Deep placement: A method of nitrogen fertilizer application compatible with algal nitrogen fixation in wetland rice soils

Summary The effect of different methods of nitrogen fertilizer application on the algal flora and biological nitrogen fixation (Acetylene-reducing activity) in a wetland rice soil was studied in pot and field experiments. Broadcast application of urea inhibited nitrogen fixation and favored the growth of green algae. In contrast, deep placement of urea supergranules (1–2 g urea granules) did not suppress the growth of N₂-fixing blue-green algae and permitted acetylene-reducing activity on the soil surface to continue virtually uninhibited.     

Nested spatial patterns in seed bank and vegetation of Mediterranean old-fields

A nested sampling design was used to describe the spatial patterns for the species richness and composition in the seed bank and vegetation of three Mediterranean old-fields (1, 7, and 15 yr after the last ploughing). Three scales were examined hierarchically: sampling units within plots of 0.25 m² for the vegetation and of 0.05 m² for the seed bank, 100 m² plots within fields, and fields of 1000 m². In spite of the strong spatial variation among sampling units, species richness and composition of both seed bank and vegetation showed hierarchically structured patterns of heterogeneity, while each old-field was a homogeneous entity. These spatial patterns tended to be partially masked when the data were aggregated at the scale of the plot. Such results stress the use of a nested sampling design for studying variation in species richness and taxonomic composition in both vegetation and seed bank. This design, in combination with CCA, also showed that the vegetation showed a coarser grain than the seed bank, probably in relation to seed clumping.     

Placing Ancient DNA Sequences into Reference Phylogenies

Joint phylogenetic analysis of ancient DNA (aDNA) with modern phylogenies is hampered by low sequence coverage and post-mortem deamination, often resulting in overconservative or incorrect assignment. We provide a new efficient likelihood-based workflow, pathPhynder, that takes advantage of all the polymorphic sites in the target sequence. This effectively evaluates the number of ancestral and derived alleles present on each branch and reports the most likely placement of an ancient sample in the phylogeny and a haplogroup assignment, together with alternatives and supporting evidence. To illustrate the application of pathPhynder, we show improved Y chromosome assignments for published aDNA sequences, using a newly compiled Y variation data set (120,908 markers from 2,014 samples) that significantly enhances Y haplogroup assignment for low coverage samples. We apply the method to all published male aDNA samples from Africa, giving new insights into ancient migrations and the relationships between ancient and modern populations. The same software can be used to place samples with large amounts of missing data into other large non-recombining phylogenies such as the mitochondrial tree.     

拟单性木兰属（木兰科）植物的分类学修订

根据标本研究和野外调查,对木兰科(Magnoliaceae)的拟单性木兰属(Parakmeria Hu &; Cheng)进行了分类学修订。回顾了此属的分类学简史,阐述了保留拟单性木兰属的理由,将Magnolia Linn. subgenus Gynopodium Figlar &; Noot. section Gynopodium 作为拟单性木兰属的新异名,将Magnolia yunnanensis (Hu) Noot. 和M. nitida W. W. Smith var. robusta B. L. Chen &; Noot.作为云南拟单性木兰(Parakmeria yunnanensis Hu)的新异名,将Magnolia omeiensis (Cheng) Dandy、M. lotungensis Chun &; C. H. Tsoong、M. nitida W. W. Smith var. lotungensis (Chun &; C. H. Tsoong) B. L. Chen &; Noot. 和Parakmeria lotungensis (Chun &; C. H. Tsoong) Law作为峨眉拟单性木兰(Parakmeria omeiensis Cheng)的新异名,确认拟单性木兰属含４种植物,列出了分种检索表,描述了各种的地理分布和生长环境。     

Is spectral distance a proxy of beta diversity at different taxonomic ranks? A test using quantile regression

Beta diversity represents a powerful indicator of ecological conditions because of its intrinsic relation with environmental gradients. In this view, remote sensing may be profitably used to derive models characterizing or estimating species turnover over an area. While several examples exist using spectral variability to estimate species diversity at several spatial scales, most of these have relied on standard correlation or regression approaches like the common Ordinary Least Square (OLS) regression which are problematic with noisy data. Moreover, very few attempts were made to derive beta diversity characterization models at different taxonomic ranks. In this paper, we performed quantile regression to test if spectral distance represents a good proxy of beta diversity considering different data thresholds and taxonomic ranks. We used plant distribution data from the North and South Carolina including 146 counties and covering a variety of vegetation formations. The dissimilarity in species composition at different taxonomic ranks (using Sørensen distance) among pairs of counties was compared with their distance in NDVI values derived from 23 yearly MODIS images. Our results indicate that (i) spectral variability represents a good proxy of beta diversity when appropriate statistics are applied and (ii) a lower taxonomic rank is important when changes in species composition are examined spatially using remotely sensed data.     

绿色植物室内应用探讨

本文主要从室内环境特点、植物的耐荫性、观赏性探讨绿色植物在室内的应用;通过多年的观察,筛选出适宜室内摆放的植物种类、应用方式及摆放时限;并简述植物在室内摆放的管理要点。     

中国黄杨属植物数量分类的研究

本文采用系统聚类分析方法对中国黄杨属植物20种、3亚种和2变种进行了分类学研究,研究结果表明：营养器官的32个特征性状、繁殖器官的35个特征性状和总的67个特征性状的系统聚类结果与该属植物形态分类结果相吻合,从而为该属植物新分类群的建立,种、亚种和变种的鉴定以及某些划分不合理的种群纠正提供了一种新的科学依据和手段。     

蓝藻OscilatoriaceaerDNA16S-23S基因间隔区的序列分析及其分类学意义

采用末端终止法对蓝藻类颤藻科Ｏｓｃｉｌａｔｏｒｉａｓｐ．ｒＤＮＡ１６Ｓ－２３Ｓ基因间隔区进行了序列测定,获得了Ｏｓｃｉｌａｔｏｒｉａｓｐ．ｒＤＮＡ基因间隔区４２７个核苷酸,其中包含１个异亮氨酸ｔＲＮＡ基因（ｔＲＮＡＩｌｅ）。并通过计算机联网从国际分子生物学数据弹库中获取颤藻科其它种的ｒＤＮＡ基因间隔区序列,通过比较分析,从分子水平对颤藻科Ｏｓｃｉｌａｔｏｒｉａｃｅａｅ属间的某些分类学问题进行了讨论,并根据序列中核苷酸差异值探讨了颤藻科属间界定的分子标准。提出了ｒＤＮＡ基因间隔区是良好的分子标记,可用于“赤潮”或“水华”蓝藻专一性核酸分子探针的研制     

Consequences of habitat fragmentation for plant species: Do we know enough?

Habitat fragmentation is one of the most important causes for the decline of plant species. However, plants differing in phylogeny, habitat requirements and biology are likely to respond differently to habitat fragmentation. We ask whether case studies on the effects of habitat fragmentation conducted so far allow generalizations about its effects on the fitness and genetic diversity of populations of endangered plant species. We compared the characteristics of plant species endangered in Germany whose sensitivity to habitat fragmentation had been studied with those of the endangered species that had not been studied. We found strong discrepancies between the two groups with regard to their taxonomy and traits relevant to their sensitivity to habitat fragmentation. Monocots, graminoids, clonal, abiotically pollinated and self compatible species were underrepresented among the studied species, and most study species were from a few habitat types, in particular grasslands. We conclude that our current knowledge of the effects of habitat fragmentation on plant populations is not sufficient to provide widely applicable guidelines for species management. The selection of species studied so far has been biased toward species from certain habitats and species exhibiting traits that probably make them vulnerable to habitat fragmentation. Future studies should include community-wide approaches in different habitats, e.g. re-visitation studies in which the species pool is assessed at different time intervals, and population-biological studies of species from a wide range of habitats, and of different life forms and growth strategies. A more representative picture of the effects of habitat fragmentation would allow a better assessment of threats and more specific recommendations for optimally managing populations of endangered plants.