秦岭太白山北坡蝗虫的群落结构

在秦岭太白山北坡23个样地内采集到蝗虫2总科7科25属34种。应用数量分类、多样性指数及相似性分析方法对太白山北坡蝗虫群落垂直分布样方资料进行了分析。应用数量分类法可将蝗虫群落按植被类型分为8种,即农耕带、栓皮栎林带、锐齿栎林带、辽东栎林带、桦木林带、冷杉林带、落叶松林带、高山草饲带。太白山蝗虫群落垂直分布规律明显。其中高海拔（如高山草甸带）的蝗虫种类数和多样性明显低于中低海拔,中低海拔（锐齿栎林带）蝗虫种类和多样性指数最大。但低海拔的农耕带人为干扰大,植被较单一,蝗虫优势种的优势度大,蝗虫密度大,而种类数较少。     

Photochemical degradation of chromophoric-dissolved organic matter exposed to simulated UV-B and natural solar radiation

Photochemical degradation of chromophoric-dissolved organic matter (CDOM) by UV-B radiation decreases CDOM absorption in the UV region and fluorescence intensity, and alters CDOM composition. CDOM absorption, fluorescence, and the spectral slope indicating the CDOM composition were studied using 0.22-μm-filtered samples of Meiliang Bay water from Lake Taihu that were exposed to short-term (0–12 h) simulated UV-B radiation and long-term (0–12 days) natural solar radiation in summer. CDOM absorption coefficient and fluorescence decreased with increasing exposure time, which relates to the amounts of absorbed light energy. The decreases of CDOM absorption and normalized fluorescence corresponded to first order kinetics reactions. Different decreases of CDOM absorption and fluorescence at different wavelengths suggested that the composition of CDOM changed when it absorbed ultraviolet radiation. Photochemical degradation increased the spectral slope during 275–295 nm region (S _275–295) but decreased the spectral slope during 275–295 nm region (S _350–400). The slope ratio S _R (S _275–295:S _350–400) increased in the photochemical process, which could be used as an indicator of photobleaching and composition change of CDOM. Our results show that photochemical degradation is important in the cycling of CDOM, which indicated change in the composition of CDOM. Handling editor: Luigi Naselli-Flores     

祁连山冷龙岭南麓垂直带植被移地试验中鹅绒委陵菜克隆生长特征

在祁连山东段冷龙岭南麓海拔3 200～3 800 m的4个样地间按主要植被类型进行双向移地试验,以自然垂直带移地样方内鹅绒委陵菜(Potentilla anserina)为研究对象,调查其克隆生长对气候变化的响应和适应特征.结果表明:鹅绒委陵菜从海拔3 200 m和3 400 m分别双向移至4个不同海拔区生长1年后,所有样地中1条匍匐茎的植株最多(占43.66%),4条匍匐茎的最少(占4.23%);随海拔升高,它们的匍匐茎总条数分别表现为逐渐增多和减少-增加-减少的趋势,基株高度和基叶数均呈先增加后减少的显著变化趋势,分株数逐渐增加,间隔子长度分别呈先增加后减少和增加-减小-增加的趋势;匍匐茎长度在移到3 400 m时最大,移到3 800 m时最小.研究发现,移地后鹅绒委陵菜的匍匐茎数、基株高度、基叶数、分株数、间隔子长度等均可发生变化;鹅绒委陵菜对不同海拔高度的生态环境表现出不同的克隆生长特征,以适应环境稳定种群.     

坡位对北京东灵山辽东栎林物种多度分布的影响

海拔与坡位是气象因子和立地因子的综合表现.坡位影响环境因子在空间上的分布状况,与海拔共同营造物种生存的小生境,形成群落多度格局.本文选用5个描述种-多度关系的生态位模型(断棍模型BSM、生态位优先占领模型NPM、生态位重叠模型ONM、随机分配模型RAM、优势优先模型DPM),对北京东灵山辽东栎林的乔、灌、草3个层沿海拔梯度分别在上、中、下坡位进行群落多度格局调查.结果表明:在乔木层,从低海拔到高海拔、从下坡位到上坡位,能很好地反应群落多度格局变异的模型有由RAM、NPM向DPM过渡的趋势;能很好地拟合灌木层群落多度格局的生态位模型依次是NPM、BSM、RAM,DPM在高海拔地段拟合的效果也很好;BSM在草本层的拟合效果最好,其次是NPM和ONM.协方差分析表明,海拔和坡位都没有对辽东栎林的群落多度格局产生显薯影响.     

Patterns in species richness,species density,and evenness in groundfish assemblages on the continental slope of the U.S. Pacific coast

For many taxa, diversity, often measured as species richness, decreases with latitude. In this report patterns of diversity (species richness, species diversity, and evenness) in groundfish assemblages were investigated in relation to depth (200–1200 m) and latitude (33–47°N) on the continental slope of the U.S. Pacific coast. The data originated from the 1999–2002 upper continental slope groundfish surveys conducted by the National Marine Fisheries Service. When the data were pooled across depths, species density and evenness were found to decline with latitude. All three diversity measures declined with depth, with the lowest overall diversity in the 600- to 900-m depth range where longspine thornyhead Sebastolobus altivelis constituted close to 70% of the catch. When latitudinal gradients were examined within four depth zones (200–300 m, 400–500 m, 600–900 m, and 1000–1200 m) more complex patterns emerged. At depth species richness and evenness were inversely correlated with latitude as longspine thornyhead dominated catches to the north. However, in shallower areas of the slope, species richness and evenness were positively correlated with latitude. Latitudinal patterns of diversity in the deeper zones and when pooled across depths were positively correlated with temperature and broadly consistent with the Ambient Energy hypothesis discussed by Willig et al. [Annu Rev Ecol System 34:273–309 (2003)].     

Identification of tenuazonic acid as a novel type of natural photosystem II inhibitor binding in QB-site of Chlamydomonas reinhardtii

Tenuazonic acid (TeA) is a natural phytotoxin produced by Alternaria alternata, the causal agent of brown leaf spot disease of Eupatorium adenophorum. Results from chlorophyll fluorescence revealed TeA can block electron flow from Q_A to Q_B at photosystem II acceptor side. Based on studies with D1-mutants of Chlamydomonas reinhardtii, the No. 256 amino acid plays a key role in TeA binding to the Q_B-niche. The results of competitive replacement with [¹⁴C]atrazine combined with JIP-test and D1-mutant showed that TeA should be considered as a new type of photosystem II inhibitor because it has a different binding behavior within Q_B-niche from other known photosystem II inhibitors. Bioassay of TeA and its analogues indicated 3-acyl-5-alkyltetramic and even tetramic acid compounds may represent a new structural framework for photosynthetic inhibitors.     

Characteristics of the optimum combination of synthetic soils by plant and soil properties used for rock slope restoration

Bare rock slopes often deteriorate microclimates and drive water erosion and landslides. Moreover, they impose hidden troubles on humans and have increasingly been brought to the attention of the public. In order to optimize synthetic soils (SS) for improving the outside soil spray seeding (OSSS) technique used for the restoration of rock slopes, we investigated physico-chemical properties and plant growth of a series of SS designed with orthogonal array OA₂₅ (5⁵). Five additive components, cement, inorganic compound fertilizers, peat soil, wood chip and water–absorbent polymers at five levels, were applied to optimize the synthetic soils. In the present study, we only investigated the effects of a single additive component on all the indicators measured. Primarily, results showed that the contributions of cement to plant biomass, pH and water holding content; the contributions of inorganic compound fertilizers to plant biomass and total nitrogen, available nitrogen, total phosphorus and available phosphorus; the contributions of both peat soil and wood chip to plant biomass, water holding content and organic carbon; and the contributions of water absorbent polymers to the plant biomass, water holding content and available nitrogen were all significant. According to the plant growth and physico-chemical properties of the synthetic soils, Treatment-12 consisting of 1.5% cement, 0.4% inorganic compound fertilizers, 1.5% peat soil, 0.3% water absorbent agent and 2.0% wood chip, was the optimum combination among the 25 treatments for the restoration of rock slopes. The properties of the optimized SS to support growth of plants and to resist erosion were verified by an experiment using an actual rock slope.     

Variability in natural behaviour, and observed reactions to an ROV, by mid-slope fish species

The behaviour of eight large benthopelagic fish taxa was analysed using video records collected with an ROV on the mid-slope of the Bay of Biscay. The studied species were roundnose grenadier (Coryphaenoides rupestris), orange roughy (Hoplostethus atlanticus), deep-sea scorpionfish (Trachyscorpia cristulata echinata), and black scabbardfish (Aphanopus carbo), as well as individuals belonging to the families Alepocephalidae, Chimaeridae, and Scyliorhinidae, and to the order Squaliformes. Some of the observed fish were grouped at the family taxonomical level due to visual identification to species being unreliable. Assumed natural (undisturbed) behaviour was categorised in terms of (i) body position with respect to the bottom sea floor, (ii) locomotion and (iii) activity type. Reaction (disturbed) behaviour to the approaching ROV was categorised in terms of reaction type and distance. Environmental conditions (depth, temperature, current speed and direction) and observation conditions (ROV speed and altitude) were recorded simultaneously with fish observations in order to explain the variability in the observed reaction behaviour. A multivariate analysis identified three groups corresponding to a behaviour pattern of a sit and wait strategist (one species), an active bottom hunter (three taxa), and a group of species displaying little activity in their bottom habitat (three taxa). At species level the environmental and observation conditions had some explanatory power for individual behaviour variability. It is hypothesised that the varied behaviour of mid-slope benthopelagic fish contributes to maintain a high species diversity of large predators in an energy poor environment.     

雨强对黄土坡面土壤水分入渗及再分布的影响

基于典型黄土的坡地人工降雨实验,对比研究了降雨、入渗及再分布规律;以雨强为主要影响因素,分析了降雨入渗及水分再分布过程中水土物质迁移的定量关系．结果表明,雨强变化对黄土坡面降雨入渗及土壤水分再分布的微观水分运动过程具有重要影响．雨强增大时,入渗和再分布湿润锋均随降雨历时延长而逐渐增加,但水分再分布过程的湿润锋增加速率比入渗慢得多;入渗湿润锋与时间关系可用幂函数表示,同时可表示为雨强的幂函数关系．再分布湿润锋与时间也存在定量关系．雨强越大,初始和稳定的土壤水分入渗率越高,累积入渗量随降雨时间增加得越快．此外,雨强越大,坡顶与坡脚湿润锋深度差异越小,坡面再分布过程的土壤含水量在各层的差异和递减趋势越明显．     

龙角山林区维管植物物种多样性

以龙角山地区216个样方的调查资料为基础,用Shannon-Wiener多样性指数和Sφrensen相似性指数,研究了龙角山林区野生维管植物物种多样性的空间分异规律及其原因。结果表明,乔木层物种多样性比较低,而灌木层和草本层的物种多样性则比较高;野生维管植物物种多样性随海拔高度的升高而降低;不同坡向的野生维管植物物种多样性存在着差异,北坡>东坡和西坡>南坡;坡向和海拔是影响该地区野生维管植物物种多样性空间分布的主要因子。坡向对当地的野生维管植物物种组成成分也有明显影响,其中北坡与南坡之间的野生维管植物物种组成差异最大,东坡与西坡之间的野生维管植物组成差异最小;海拔高程的变化对野生维管植物物种组成也有影响,但影响不明显。