广东内伶仃岛自然保护区的苔藓植物

报道广东内伶仃岛自然保护区的苔藓植物共１９ 科、３４ 属、６１ 种, 其中藓类１３ 科、２６属、５０ 种, 苔类６ 科、８ 属、１１ 种。全缘疣鳞苔（ Ｃｏｌｏｌｅｊｅｕｎｅａ ｓｃｈｗａｂｅｉ） 等３ 种苔类和拟阔叶小石藓（ Ｗｅｉｓｉａ ｐｌａｔｙｐｈｙｌｌｏｉｄｅｓ） 等１０ 种藓类为广东省新记录。分析了保护区内的苔藓植物区系特点, 并与车八岭、黑石顶、鼎湖山及南岭自然保护区的苔藓植物区系进行了比较。研究表明, 内伶仃岛的苔藓植物区系由于受地理位置及地形特征的影响而具有一定的特殊性。     

中国黄耆属植物旱生类群的区系特点和生态地理分布

根据种的现代地理分布、分布区类型、地理宗的替代关系和生态２特点对中国黄耆属植物的旱生类群进行了研究。结果表明,国产该类群植物９３种,可划分为８个分布区类型和１４个亚型。依其生态理分布规律,又可将这些类群划分为４个生态系列或称为生态区,即帕米尔－昆仑－羌唐生态区,天山－阿尔泰生态区、伊犁－塔城谷地生态区和蒙新荒漠东部生态区。分析认为：黄耆属植物旱生类群的区系发生在中亚西部,中国类群的发生具有显著的中     

The impact of changing the season in which cereals are sown on the diversity of the weed flora in rotational fields in Denmark

1. Surveys have shown that there has been a dramatic decrease in the weed flora of fields under rotational cultivation during the last 30 years. This trend has been particularly noticeable in winter cereals, a crop of increasing importance in the landscape.
2. The weed flora of spring and winter cereals was compared in 19 unsprayed fields during a 5-year study to test the hypothesis that cereal type exerts no effect on the flora or on the absolute and relative abundance of single species.
3. Plant and species densities, and accumulated species richness, were lower in winter than in spring cereals.
4. Floristic similarity was greater among spring cereal fields and between spring and winter cereals within the same fields than among winter cereal fields.
5. Species that occurred with unequal density in spring and winter cereals occurred at higher densities in the spring cereals; these species germinated mainly in the spring. However, for a few species the relative plant abundance was highest in winter cereals; these species were able to germinate both in the spring and autumn.
6. Some species – on the relative scale – occurred indifferently of season of sowing; all but one of these species were able to germinate both in the spring and autumn.
7. Plant species and taxa that are important food resources for arthropod herbivores occurred at greater densities in spring than in winter cereals and, in addition, occurred with the highest relative abundance in spring cereals.
8. Change in land use from spring to winter cereals involves not only an immediate reduction of more than 25% in the density of plants and species, but also a change and increased uncertainty in the composition of the weed flora. These findings may have serious implications for the ecology of wildlife in the agricultural landscape.     

Floristic analysis of vascular plant genera of North America north of Mexico: characteristics of phytogeography

The phytogeographical characteristics of North America north of Mexico (NANM) were examined based on an analysis of the 1904 indigenous genera of the vascular plants known to the area. According to the worldwide distribution patterns of the genera, the 1904 genera were grouped into ten phytogeographical elements (categories). About 67.3% of the genera found in the native flora of NANM also occur in other areas of the world; of these, 71.4% occur in the Old World. About 32.7% of the 1904 genera are endemic to North America. The origins of the floristic relationships between North America and the rest of the world and the origin of the present-day flora of North America are discussed. The current floristic patterns of the NANM vascular plant genera resulted in part from palaeogeological events such as the unification of tectonic plates into a single supercontinent, Pangaea, and then the breakup of the united supercontinent into Laurasia and Gondwana followed by the fragmentation of Laurasia and Gondwana into individual continents as they are today due to the movement of plate tectonics. Many of the endemic genera of North America likely originated in the North American continent during the Tertiary, particularly during the uplifting of Rocky Mountains.     

Effects of cultivation practice on floristic and flowering diversity of spontaneously growing plant species on arable fields

In the past, the floristic diversity of arable fields has been described in terms of species diversity (SD) and their degree of coverage (C), but never in combination with the recording of the actually flowered species (FS) and their flowering intensity (FI) to striking differences in the cultivation methods on arable land. In relation to SD and C, however, FS and FI may provide important additional information on the functional biodiversity of fields. The aim was therefore to investigate the effects of (a) conventional, (b) organic, and (c) smallholder (never application of herbicides) on the floristic diversity. Using a region in Germany, we investigated SD, C, FS, and FI synchronously in (a), (b), and (c), by 356 vegetation surveys (5 × 5 m plots) conducted in spring and summer in 2019 in winter cereals. Statistical tests were used to analyze the differences between (a), (b), and (c). The medians were used to compare the floristic diversity of (a), (b), and (c) and finally relationships of FS and FI to SD were analyzed in relation to the cultivation methods. Significant differences in SD, C, FS, and FI were found between the (a), (b), and (c) in spring and summer characterized by sharp declines from (c) to (b) to (a). A drastic reduction in floristic diversity from (c) 100 to (b) 52 to (a) 3 was determined. Plants in flower (FS, FI) were very poorly in (a), moderately well to well in (b), and well to very well represented in (c). (C) to (a) was characterized by a sharp decline and from (a) to (b) by sharp increase in floristic diversity. With current acreage proportions of (a) in mind, this would affect, about one third of land area in Germany, associated with a drastic reduction in functional biodiversity for insects.     

滇东南热带雨林种子植物区系的初步研究

通过对滇东南地区热带雨林植被的初步调查 ,统计滇东南热带雨林种子植物区系有种子植物 119科 ,378属 ,6 73种 (包括变种和亚种 )。种子植物分布区类型组成是主产热带和亚热带的科占 82 .35% ;热带分布属占非世界属数的 93.87% ;典型热带分布种占总种数的 75.93%。热带分布属中以亚洲热带分布属最多 ,占非世界属数的 4 0 .2 7% ;典型热带分布种中以热带亚洲分布及其变型越南 (印度支那 )至云南 (华南 )分布占比例最高 ,分别为 71.4 7%和 16 .34 %。分布区类型分析表明滇东南热带雨林种子植物区系具有热带亚洲区系的特点 ,属于古热带植物区中的马来亚森林植物亚区之中的北部湾区系。进一步分析表明此区系具热带北缘的性质。分布区类型的组成也表明此区系古特有种丰富。     

Distribution of shrublands in relation to soil and climate in mid-subtropical China

Aims Understanding relationships between vegetation and environments is of importance for ecosystem restoration and management. However, information on how environments influence the floristic patterns of shrublands is lack, especially in the subtropical China. In this study, we explored how environments regulate species composition of shrublands at landscape scale in mid-subtropical China.Methods We investigated species composition and measured the climate and soil environments for 207 shrubland plots in mid-subtropical China (24°39′–30°08′N, 108°47′–114°15′E). We applied a hierarchical cluster analysis and indicator species analysis based on the Bray–Curtis similarity index to identify the main shrubland types and employed principal coordinate analysis (PCoA) to explore the relationship between floristic composition and environment.Important findings We identified four shrubland types occurring in different environmental conditions. Montane shrubland, dominated by species suitable for cool climates (e.g. Rhododendron simsii), were distributed in steep areas at comparatively high altitudes; foothill shrubland, dominated by mesophilous species (e.g. Loropetalum chinense), were distributed in low mountains and hills; pioneer shrubland, dominated by fast grow and short-life cycles species (e.g. Rhus chinensis), were distributed at low altitudes with dense population; and finally, limestone shrubland, dominated by calcicole plants (e.g. Coriaria nepalensis), were distributed in the extensive karst areas. Communities occurring in high pH soils were completely separated from those in low pH soils according to the hierarchical cluster analysis. PCoA ordination associated the four types with distinct edaphic and climatic gradients. Soil pH explained 63.3% of variation in PCoA, followed by soil depth and soil bulk density.     

福州市居住区景观树木多样性分析

对福州市辖区内自1995年建成的36个居住区景观树木构成和物种多样性进行调查,并根据建成年代和相对城市环线位置进行分析。结果表明,36个居住区共有155种12 694株景观树木,隶属于42科和97属。在树种构成分析中,将树种按常见程度分为6个组,标志组有20种,共7560株,优势组、常见组、少见组、稀有组以及孤生组分别有17、19、49、38、12种和2383、1297、1269、173、12株。多样性分析表明,福州市居住区景观树木多样性与发达城市比较还存在差距,尤其是旧居住区的景观树木物种多样性更低,树种选择也更为单一。此外,取样居住区中部分安置房居住区的景观树种多样性低于同时期非安置房居住区。     

西藏昆仑针茅草原的基本特征

正昆仑针茅(Stipa roborowskyi)是青藏高原特有的寒旱生多年生密丛型禾草,广泛分布于藏南喜马拉雅山北坡和雅鲁藏布江谷地、阿里地区、羌塘高原中南部和昆仑山地,以及印度和克什米尔地区(Wu et al.,2006;中国科学院中国植被图编辑委员会,2007)。昆仑针茅草原是西藏重要的草原类型之一,但分布较为零散,没有像紫花针茅(S.purpurea)草     

Early environments drive diversity and floristic composition in Mediterranean old fields: Insights from a long-term experiment

While many studies have explored how previous and current environmental conditions affect the performance of individual organisms, their relative importance as drivers of current diversity and composition of communities is virtually unknown. We evaluated the response of herbaceous communities to previous (experienced during early establishment) and current environmental conditions by comparing their composition and diversity in an abandoned Mediterranean cropland planted with Quercus ilex subsp. ballota L. seedlings. These seedlings received different experimental treatments (summer irrigation and artificial shading) during the first three years after planting, and were interrupted from then on. We tested two complementary hypotheses: (i) the previous environments experienced by the herbaceous communities during their establishment have a long-term carry-over effect on diversity and composition of species assemblages and (ii) these communities are influenced by their current environment, particularly by the woody layer and the soil conditions. Overall, we observed an important contribution of initial environmental conditions in determining the current diversity and composition of herbaceous communities. Amelioration of environmental conditions, particularly water stress, during community establishment resulted in a decrease in alpha and beta diversity, possibly as a consequence of decreasing environmental heterogeneity. Previous environments accounted for 26.3% of the explained variance in current community composition. Annuals, legumes and forbs also responded significantly to previous environments, which explained 27.9%, 36.2% and 30.1%, respectively, of the variance in their composition. Our results suggest that those species present at a particular site early in succession pre-empt the site and influence vegetation dynamics on that site for a long time. This study provides important insights for understanding the mechanisms underlying the ecological effects of issues like cropland reforestation and woody vegetation encroachment.