Species richness in sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis> D. DON) plantations in southeastern Kyushu,Japan: the effects of stand type and age on understory trees and shrubs

 The species richness of trees, shrubs and climbing plants was investigated in 41 sugi (Cryptomeria japonica D. Don) plantations of different stand age and area in southern Kyushu, southwestern Japan. Altogether 174 species were found, of which 145 infrequent species were selected for analysis. Two groups were extracted from the species list according to their occurrence in older (49 spp.) or younger (28 spp.) stands, the latter containing a higher percentage of climbing plants and species with wind-dispersed seeds. In contrast, the older stand group contained major tree components typical of seminatural, evergreen broadleaved forests in the region and was more heavily dependent on stand age, especially for species with gravity- and frugivore-dispersed seeds, showing a gradual increase up to 60 years old. The species richness was less correlated with edge perimeter facing seminatural forests and the years after latest thinning. The juxtaposition of plantation compartments with stands of seminatural forest or other plantations, as well as the compartment's origin as former plantation site or a seminatural stand, had relatively little influence on species richness. However, topographic variation was important in determining the species composition, with valley stands having higher species richness and containing many plants typical of the regional seminatural forests. These results suggest that (1) the major trend of species richness is determined by the presence of old stand type species, (2) topographic variation of species richness remains even after establishment of plantations, and (3) the normal rotation period of sugi plantations (35–40 years) may therefore be too short to conserve the maximum potential species diversity within the working forest. Received: June 4, 2001 / Accepted: August 26, 2002 Acknowledgments We wish to thank the staff of the Miyazaki University Forests for cooperation in the fieldwork. A part of this study was supported by the Grant-in-Aid for Scientific Study from the Ministry of Education, Science and Culture of Japan (no. 09041071 and no. 10460068). Correspondence to:S. Ito     

Exploring life growth patterns in birch (Betula pendula)

The conversion of homogeneous plantations of conifers to mixed or broadleaved forests is part of sustainable forest management strategies in Western Europe. For the conversion of pine plantations on sandy soils, birch seems a convenient choice. Yet, thus far, little is known about the growth of mature birches outside Northern Europe. We sampled 32 birch trees in forests throughout the sandy ecoregion in northern Belgium at sites that varied in soil and local stand conditions. Half of the birches showed the characteristic pattern in growth (expressed as basal area increment) with a sharply increasing growth till around the age of 25 years followed by a steep decrease in growth. The growth was strongly related to tree age and crown dimensions, only weakly related to soil conditions, and not related to the local stand conditions.     

云南热区西南桦人工纯林林地土壤的有机碳含量研究

在云南西双版纳的普文试验林场,通过对不同龄期西南桦人工纯林林地土壤有机碳含量的比较,并以当地的山地雨林、林龄较为接近的西南桦次生林和黄水(黄牛水 水锦树)次生林林地的土壤有机碳含量为参照,作了对比分析;还对西南桦人工纯林林地土壤的有机碳含量与其土壤肥力状况及物理性状的相关性进行了研究。结果表明:西南桦人工纯林随着林龄的增长,其林地土壤有机碳含量呈现出先维持再积累上升的趋势;15年生的西南桦人工纯林林地土壤的有机碳含量水平与黄水(黄牛水 水锦树)次生林相近,随其林龄的增长,预计会超过黄水(黄牛水 水锦树)次生林而接近于山地雨林。西南桦人工纯林林地土壤有机碳含量与其土壤全N、水解N、速效K含量、总孔隙度和毛管孔隙度等指标呈显著正相关,与土壤容重呈显著负相关,因此,西南桦人工纯林林地土壤的有机碳水平可用以指示其土壤的肥力状况。     

The response of small mammals to natural and human-altered edges associated with Afromontane forests of South Africa

An increase in edge area reduces the effective size of habitat fragments and thus the area available for habitat-interior specialists. However, it is unclear how edge effects compare at different ecotones in the same system. We investigated the response of a small mammal community associated with Afromontane forests to edge effects at three different habitat transitions: natural forest to grassland (natural edge, structurally different vegetation types), natural forest to mature plantation (human-altered edge, structurally similar vegetation types) and natural forest to harvested plantation (human-altered edge, structurally different vegetation types). We predicted that edge effects should be less severe at natural ecotones and at similarly structured contiguous vegetation types than human-altered ecotones and differently structured contiguous vegetation types, respectively. We found that forest species seemed to avoid all habitat edges in our study area. Surprisingly, natural edges supported a less diverse small mammal community than human-altered forest edges. However, edge effects were observed deeper into native forests surrounded by mature alien plantations (and more so at harvested plantations) than into native forests surrounded by native grasslands. The net effect of mature plantations was therefore to reduce the functional size of the natural forest by creating a larger edge. We suggest that when plantations are established a buffer zone of natural vegetation be left between natural forests and newly established plantations to mitigate the negative effects of plantation forestry.     

Abundance and use of cavity trees at the tree- and stand-levels in natural and plantation forests in Hokkaido, Japan

The conservation of cavity trees in plantations is important for maintaining biodiversity because cavity trees are one of the forest attributes most strongly affected by forestry operations. We surveyed the occurrence of cavities at the tree-level and the abundance of cavity trees and the number of uses by secondary cavity users at the stand-level in natural and conifer plantation forests in Hokkaido, Japan. We classified cavities into two types by their formation processes: excavated and non-excavated. Excavated cavities were more common in dead trees than in live trees. Non-excavated cavities showed high occurrence in dead and live broad-leaved trees. The abundance of non-excavated cavity trees was two times greater than that of excavated cavity trees in natural forests, but, in plantations, excavated cavity trees were dominant. The abundance of non-excavated cavity trees was lower in thinned plantations than in not-thinned plantations. The number of cavity uses increased with the number of cavity trees, indicating the importance of maintaining cavity trees. Conifer plantations are established by removing native broad-leaved trees, which results in a lower abundance of non-excavated cavity trees in these locations. The conservation of broad-leaved trees is important for maintaining the current and future resource of non-excavated cavity trees in plantation forests, as is the conservation of dead trees, which showed a high occurrence of excavated cavities.     

论林木引种与森林可持续经营

森林是实现环境与发展相统一的关键和纽带,在实现国家可持续发展中具有不可替代的作用。外来树种是森林遗传资源的重要组成部分,具有一些乡土树种难以替代的优势。外来树种人工林可持续经营的核心问题是树种与种源的正确选择,为此,保存和丰富必要的基因资源就显得极为重要。外来树种具有一定程度的环境风险,但并没有人们想象的那样大。对当地生物多样性的影响有利有弊,关键是如何科学运作,包括确定合适的地域范围,与乡土树种的合理空间布局,以及如何使之在当地生态系统中形成密不可分的生物链。最危险的情况出现于因检疫不严而带来的病虫危害。     

Hybrid poplar plantations in a floodplain have balanced impacts on farmland and woodland birds

Hybrid poplar plantations are increasing worldwide and are often accused of impoverishing bird communities. We conducted 124 bird point counts in a landscape where plantations, semi-natural forests and farmland occupied similar surface areas. As expected, birds occurred at higher densities in areas dominated by forests than dominated by plantations, mostly due to the scarcity of late-successional forest birds in plantations. Contrary to expectations, bird communities were the poorest in farmland dominated areas and the most specialised in areas dominated by young plantations. Indeed, many grassland species, including some of conservation concern in Europe, frequently used young plantations. However, plantations have probably depleted grassland bird communities by fragmenting open areas, while playing a limited positive role on forest species. Total length of unpaved roads had a positive effect on community specialisation index, while total length of paved roads and mean forest/plantation patch size played no role. Bird density increased with the development of the understory vegetation in mature poplar plantations. We conclude that poplar should not be planted at the expense of areas of high conservation value; in other cases, they may increase the overall diversity of bird communities. At the plantation scale, we advocate stopping understory removal as soon as possible and maintaining old trees and hedgerows alongside or within plantations to provide suitable breeding habitats for bird species that may be foraging in the plantations.     

Understory succession in post-agricultural oak forests: Habitat fragmentation affects forest specialists and generalists differently

The herbaceous understory forms the richest stratum in temperate broadleaved forests in terms of plant diversity. Understanding the process of understory succession is thus of critical importance for the development of management guidelines for biodiversity restoration in post-agricultural plantation forests.We studied effects of stand age, forest fragmentation, and soil and canopy conditions on species richness and abundance of four species groups in the understory of post-arable oak plantations in southern Sweden: herbaceous forest specialists, habitat generalists and open-land species, and woody species.The group of forest specialists may approach the richness of continuously forested sites after 60-80 years in non-fragmented plantations, but many forest species were sensitive to habitat fragmentation. Open-land species richness decreased during succession, while the richness of woody species and of generalists remained stable, and was not affected by fragmentation. Abundance of generalists gradually decreased in non-fragmented plantations, probably due to competition from colonizing forest specialists. Soil pH in post-arable stands remained consistently higher than in continuously forested stands, which maintained differences in species composition. The development of a shrub layer seemed to imply a competitive advantage for forest specialists compared to generalist species.For successful recovery of a rich understory, we suggest that post-arable plantations should be established on loamy soils of intermediate to high pH proximate to older forest with source populations, and that a continuous overstory canopy cover of 70-80% is maintained by regular light thinnings and promotion of a shrub layer.     

Rationale and methods for conserving biodiversity in plantation forests

Industrial forest managers and conservation biologists agree on at least two things: (1) plantation forests can play a role in conserving biodiversity, and (2) plantations will occupy an increasing proportion of future landscapes. I review literature from around the world on the relationship between biodiversity and plantation management, structure, and yield. The dynamics of plantation ecology and management necessarily differ by landscape, geographic area, ecosystem type, etc. This review provides a broad array of management recommendations, most of which apply to most regions, and many patterns are evident. I suggest a new plantation forest paradigm based on the hypothesis that minor improvements in design and management can better conserve biodiversity, often with little or no reduction in fiber production. There is ample evidence that these methods do benefit biodiversity, and can also entail various economic benefits. Adherence to these recommendations should vary by plantation type, and depending on the proportion of the surrounding landscape or region that is or will be planted. Stand-level variables to consider include socio-economic factors, native community type and structure, crop species composition, and pest dynamics. During establishment, managers should consider innovations in snag and reserve tree management (e.g. leave strips), where mature native trees and/or understory vegetation are left unharvested or allowed to regenerate. Polycultures should be favored over monocultures by planting multiple crop species and/or leaving some native trees unharvested. Native species should generally be favored over exotics. Site-preparation should favor methods that reflect natural disturbances and conserve coarse woody debris. Plantations that have already been established by traditional design can also conserve biodiversity via small modifications to operations. Earlier thinning schedules or longer rotations can strongly affect biodiversity, as can reserve trees left after plantation harvest to remain through a second rotation.     

黄冕林场桉树人工林经营利用与经济效益分析

对广西黄冕林场3-5年生桉树人工林进行生长调查,探讨分析桉树经营利用经济效益。结果表明：桉树人工林中,不同林龄和同一林龄桉树人工林之间生长差异明显。不同的立地条件、初植林分密度对桉树人工林胸径、树高等生长影响很大。随着林分密度（标准地样木数）的增大,样木数与生长指标之间具有较强的负相关性。随着林龄的增大,这种林分密度负效应就越明显。从财务指标看,随着林龄的增大,总产值、纯利润和NPV均呈现增大的趋势,但IRR却并不如此,而是先增大后减少,在4a时,IRR达到最大值。从年份看,投资回收期为3a。结果表明桉树在广西黄冕林场这样的立地条件和气候条件下,表现适生、速生,且经济效益好,是营造短周期用材林的好树种。但为获得好的经济效益,必须注意树种、立地条件和栽培等措施的选择。     

Structure and diversity of small-mammal communities of lowland forests in the rural central European landscape

Small-mammal communities were monitored over 4 years in South Moravian rural lowland forests in order to study relationships with various forest habitat types. Early successional sites (plantations) and forest edges maintained communities with higher abundance and diversity. Lowest total abundance was observed in unmanaged lowland forest and highest abundance in plantations with irregular undergrowth management. Low diversity was typical of non-fruiting monocultures. In plantations, both diversity and abundance were affected by herb layer removal, with sites subject to regular cutting, displaying lower levels. Significant differences in diversity and species richness were only detected between early and late successional sites, with the former showing higher values. Two basic small-mammal community groups were determined; (1) those inhabiting sites with a thick herb undergrowth and an open tree canopy (plantation) and (2) those inhabiting stands with sparse or no herb layer and a closed canopy (high forest). Forest stands support long-term populations of dominant small forest-dwelling mammal species and, as such, serve as reservoirs, even in rural landscapes dominated by intensive arable farming. Managed early succession lowland forests represent important refuges for a number of small open-habitat mammals negatively affected by intensive farming.     

湖南省马尾松毛虫灾害与松林林分状况的关系

马尾松毛虫灾害与松林林分状况关系密切,松阔混交林、国外松占40%以上松林和植被覆盖度达90%以上的松林一般不发生松毛虫灾害。松林蓄积量越大,松毛虫发生面积越小。     

Ground-dwelling invertebrates in reforested conifer plantations

Plantation forests are an important part of the forest estate in many countries. In Ireland, they cover around 9% of the land area and many that are commercially mature are now being felled and reforested. The potential biodiversity value of such second rotation forests has yet to be determined, yet this may be particularly significant in Ireland where cover of semi-natural woodland is only 1%. Invertebrates are a vital component of forest biodiversity, functioning as decomposers and pollinators, herbivores, predators and prey. Spiders and Carabid beetles are often used in biodiversity assessment as they are easily captured using pitfall traps, are taxonomically well known and respond to changes in habitat structure. This study aimed to examine spider and Carabid beetle diversity in second rotation Sitka spruce (Picea sitchensis) plantations at different stages of the forest cycle (5, 8–12, 20–30, 35–50 years), and compare the spiders captured in second rotation forests with those from first rotation. Spider and beetle diversity was influenced by stand structural development in second rotation plantations with numbers of forest-associated species increasing over the forest cycle. Overall, spider richness declined over the forest cycle and this was related to decreasing cover of field layer vegetation and fewer open-associated species. In contrast, total beetle richness increased and became more specialised over the forest cycle which may be related to slower colonisation of disturbed areas by beetles in comparison with spiders, and fewer open specialists at the early stages of second rotation. Spider assemblages were distinguished between rotations. This may be related to differing habitat conditions in second rotation forests including dryer soils with lower pH, differing vegetation complexity and presence of brush piles. Few of the forest species accumulated during first rotation were retained and the early stages of second rotation forest cycle was characterised by a generalist open fauna. Nonetheless, as the forest cycle progressed the spider assemblages between rotations became more similar. Current forest policy supports retaining over-mature trees and creating a mosaic of different aged stands within a plantation. Such measures may provide refuge for forest species after clearfell. In countries where forest fragments exist in a landscape dominated by agriculture, consideration should be given to the capacity of mature forest adjacent to felled stands to support forest species, and to the configuration of over-mature areas retained after felling.     

Structure and diversity of small mammal communities of mountain forests in Western Carpathians

We sampled the small mammal (SM) community in mountain forest ecosystems of the Beskydy Mountains over 5 years in order to study associations with different types of forest habitat. Fourteen species were determined, three being eudominant (yellow-necked mouse—Apodemus flavicollis (45 %), bank vole—Clethrionomys glareolus (23.3 %) and field vole—Microtus agrestis (15.7 %) and one dominant common shrew—Sorex araneus (9.3 %)). Highest abundance was observed in young succession sites (plantations) with dicotyledonous plants dominant (>50 %) in the undergrowth. Highest diversity was observed in plantations and primeval forests. Lowest total abundance and diversity were observed in mature monocultures. Significant differences in diversity were only found between old monocultures and other sites. Using a faunistic similarity index, two basic SM community groups were determined: those inhabiting (1) early (plantation) and late (reserve) successional forest ecosystems with a dense dicotyledonous plant herb layer, and (2) plantations with a dense grass herb layer and forests with a dense canopy closure (fruiting monoculture). Redundancy analysis confirmed separate habitat preferences of the three eudominant species. Generalised linear model indicated increasing preference of field vole for plantations with dominance of grass and <10–15 % admixed dicotyledonous plants while decreasing preference at ratios >10–15 %, and increasing preference of bank vole for plantations with a dicotyledonous plant ratio of >10–15 %. The biotopes monitored proved suitable for long-term survival of the dominant SM species. Early successional plantations and forest reserves also represent important refuges for a number of rarer SM species presently under threat.     

湖南杉木人工林近自然经营问题探讨

德国人工林在19世纪,与湖南杉木人工林有相似之处,采用单一树种营造大面积人工林,造成地力消耗很大,无法实现林木的可持续利用。本文从杉木经营历史,分析了现有栽培制度下的炼山、幼林抚育、轮伐期短、林分结构单一等现状所导致的杉木人工林生产力下降、林地地力衰退。本研究引进德国森林近自然经营理念及原则改造杉木人工林,分别对杉木幼林、中林、成林进行第1代目标树经营,为第2代目标树形成创造有利条件,使林地地力得到恢复,达到可持续经营的目的,同时获得较大经济效益。     

Do commercial forest plantations reduce pressure on natural forests? Evidence from forest policy reforms in Uganda

This paper investigates if and how the establishment of private commercial forest plantations in degraded forest reserves can conserve natural forests in Uganda. It uses difference-in-difference and decomposition analyses on household data collected from intervention and control villages in the neighborhood of forest reserves. We find that commercial forest plantations are weakly effective in conserving natural forests. The reduction in forest use is unevenly distributed across households depending on location and resource endowments such as farmland and livestock. The results suggest that the conservation effectiveness can be enhanced by complementary interventions that change characteristics that reduce forest use, such as more education for forest users.     

The potential of hinoki (Chamaecyparis obtusa [Sieb. et Zucc.] Endlicher) plantation forests for the restoration of the original plant community in Japan

We estimated the potential of plantation forests for the restoration of the original plant community. We compared the understory vegetation in hinoki (Chamaecyparis obtusa [Sieb. et Zucc.] Endlicher) plantations at the understory re-initiation stage and in adjacent natural forests. To estimate the effect of the original natural forests on the understory species composition of plantation forests, we established study sites in five types of natural forests (mature evergreen broadleaf, mature deciduous broadleaf, mature evergreen coniferous, immature deciduous broadleaf warm-temperate, and immature deciduous broadleaf cool-temperate) and nearby plantation forests. The understory vegetation of the plantation forests had a higher species richness, a higher proportion of early-seral species, and a higher proportion of herb or fern species than the natural forests. The differences between natural and plantation forests varied according to the species composition of the natural forests. The composition of the understory vegetation of the plantations at the understory re-initiation stage was similar to that of the immature deciduous forests. The characteristics of immature, disturbed forests remained in the understory vegetation of the hinoki forests. No great loss of species was observed. Our findings suggest that most of the original forest species still survive in the understory of the plantation forests. These forests have the potential to follow the successional pathway to broadleaf or mixed forests via thinning or clear-cutting without planting.     

鄂西南鹅掌楸天然林林分结构特征

以鄂西南鹤峰县鹅掌楸天然林为研究对象,通过对林分空间结构(角尺度、大小比、混交度)和林分非空间结构 (径级结构、树高结构、重要值)的研究与分析,直观地反映其林分结构的特征,查清该区鹅掌楸种群的发展现状,为鹅掌楸 天然林的合理保护与科学经营提供依据 。在鹅掌楸天然林集中生长的代表性地段建立 17个 20mx20m调查样地,进行 每木定位与检尺调查,应用 Excel2019、Winkelmas2.0软件对样地调查数据进行处理与分析 。结果表明:研究区鹅掌楸 天然林中共 73个树种,鹅掌楸为该群落的优势种,生长处优势地位( =0.17),种群整体呈轻微聚集分布(为 0.56),同 时该种群在林分中呈现极强度混交状态( =0.85):种群整体径级、树高分布都呈右偏正态分布,小径级林木株数很少, 种群整体呈现稳定型一衰退型 。FSI均值为 0.82,FSD 均值为 0.30,林分空间结构为接近于理想状态(41.18%)或达 到理想状态(58.82%)。鹅掌楸天然林处于演替后期,林分结构整体上较为理想,可对处于聚集分布的林木进行适当调整, 辅以 一定人为促进更新的措施,促使鹅掌楸林分结构更加合理。     

关于我国人工林长期生产力的保持

为了保持我国人工林的长期生产力和提高森林质量,达到可持续经营的目的。作者在以往研究工作的基础上,广泛收集了国内外有关成果与资料,概括论述了我国人工林森林生产力的现状、不能保持生产力的原因与机理以及长期保持人工林生产力的技术对策。按第八次清查的全国森林资源数据,每公顷蓄积量为89.79 m^3,其中天然林为104.6 m^3,人工林为52.76 m^3,人工林森林生产力明显低于天然林;我国优势树种人工林每公顷蓄积量也不高,如杉木为69.8 m^3,马尾松为56.2 m^3,落叶松为58.6 m^3,这些数据比日本2002年3月公布的人工林相似树种的数据低很多,如日本针叶树蓄积量为227.97 m^3·hm^-2,柳杉为295.83 m^3·hm^-2,落叶松为189.88 m^3·hm^-2。关于年生长量,按全国第七次资源清查的中龄林与近熟林的数据做统计:杉木人工林5.2~4.2 m^3·hm^-2,马尾松为3.2~1.8 m^3·hm^-2,柏木为3.4~3.2 m^3·hm^-2;但按作者掌握的我国重点或示范性、试验性小面积人工林生长量看,却很高,按我国编制的速生丰产林标准的生长量数据看比较高。我国大面积人工林生产力不高,短周期经营的杨树、桉树人工林也不高,主要原因是:(1)纯林化与针叶化严重。按第八次全国森林资源统计,纯林占人工林的85%,而且针叶化明显,人工乔木林10个优势树种中针叶林比例高达56.9%。人工纯林结构简单,生物多样性低,生物学上缺乏稳定性。人工纯林特别是针叶纯林,抗性低,抗自然灾害和大气污染能力均差,人工纯林维护地力的能力也弱。(2)集约育林的技术措施:立地控制技术未得到推广,适地适树适品种原则在育林中未能认真贯彻;密度、植被、地力控制技术也执行不力,大面积上的人工林仍属于粗放经营;连作引起林地土壤理、化、生物特性恶化,土壤质量衰退,导致林木生长不良,林分生产力逐代下降;造林作业造成水土流失,如杉木造林,传统的育林技术未得到明显改进,福建尤溪炼山后进行的3年观测结果表明,炼山和水土流失损失的有机质高达989.35 kg·hm^-2,养分586.26 kg·hm^-2。桉树在砖红壤进行的机耕整地,水土流失也很严重,不合理的造林作业,最终导致土壤质量与森林生产力下降。短周期培育人工林带来了2个重要问题,一是对林地肥力要求高,二是如何利用无性系才能保持长期生产力。短周期经营采用的无性系,生长速度快,生长量大,轮伐期短,养分需求量大,如刚果12号W5无性系,通常利用地上部分,以5~7 a的轮伐期计,消耗的养分达571.75 kg·hm^-2,我国培养短周期人工林的土壤质量本底原本普遍不高,如果采取连作,土壤有机质养分会明显下降,土壤质量衰退,并对其功能产生危害。我国杨树、桉树等人工林要达到短周期持续经营,还需要实行多无性系造林。我国人工林长期生产力保持的技术对策,应采取先进的集约育林措施,包括遗传控制、立地控制、密度控制、植被控制与地力控制。     

干旱和涝渍胁迫对入侵物种喜旱莲子草生长的影响

苦郎树是一种沿海防沙固堤的半红树植物，不仅在红树林群落中具有重要的生态价值，叶片提取物还有一定的医药价值。本研究通过4种光响应模型对苦郎树光响应曲线拟合，计算光合参数进行对比分析，评估最适拟合模型，并研究其光合特性。结果表明：不同模型对苦郎树光响应拟合存在差异，四种模型拟合优度均在0.996以上，苦郎树气孔导度随光合辐射增加而增加，在1800 μmol·m-2·s-1有效光合辐射下达到最大；在500 μmol·m-2·s-1有效光合辐射下水分利用效率最高，胞间二氧化碳维持在一个不变的浓度，与大部分植物的光合特性相似。非直角双曲线模型对苦郎树拟合效果最佳，如何精确拟合光饱和点还需进一步研究，应需要根据实际情况选用最适宜的光响应拟合模型，为海岸生态、防风固堤和园林绿化等工作提供理论依据。