共查询到20条相似文献,搜索用时 31 毫秒
1.
The intentional introduction of exotic species can increase the level of local biodiversity, enrich people’s material lives,
and bring significant social and economic benefits that are also the symbols of human progress. However, along with the frequent
intercourse among countries and regions, the frequency of uncontrolled crossregional migration of species is increased and
there is a lack of scientific management strategy for the intentional introduction of exotic species. Exotic species invasion,
which is behind habitat fragmentation, has become the second largest threatening factor to the maintenance of the global-scale
level of biological diversity. Exotic species invasion can destroy the structure of an ecosystem, disturb the economic life
of a society, and do harm to human health. In this paper, the authors review some of the ecological explanations for issues
such as “what causes or mechanisms have led to the successful invasion of exotic species”, including the “ideal weeds characteristics”,
“biodiversity resistance hypothesis”, “enemies release hypothesis”, “evolution of increased competitive ability hypothesis”,
“niche opportunity hypothesis”, and “novel weapon hypothesis”. The authors also analyze and evaluate the background and theoretical
basis of the hypotheses, providing explanations for some phenomena, as well as the deficiencies of these explanations. 相似文献
2.
Forestry is obliged to record as well as maintain and/or enhance biological diversity in forests due to national and international
agreements. Accordingly, it is necessary to work out methodological approaches for the assessment of biodiversity in forests.
In the study presented here, we focus on the total plant species pool (563 vascular plant and bryophyte species) of pine (Pinus sylvestris L.) forests in NE Germany to identify indicators for plant species richness. We distinguished several groups like “herb”,
“grass-like”, “woody”, “endangered”, and “exotic species”, for which we detected indicators for low (class #1), intermediate
(class #2), and high (class #3) species numbers. From a total of 84 species, which were identified by a three-step procedure,
most indicators were found for class #3. Only few indicators have been revealed for intermediate species numbers, i.e. class
#2. With help of Ellenberg’s ecological indicator values and information on the main occurrence in Central European vegetation
types and plant communities, respectively, we characterized the indicator species ecologically. The ecological site preferences
of the indicator species in general reflect the fact that species richness is highest in base-rich, light, and anthropogenically
disturbed pine forests. On the contrary, species-poor forests were revealed by indicators, which mainly occur on acidic sites.
It is concluded that a considerable set of indicators for species richness can help facilitate biodiversity assessments in
forestry and ecosystem restoration practice.
Electronic Supplementary Material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
3.
Brada B 《Culture, medicine and psychiatry》2011,35(2):285-312
This essay argues that what makes “global health” “global” has more to do with configurations of space and time, and the claims
to expertise and moral stances these configurations make possible, than with the geographical distribution of medical experts
or the universal, if also uneven, distribution of threats to health. Drawing on a study of public–private partnerships supporting
Botswana’s HIV/AIDS treatment program, this essay demonstrates ethnographically the processes by which “global health” and
its quintessential spaces, namely “resource-limited” or “resource-poor settings,” are constituted, reinforced, and contested
in the context of medical education and medical practice in Botswana’s largest hospital. Using Silverstein’s work on orders
of indexicality, I argue that the terms of “global health” are best understood as chronotopic, and demonstrate how actors
orient themselves and others spatio-temporally, morally, and professionally by using or refuting those terms. I conclude by
arguing that taking “global health” on its own terms obscures the powerful forces by which it becomes intelligible. At stake
are the frames within which medical anthropologists understand their objects of study, as well as the potential for the spaces
of “global health” intervention to expand ever outward as American medical personnel attempt to calibrate their experiences
to their expectations. 相似文献
4.
Adams MB 《Journal of the history of biology》2000,33(3):457-491
This paper seeks to reinterpret the life and work of J. B. S. Haldane by focusing on an illuminating but largely ignored essay
he published in1927, “The Last Judgment” – the sequel to his better known work, Daedalus (1924). This astonishing essay expresses a vision of the human future over the next 40,000,000 years, one that revises and
updates Wellsian futurism with the long range implications of the “new biology” for human destiny. That vision served as a
kind of lifelong credo, one that infused and informed his diverse scientific work, political activities, and popular writing,
and that gave unity and coherence to his remarkable career.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
A seaweed with the local name “endong” is a rare eucheumoid variety that has recently been farmed in Tawi-Tawi, southern Philippines.
Local farmers describe it as “eel-like” because of its long, slender and smooth thalli. Being somewhat similar in appearance
to the dominantly farmed seaweed “tambalang” (Kappaphycus alvarezii var. tambalangii), farmers mix their harvests of “endong” with those of “tambalang”. We analyzed the hydrocolloid extract from “endong” using
spectroscopic and chemical techniques. The extract’s infrared and nuclear magnetic resonance (1H and 13C) spectra, and sulfate and 3,6-anhydrogalactose contents revealed carrageenan of the iota-type, similar to extracts from
another farmed species, Eucheuma denticulatum. This result implies that “endong” carrageenan exhibits physico-chemical properties different from those of kappa-carrageenan
of “tambalang”. The findings of this study are of significance to the seaweed industry, as carrageenan quality problems could
potentially arise from a mixed harvest. Seaweed farmers are advised to separate their harvests of “endong” and “tambalang”.
Presented at the 19th International Seaweed Symposium, Kobe, Japan 相似文献
6.
Inconsistent use of terminology plagues the study and management of biological invasions. The term “invasive” has been used
to describe inter alia (1) any introduced non-indigenous species; (2) introduced species that spread rapidly in a new region; and (3) introduced
species that have harmful environmental impacts, particularly on native species. The second definition in various forms is
more commonly used by ecologists, while the third definition is pervasive in policy papers and legislation. We tested the
relationship between the invasiveness of an introduced species and its impact on native biodiversity. We quantified a species’
invasiveness by both its rate of establishment and its rate of spread, while its impact was assigned a categorical ranking
based on the documented effects of the invader on native species populations. We found no correlations between these variables
for introduced plants, mammals, fishes, invertebrates, amphibians and reptiles, suggesting that the mechanisms of invasion
and impact are not strongly linked. Our results support the view that the term “invasive” should not be used to connote negative
environmental impact. 相似文献
7.
Richard Bellon 《Journal of the history of biology》2006,39(1):1-39
Joseph Hooker first learned that Charles Darwin believed in the transmutation of species in 1844. For the next 14 years, Hooker
remained a “nonconsenter” to Darwin’s views, resolving to keep the question of species origin “subservient to Botany instead
of Botany to it, as must be the true relation”. Hooker placed particular emphasis on the need for any theory of species origin
to support the broad taxonomic delimitation of species, a highly contentious issue. His always provisional support for special
creation waned during the 1850s as he lost faith in its expediency for coordinating the study of plant geography, systematics
and physiology. In 1858, Hooker embraced Darwin’s “considerable revolution in natural history,” but only after Darwin had
carefully molded his transmutationism to meet Hooker’s exacting specifications. 相似文献
8.
Hartree-Fock and density functional theory (B3LYP) calculations were applied to the study of the anti-tumor drug FR900482
and some of its analogs. Optimum geometries were obtained and it was found that the most stable conformations feature the
N-H bond of the aziridine ring nitrogen “down” and the oxygen bridge and aziridine nitrogen “up”. It was also found that the
analog containing NH2 (in place of the -CHO of the natural product) is the most prone to oxidation.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
It seems that a simple name for FR900482 has not been adopted so far because there is still a search for the most stable analog. 相似文献
9.
Kim Fortun 《Dialectical Anthropology》2010,34(1):77-86
The global chemical industry has a rich history of investment in campaigns to educate the public about what it does. Beginning
in the 1930s, first Dupont then the industry overall promised “Better Living Through Chemistry.” In the 1990s, the industry
promoted its own environmentalism. The 2005 launch of the American Chemistry Council’s essential2life campaign was yet another
update. This essay examines the shifting logics of chemical industry public education campaigns, focusing particularly on
the disavowals of the essential2life campaign. The essay also raises questions about forms of collective deliberation—among
scientists, among activists and within industry—that reduce vulnerability to what Kirsch and Benson call “corporate oxymorons,”
facilitating critical awareness of ways vested interests shape articulations of history and knowledge. 相似文献
10.
Jun-Ichi Kojima 《The Botanical review》2003,69(1):44-58
Acceptable methods of defining taxon (or clade) names in the draft PhyloCode, or so-called phylogenetic nomenclature, are
“node based,” “stem based,” and “apomorphy based.” All of them define a clade name by pinpointing a node; whereas node-based
and stem-based definitions require two or more taxon “specifiers” to define names, an apomorphy-based definition requires
two specifiers of different types; namely, a single-taxon specifier and a character specifier. The taxon specifier in an apomorphy-based
definition is completely different from the “type” in the Linnaean system. Taxon (or clade) names in the PhyloCode are characterized
in two entirely different manners: One is a name that does not change, either in its orthography or in the contents of the
taxon referred to by it (or its meaning) over time; the other is a name that is just like a pure mark and thus has no meaning.
Communication through such PhyloCode names is very ineffective or impossible. 相似文献
11.
Ana Hernando Rosario Tejera Javier Velázquez María Victoria Núñez 《Biodiversity and Conservation》2010,19(8):2221-2233
The main goal of Natura 2000 network is to guarantee the favourable conservation status of habitats and species ensuring European
biodiversity. As a result, certain forest areas have been included in this network listed as 9230-Quercus pyrenaica habitat
and 9340-Quercus ilex subsp. rotundifolia forest habitat. These areas were previously used for firewood extraction or livestock
grazing and browsing. Nowadays these habitats are coppice forests with asexual regeneration, which is far from the desired
conservation status. Traditional timber harvesting plans do not take account of the new objectives required for these Natura
sites, which attempt to ensure biodiversity and recreational uses instead of simply focusing on timber production. This paper
proposes a flexible methodology (applied to the study area “Dehesa Boyal” in ávila, Spain) for managing Natura 2000 forest
sites by stands for sustainable forest management and the new requirements. The methodology has two phases. The first, “Division
of the forest area into stands”, defines homogeneous patches of vegetation distinct in species composition, physiognomic structure
and future management. The second, “Conservation status assessment of stands”, quantifies the conservation status of each
previously classified stand considering a series of factors such as: functional health, restoration, floral richness and structure.
A total value integrating the conservation status of stands is then calculated for the habitat. Both phases use Geographic
Information System tools for managing information and visualizing results. The proposed methodology provides forest managers
with a good knowledge of the territory and subsequently enables them to take appropriate conservation measures to maintain
biodiversity. 相似文献
12.
Mankind has observed and documented life cycle stages of plants and animals for a long time. However, it was comparatively
recently that the newly emerging science was given its name. The name of Charles Morren and the year 1853 are being cited,
although not frequently. Exact information is hardly known among present-day phenologists, yet new evidence shows that the
term “phenology” was already in use in 1849. In the early 1840s, physicist and astronomer Adolphe Quetelet set up an observational
network named "Observations of periodical Phenomena of the Animal and Vegetable Kingdom” and issued instructions for it. Even though biologist Charles Morren welcomed Quetelet's initiative, differences between
Morren and Quentlet regarding the instructions for the observations and the potential results soon arose and a debate started,
which lasted for nearly 10 years. In the wake of these disagreements, Morren was compelled to create a new term to denote
his ideas on “periodical phenomena”. At first, he temporally used the word anthochronology, but in the end he coined the word phenology. The term was first used in a public lecture at the Académie royale des Sciences, des Lettres et des Beaux-Arts de Belgique’ in Brussels on 16 December 1849, and simultaneously in the December 1849 issue of volume V of the Annales de la Société royale d’Agriculture et de Botanique de Gand. One had to wait until 1853 before the new name appeared in the title of one of Morren’s publications. Based on evidence
from archives and original publications, we trace the 10-year-long scientific debate between Morren and Quetelet. Morren states
his biologist’s view on the subject and extends the more climate-related definition of Quetelet of “periodical phenomena”. 相似文献
13.
Desmond A 《Journal of the history of biology》2001,34(1):3-50
A summary of revisionist accounts of the contextual meaning of`“professional” and “amateur,” as applied to the mid-Victorian
X Club, is followed by an analysis of the liberal goals and inner tensions of this coalition of gentlemen specialists and
government teachers. The changing status of amateurs is appraised, as are the new sites for the emerging laboratory discipline
of “biology.” Various historiographical strategies for recovering the women’s role are considered. The relationship of science
journalism to professionalization, and the constructive engagement of X Club publicists with their empowering audiences, are
discussed. Finally, the article assesses how far the content and boundary closure of ``biology,' forged by Thomas Henry Huxley,
were related to `professional' and political goals. Purebiology’s social and medical roots are examined, and the way inter-professional
and wider Darwinian conflicts resulted in anew lexicon of words for the X Clubbers around 1870, including“evolution” and “agnosticism,”
as well as “biology.” Biology’srole in the forging of British national identity is discussed, as are its relationship to the
social strategies of liberal, Dissenting, and industrial groups in the country, whose authority sustained the new laboratory
rhetoric.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
Philipp Emanuel Hirsch 《Biological invasions》2009,11(3):515-521
Biological invasions are a major threat to global biodiversity. Invasive freshwater crayfish in that context are especially
prominent for their negative effects on both ecosystem integrity and native crayfish. However, some systems may have supported
a crayfish species not originally native to the system without perceivable negative consequences for the ecosystem while other
invasive crayfish species may constitute a major threat to ecosystem stability. Here I present an example how two crayfish,
the spiny-cheek and the Galician crayfish both by researchers and governmental agencies considered non-native differ in their
threats to the native ecosystem. Whereas the spiny-cheek crayfish is a recent potentially disease-transmitting and still spreading
invader with high local densities the Galician crayfish might be part of the lake’s fauna since several hundred years, appears
in lower densities and is unlikely to be a vector of disease. Therefore, regardless of the Galician crayfish’s actual date
of introduction it is thus a rather “old and integrated” invader, which is now being faced and itself potentially threatened
by the emergence of a “new and dangerous” invader: the spiny-cheek crayfish. This also exemplifies that in the face of often
insufficient scientific information about dates of species introductions care should be taken in postulating species as invasive
and dangerous without any form of risk assessment for their impact on the ecosystem. 相似文献
15.
E. V. Balushkina 《Inland Water Biology》2009,2(4):355-363
In the years 1994–2005, the values of the integrated index IP’ at some stations of the Neva Bay changed from 38.1 to 81.9%, water quality changed from class 3 to class 5, and the states
of some areas of the ecosystem that were evaluated as “tense” went to “catastrophic.” The integrated mean assessment of water
quality according to the IP’ index over the entire Neva Bay throughout 12 years (1994–2005) remained relatively stable, waters were assessed as “polluted”
(fourth class), and the state of the ecosystem was considered “critical.” The state of the eastern part of the Gulf of Finland
in 1994–2005 was less favorable. The species diversity of zoobenthos in the resort zone of the eastern part of the Gulf of
Finland is considerably lower than in the Neva Bay. Waters of the resort zone of the eastern part of the Gulf of Finland in
1994–2005 were assessed as one class lower than in the Neva Bay, i.e., as “polluted-dirty” (fourth-fifth class), and the state
of the ecosystem was assessed as being in a “crisis.” In the resort zone, there was a decline in species diversity and abundance
and biomass of benthic animals; i.e., all characteristics of the degradation of benthic animal communities were observed. 相似文献
16.
Niche division and abundance: an evolutionary perspective 总被引:1,自引:0,他引:1
In recent years, biodiversity has become an issue of broad academic interest, and its assessment and maintenance are now
recognized as an important area of ecological research. While the concept of biodiversity encompasses, first and foremost,
the total number of species co-occurring in a locality, it has increasingly been realized that information on the relative
abundances of co-occurring species is also required for a better understanding of the patterns and dynamics of biodiversity.
In many areas of ecological research, “abundance” constitutes a key variable that characterizes populations and communities.
The relative abundances of species in natural communities reflect evolutionary and contemporary processes occurring on different
spatiotemporal scales. The idea of niche apportionment has been developed to provide an integrated conceptual framework for
the study of species abundance patterns in communities. This article reviews a number of important issues surrounding the
concept of niche apportionment, including some aspects that have received very little or no consideration in previous ecological
literature. The main emphasis here is on possible evolutionary implications and backgrounds. Further, as a universal factor
which affects species abundance in one way or another, body size is highlighted and its relationship with abundance (“density–body-size
relation”) is considered, referring in particular to a recent comprehensive analysis of freshwater benthic data. Consideration
of this and other studies has led to the formulation of the biomass equivalence rule, that suggests the independence of the
biomass measure of abundance from body size, which strengthens the logical basis of niche apportionment models. It is suggested
that, compared with Hubbell's neutral theory of biodiversity, niche apportionment with the biomass equivalence rule represents
a conceptually more sound and widely applicable approach to elucidating species abundance patterns.
Received: February 4, 2002 / Accepted: October 25, 2002
Correspondence to:M. Tokeshi 相似文献
17.
The role of trade-offs in biodiversity conservation planning: Linking local management, regional planning and global conservation efforts 总被引:4,自引:0,他引:4
Biodiversity conservation planning requires trade-offs, given the realities of limited resources and the competing demands
of society. If net benefits for society are important, biodiversity assessment cannot occur without other sectoral factors
“on the table”. In trade-offs approaches, the biodiversity value of a given area is expressed in terms of the species or other
components of biodiversity that it has that are additional to the components protected elsewhere. That “marginal gain” is
called thecomplementarity value of the area. A recent whole-country planning study for Papua New Guinea illustrates the importance of complementarity-based
tradeoffs in determining priority areas for biodiversity conservation, and for designing economic instruments such as biodiversity
levies and offsets. Two international biodiversity programs provide important new opportunities for biodiversity trade-offs
taking complementarity into account. Both the Millennium Ecosystem Assessment and the Critical Ecosystems or “hotspots” programs
can benefit from an explicit framework that incorporates tradeoffs, in which a balance is achieved not only by land-use allocation
among areas, but also by the crediting of partial protection of biodiversity provided by sympathetic management within areas.
For both international programs, our trade-offs framework can provide a natural linkage between local, regional and global
planning levels. 相似文献
18.
Hidden treatments in ecological experiments: re-evaluating the ecosystem function of biodiversity 总被引:68,自引:0,他引:68
Michael A. Huston 《Oecologia》1997,110(4):449-460
Interactions between biotic and abiotic processes complicate the design and interpretation of ecological experiments. Separating
causality from simple correlation requires distinguishing among experimental treatments, experimental responses, and the many
processes and properties that are correlated with either the treatments or the responses, or both. When an experimental manipulation
has multiple components, but only one of them is identified as the experimental treatment, erroneous conclusions about cause
and effect relationships are likely because the actual cause of any observed response may be ignored in the interpretation
of the experimental results. This unrecognized cause of an observed response can be considered a “hidden treatment.” Three
types of hidden treatments are potential problems in biodiversity experiments: (1) abiotic conditions, such as resource levels,
or biotic conditions, such as predation, which are intentionally or unintentionally altered in order to create differences
in species numbers for “diversity” treatments; (2) non-random selection of species with particular attributes that produce
treatment differences that exceed those due to “diversity” alone; and (3) the increased statistical probability of including
a species with a dominant negative or positive effect (e.g., dense shade, or nitrogen fixation) in randomly selected groups
of species of increasing number or “diversity.” In each of these cases, treatment responses that are actually the result of
the “hidden treatment” may be inadvertently attributed to variation in species diversity. Case studies re-evaluating three
different types of biodiversity experiments demonstrate that the increases found in such ecosystem properties as productivity,
nutrient use efficiency, and stability (all of which were attributed to higher levels of species diversity) were actually
caused by “hidden treatments” that altered plant biomass and productivity.
Received: 16 December 1996 / Accepted: 2 March 1997 相似文献
19.
In the information processing procedure of stereo vision, the uniqueness constraint has been used as one of the constraints to solve the “correspondence problem”. While the uniqueness constraint is valid in most cases, whether it is still valid in some particular stimulus configuration (such as Panum’s limiting case) has been a problem of widespread debate for a long time. To investigate the problem, we adopted the Panum’s limiting case as its basic stimulus configuration, and delved into the phenomenon of binocular fusion from two distinct aspects: visual direction and orientation disparity. The results show that in Panum’s limiting case binocular fusion does not comply with the rules governing regular binocular fusion as far as visual direction and orientation disparity are concerned. This indicates that double fusion does not happen in Panum’s limiting case and that the uniqueness constraint is still valid. 相似文献
20.
In the information processing procedure of stereo vision, the uniqueness constraint has been used as one of the constraints
to solve the “correspondence problem”. While the uniqueness constraint is valid in most cases, whether it is still valid in
some particular stimulus configuration (such as Panum’s limiting case) has been a problem of widespread debate for a long
time. To investigate the problem, we adopted the Panum’s limiting case as its basic stimulus configuration, and delved into
the phenomenon of binocular fusion from two distinct aspects: visual direction and orientation disparity. The results show
that in Panum’s limiting case binocular fusion does not comply with the rules governing regular binocular fusion as far as
visual direction and orientation disparity are concerned. This indicates that double fusion does not happen in Panum’s limiting
case and that the uniqueness constraint is still valid. 相似文献