混交林营造及其机理的研究概况

从混交林的增产效益，生态效益和防护效益，混交林的树种选择，混交比例和混交方式等方面的营造技术以及混交林内树种间在生物化学，生物场，生物量和养分生物循环等方面的相互关系出发，阐述了国内外混交林营造及其机理的研究概况。     

混交林培育方法

正混交林营造成功的关键在于正确处理树种间的关系,使主要树种在伴生树种的辅佐下取得最好的生长效果。造林前首先根据造林地的条件和造林目的选择适宜的主要树种,再确定相应的伴生树种、混交方式和混交比例。造林时,通过控制造林时间、造林密度、株行距、苗木年龄和造林方法等措施调节树种间关系。为了协调两个树种之间的相互关系,有时还可以引进第3个树种栽培于二者之间,这个树种称为缓冲树种。黄土高原的混交林的营造在无林地区是按照设     

研究树种混交的意义、原理和方法

(接上期)三、树种间相互作用的方式与调节树种间的相互作用是混交林不同于纯林的主要特点,正确认识和处理各树种间的相互关系是营造混交林的主要问题。(一)树种间相互作用的方式:共同生活的树种间特别是全部森林植物之间相互影响的方式,是多种多样的。在教科书中,一般把它分成两大类:(1)直接关     

浅析调节混交林的种间关系

文章通过合理设计混交林的树种混交类型、比例和混交方式进行调节混交林的种间关系。营造混交林能够促进复层结构,充分利用空间和营养,利于提高地力和保护生物多样性,生态和经济效益高而稳定,增强预防病虫害的能力,因此要大力提倡合理营造混交林,并且要调节好混交林的种间关系。     

曲靖市混交林营造技术探讨

文章指出了营造混交林是解决纯林弊端的重要途径。从曲靖市的实际出发,分析了营造混交林的意义与优势、营造混交林的应用条件,提出了确定主要树种、选择混交树种、确定合理的混交比例、选择适当的混交方法、控制造林时间、抚育调控种间关系等混交林营造的关键技术,以期为曲靖市或者其他兄弟州市在营造林生产上推广应用混交林营造技术提供一定的科学决策依据。     

曲靖市混交林营造技术探讨

以曲靖市为例,阐述了营造混交林在充分利用空间和营养面积、有利于改善立地条件、提高林产品的数量和质量、增加林分的生态效益和社会效益、抗灾害能力强等方面的意义与优势,分析了营造混交林的造林目的、立地条件、树种特性、经营条件等应用条件,总结了确定主要树种、选择混交树种、确定混交比例、选择混交方法、控制造林时间、抚育调控种间关系等混交林营造的关键技术,以期为曲靖市或者其它兄弟州市营造混交林提供一定的技术参考。     

国内外混交林研究概况(下)

六、混交林的基础研究 混交林树种间相互作用的方式多种多样,并随时间、地点、条件而变化。研究树种间的相互关系和混交林及其纯林的生态、生理差异,是阐明混交林生长发育规律,制订营林措施的理论基础。 (一)林分结构的研究 国内外对混交林各部分(干、枝、叶、     

林木种间的化感作用

植物化感作用是自然界普遍存在的一种现象, 在农作物耕作、杂草控制、病虫害防治以及林木营造等方面发挥着重要作用。树种搭配是成功营造人工混交林的关键, 林木种间的化感作用在混交树种的选择上起着重要作用。文中从化感物质的收集与提取、化感物质的鉴定以及化感作用的表达等方面, 对人工混交林常见树种间化感作用的研究情况和成果进行综述, 以期为混交林选择树种组合提供科学依据, 为生态公益林建设服务。     

人工混交林种间关系的调控技术

混交林种间关系是树种间通过复杂相互作用而对彼此产生利害作用的最终结果,种间关系的发展演变直接影响到混交林营造的效果。在森林培育中,要充分掌握混交林种间关系的表现形式和作用形式,在选择种间关系协调的混交树种组合基础上,可通过调整混交比例、混交方法、混交时间,加强抚育管理、间伐等营林技术调控混交林的种间关系,达到培育混交林的目的。     

混交林研究进展

从混交林的滋交效益、营造技术、营造途径、树种间的生物化学作用和养分关系方面阐述了混交林研究的进展及发展趋势。     

Insect Herbivore Responses to Management Practices in Conifer Forests in North America

ABSTRACT

Pine-dominated forests in southeastern North America and at low-to-mid elevations in western North America historically were characterized by frequent, low-intensity fire that maintained wide spacing of site-adapted tree species, conditions that optimized biochemical defenses of trees and dispersal distances of herbivorous insects. Mixed conifer forests at higher elevations were wetter, denser, and characterized by infrequent stand-replacing fire and relatively isolated insect outbreaks. Increased density and altered tree species composition in managed forests have increased forest vulnerability to extensive outbreaks of bark beetles and defoliators. Herbivore-generated tree mortality and litter accumulation increase the likelihood of catastrophic fire. Management practices that produce an appropriate mixture of site-adapted tree species and wide host spacing are recommended to minimize the negative effects of herbivorous insects and fire. However, the creation of stumps, as a result of mechanical thinning, can favor lower-bole and root-colonizing insects that also may vector root diseases.     

近自然森林经营理论在龙里林场国家储备林改培中的应用

指出了龙里林场现有国家储备林中以马尾松人工林为主,树种结构单纯、层次结构简单、生态效益差、生态系统脆弱,容易发生雪压、风倒、火灾,松毛虫危害严重。为了改善林场马尾松人工林的健康状况,提高物种多样性和生态稳定性,优化林分的树种、水平、垂直结构,进一步提高林分质量,模仿马尾松自然演替规律,通过择伐,在林下补植了乡土珍贵树种,以把马尾松人工林尽可能地改造为接近自然状态的异龄针阔混交林,结果表明:近自然改造具有如下优点:①确保了持续的主林层郁闭,实现了森林的永续利用。②将培育珍贵树种与马尾松大径材有机结合起来,兼顾了森林的经济、生态、社会效益。③有利于提高林分质量,保证了森林的健康可持续发展。     

南宁市速生桉发展最大面积的论证研究

发展速生桉在一定程度上有效缓解了广西区乃至我国木材紧缺的局面。以南宁市林地布局及空间分析为基础,综合考虑扣除公益林后的林地面积以及速生桉生长的立地条件,确定全市发展速生桉的最大理论面积为38．46万hm^2。根据南宁市五大类培育树种的规划比例以及林地保护利用规划成果,提出速生按建议发展最大面积为31．92万hm^2。并提出合理调整林种、树种结构,增强森林的综合功能及效益等建议。     

Breeding bird community composition in different successional vegetation in the montane coniferous forests zone of Taiwan

To examine the relationship between forest succession following fire and the composition of bird communities, we investigated the vegetation structure, bird population density, foraging behavior and guild structure in bamboo grasslands (11 years since the last fire), pine savanna (41 years), pine woodland (58 years), old-growth hemlock forest (never burned), and old-growth spruce forest (never burned) in the Tatachia area of central Taiwan. Canopy height, total foliage cover, tree density, total basal area of tree, total basal area of snags, foliage height diversity, and tree species richness all increased with successional age. However, shrub cover peaked in intermediate successional stages. The vertical profile of foliage cover was more diverse in later successional forests, which had more breeding bird species and ecological guilds. All the breeding bird species recorded in early and intermediate stages were also found distributed in the late successional forests. Because Taiwan has high precipitation and humidity, and most forest fires in Taiwan are caused by human activities, forest fires and large areas of early successional vegetation were probably rare in the mountain areas of Taiwan prior to the arrival of humans. Therefore, bird species have not had enough time to adapt to areas with early or intermediate successional vegetation. Moreover, late successional forests host all the major plant species found in the early and intermediate stages and have higher foliage height diversity index, which was positively correlated with the bird species richness and bird species diversity index in this study. As a result, all breeding bird species and guilds in the area can be found in late successional forests. Efforts for conserving avian diversity in Taiwan should focus on protecting the remaining native old-growth forests.     

短轮伐期菇木林栽培试验研究

马褂木具有较强的竞争能力 ,生态适应性强 ,生长快 ,成材早 ,在早期就可表现出速生丰产性能 ,是最佳的短轮伐期菇木树种 ;马褂木既可营造纯林 ,也可营造混交林 ,保存率高达 90 %～ 96 %,明显优于其它伴生树种。杜英、枫香也是适宜的菇木树种 ,杜英生长速度较快 ,与马褂木、厚朴分别混交 ,生长效果都较好。枫香与马褂木混交 ,种间关系协调 ,树种生物学特性互补 ,林分空间结构分布合理 ,是一种成功的混交模式。酸枣生长快 ,适应能力强 ,保持率较高 ,但侧枝多 ,冠幅庞大 ,适合营造混交林 ,且混交比例不宜太大 ;与马褂木混交 ,种间关系协调 ,相互促进生长。厚朴的生长潜力还没有充分发挥 ,需进一步观察。乐昌含笑、白玉兰初期生长缓慢 ,暂不适用作菇木树种。     

延安市退耕还林工程林种、树种组成分析研究

林种结构和树种组成是退耕还林工程的关键问题之一,本文分析了延安市退耕还林工程实施以来造林林种和树种组成,指出其存在林种选择上经济林面积过小,使退耕农户从退耕地中收益减少;树种单一,纯林面积过大等问题。建议要因地制宜地发展经济林,适地适树,乔灌草结合,多营造混合林。     

山西省秋千沟林场林种和树种结构的研究

选用分析系统递阶层次结构的层次分析法作为数学工具。对山西省秋千沟林场的林种、树种结构进行了研究。结果表明，该法对于“目标结构比较复杂，缺乏必要数据的结构优化问题”比较适用，可按兼顾生态效益、社会效益、经济效益，又有所侧重的原则，将各林种、树种的面积比例落实到合理的水平上。     

三北防护林体系工程发展现状及对策

为了改善生态环境,中国政府于１９７８年开始在三北地区建设林体系。１５年来,共计完成人工造林１３３０ｈｍ＾２,零星植树３０亿株,森林被覆盖率已由１５年前的５．００５％提高到８．６％,不仅取得了明显的生态效益和经济效益,也走出一条有中国特色的林建设道路。今后的发展对策为：强化政府行为;调整经济政策;优化林种树种结构;增加科技含量。     

Individual-based analysis of tree establishment and forest stand development within 25?years after wind throw

Wind throw is a common disturbance in forest ecosystems. Because many forests are intensively used our knowledge on forest dynamics after such disturbances is limited. In the Bavarian Forest National Park/Germany after the wind throw event in summer 1983, we started our long-term observation in nearly natural Norway spruce forests within 5-year intervals up to 2010. A part of the affected stands was cleared, while another part was left untouched for natural development. Here, we focused on the tree species regeneration, using an individual-based approach. We expected that tree species regeneration in both management types would follow different succession pathways. Indeed, we found different regeneration characteristics, depending on whether the area had been cleared or left unmanaged. For example, for the target species Norway spruce, a chronic regeneration during the first two decades with low numbers, but a high survival rate of individuals, and for the pioneer species birch, pulse regeneration with high numbers of individuals only at the beginning and high individual loss during the following years occurred. Unmanaged and cleared wind throw areas, respectively, offer different quantities of micro-sites: the pit and mound structure as mineral soil disturbance was limited to less than 1/4 in the untouched area, whereas there was mineral soil disturbance more or less everywhere on the cleared parts. Type and intensity of disturbance allow a wide range of succession pathways after wind throw, based on the fundamental processes of germination and competition. Therefore, for protection area management as well as for forest management, the human activity immediately after the event is crucial. Because each management impact will change the succession pathway fundamentally any impact has to be omitted in protection areas with the main goal of natural vegetation succession. Also in managed forests abdication of any impact on small areas may improve the natural structures and biodiversity of forests.     

不同强度间伐对长白山天然林林下植物多样性的影响

对吉林森工集团松江河林业局辖区内的阔叶红松林、杂木林和杨桦林采取30%～40%（T1）、20%（T2）株数强度的均匀间伐处理,以不间伐处理为对照（CK）,对间伐2 a后林下植物木本、草本植物进行调查,采用Simpson、Shannon-Wiener多样性指数和Pielou均匀度指数进行植物多样性分析,探讨不同强度间伐对3个林型林下植物多样性的影响。研究结果表明：T1间伐后3个林型的物种丰富度均有增加（杂木林木本植物例外）,T2间伐后杨桦林木本植物丰富度降低,草本植物丰富度增加。两种间伐处理均增加阔叶红松林木本植物多样性,T1处理尤为明显。T1处理增加杂木林和杨桦林木本植物多样性,而T2间伐处理有较弱的降低作用。两种间伐处理均降低阔叶红松林和杂木林草本植物多样性,与强度无明显关系。随着间伐强度的增加杨桦林草本植物多样性增大。在长白山天然林中,较大间伐强度T1（30%～40%）能够有效提高植物多样性。