Population models in a periodically fluctuating environment

Summary We investigate the behavior of population models in the presence of a periodically fluctuating environment. We consider in particular single-species models and models of interspecific competition. It is shown that the fluctuations cause constant equilibrium states to be replaced by periodic equilibrium states, with a shift in the mean value relative to the constant-environment state. It is shown also that the locations of points of exchange of stability may be changed as a result of the fluctuations.     

Floristic composition of Jandaf Mountain as biodiversity hotspot area in southwestern Saudi Arabia

Arid environments around the world are characterized by lower plant diversity. However, some specific locations have relatively high species richness and have significant importance in terms of vegetation structure and plant diversity. Jabal Al-Jandaf is located in an arid area within the eastern side of mountainous region in the southwest of Saudi Arabia. It consists of valleys, lower plain and upper plain habitats with unique and diverse vegetation. These habitats range from 1000 m above sea level near the Tarj valley to 1910 m at the summit. In this study, we conducted a first survey of the floristic diversity at Jandaf Mountain. Furthermore, we applied the criteria of the Important Plant Area (IPA) and the High Conservation Value (HCV) approaches to assess whether the plant community at Jandaf Mountain qualifies as a significant conservation area. We found that the study area has great plant diversity with plant composition varying among the different habitats (e.g., valleys, upper and lower elevations) within the study area. We recorded 118 species from 97 genera belonging to 42 families, including endemic (e.g. Aloe pseudorubroviolacea), near-endemic (e.g. Monolluma quadrangular), and endangered species (e.g. Dracaena serrulata, Combretum molle, and Moringa peregrine). The plant diversity at Jandaf Mountain achieves the criteria outlined in the IPA and HCV approaches. Therefore, we conclude that Jandaf Mountain has a unique vegetation structure, and the area qualifies for conservation as a high value area for biodiversity and conservation of global significance.     

Study Design for Assessing Species Environment Relationships and Developing Indicator Systems for Ecological Changesin Floodplains – The Approach of the RIVA Project

In this article the study design and data sampling of the RIVA project – “Development and Testing of a Robust Indicator System for Ecological Changes in Floodplain Systems” – are described. The project was set up to improve existing approaches to study species environment relationships as a basis for the development of indicator systems and predictive models. Periodically flooded grassland was used as a model system. It is agriculturally used at a level of intermediate intensity and is the major habitat type along the Middle Elbe, Germany. We chose a main study area to analyse species environment relationships and two reference sites for testing the transferability of the results. Using a stratified random sampling scheme, we distributed 36 study plots across the main study site and 12 plots each within the reference sites. In each of the study plots, hydrological and soil variables were measured and plants, molluscs, and carabid beetles were sampled. Hoverflies were collected on a subset of the sampling plots. A brief summary of first results is then provided. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

菌物生物多样性及其资源研发前景——献给《菌物研究》创刊10周年

文中首先给予菌物,即泛真菌(Pan-Fungi)以明确定义,它是地球生物圈中一切真核菌类生物的总称,是地球生物圈中生物多样性的重要组成部分,也是具有实现大规模工业化开发潜力的重要资源生物类群。在对物种和基因之间的关系进行分析之后认为,所谓生物多样性,实际上是指生存于地球生物圈中多种多样生态系统中的、含有多种多样基因的物种多样性。文中指出,地球生物圈中生存的真菌至少有250万种。然而,已被人类所认识和命名的真菌仅为9.786 1万种,占估计种数的3.9%,尚有96.1%的真菌有待于人类去发现。人类的平均寿命由1796年以前的18岁提高到60岁经历了2个里程碑,由18岁至40岁借助于牛痘的发明;由40岁至60岁则借助于来自真菌的抗菌素——青霉素的应用。人类的平均寿命正在面临癌症发病和死亡的威胁,如何才能使人类的平均寿命跨越第三个里程碑,从而进入更加健康长寿的新生活阶段?除了进行环境和食品安全治理以及保持健康生活习惯外,丰富的菌物资源的发掘与利用也许正是人类所期待的。文中对提到的304种具有抑制肿瘤活性的药用真菌为基础,系统地进行抗癌活性物质的筛选,从而构建健康人群的抗癌"防火墙",同时制定癌症患者的康复计划,使药用真菌在提高人类平均寿命、使人类进入更加健康长寿的第三个里程碑中发挥应有的作用。迄今包括新药开发在内的菌物资源研发中鲜有成效的原因之一,也许与菌物分类学及其成果未受到足够重视不无关系。其结果便导致该研发项目的菌物多样性基础先天不足,从而难以发挥我国菌物多样性在资源开发中的优势。面对如此丰富的菌物资源宝库,为了研究和开发菌物资源,创建我国自己创新产品的知识产权,与菌物资源研发的上游和中游专业人员紧密合作,共担责任,共享成果,在加强菌物分类学三大存取系统并重的前提下,结合菌物活性物质筛选平台,作为菌物资源研发的新途径与新模式,进行包括创新药物在内的菌物资源研发项目的立项,实在势在必行。此外,从产于极端环境的菌物中进行抗逆基因筛选及其功能分析与应用对于人类环境的改善具有巨大的潜力。     

Diversity and distribution pattern of epiphyllous liverworts and its ecological determinants

Epiphyllous liverworts form a special group of bryophytes that primarily grow on leaves of understory vascular plants, occurring in constantly moist and warm evergreen forest in tropical and subtropical regions. Epiphyllous liverworts may influence ecosystem processes including carbon, nitrogen and water cycles. Furthermore, they are very sensitive to climate change and forest fragmentation, and can be used as bioindicators for changes in ecological conditions and escalating loss of biodiversity. In this paper, we reviewed studies on morphological traits, species diversity, geographical distribution and environmental conditions (including characteristics of hosts and habitats) of epiphyllous liverworts, discussed the possible reasons for the mechanisms underlying the diversity pattern of epiphyllous liverworts. According to these studies, we proposed that further ecological studies on epiphyllous liverworts should be more focused on their formation, mechanisms of matter exchange and energy flux, ecological functions in forest ecosystem, the response to climate changes and their broader-scale ecology.     

山东半岛滨海沙滩前缘的野生植物

滨海沙滩是以海水影响为基本过程的地貌类型, 适应这种环境的植物类群与适生于内陆的沙地植物可能存在巨大差别。在野外调查的基础上, 分析了山东半岛滨海沙滩前缘的植物种类及其种间关系。结果表明: (1) 滨海沙滩前缘具有独特的优势种库, 包括沙钻苔草(Carex kobomugi)、肾叶打碗花(Calystegia soldanella)、粗毛鸭嘴草(Ischaemum bartatum)、单叶蔓荆(Vitex trifolia var. simplicifolia)、矮生苔草(Carex pumila)和沙引草(Messerschmidia sibirica)等; (2) 优势种库的成员都是潜在优势种, 它们之间主要呈抑制效应, 对库外物种几乎没有抑制效应, 甚至有互补或互利效应。在进化过程中, 这些潜在优势种可能已适应风暴潮的干扰, 不会因受风暴潮灾害而灭亡。当植物适应风暴潮后, 滨海沙滩不再是灾难环境, 反而变为适宜生境。为持续利用这些物种, 不仅要保护其赖以生存的天然生境, 还要开展引种栽培, 消除人们对野生资源的采挖动机。根据物种间的天然联系, 栽培时宜将具有互利或互补关系的物种间混种植, 不宜将具有抑制关系的物种间混种植。     

Optimal conservation strategy in fluctuating environments with species interactions: resource-enhancement of the native species versus extermination of the alien species

Alien species are often a major threat to native species. We consider optimal conservation strategies for a population whose viability is affected both by an alien species (such as a competitor, a predator, or a pathogen) and by random fluctuations of the environment (e.g. precipitation, temperature). We assume that the survivorship of the native population can be improved by providing resources such as food and shelter, and also by an extermination effort that decreases the abundance of the alien species. These efforts decrease the extinction probability of the native population, but they are accompanied by economic costs. We search for the optimal strategy that minimizes the weighted sum of the extinction probability and the economic costs over a single year. We derive conditions under which investment should be made in both resource-enhancement and extermination, and examine how the optimal effort levels change with parameters. When the optimal strategy includes both types of efforts, the optimal extermination effort level turns out to be independent of the density and economic value of the native species, or the variance of the environmental fluctuation. Furthermore, the optimal resource-enhancement effort is then independent of the density of the alien species. However, the parameter dependencies greatly change if one of the efforts becomes zero. We also examine the situation in which the impact of the alien species is uncertain. The optimal extermination effort increases with the uncertainty of this impact except when the cost of extermination is very high.     

西双版纳不同经济作物环境泥蜂物种多样性研究

泥蜂是一类重要的捕猎性天敌昆虫和传粉昆虫。本研究于2018年6月-2019年11月对西双版纳地区观赏经作区、柚林区、古茶林区和农田区（样地Ⅰ-Ⅳ）4个调查区采用马氏网诱捕方法定期定点调查,每月调查一次。结果如下：西双版纳调查区域分布有泥蜂类群3科15族27属110种;其中,泥蜂科包括3族5属7种;蠊泥蜂科包括2族3属8种;方头泥蜂科包括10族19属95种,为该地区的优势科。脊短柄泥蜂属Psenulus、小唇泥蜂属Larra和短翅泥蜂属Trypoxylon为优势属,刻臀小唇泥蜂Larra fenchihuensis、磨光小唇泥蜂红腿亚种Larra polita luzonensis为优势种。4个作物区的优势科均为方头泥蜂科,但不同作物区泥蜂的优势属种存在差异,观赏经作区（样地Ⅰ）优势属为脊短柄泥蜂属和短翅泥蜂属,优势种为普氏脊短柄泥蜂指名亚种Psenulus pulcherrimus pulcherrimus（17.4%）和岩田隆痣短柄泥蜂Carinostigmus iwatai（15.6%）;柚木林区（样地Ⅱ）优势属为脊短柄泥蜂属和短翅泥蜂属,优势种为普氏脊短柄泥蜂指名亚种（17.7%）和锡兰脊短柄泥蜂Psenulus ceylonicus（11.3%）;古茶林区（样地Ⅲ）优势属为短翅泥蜂属和小唇泥蜂属,优势种为刻臀小唇泥蜂（15.6%）和吉打州短翅泥蜂Trypoxylon kedah（12.5%）;农田区（样地Ⅳ）优势属为小唇泥蜂属和短翅泥蜂属,优势种为刻臀小唇泥蜂（21.7%）和磨光小唇泥蜂红腿亚种（21.7%）。15属多区分布,12属单区分布。植被差异是影响泥蜂物种多样性的重要因子,植被群落复杂程度影响泥蜂群落特征指数,植被群落越复杂的环境,泥蜂群落种类越丰富,物种多样性越高。泥蜂物种多样性随季节的变化而明显变化,降雨量和温度等气候因素是影响泥蜂多样性变化的重要因子。4个样地之间泥蜂群落相似性系数表示为中等不相似或极度不相似水平,表明不同样地中泥蜂群落组成差异很大。本研究明确了西双版纳4个不同经济作物环境中的泥蜂物种多样性,可为天敌昆虫资源的保护和利用以及害虫生物防治等研究提供依据。     

新疆地衣资源多样性研究进展

在生物多样性中,地衣是一类独特的生物。新疆地衣资源丰富,至今在新疆已定名的地衣有398种,隶属于98属;包括不完全真菌类地衣4属4、种。深入了解新疆地衣物种多样性和其生态环境及地衣的应用价值,有利于合理利用新疆的生物资源,有效保护生态环境。     

西藏东南高寒森林大型真菌多样性与植被及环境的关系

通过对西藏东南高寒森林地区3个样地的9个样方两年内较为系统的调查,研究了大型真菌多样性及其与植被类型和大型真菌发生的其他诸多因素之间的关系.基于不同样方物种种类的样方层序聚类分析表明大型真菌的物种发生受植被类型影响较大.多样性指数分析表明急尖长苞冷杉林内的物种丰富度指数和多样性指数大于青冈树和落叶松混交林,后者大于青冈林.应用典范对应分析研究不同植被类型大型真菌物种发生和环境因素的关系,结果表明大型真菌物种的发生受不同环境因子的驱动,其发生是植被类型和环境因素共同作用的结果.     

叶附生苔植物物种多样性分布格局及生态成因

叶附生苔植物(以下简称叶附生苔)是一类附生在维管植物叶片表面的、一般只出现在热带雨林和常绿阔叶林中的苔类植物。它们具有重要的生态功能, 如影响碳、氮、水循环, 对气候变化和森林破碎化反应敏感, 可用作环境变化的指示植物。该文对叶附生苔的形态特性、物种多样性的研究历史和进展、地理分布格局, 以及对环境的要求(附主和生境的特性)等进行了综述, 探讨了叶附生苔多样性分布格局形成的可能原因, 即环境(空气湿度高、林冠层发育好、干扰少)和适应特征(无性繁殖、形体微小)的选择。根据全球叶附生苔研究进展状况及所存在的问题提出未来可开展的研究方向, 如叶附生苔的形成原因、与附主间的物质交换和能量流动机制、在森林生态系统中的生态功能、气候变化指示作用研究等, 大尺度上的研究也值得关注。     

Fish Assemblages and Habitat in a Malaysian Blackwater Peat Swamp

Fish captured by electrofishing from lotic reaches within and immediately outside the North Selangor blackwater peat swamp forest were placed into six assemblages. Species richness varied among assemblages from 7 to 32 but most species were not regular members of an assemblage. Swamp water was low in dissolved oxygen and buffering capacity and high in color and acidity. Assemblages were associated with four discrete aggregations of abiotic conditions including oxygen, pH, color, conductivity and organic content of the substrate. Assemblages relatively rich in species and numerical abundance were associated with habitats comparatively high in oxygen and color and low in acidity. Species-poor assemblages were associated with habitats particularly low in oxygen and high in acidity.     

山东半岛滨海沙滩前缘的野生植物

滨海沙滩是以海水影响为基本过程的地貌类型,适应这种环境的植物类群与适生于内陆的沙地植物可能存在巨大差别。在野外调查的基础上,分析了山东半岛滨海沙滩前缘的植物种类及其种间关系。结果表明：（1）滨海沙滩前缘具有独特的优势种库,包括沙钻苔草（Carex kobomugi）、肾叶打碗花（Calystegia soldanella）、粗毛鸭嘴草（Ischaemum bartatum）、单叶蔓荆（Vitex trifolia var.simplicifolia）、矮生苔草（Carex pumila）和沙引草（Messerschmidia sibirica）等;（2）优势种库的成员都是潜在优势种,它们之间主要呈抑制效应,对库外物种几乎没有抑制效应,甚至有互补或互利效应。在进化过程中,这些潜在优势种可能已适应风暴潮的干扰,不会因受风暴潮灾害而灭亡。当植物适应风暴潮后,滨海沙滩不再是灾难环境,反而变为适宜生境。为持续利用这些物种,不仅要保护其赖以生存的天然生境,还要开展引种栽培,消除人们对野生资源的采挖动机。根据物种间的天然联系,栽培时宜将具有互利或互补关系的物种间混种植,不宜将具有抑制关系的物种间混种植。     

利用数值模拟重构物种多样性格局的形成过程

生命形成的过程极其漫长, 经历了地球系统复杂的沧海桑田变化。当前人类所观察到的物种分布格局的形成除了由物种本身特征决定外, 还受到环境变化、人类活动以及各种随机事件的影响。受限于实验条件、时间、经费、人力等诸多因素, 我们尚无法完整地观察并记录到物种多样性形成的全过程, 只能通过片段化数据来推测该过程。信息科学中包括数值模拟在内的仿真技术以其高效、可控及全过程记录等优势, 能从某种程度上解决物种多样性格局形成过程中的部分数据黑箱问题。本文介绍了数值模拟的概念和工作原理及在物种多样性研究中应用的特点, 列举了物种生态位、扩散模式、种间互作及物种分布应对气候变化等方面的数值模拟研究, 基于已有研究系统地介绍了如何综合上述数值模拟研究构建虚拟物种、气候和场景来解释物种多样性的形成与维持机制, 并阐述了数值模拟在物种多样性研究中的优缺点及应用前景。     

方山中山丘陵区植物多样性研究

以方山地区27个样方的调查资料为基础,从物种种类组成的相似性,不同层次的物种丰富度,物种多样性等方面对方山植物多样性进行分析.结果表明,该地区乔木层物种丰富度较低,而灌木层和草本层较高;该地区物种多样性随海拔高度的升高而降低;在同一海拔高度上,北坡的物种多样性大于南坡;人类活动对该地区植物物种多样性有明显影响.     

草地植物群落最优分类数的确定——以黄河三角洲为例

植被生态学研究中常需要将样地-物种属性数据划分为多个具有生态意义的集群,在植被分类过程中不仅要在分类方法上做选择,还要确定该植被数据分多少类最合适.有很多指标来确定群落划分中的最优分类数,但都没有得到一致的认可.将黄河三角洲227个样地数据用ward等级聚类法进行了分类.为了找到最优的分类数和判断指标,用不同的判断标准对植被数据分为2到15类时进行分析.主要从3个方面对最优分类数进行判断:1)比较集群内的同质性和集群间的异质性;2)基于集群的物种组成、环境变量的不同,确定集群与环境的相关性;3)基于物种在不同集群内的频度与多度.判断指标主要包括:average silhouette width指数、Goodman and Kruskal's Gamma系数、Dunn指数、集群分布的熵、wb.ratio指数、Calinski and Harabasz 指数、C-index指数、partana指数、biserial指数.用多响应置换过程对集群间物种组成和环境差异显著性进行分析.用指示物种从生态角度对各集群进行判别,并对指示物种的显著性进行了分析.不同判断标准得到的黄河三角洲最优分类数不同,得到的最优分类数包括分为2、5、7、和15类;多方面综合判断,认为在分为7类时最好.群落分类中应该有较优的断点,划分类较少时,集群特征不明确;划分类较多时,集群特征虽然更明确,但可能会导致较多的小集群,且小集群间环境差异不显著.7类较优,能满足物种组成差异、环境差异、群落内和群落间差异、所含信息量多的要求.分为2-6类时应该都是有意义的,只是所代表的群落特征不同.各判断标准中,dunn、silhouette、Calinski和Harabasz指数和指示物种能比较有效的判断最优分类数.不同的分类方法和物种属性数据的得到的结果有待进一步研究.     

Effects of Wildflower Strip Quality,Quantity, and Connectivity on Butterfly Diversity in a Swiss Arable Landscape

The effects of habitat restoration measures designated to promote farmland biodiversity have been documented at the field scale, but little is known about their role in restoring the agricultural mosaic. In this study, we analyzed the effects of wildflower strips (WFS) at the field scale and in the landscape context on butterflies in a Swiss arable landscape. Three hypotheses were tested: (1) butterfly diversity and abundance are higher in WFS than in conventional fields; (2) butterfly diversity and abundance are enhanced by the amount, proximity and connectivity of WFS in the landscape context; (3) additional factors influence butterfly diversity and abundance according to individual site conditions and landscape context characteristics linked to other landscape elements. WFS had more species and individuals of butterflies than conventional habitats. However, promoted species were mainly generalists; few specialists were enhanced. The diversity of all butterflies and of generalists increased linearly with percent cover of WFS, reflecting an effect of restoration measures depending on the landscape context. The influence of proximity and connectivity of WFS were, however, not significant. The occurrence of specialists was conditioned by plant species richness, while the effect of WFS for overall diversity was affected by the amount of grassland in the surroundings. We conclude that to increase the effectiveness of biodiversity‐orientated restoration measures, their implementation should be steered toward increasing the share of WFS in the landscape. However, the combination of WFS with additional restoration measures might be needed to halt the decline of specialist species.     

杭州西溪湿地大型底栖动物群落特征及与环境因子的关系

为揭示现阶段西溪湿地大型底栖动物群落现状及其对湿地生态保护工程的响应,于2009年8月至2010年5月对西溪湿地在3个不同时期建设的区域(Ⅰ区、Ⅱ区和Ⅲ区)中的大型底栖动物进行季度调查.共记录大型底栖动物3门8纲15科45种.霍甫水丝蚓(Limnodrilus hoffmeisteri)、多毛管水蚓(Aulodrilus pluriseta)和梨形环棱螺(Bellamya purificata)是现阶段西溪湿地大型底栖动物的优势种.最早建设的Ⅰ区的环节动物密度在各季节均低于建设较晚的Ⅱ区和Ⅲ区,而软体动物的密度和生物量的变化趋势则相反;Ⅰ区大型底栖动物的总密度虽然与Ⅱ区和Ⅲ区没有明显差异,但总生物量、物种数、Margalef物种丰富度指数和Shannon-Wiener多样性指数均显著上升.上述结果表明,西溪湿地生态保护工程早期建设区域的底栖动物多样性趋于增加,水生生态系统环境质量得以改善.ANOSIM分析显示,西溪湿地不同区域或季节间大型底栖动物群落结构均存在显著差异,且这些差异的主要贡献物种为多毛管水蚓(Aulodrilus pluriseta)和梨形环棱螺(Bellamya purificata),表明这两个优势物种对西溪湿地底栖环境变化反应敏感,可作为湿地环境评价的指示物种.BIO-ENV分析表明,水温是影响春季和夏季大型底栖动物群落结构的主要环境因子,水深是影响秋季和冬季大型底栖动物群落的主要因子,同时底泥总磷含量对解释大型底栖动物生物量和群落结构具有一定作用.