Species richness, abundance, rarity and environmental gradients in coastal barren vegetation

Coastal barrens in Nova Scotia are heathlands characterised by short, predominantly ericaceous vegetation, sparse tree cover, exposed bedrock, pockets of Sphagnum bog, and stressful climatic conditions. Although coastal barrens are prominent in the physical and cultural landscape, they are largely unprotected. We selected six barrens along the Atlantic coast, and surveyed 20 1-m² plots at each barren for vascular plants, macrolichens, mosses and environmental factors. We recorded 173 species (105 vascular, 41 macrolichen, 27 moss), including six provincially rare vascular species found predominantly in nearshore areas with high levels of substrate salt and nutrients, variable substrate depth, and short vegetation. Although vascular plant and moss richness were similarly correlated with vegetation height, substrate depth, organic matter content, and rock exposure, there were no clear correlations between vascular plant, macrolichen and moss richness across all sites. Vascular plant rarity and species richness were not correlated, but had inverse relationships with key environmental gradients. Tailoring conservation efforts to protect areas of high richness may thus mean that rare species are missed, and vice versa. Ordination and ANOSIM show that barrens vegetation differs widely among sites; therefore, protecting any singular coastal barren will not protect the entire range of vegetation communities and species in this heathland type. Conservation planning should emphasize protecting environmental gradients correlated with richness, rarity and plant community structure, including substrate depth and moisture, and vegetation height. Additionally, protected areas should include a coastal-inland gradient and a diversity of substrate types, including exposed rock and trees.     

缺硫对万寿菊镉积累的影响

采用营养液培养法,研究了缺硫对万寿菊(Tagetes erecta)各器官镉积累的影响,以及巯基化合物和有机酸等在各器官镉积累中的作用.结果表明:0.1 mg·L-1镉处理7 d,缺硫处理显著降低了植物根、茎和叶中的镉含量,较对照分别降低了47%、38%和61%;缺硫对植物体内半胱氨酸、γ-谷氨酰半胱氨酸、谷胱甘肽和有机酸的合成没有显著影响,而且3种巯基化合物的含量都很低;缺硫植物根部合成的植物络合素的量显著降低,这可能是植物体内镉积累减少的主要原因;在植物的各器官中,叶片中的有机酸含量最高,而在叶片中未检测到植物络合素,由此可推断,叶片中积累的镉主要与有机酸结合;缺硫影响了根部植物络合素的合成,进而降低了植物体内镉的积累,而缺硫没有影响植物体内有机酸的合成,有机酸可能仅是参与植物组织中与镉的络合作用.     

上海地区藓类环境生理学特性的初步研究

对22种上海地区藓类植物进行了包括抗旱性、温湿度及光照、生长基质及组织培养等环境生理学方面的研究．结果表明,在同样环境条件下不同种的抗旱表现不同,生长在不同生境下的同一种的表现亦不同;沙壤添加有机质和短光照有利于藓类的生长;适当的激素处理可有效地促进藓类植物的繁殖生长;Hogland培养基适用于藓类植物的组织培养     

Cytological Observation of 4 Chinese Moss Species

In this paper the chromosome countings of 4 moss species are reported for the first time in China. The materials used for investigation were taken from immature capsules. Meiosis in spore mother cells and also mitosis in the case of Plagiomnium cuspidatum were observed, with the result: Didymodon constrictus, n=14, Entodon schensianus, n=10+lm; Plagiomnium cuspidatum, n=6, Cratoncuron jilicinum, n=10. The chromosome numbers ofthe former two species are reported for the first time.     

Observations on Chromosomes of Fourteen Moss Species from the Qinling Range,China

The chromosome numbers in fourteen moss species from the Qinling Range, and karyotype of Mnium lycopodioides are reported in this paper. Immature capsules were used as material. Bryum capillare L. ex Hedw was found. to have n = 10; Mnium lycopodioides Schwaegr. n = 6 with the karyotype formula n = 6 = 3m+3sm (1SAT); Plagiomnium maximoviczii (Lindl.)T. Kop. n=6; Bartramia halleriana var. elongate Turn. n=10+2m; Thuidium delicatulum (Hedw.) Mitt. n= 11; Thuidium philibertii Limpr. n= 10+m; Hygrohypnum ochraceum (Wils.) Loesk. n=10; Drepanocladus uncinatus (Hedw.) Warnst. n = 7+3m; Campylium chrysophyllus (Brid.) J. Lange. n = 10; Brachythecium starkei (Brid.) B. S. G. n=6; Brachythecium buchananii (Hook.) Jaeg. n=6; Brotherella yokohamae (Broth.)Broth. n= 9+2m; Gollamia neckerella (C. MÜll. )Broth. N=7; Pogonatum fastigiatum Mitt. n = 7. No report on the chromosome number of Brotherella yokohamae and Gollania neckerella has been found. The chromosome numbers in Brachythecium starkei andBrachythecium buchananii (Hook.) Jaeg. are different from previous reports, while the others are in accordance with the previous reports.     

Phytogeography of bryophyte and lichen vegetation in the Windmill Islands,Wilkes Land,Continental Antarctica

The distribution and frequency of bryophyte and lichen vegetation on ice-free regions of the Windmill Islands are presented using data derived from aerial photography and ground surveying. The qualitative and quantitative plant cover of sites are listed and related to the topography and major soil characteristics of each site. The richest associations of macrolichens and bryophytes occurred on the metamorphic northern peninsulas. Species richness and frequency was generally reduced on the charnockitic southern peninsula and the islands which have been deglaciated longer. Salinity varied significantly throughout the region with the highest levels in the northern islands reflecting the presence of penguin colonies. In such sites bryophytes and lichens were virtually absent. Wind blown sea-spray contributed far less salts than direct excretion from penguins. On the peninsulas snow cover and site exposure appeared to delimit plant distribution. Higher salt levels from sea-spray on the northern aspects of the peninsulas seemed to have negligible impact on vegetation patterns with the possible exception ofBiatorella cerebriformis which was encountered only inland. The total phosphorus and nitrogen levels of the skeletal soils were generally low except in eutrophic sites adjacent to penguin colonies. The vegetation patterns are discussed in terms of the climate, topography and species autecology.     

Host-specificity of moss-associated fungal communities in the Ny-Ålesund region (Svalbard,High Arctic) as revealed by amplicon pyrosequencing

Fungal communities play a significant role in regulating ecological processes in the Arctic tundra. However, the extent to which the Arctic moss species and host types (moss, lichen and vascular plant) determine the richness, diversity, and composition of fungal communities at a local scale has not been quantitatively explored. Using 454 pyrosequencing in the current study, we characterized the fungal communities associated with six moss species (Andreaea rupestris, Bryum pseudotriquetrum, Hymenoloma crispulum, Polytrichastrum alpinum, Racomitrium lanuginosum, and Sanionia uncinata) and compared them with fungal communities associated with lichens and vascular plants in the Ny-Ålesund region (High Arctic). Host-species preference had greater explanatory power than geographical factors (longitude, latitude, elevation) in shaping moss-associated fungal communities. Fungal communities associated with mosses differed significantly from those associated with vascular plants and lichens, suggesting specificity of the fungal communities among three host types. Pairwise comparison analysis also indicated that the relative abundance of many taxonomic groups (e.g., Chaetothyriales, Leotiales, Catenulifera, Alatospora, and Toxicocladosporium) significantly differed between mosses and the other two host types. These results suggest host factors significantly affect the distribution of the fungal species associated with these moss species in the local-scale Arctic tundra.     

A report on the predominant occurrence of a dermatophyte species in cultivated soil from Kuwait

From several soil samples screened for the occurrence of keratinolytic fungi, soils cultivated with ornamental plants were found to contain strains of the dermatophytic fungusMicrosporum gypseum. One soil sample was dominated by this species.     

Factors determining the centrifugal organization of remnant Festuca grassland communities in Alberta

Abstract. This paper describes the species composition of remnant grasslands in the aspen parkland region of Alberta and its relation to soil characteristics and small‐scale disturbance. Our findings are consistent with the centrifugal model of communities with Festuca hallii dominating undisturbed ‘core’ habitat and the composition of more ‘peripheral’ habitats varying in soil properties and in the magnitude of disturbance. Invasive non‐native species are not present in the core habitat and are present only in the disturbed sites, most abundantly in those with the highest soil nitrogen. The centrifugal model, as it applies to these remnant grasslands, differs from its previous application to wetlands and forests in that the core communities are not on the most fertile sites, but on the least disturbed. These findings have implications for the management of prairie remnants to exclude invasive exotic species.     

Genetic analysis of the effects of re-transformation of transgenic lines of the mossPhyscomitrella patens

Genetic analysis of the progeny of crosses involving strains of the mossPhyscomitrella patens obtained by re-transforming a stable transgenic line, indicates that the plasmid used for re-transformation inserts at or near the chromosomal location of the related plasmid used to obtain the original transgenic line. The resulting structure may be subject to gene silencing.