Abstract：
:Seedling establishment has long been believed to be rare on alpine tundra because of predicted life history trade-offs, the clonality of alpine species, and the harshness of the alpine climate. Contrary to the idea that seedlings are rare on alpine tundra, a 4-yr demographic study of seedlings at Niwot Ridge, Colorado, USA, found seedlings at high densities, particularly in wetter plant communities. Higher germination densities were associated with higher soil moistures both across communities and across time. Mortality of seedlings was highest in the first year and decreased in subsequent years. Species' abundances differed between seedling and adult populations. Many forbs that lacked vegetative reproduction were significantly more abundant among seedling populations, and many monocots and clonal forbs were more abundant among adult populations. In a comparison with published demographic rates, seedling recruitment and mortality rates of Niwot Ridge species fell above or within rates for a wide range of perennial species. Therefore, germination and seedling establishment stages are no more limiting to sexual reproduction in alpine plants than in other perennial plants.
journal_name
Am J Botjournal_title
American journal of botanyauthors
Forbis TAdoi
10.3732/ajb.90.8.1197subject
Has Abstractpub_date
2003-08-01 00:00:00pages
1197-206issue
8eissn
0002-9122issn
1537-2197pii
90/8/1197journal_volume
90pub_type
杂志文章abstract：:Koch et al. (Nature 428: 851-854) measured various parameters that were thought to limit the height of Sequoia sempervirens from northern California and concluded that the maximum height for this species is 122-130 m because within this range: (1) Irreversible embolism formation was proposed to occur when the xylem pr...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.0800144
更新日期：2009-02-01 00:00:00
abstract：:In volume 97(2) of the American Journal of Botany (pp. 268-275), we published an article entitled "Structural, physiological, and stable carbon isotopic evidence that the enigmatic Paleozoic fossil Prototaxites formed from rolled liverwort mats". Here, we respond to a letter and a commentary on our article in the pres...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1000172
更新日期：2010-07-01 00:00:00
abstract：PREMISE OF THE STUDY:High intraspecific cytogenetic variation in the sedge genus Carex (Cyperaceae) is hypothesized to be due to the "diffuse" or non-localized centromeres, which facilitate chromosome fission and fusion. If chromosome number changes are dominated by fission and fusion, then chromosome evolution will re...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1000046
更新日期：2011-01-01 00:00:00
abstract：:The evolutionary origins of the morphological and taxonomic diversity of angiosperms is poorly known. We used the genus Melianthus to explore the diversification of the southern African flora. Melianthus comprises eight species, and a phylogeny based on one nuclear and two plastid genes, as well as a morphological dat...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.93.7.1052
更新日期：2006-07-01 00:00:00
abstract：PREMISE OF THE STUDY:A knowledge of pollen characters in early-diverging angiosperm lineages is essential for understanding pollen evolution and the role of pollen in angiosperm diversification. In this paper, we report and synthesize data on mature pollen and pollen ontogeny from all genera of Nymphaeales within a com...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1500249
更新日期：2015-10-01 00:00:00
abstract：PREMISE OF THE STUDY:Productivity in drylands may depend on the sensitivity of interactions between plants and biocrusts. Given future climate variability, it is essential to understand how interactions may be context-dependent with precipitation regime. Furthermore, little is known about the additional interactions of...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.1002/ajb2.1120
更新日期：2018-07-01 00:00:00
abstract：PREMISE OF THE STUDY:Species differ in their temperature germination niche. Populations of a species may similarly differ across the distribution range of the species. Anticipating the impacts of climate variability and change requires understanding the differential sensitivity to germination temperature among and with...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1600278
更新日期：2017-01-01 00:00:00
abstract：UNLABELLED: PREMISE OF THE STUDY:Microsatellite loci were developed to characterize genetic variation and population subdivision in Khaya senegalensis (Desr.) A. Juss. (Meliaceae). • METHODS AND RESULTS:Microsatellite loci were identified from genomic DNA sequences generated using the 454 GS-FLX titanium platform. Pr...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1000300
更新日期：2010-11-01 00:00:00
abstract：:Individual plants of Asclepias exaltata (Asclepiadaceae) typically express an unusual self-incompatibility system under single-gene control. Hand-pollinations performed in six natural populations detected occasional self-fertile plants. The frequency of self-fertile individuals ranged from 0 to 34.0% and differed sign...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-08-01 00:00:00
abstract：:Whereas the "law of the minimum" (LM) states that plant growth is limited by a single resource at any one time, the "multiple limitation hypothesis" (MLH) proposes that optimum plant behavior results from balancing resource costs and benefits so that all resources limit plant growth simultaneously. We tested the hypot...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.90.1.143
更新日期：2003-01-01 00:00:00
abstract：:Chrysothamnus nauseosus (Asteraceae) is a complex polymorphic shrub species widely distributed in western North America. In a study of 86 populations belonging to 15 subspecies, achene mass varied among populations over a sevenfold range. Achene mass was closely correlated with capitulum size at the subspecies level, ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1997-04-01 00:00:00
abstract：PREMISE:Outcomes of species interactions, especially mutualisms, are notoriously dependent on environmental context, and environments are changing rapidly. Studies have investigated how mutualisms respond to or ameliorate anthropogenic environmental changes, but most have focused on nutrient pollution or climate change...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.1002/ajb2.1404
更新日期：2020-02-01 00:00:00
abstract：:The pathways of micro- and megagametophyte development in Agave fourcroydes (henequén) and A. angustifolia were studied. We used histology and light microscopy to observe anther ontogeny and ovary differentiation in relation to flower bud size. Both species have the same sexual reproductive strategies and gametophyte ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2001-11-01 00:00:00
abstract：PREMISE OF THE STUDY:Microsatellite primers were developed in the native legume tree Anadenanthera colubrina var. cebil to study the genetic diversity and genetic structure in natural populations in Argentina. METHODS AND RESULTS:Nine microsatellite markers were identified using a genomic library enriched for tandemly...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1200078
更新日期：2012-09-01 00:00:00
abstract：PREMISE OF THE STUDY:Microsatellite loci were developed from Imperata cylindrica, a traditional medicinal herb in Asia and among the top 10 worst invasive weeds in the world, to aid in the identification of the limits of asexual clonal individuals. METHODS AND RESULTS:A total of 21 microsatellite markers, including 18...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1200152
更新日期：2012-11-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.89.11.1818
更新日期：2002-11-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.89.6.908
更新日期：2002-06-01 00:00:00
abstract：:Survival and fecundity are basic components of demography and therefore have a strong influence on population dynamics. These two key parameters and their relationship are crucial to understand the evolution of life histories. It remains, however, to be empirically established how life span, fecundity, and population ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.95.2.258
更新日期：2008-02-01 00:00:00
abstract：:Trichomanes intricatum, the sporophyte-less filmy fern of the eastern United States, has been considered to be a species whose sporophyte generation has become extinct or is possibly still present among the many species of Trichomanes s.l. in the new world tropics but unable to grow in a temperate climate. A close rel...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.0800122
更新日期：2008-12-01 00:00:00
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journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.92.9.1425
更新日期：2005-09-01 00:00:00
abstract：:The boreotropical flora concept suggests that relictual tropical disjunctions between Asia and the Americas are a result of the expansion of the circumboreal tropical flora from the middle to the close of the Eocene. Subsequently, temperate species diverged at high latitudes and migrated to other continents. To test t...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2001-12-01 00:00:00
abstract：PREMISE OF THE STUDY:The ability of insect visitors to learn to manipulate complex flowers has important consequences for foraging efficiency and plant fitness. We investigated learning by two butterfly species, Danaus erippus and Heliconius erato, as they foraged on the complex flowers of Asclepias curassavica, as wel...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1700040
更新日期：2017-08-01 00:00:00
abstract：PREMISE OF THE STUDY:Plants adjust their phenology in response to seasonal cues experienced both by their parents and by themselves, and coordinating responses to these cues is necessary for expressing adaptive phenology. We investigated how cues are integrated across time to influence an important progeny phenotype, i...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1600389
更新日期：2017-04-01 00:00:00
abstract：PREMISE OF THE STUDY:Population genetic structuring over limited timescales is commonly viewed as a consequence of spatial constraints. Indirect approaches have recently revealed reproductive isolation resulting from flowering time (so-called isolation by time, IBT). Since phenological processes can be subject to selec...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1200147
更新日期：2012-09-01 00:00:00
abstract：UNLABELLED: PREMISE OF STUDY:Phylogenetic relationships of the papilionoid legumes (Papilionoideae) reveal that the early branches are more highly diverse in floral morphology than are other clades of Papilionoideae. This study attempts for the first time to comprehensively sample the early-branching clades of this ec...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1200380
更新日期：2012-12-01 00:00:00
abstract：:In contrast to most angiosperms, in which fertilization occurs 1 or 2 days after pollination, in some plant orders, including the Fagales, fertilization is delayed from 4 days to more than 1 year, raising questions regarding why fertilization is delayed and where and how pollen tubes remain in the pistil during the de...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.93.12.1748
更新日期：2006-12-01 00:00:00
abstract：:Microscopic structures (petrofilaments) may develop during palynological laboratory processing procedures that are superficially similar to secondary wall thickenings and elaters. These filaments form from angular bodies that resemble fungal spores and resin bodies. The angular bodies are a type of hydrocarbon called ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：2000-05-01 00:00:00
abstract：:This paper presents the first broad overview of three main features of microsporogenesis (male meiosis) in angiosperms: cytokinesis (cell division), intersporal wall formation, and tetrad form. A phylogenetic comparative approach was used to test for correlated evolution among these characters and to make hypotheses a...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.0800110
更新日期：2008-11-01 00:00:00
abstract：PREMISE:Polyploidy may serve to contribute to range size if autopolyploid cytotypes are adapted to differing ecological conditions. This study aims to establish the geographic distribution of cytotypes within the giant goldenrod (Solidago gigantea), and to assess whether cytotypes exhibit differing ecological tolerance...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.1002/ajb2.1556
更新日期：2020-11-01 00:00:00
abstract：:Reproductive traits of tropical tree species vary predictably in relation to successional stage, but this variation may be due to the species' phylogenetic histories rather than selective pressures imposed by regeneration requirements. Reproductive phenology, tree size at the onset of reproduction, and fecundity of 11...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1999-12-01 00:00:00
