秦岭西部山地次生林和人工林大型土壤动物群落结构特征

人类对次生林生态系统的长期扰动必然会对地下生态过程产生深刻影响,而土壤动物群落结构和功能多样性对地下生态过程的演变有重要的指示意义.本文以小陇山林区恢复近30年的次生林和栽植近30年的油松、日本落叶松、欧洲云杉和粗枝云杉林为对象,通过对5种林型土壤动物群落密度调查,采用PCA排序和方差分析等方法,探讨了不同林型土壤动物群落结构特征和营养结构.结果表明:油松林和日本落叶松林土壤动物群落密度是次生林的3.0和2.1倍;油松和日本落叶松人工林土壤动物群落中消费者/分解者比值明显高于次生林,油松林和日本落叶松林消费者/分解者的比值显著高于欧洲云杉林和粗枝云杉林;不同人工林土壤动物群落结构存在明显差异,油松林和日本落叶松林土壤动物群落密度是粗枝云杉林的4.5和3.1倍,而油松林土壤动物群落类群丰富度是欧洲云杉林和粗枝云杉林的1.5倍.     

侧柏不同器官水提取物对油松种子萌发和幼苗生长的他感效应

研究了侧柏（Platycladus orientalis）根、枝、叶、果实不同浓度水提取物及枝叶挥发油对油松种子萌发和幼苗生长的他感效应。结果表明：侧柏各器官及挥发油都含有化感物质,均对油松种子萌发及幼苗生长表现出“高抑低促”效应,而且低浓度时的促进作用明显强于高浓度时的抑制作用。与对照相比,在浓度为2 mg·mL^-1时,侧柏根水提取物对油松幼苗根长和鲜重的促进能力最强,其根长和鲜重分别比对照提高了79.78%和376.60%;侧柏叶水提取物对油松幼苗苗高促进能力最强,比对照提高了102.41%;侧柏枝水提取物对油松种子发芽的促进能力最强,发芽率比对照提高了65.63%。而在浓度为30 mg·mL^-1时,除了侧柏根和枝水提取物对油松种子萌发（87.50%）和鲜重（85.11%）表现出明显的抑制作用外,其它提取物对油松幼苗根长和苗高生长的抑制作用均不明显。侧柏枝叶挥发油对油松种子萌发,幼苗生长均表现为促进作用,特别对油松种子萌发具有显著的促进作用,其促进率达70.37%。说明侧柏和油松混交,可能有利于油松树木生长及生产力的提高。     

TWO TYPES OF AUXILIARY CELL AMPULLAE IN GRATELOUPIA (HALYMENIACEAE,RHODOPHYTA), INCLUDING G. TAIWANENSIS SP. NOV. AND G. ORIENTALIS SP. NOV. FROM TAIWAN BASED ON rbcL GENE SEQUENCE ANALYSIS AND CYSTOCARP DEVELOPMENT1

Few species in the genus Grateloupia have been investigated in detail with respect to the development of the auxiliary cell ampullae before or after diploidization. In this study, we document the vegetative and reproductive structures of two new species of Grateloupia, G. taiwanensis S.‐M. Lin et H.‐Y. Liang sp. nov. and G. orientalis S.‐M. Lin et H.‐Y. Liang sp. nov., plus a third species, G. ramosissima Okamura, from Taiwan. Two distinct patterns are reported for the development of the auxiliary cell ampullae: (1) ampullae consisting of three orders of unbranched filaments that branch after diploidization of the auxiliary cell and form a pericarp together with the surrounding secondary medullary filaments (G. taiwanensis type), and (2) ampullae composed of only two orders of unbranched filaments in which only a few cells are incorporated into a basal fusion cell after diploization of the auxiliary cell and the pericarp consists almost entirely of secondary medullary filaments (G. orientalis type). G. orientalis is positioned in a large clade based on rbcL gene sequence analysis that includes the type species of Grateloupia C. Agardh 1822 , G. filicina. G. taiwanensis clusters with a clade that includes the generitype of Phyllymenia J. Agardh 1848 , Ph. belangeri from South Africa; that of Prionitis J. Agardh 1851 , Pr. lanceolata from Pacific North America; and that of Pachymeniopsis Y. Yamada ex Kawab. 1954, Pa. lanceolata from Japan. A reexamination of the type species of the genera Grateloupia, Phyllymenia, Prionitis, and Pachymeniopsis is required to clarify the generic and interspecific relationships among the species presently placed in Grateloupia.     

DROUGHT EFFECTS ON CARBON EXCHANGE IN A SUBTROPICAL CONIFEROUS PLANTATION IN CHINA

 干旱对陆地生态系统的影响已成为全球变化研究的焦点问题之一。该研究基于生态系统过程模型——CEVSA2, 结合涡度相关通量观测, 分析了不同程度干旱对亚热带人工针叶林碳交换的影响及其关键控制因素。结果表明: 1)干旱使生态系统碳交换显著下降, 2003和2004年的干旱使得年净生态系统生产力(Net ecosystem production, NEP)相比无干旱影响情景的模拟结果分别减少了63%和47%; 2)光合和呼吸对干旱具有不同的响应, 干旱时光合的下降比呼吸更为显著, 这导致了NEP的显著下降; 3)当饱和水气压差(Vapor pressure deficit, VPD)达到1.5 kPa以上时, 生态系统的光合、呼吸和净碳吸收均开始下降, 当VPD大于2.5 kPa、土壤相对含水量(土壤含水量/土壤饱和含水量)(Relative soil water content, RSW)低于40%时, 生态系统的碳收支由碳汇转为碳源; 4)土壤干旱是造成碳交换下降的主要驱动因素, 对年NEP下降的平均贡献率为46%, 而大气干旱的贡献率仅为4%。     

Phytochemical analysis and in vitro antiviral activities of the essential oils of seven Lebanon species

The chemical composition of the essential oils of Laurus nobilis, Juniperus oxycedrus ssp. oxycedrus, Thuja orientalis, Cupressus sempervirens ssp. pyramidalis, Pistacia palaestina, Salvia officinalis, and Satureja thymbra was determined by GC/MS analysis. Essential oils have been evaluated for their inhibitory activity against SARS-CoV and HSV-1 replication in vitro by visually scoring of the virus-induced cytopathogenic effect post-infection. L. nobilis oil exerted an interesting activity against SARS-CoV with an IC(50) value of 120 microg/ml and a selectivity index (SI) of 4.16. This oil was characterized by the presence of beta-ocimene, 1,8-cineole, alpha-pinene, and beta-pinene as the main constituents. J. oxycedrus ssp. oxycedrus oil, in which alpha-pinene and beta-myrcene were the major constituents, revealed antiviral activity against HSV-1 with an IC(50) value of 200 microg/ml and a SI of 5.     

红松人工林矿质营养元素含量与贮量的研究

以黑龙江省东北林业大学老山人工林实验站26林班白浆土栽培的红松人工林为试验地,林龄20年,公顷株数为3240株,研究结果表明,矿质元素贮量为502.37 kg·h^-1·m^-2,平均每年为25.12 kg·h^-1·m^-2。其中乔木层占总量的81.46%,灌木层占11.17%,草本层占2.56%,凋落层占4.81%。为增加矿质元素含量与贮量,应调整林分结构,促进生长,提高林地生产力。     

Species diversity and interspecific association in development sequence of Hippophae rhamnoides plantations in the Loess Hilly Region, China

Based on our field investigation, we analyzed the characteristics of species diversity and interspecific association at different development stages of Hippohae rhamnoides plantations. The results show that the species diversities of the shrub layer, grass layer and the whole community of the H. rhamnoides plantations all fluctu-ated in an "S" shape pattern. At different development stages, the species richness and diversity were higher in the grass layer than in the shrub layer. The shrub species diversity was lower on bare land, but increased gradually with development of the community. The shrub evenness index was higher in 13-year forest stand, while the grass diversity index was higher in the 3-year and 25-year plan-tations and lower in the 8-year plantation. The positive and negative absolute values of interspecific association between H. rhamonides and other principal species chan-ged in a parabolic pattern. The significance level and intensity of interspecific association were lower or weaker in thel3-year plantation, indicating that the species sub-stitution rate slowed down, competition became less intense and community composition and its structure reached a relatively stable state. Therefore, to improve the ecological environment, priority should be given to the protection of the H. rhamnoides plantations younger than 13 years, while for those of 25 year plantations, mod-erate thinning should be made to promote their regenera-tion.     

Perceptions of biodiversity, environmental services, and conservation of planted mangroves: a case study on Nijhum Dwip Island, Bangladesh

Restoration of mangroves is often considered a way to minimize losses incurred from their decline and to provide additional services to coastal communities. However, the success of restoration programs is often focused on biological or ecological criteria. The situation is no exception in Bangladesh, which houses the world’s largest mangrove plantations. This study has been undertaken in a south-central estuarine island (Nijhum Dwip) of the Bangladesh coast and aims to understand societal perception on the achievements of a plantation program. Through 110 household interviews and seven group discussions, an assessment was conducted of peoples’ perception about major flora and fauna of the mangrove ecosystem, benefits derived from the forest, present condition of the forest, causes of degradation, and ways to improve the situation. Around one-fourth of the respondents mentioned that they were highly dependent on the ecosystem. The most important perceived benefits were: provision of raw materials, prevention against natural disasters, climate regulation and soil retention. However, the majority (>80%) of the respondents perceived the ecosystem to be degrading. Encroachment and illicit felling were identified as the main causes of such degradation. In order to arrest the continued degradation allowed by conventional forest management flaws, adaptive co-management has been recommended to conserve this ecosystem in a more equitable way.     

Effects of Forest Use on Aphyllophoraceous Fungal Community Structure in Sarawak, Malaysia

Aphyllophoraceous fungi are expected to reflect changes in the environmental conditions caused by forest use. To reveal the effects of forest uses on the fungal community structure, we performed a 3‐month survey of aphyllophoraceous species in five forest types (undisturbed primary forest, isolated patches of primary forest, old and young fallow forest, and rubber plantations) in Sarawak, Malaysia in 2005. We used a canonical correspondence analysis (CCA) to reveal the relationships between fungal community composition and the environmental variables (canopy openness, soil water potential, amount and composition of coarse woody debris, litter mass, basal area, plant species composition). A total of 155 samples from 67 species were collected during the study period. The fungal species density represented by the number of species in a transect differed significantly among forest types. The fungal species density increased significantly with increasing number of pieces of coarse woody debris (CWD), but decreased significantly with increasing the scores of second axis of principal component analysis (PCA) for plant species composition. In the CCA ordination, automatic forward selection revealed that only the number of pieces of CWD significantly affected the fungal species composition. The occurrences of Flabellophora licmophora, Coriolopsis retropicta, Microporus vernicipes, and Amauroderma subrugosum were positively correlated with the number of pieces of CWD. Our study clearly demonstrated that forest use negatively affected aphyllophoraceous fungal diversity and suggest that the quantity of CWD would be an important determinant of fungal diversity and composition.     

Do Eucalyptus plantations host an insect community similar to remnant Eucalyptus forest?

Abstract We examined the potential of forest plantations to support communities of forest‐using insects when planted into an area with greatly reduced native forest cover. We surveyed the insect fauna of Eucalyptus globulus (Myrtaceae) plantations and native Eucalyptus marginata dominated remnant woodland in south‐western Australia, comparing edge to interior habitats, and plantations surrounded by a pastoral matrix to plantations adjacent to native remnants. We also surveyed insects in open pasture. Analyses focused on three major insect orders: Coleoptera, Lepidoptera and Hymenoptera. Plantations were found to support many forest‐using insect species, but the fauna had an overall composition that was distinct from the remnant forest. The pasture fauna had more in common with plantations than forest remnants. Insect communities of plantations were different from native forest both because fewer insect species were present, and because they had a few more abundant insect species. Some of the dominant species in plantations were known forestry pests. One pest species (Gonipterus scutellatus) was also very abundant in remnant forest, although it was only recently first recorded in Western Australia. It may be that plantation forestry provided an ecological bridge that facilitated invasion of the native forest by this nonendemic pest species. Plantation communities had more leaf‐feeding moths and beetles than remnant forests. Plantations also had fewer ants, bees, evanioid wasps and predatory canopy beetles than remnants, but predatory beetles were more common in the understory of plantations than remnants. Use of broad spectrum insecticides in plantations might limit the ability of these natural enemies to regulate herbivore populations. There were only weak indications of differences in composition of the fauna at habitat edges and no consistent differences between the fauna of plantations adjacent to remnant vegetation and those surrounded by agriculture, suggesting that there is little scope for managing biodiversity outcomes by choosing different edge to interior ratios or by locating plantations near or far from remnants.