长江三峡库区种子植物的中国特有分布

报道了分布于长江三峡库区的中国种子植物特有属及特有植物在库区的水平与垂直分布概况,对库区的特有分布的特点也进行了简要的分析和探讨。     

Inefficient nitrogen resorption in genets of the actinorhizal nitrogen fixing shrubComptonia peregrina: physiological ineptitude or evolutionary tradeoff?

Nutrient resorption was measured in an actinorhizal nitrogen-fixing shrub,Comptonia peregrina, for five years in the understory of a deciduous oak forest in Rhode Island, USA. Mean resorption of nitrogen was extremely inefficient (11%) compared to most deciduous species (50%+), yet resorption of phosphorus was efficient (53%) and comparable to other species. Of the seven additional nutrients studied, only copper (6%) and zinc (10%) were resorbed from senescing leaves. Resorption of nitrogen (5%–20%) and phosphorus (40%–71%) varied significantly among years. Copper was resorbed from leaves in three years and accreted into leaves in two years. Five-year resorption means differed among individual genets by as much as a factor of 2.5 for nitrogen, and 1.3 for phosphorus. Resorption of nitrogen, copper, and zinc were highly correlated, yet resorption of phosphorus remained autonomous from other nutrients. The ecophysiological tradeoffs inComptonia which have resulted in the cooccurence of actinorhizal nitrogen fixation, inefficient nitrogen resorption, and efficient phosphorus resorption suggest that plant nutrient status does have an impact on resorption efficiency and that the evolution of nutrient conservation strategies is nutrient-specific.     

Insights into the secretory pathway and vesicular transport in plant cells

Summary— The vectorial transport of membrane and macromolecules within the cytoplasm of eukaryotic cells has been the subject of intense investigation over the last decade. In this paper we review some of the recent advances made in our understanding of vesicle transport and the secretory pathway in plant cells.     

Vegetation change in acidic dry grasslands in Moravia (Czech Republic) over three decades: Slow decrease in habitat quality after grazing cessation

Aims

Shallow soils on acidic bedrock in dry areas of Central Europe support dry grasslands and heathlands that were formerly used as extensive pastures. These habitats are of high conservation value, but their abandonment in the 20th century triggered slow natural succession that poses a threat to specialized plant species. We asked how this vegetation and its plant diversity have changed over the past three decades and whether protected areas have positively affected habitat quality.

Location

Southwestern and central Moravia, Czech Republic.

Methods

In 2018–2019, we resurveyed 94 vegetation plots first sampled in 1986–1991 at 47 acidic dry grassland and heathland sites. We compared the number of all vascular plant species, Red List species and alien species per plot using parametric and non-parametric tests, life-form spectra using the chi-square test, species composition using detrended correspondence analysis, and indicator values using a permutation test. We also compared these changes between sites within and outside protected areas.

Results

Vegetation changes over the past three decades have been relatively small. However, we detected a decrease in total species richness, the number of Red List species and the number of characteristic species of dry grasslands. Neophytes were infrequent, while archaeophytes increased slightly. The competitive tall grass Arrhenatherum elatius, annual species and young woody plants increased in abundance or newly established at many sites. Indicator values did not change except for a slight increase in nutrient values. These negative trends occurred both within and outside protected areas but were more pronounced outside.

Conclusions

Formerly grazed acidic dry grasslands and heathlands in Moravia are slowly losing habitat specialists, including threatened plant species, and are increasingly dominated by Arrhenatherum elatius. Conservation management, especially cutting in protected areas, slows down the negative trends of decline in plant diversity and habitat quality but is insufficient to halt these processes completely.     

Elevated CO2 and the mineral content of herbaceous and woody plants

The CO₂ enrichment effects (300–650 µmol mol^-1) on mineral concentration (N, P, K, Ca, Mg, Mn, Fe, Zn), absolute total mineral contents per individual and of whole stands of four herbaceous (Trifolium repens L.,Trifolium pratense L.,Lolium perenne L.,Festuca pratensis HUDS.) and two woody species (Acer pseudo-platanus L.,Fagus sylvatica L.) were investigated.In general, the mineral concentration of the plant tissues decreased (all six species: N>Ca>K>Mg) with the exception of P. Mn and Fe were only determined for the tree species. Both decreased in concentration (Mn>Fe). Zn was only analysed forTrifolium pratense andFestuca pratensis and decreased significantly in the grass.Despite of decreases in concentrations of as much as 20% in some cases there were increases in absolute amounts per individual and, therefore, in the whole vegetation up to 25% because of the enhanced dry matter accumulation at elevated CO₂ supply.Dedicated to Prof. Dr. R. Bornkamm, TU-Berlin, on behalf of his 60th birthday     

Isolation of polysaccharide-free DNA from plants

A quick procedure for the isolation of polysaccharide-free DNA from different plant species and cell suspension or callus cultures is described. The originality of the method lies in the use of a mixture of glycoside hydrolases that leads, after phenol and chloroform extraction, to the isolation of pure DNA without any polysaccharide contamination. The highly purified DNA can be used for nucleotide analysis by HPLC, RFLP analysis and PCR amplification.