Effect of inventory plot patterns in the floristic analysis of tropical woodland and dense forest

This study was set up to examine the effect of plot patterns on the accuracy of phytosociological characterization of tropical vegetation. Fifteen and twenty square plots of 1 ha were demarcated, respectively, in woodland and dense forest in Bénin. Each 1 ha plot was divided into 100 quadrats of one 100 m². Species of trees in each quadrat were identified and recorded. The cost in terms of time required to record tree species in each 1 ha plot and five random quadrats in a 1 ha plot were also recorded to compute the mean inventory effort for a team of three foresters. From the 100 quadrats in a 1 ha plot, fourteen independent subplots of square and rectangular plots with different sizes were considered by grouping together adjacent quadrats of 100 m². Eigenanalysis was carried out to compare the subplots. Moreover, the relationship between the relative loss of accuracy (RLA) and the size of subplots was modelled. Plot size highly influenced the RLA (P < 0.05). Findings indicated that the square plots of 1500 and 1000 m² with an inventory effort of 0.35 and 0.20 man‐days per subplot, respectively in tropical dense forests and woodlands appeared to be the most efficient in the phytosociological characterization of woody vegetation.     

甘肃藜科植物研究

根据对藜科植物标本的收集、整理和系统鉴定,本地区藜科植物共有67种,隶属于21属,8族,在我省有2个分布丰富区：河西走廊地区和青藏高原东缘的甘南地区。分析表明,本区藜科植物可划为5个分布型和3个变型,其中以地中海区、西亚和中亚分布最多（占33.4％）,除世界分布和中国特有外,均为温带性地理成分（占71％）,结合对孑遗属的分析,说明了本区系的主要特征为典型的温带性质和具有一定的古老性,并与相邻地区有一定的联系;本区系起源于白垩纪至第三纪的古地中海沿岸,伴随着青藏高原的隆起、海浸海退以及气候的变迁形成了现今的区系成分。根据植物区系分区的原则和方法,将甘肃藜科植物区系划分为5个区系小区：走廊小区,祁连山小区,中部小区,甘南小区和陇南小区,其中走廊小区和甘南小区不仅是本区藜科植物主要的分布区,而且也是我省重要的农业区和畜牧业基地,因此,对各小区的区系特征进行了论述并提出了相应的生产实践的建议,以期为我省的防风固沙、植被恢复和草场建设等提供理论依据。     

中药黄芪植物分类及其区系地理分布研究

确认了中药黄芪的原植物有膜荚黄芪(Astragalus membranaceus (Fisch.) Bunge)、蒙古黄芪(A. mongholicus Bunge)和北蒙古黄芪(A. borealimongolicus Y. Z. Zhao)3种,其中北蒙古黄芪为一新种;确定了这三种植物的区系地理成分：膜荚黄芪为东亚北部—西伯利亚南部森林带的分布种,蒙古黄芪为华北森林草原带的分布种,北蒙古黄芪为蒙古高原北部草原带的分布种,3种黄芪存在着明显的地理替代分布格局。     

闽西常绿阔叶林植物区系分析

采用群落生态学的方法对闽西常绿阔叶林植被展开调查。结果表明:闽西常绿阔叶林植物种类丰富,维管植物计有116科235属398种(包括亚种和变种) ;在科、属和种的分布区类型统计与分析中,热带分布55科、温带分布21科,热带分布142属、温带分布68属,热带分布231种、温带分布148种,其中中国特有分布类型有1科、7属51种,热带、亚热带分布区类型与温带分布区类型的比例分别为100∶38 .18、100∶47 .89和100∶64 .07 ,说明闽西常绿阔叶林植物区系具有明显的热带、亚热带地理性质;构成闽西绿阔叶林群落乔木与灌木层的数量优势表征科为樟科、壳斗科、木兰科、山茶科、茜草科、大戟科、桑科、冬青科等多为热带或亚热带科,均为华夏植物区系的典型成分,且含有许多古老、原始的类群;通过比较不同纬度分布的常绿阔叶林植物区系,闽西常绿阔叶林植物区系具有显著的中亚热带植物区系向南亚热带植物区系过渡的特点。     

新疆北部松萝属地衣生态分布与地理区系成分分析

根据多年的实地调查资料和前人研究资料,对新疆北部松萝属地衣的种类以及它们的分布区、区系特征和垂直分布进行了初步研究。结果表明,分布在新疆北部的松萝属地衣共有22种,主要分布在天山和阿勒泰山,生长在树皮、树枝和朽木上。根据它们对环境的适应特征和选择性,将新疆北部松萝属地衣的主要地理成分分为环极北极及北方成分、北美-欧洲成分、世界广布种、北美成分、环极低北极及北方成分、欧洲成分、东亚—北美成分等7种。研究还发现分布在阿勒泰山和天山的松萝属地衣的垂直分布有明显的差异。阿勒泰山的地衣分布海拔比较高,分布范围比较广泛。     

Floristic patterns and plant traits of Mediterranean communities in fragmented habitats

Aim To contrast floristic spatial patterns and the importance of habitat fragmentation in two plant communities (grassland and scrubland) in the context of ecological succession. We ask whether plant assemblages are affected by habitat fragmentation and, if so, at what spatial scale? Does the relative importance of the niche differentiation and dispersal‐limitation mechanisms change throughout secondary succession? Is the dispersal‐limitation mechanism related to plant functional traits? Location A Mediterranean region, the massif of Albera (Spain). Methods Using a SPOT satellite image to describe the landscape, we tested the effect of habitat fragmentation on species composition, determining the spatial scale of the assemblage response. We then assessed the relative importance of dispersal‐related factors (habitat fragmentation and geographical distance) and environmental constraints (climate‐related variables) influencing species similarity. We tested the association between dispersal‐related factors and plant traits (dispersal mode and life form). Results In both community types, plant composition was partially affected by the surrounding vegetation. In scrublands, animal‐dispersed and woody plants were abundant in landscapes dominated by closed forests, whereas wind‐dispersed annual herbs were poorly represented in those landscapes. Scrubby assemblages were more dependent on geographical distance, habitat fragmentation and climate conditions (temperature, rainfall and solar radiation); grasslands were described only by habitat fragmentation and rainfall. Plant traits did not explain variation in spatial structuring of assemblages. Main conclusions Plant establishment in early Mediterranean communities may be driven primarily by migration from neighbouring established communities, whereas the importance of habitat specialization and community drift increases over time. Plant life forms and dispersal modes did not explain the spatial variation of species distribution, but species richness within the community with differing plant traits was affected by habitat patchiness.     

云南哀牢山国家级自然保护区蕨类植物区系地理研究

通过野外调查和资料整理分析,哀牢山国家级自然保护区共有蕨类植物48科,118属,446种(包括变种和变型)。优势科为鳞毛蕨科、水龙骨科和蹄盖蕨科,优势属为耳蕨属、蹄盖蕨属、鳞毛蕨属和卷柏属。区系分析结果表明:该蕨类区系是亚热带性质的区系;热带亚洲成分随着海拔的升高,比例逐渐降低,而中国-喜马拉雅成分随着海拔的升高逐渐增加;地理成分的东西坡差异不明显;该蕨类区系与喜马拉雅地区和热带亚洲的关系较密切,而与日本的关系较疏远;该蕨类区系具有较丰富的中国特有成分;哀牢山明显处于滇西北、滇东南这两大中国特有多样性中心之间,成为联系的纽带。     

甘肃省裸子植物区系分析

在全面系统的查阅、鉴定、登记标本的基础上,依据吴征镒中国种子植物分布区类型划分方案和廉永善中国特有类群分布亚型的划分方案,对甘肃省裸子植物区系进行了数量统计和区系特征分析,绘制了甘肃省裸子植物种、属地理分布图,种、属数量随海拔变化的关系图和各分布区类型、亚型随海拔变化的关系图.结果表明,甘肃省裸子植物植物区系组成属温带性质,而且甘肃省裸子植物区系具有显著的交汇过渡性质和主体成分二元化结构的特点.并讨论了甘肃省裸子植物种、属分布多度中心变化的状况和青藏高原隆升对甘肃省裸子植物区系组成的影响.     

Modelling the distribution of a threatened habitat: the California sage scrub

Aim Using predictive species distribution and ecological niche modelling our objectives are: (1) to identify important climatic drivers of distribution at regional scales of a locally complex and dynamic system – California sage scrub; (2) to map suitable sage scrub habitat in California; and (3) to distinguish between bioclimatic niches of floristic groups within sage scrub to assess the conservation significance of analysing such species groups. Location Coastal mediterranean‐type shrublands of southern and central California. Methods Using point localities from georeferenced herbarium records, we modelled the potential distribution and bioclimatic envelopes of 14 characteristic sage scrub species and three floristic groups (south‐coastal, coastal–interior disjunct and broadly distributed species) based upon current climate conditions. Maxent was used to map climatically suitable habitat, while principal components analysis followed by canonical discriminant analysis were used to distinguish between floristic groups and visualize species and group distributions in multivariate ecological space. Results Geographical distribution patterns of individual species were mirrored in the habitat suitability maps of floristic groups, notably the disjunct distribution of the coastal–interior species. Overlap in the distributions of floristic groups was evident in both geographical and multivariate niche space; however, discriminant analysis confirmed the separability of floristic groups based on bioclimatic variables. Higher performance of floristic group models compared with sage scrub as a whole suggests that groups have differing climate requirements for habitat suitability at regional scales and that breaking sage scrub into floristic groups improves the discrimination between climatically suitable and unsuitable habitat. Main conclusions The finding that presence‐only data and climatic variables can produce useful information on habitat suitability of California sage scrub species and floristic groups at a regional scale has important implications for ongoing efforts of habitat restoration for sage scrub. In addition, modelling at a group level provides important information about the differences in climatic niches within California sage scrub. Finally, the high performance of our floristic group models highlights the potential a community‐level modelling approach holds for investigating plant distribution patterns.