, insufficient or inappropriate management practices applied in the areas exacerbated the occurring phenomena.  相似文献   

14.
Most large‐scale multispecies studies of tree growth have been conducted in tropical and cool temperate forests, whereas Mediterranean water‐limited ecosystems have received much less attention. This limits our understanding of how growth of coexisting tree species varies along environmental gradients in these forests, and the implications for species interactions and community assembly under current and future climatic conditions. Here, we quantify the absolute effect and relative importance of climate, tree size and competition as determinants of tree growth patterns in Iberian forests, and explore interspecific differences in the two components of competitive ability (competitive response and effect) along climatic and size gradients. Spatially explicit neighborhood models were developed to predict tree growth for the 15 most abundant Iberian tree species using permanent‐plot data from the Spanish Second and Third National Forest Inventory (IFN). Our neighborhood analyses showed a climatic and size effect on tree growth, but also revealed that competition from neighbors has a comparatively much larger impact on growth in Iberian forests. Moreover, the sensitivity to competition (i.e. competitive response) of target trees varied markedly along climatic gradients causing significant rank reversals in species performance, particularly under xeric conditions. We also found compelling evidence for strong species‐specific competitive effects in these forests. Altogether, these results constitute critical new information which not only furthers our understanding of important theoretical questions about the assembly of Mediterranean forests, but will also be of help in developing new guidelines for adapting forests in this climatic boundary to global change. If we consider the climatic gradients of this study as a surrogate for future climatic conditions, then we should expect absolute growth rates to decrease and sensitivity to competition to increase in most forests of the Iberian Peninsula (in all but the northern Atlantic forests), making these management considerations even more important in the future.  相似文献   

15.
The main ecosystem services (ES) central European mountain forests provide are: protection against gravitational hazards, timber production, recreation, biodiversity conservation and carbon storage, which are all in high demand. These demands make managing mountain forests a challenging task, involving manifold synergies and conflicts between the different ES. There is therefore an urgent need for appropriate concepts and tools for support decisions in forest management and planning (FMP) to take into consideration all ES and to manage the wide variety of information types, parameters and uncertainties involved in assessing the sustainability of ES. Multi-criteria decision analysis (MCDA) provides a suitable set of methods for sustainability evaluations. In this study sustainability means the persistent fulfilment of the required ES. To address all the phases of the FMP process, MCDA and forest models should be applied together, with indicators providing the main interfaces to combine them. This paper aims to: i) review assessment approaches in order to select appropriate and widely accepted indicators for measuring and assessing the effects of different silvicultural management alternatives on forest ES, and ii) present additional standardisation approaches (value functions) for each indicator. Standardisations are necessary to make the different ES comparable and to study synergies and trade-offs between different management objectives in MCDA. The main ES in central European mountain regions are considered, with a clear focus on those indicators that are directly derivable from forest model outputs and that can refer to sustainable forest management practices. The scales considered are that of the single forest stand and of the larger forest management unit. A holistic indicator-based analysis framework for FMP in mountain forests can be built using the indicators and value functions described. The influence of different management alternatives on ES can then be evaluated, taking into consideration the instruments and information on forest management (forest models, inventory) available. All indicators are selected according to existing and approved approaches that only require data that is normally available in operational forest management. The framework can thus be an important element in developing a decision support system for FMP in mountain forests.  相似文献   

16.
罗旭  梁宇  贺红士  黄超  张庆龙 《生态学报》2019,39(20):7656-7669
气候变化及相应火干扰在不同尺度上影响着我国大兴安岭地区森林动态,且在未来的影响可能继续加剧。为了提高森林生态功能和应对气候变暖,国家在分类经营基础上全面实施抚育采伐和补植造林,效果较好,但抚育采伐对森林主要树种的长期影响知之甚少,其在未来气候下的可持续性也有待进一步评估,同时,探讨造林措施对未来森林的影响也显得尤为重要。本文运用森林景观模型LANDIS PRO,模拟气候变化及火干扰、采伐和造林对大兴安岭地区主要树种的长期影响。结果表明:1)模型初始化、短期和长期模拟结果均得到了有效验证,模拟结果与森林调查数据之间无显著性差异(P0.05),基于火烧迹地数据的林火干扰验证亦能够反映当前火干扰的效果,模型模拟结果的可信度较高;2)与当前气候相比,气候变暖及火干扰明显改变了树种组成、年龄结构和地上生物量,B1气候下研究区森林基本上以针叶树种为主要树种,A2气候下优势树种向阔叶树转变;3)与无采伐预案相比,当前气候下,抚育采伐使落叶松的林分密度和地上生物量分别降低了(165±94.9)株/hm~2和(8.5±5.1) Mg/hm~2,增加了樟子松、白桦和云杉等树木株数和地上生物量(3.3—753.4株/hm~2和0.2—4.0 Mg/hm~2),而对山杨的影响较小;B1和A2气候下抚育采伐显著改变林分密度,降低景观尺度地上生物量,进而表现为不可持续;4)B1气候下,推荐实施中低强度造林预案(10%和20%强度),在A2气候下,各强度造林均可在模拟后期增加树种地上生物量。  相似文献   

17.
18.

Background and Aims

The structure of a forest stand, i.e. the distribution of tree size features, has strong effects on its functioning. The management of the structure is therefore an important tool in mitigating the impact of predicted changes in climate on forests, especially with respect to drought. Here, a new functional–structural model is presented and is used to assess the effects of management on forest functioning at a national scale.

Methods

The stand process-based model (PBM) Castanea was coupled to a stand structure module (SSM) based on empirical tree-to-tree competition rules. The calibration of the SSM was based on a thorough analysis of intersite and interannual variability of competition asymmetry. The coupled Castanea–SSM model was evaluated across France using forest inventory data, and used to compare the effect of contrasted silvicultural practices on simulated stand carbon fluxes and growth.

Key Results

The asymmetry of competition varied consistently with stand productivity at both spatial and temporal scales. The modelling of the competition rules enabled efficient prediction of changes in stand structure within the Castanea PBM. The coupled model predicted an increase in net primary productivity (NPP) with management intensity, resulting in higher growth. This positive effect of management was found to vary at a national scale across France: the highest increases in NPP were attained in forests facing moderate to high water stress; however, the absolute effect of management on simulated stand growth remained moderate to low because stand thinning involved changes in carbon allocation at the tree scale.

Conclusions

This modelling approach helps to identify the areas where management efforts should be concentrated in order to mitigate near-future drought impact on national forest productivity. Around a quarter of the French temperate oak and beech forests are currently in zones of high vulnerability, where management could thus mitigate the influence of climate change on forest yield  相似文献   

19.
生态弹性是森林生态系统在遭受外在扰动后恢复到稳定状态的能力,是森林资源可持续发展的重要目标之一,且森林生态弹性对诸如气候变化、林火和营林措施等外部因子的影响较为敏感.探究这些外部因子对森林生态弹性的影响在未来森林生态系统管理方面有重要意义.本研究首先从森林组成、结构和功能等方面选取指标因子并估算了森林生态弹性值,然后运用LANDIS PRO模型,模拟气候变化、林火干扰和营林措施等对寒温带典型森林生态弹性的影响,并探讨了当前抚育采伐方案在未来气候下的可持续性.结果表明: 模型初始化的2000年林分密度和胸高断面积与2000年真实景观较为吻合,模拟的2010年森林景观与野外调查数据无明显差异,基于当前林火干扰状况的模拟结果与火烧迹地调查数据基本匹配,说明林火模块能很好地模拟当前研究区林火发生状况.林火干扰增加30%将会使该区模拟期内景观水平上森林生态弹性提高15.7%~40.8%,而林火干扰增加200%则会降低该区4.4%~24.6%的森林生态弹性.短期和中期林火干扰增加对森林生态弹性的影响大于气候变化的影响.与当前预案相比,B1气候(林火增加30%预案)和A2气候(林火增加200%预案)对整个模拟阶段景观尺度森林生态弹性的影响分别处于-15.9%~38.9%和-60.4%~34.8%范围内.与无采伐预案相比,B1和A2气候下在整个模拟时期内若继续实施当前抚育采伐方案,将不利于景观水平森林生态弹性的提高.在B1气候(林火增加30%预案)下,在各模拟时期内无需实施任何营林措施;而在A2气候(林火增加200%预案)下,建议实施中、高强度种植的营林措施以提升景观水平森林生态弹性.  相似文献   

20.
Lichens are a key component of forest biodiversity. However, a comprehensive study analyzing lichen species richness in relation to several management types, extending over different regions and forest stages and including information on site conditions is missing for temperate European forests. In three German regions (Schwäbische Alb, Hainich-Dün, Schorfheide-Chorin), the so-called Biodiversity Exploratories, we studied lichen species richness in 631 forest plots of 400 m2 comprising different management types (unmanaged, selection cutting, deciduous and coniferous age-class forests resulting from clear cutting or shelterwood logging), various stand ages, and site conditions, typical for large parts of temperate Europe. We analyzed how lichen species richness responds to management and habitat variables (standing biomass, cover of deadwood, cover of rocks). We found strong regional differences with highest lichen species richness in the Schwäbische Alb, probably driven by regional differences in former air pollution, and in precipitation and habitat variables. Overall, unmanaged forests harbored 22% more threatened lichen species than managed age-class forests. In general, total, corticolous, and threatened lichen species richness did not differ among management types of deciduous forests. However, in the Schwäbische-Alb region, deciduous forests had 61% more lichen species than coniferous forests and they had 279% more threatened and 76% more corticolous lichen species. Old deciduous age classes were richer in corticolous lichen species than young ones, while old coniferous age-classes were poorer than young ones. Overall, our findings highlight the importance of stand continuity for conservation. To increase total and threatened lichen species richness we suggest (1) conserving unmanaged forests, (2) promoting silvicultural methods assuring stand continuity, (3) conserving old trees in managed forests, (4) promoting stands of native deciduous tree species instead of coniferous plantations, and (5) increasing the amount of deadwood in forests.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号