排序方式: 共有41条查询结果,搜索用时 265 毫秒
1.
2.
Atmospheric CO2 concentration has increased by 25% over the preindustrial level. A parallel increase in C concentration and decreases in N
concentration and δ13C of plants grown throughout this century have been observed in plant specimens stored in herbaria. We tested our previous
results in a study of 12 more species collected in the western Mediterranean throughout this century (1920–1930, 1945–1955,
and 1985–1990) and tree rings of Quercus pubescens from the same area. These changes were accompanied by apparent increases in condensed tannin concentration. A decreasing trend
in δ15N both in herbarium material and tree rings was also found, indicating that ecosystems might cope with higher plant N demand
by decreasing N losses and increasing N fixation and mineralization. These results may contribute to a better understanding
of the effects of global change on carbon and nitrogen cycling.
Received: 12 November 1995 / Accepted: 17 May 1996 相似文献
3.
4.
DNA extraction and PCR amplification method suitable for fresh, herbarium-stored, lichenized, and other fungi 总被引:6,自引:0,他引:6
Oscar F. Cubero Ana Crespo Jamshid Fatehi Paul D. Bridge 《Plant Systematics and Evolution》1999,216(3-4):243-249
This paper presents a DNA extraction method suitable for fresh, herbarium-stored, lichenized and other fungal specimens. The method is fast and reliable, comparatively inexpensive and is suitable for obtaining PCR amplification quality DNA from large numbers of samples in a short time. The method has been tested with over 300 samples ofAscochyta, Phyllosticta, Ramalina, Parmelia andPhysconia. Amplifiable fungal DNA was extracted from pure cultures, leaf lesions, whole thalli and dissected only-fungal sections of lichenized fungi. In addition, the method has proved suitable for use with herbarium specimens of both lichenized and non-lichenized fungi, stored as dried pure cultures or dried infected plant material. 相似文献
5.
Eric A. Christenson 《Brittonia》1994,46(4):344-354
An inventory of critical type material in the recently rediscovered Kraenzlin Orchid Herbarium is presented. In addition,
a partial inventory of type material of Orchidaceae conserved in the general herbarium at Hamburg (HBG) is presented as a
guide to the collections. 相似文献
6.
Defining a role for herbarium data in Red List assessments: a case study of Plectranthus from eastern and southern tropical Africa 总被引:6,自引:6,他引:0
Red Lists are widely used to indicate species at risk of extinction. Specimen sheets in herbaria provide an important source of data relevant for Red List assessments. The aims of this paper are to establish which data can be sourced from specimen information to satisfy IUCN Red Data List criteria and to identify the specific criteria that can be used. Red List parameters are measured within a Geographical Information System (GIS), as this provides an objective and repeatable methodology which is less subjective than manual methods. Data used to explore this were gathered during the course of preparing a monograph on Plectranthus (Lamiaceae). Criteria relating to distribution (extent of occurrence, area of occupancy and fragmentation) and population profile (projected continuing decline and number of subpopulations) proved most suitable for assigning categories of threat. Estimates of mature individuals, generation length, population size, population reduction, extreme fluctuation and number of locations could not be derived from herbarium material without making inconsistent subjective decisions. In addition to comprehensively databased specimen information, extensive field knowledge is required to produce better estimates for assessing extinction risk. In order to enhance the usefulness of specimen information in the future, improvements in recording additional botanical data at the time of collection would be beneficial. Overall, herbaria provide a useful starting point for conservation-related work and can help to guide future work. 相似文献
7.
Marian Yallop Heike Hirst Martyn Kelly Steve Juggins Jane Jamieson Robin Guthrie 《Aquatic Botany》2009,90(4):289-295
We assessed the feasibility of using herbarium specimens to validate reference conditions in the UK by comparing diatom community composition of river sites with both recent and historic diatom samples. The question of substrate specificity was addressed by comparing epilithon (stone-derived) and epiphyton (plant-derived) samples from a number of rivers. No significant differences were found between the Trophic Diatom Index (TDI), species richness, species diversity, and percentage of motile valves between paired diatom samples (epilithic and epiphytic) from contemporary samples. Significant differences were recorded between a number of indices derived from analysis of the historic diatom samples on plant material sampled pre-1930 compared with diatoms from stones collected post-1990 from the same river location. The TDI, mean species richness, and species diversity and percentage of motile valves and nutrient tolerant valves were all significantly greater in the contemporary samples (p ≤ 0.05). The percentage of nutrient sensitive valves was significantly lower in the contemporary samples (p ≤ 0.05).The relative abundance of Achnanthidium minutissimum and Cocconeis placentula var. lineata was significantly greater on the herbarium material compared to matched contemporary samples. Calculated values for the TDI (43 ± 3) expected at reference conditions were similar to the observed TDI values derived from herbarium material (44 ± 12) showing no significant deviation in ecological status. 相似文献
8.
构建准确、有效的物种遗传信息库并运用其作为主要的物种鉴定检索数据库,是新一代植物志(iFlora)与传统植物志的本质区别。采集并准确鉴定数以万计的植物样品用于建立遗传信息库存在一定困难,随着遗传信息获取技术的快速发展,使馆藏植物标本成为获取遗传信息的重要补充,并具有提升遗传信息库建设速度和可靠性的较大潜能。本文结合已有的研究和实验室多年工作实践,论述了植物标本作为iFlora物种遗传信息提取材料的可行性和不可替代性;总结了标本遗传信息提取过程中的主要困难和存在问题,并提出一些解决方法;阐述了使用馆藏标本特别是利用模式标本材料构建遗传信息标准库对iFlora构建的重要作用和意义。 相似文献
9.
Yao-Ke Li Julian Harber Chuan Peng Zhi-Qiang Du Yao-Wu Xing Chih-Chieh Yu 《Plant Diversity》2022,44(5):505
Though Berberis (Berberidaceae) is widely distributed across the Eurasian landmass it is most diverse in the Himalaya–Hengduan Mountain (HHM) region. There are more than 200 species in China where it is one of the most common mountain shrubs. The study on the taxonomy and evolution of Berberis in this region can thus provide an important insight into the origin and diversification of its flora. A prerequisite to this is mapping and describing the various species of Berberis in the region – a task that despite recent progress is by no means complete. It is clear that in China there may be a significant number of species still to be described and that even with published species much about their distribution remains to be discovered. As a contribution to the first of these tasks seven new species from the northern Hengduan Mountain of N. Sichuan and S. Qinghai: Berberis chinduensis, Berberis degexianensis, Berberis jiajinshanensis, Berberis jinwu, Berberis litangensis, Berberis longquensis and Berberis riparia, are described here. Differences in overall morphology and especially in floral structures with each other and with similar species of Berberis in the same region are presented. The report is the result of phylogenetic analyses based on plastome and partial nrDNA sequences of both the seven proposed new species and a significant number of similar species already published. Provisional conclusions as to the insights provides on the history of the genetic divergence are discussed. 相似文献
10.
We used 71,764 specimens (14,988 alien and 56,776 native) from the herbarium CONC at Universidad de Concepción, Chile to identify
alien invasion periods. We assumed that the pattern of accumulation of specimens can be used for tracing back the distribution
in time of alien species introductions in the Chilean territory. To assess this we constructed Invasion Curves (IC) of native
and alien species and specimens recorded in the complete territory and we adapted this methodology to draw Proportion Curves
(PC). Increments in the proportion of alien vs. native species can be interpreted as expansions in population size of alien
species, either locally or by invasion of new areas. To visualize surface expansions consistent with changes in PC we arranged
four maps broadly coincident with inflexions in PC: before 1900, 1940, 1980 and 2004. Invasion curves from both native and
alien species produced a first step of positive and rapid increment followed by an extended, apparently stable phase. The
first expansion phase of alien flora (1910–1940) coincides with a first period of strong growth of Chilean agriculture as
indicated by increments in wheat and other cereals production. A more recent second maximum showed by PC (approximately between
1980 and 2000) occurs in a period when: (i) wheat surface goes down but (ii) wheat production increases, and (iii) forestry
exports increases. These changes are coincident with increased mechanization making possible more wheat production in fewer
surfaces. The expansions of alien plant species in Chile are evident on geographical distribution maps. In only one century
alien species expanded to nearly all the territory. Both the North and South extremes however, seem to be an exception to
this general trend as shown by the gaps on maps. 相似文献