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1.
The photochemical reflectance index (PRI), based on reflectance signatures at 531 and 570 nm, and associated with xanthophyll pigment inter-conversion and related thylakoid energisation, was evaluated as an indicator of photosynthetic function in a Mediterranean holm oak (Quercus ilex L.) coppice. The chlorophyll fluorescence pulse-amplitude-modulation and the eddy correlation techniques were used to estimate the photosystem 2 photochemical efficiency of leaves and the CO2 flux over the canopy, respectively. The reflectance and fluorescence techniques yielded identical estimates of the photosynthetic activity in leaves exposed to dark-light-dark cycles or to a variable irradiance in laboratory. However, there was no such correlation between photosynthetic performance and PRI when applied to a sun-exposed canopy in field conditions. Fluorescence profiles inside the canopy and especially a helpful use of multispectral reflectance imaging highlight the limitations of such method. 相似文献
2.
A. O. Averianov 《Paleontological Journal》2007,41(2):189-197
A review of 12 azhdarchid localities in Russia, Kazakhstan, Uzbekistan, and Tajikistan is given. New records of unidentifiable azhdarchids from the Khodzhakul (Cenomanian), Tyul’keli (Turonian-Coniacian), Kansai (Santonian), Malaya Serdoba, and Beloe Ozero (Campanian) localities and a new taxon, Aralazhdarcho bostobensis gen. et sp. nov. (Shakh-Shakh, Santonian-Campanian), are described. 相似文献
3.
Roche H Buet A Ramade F 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2002,133(3):393-410
The Reserve of Biosphere of Camargue [French National Nature Reserve of Camargue (NNRC)] is a protected area frequently exposed to natural and anthropogenic environmental alterations. To evaluate potential contamination of fish with lipophilic chemicals-organochlorines (OCs) and polycyclic aromatic hydrocarbons (PAHs)-a biological monitoring survey was carried out. Metabolic reserve levels were evaluated to select appropriate biological indicators able to be significant biomarkers. In addition, the incorporation of xenobiotic molecules in the lipid compartments was investigated. The contents of glycogen, total lipids, proteins and lipidic phosphorus were analyzed in liver and skeletal muscles of three teleostean: the European eel (Anguilla anguilla); the crucian carp (Carassius auratus); and the catfish (Ictalurus melas). The atmospheric origin of the PAH detected in any season in the biomass and the OCs compounds contamination by derive from agricultural treatments are established. In contradiction with some laboratory acute intoxication studies, we observe a positive correlation between tissue concentrations of contaminants and the muscular glycogen amount, a sensitive energy reserve marker. Moreover, it seems likely that the incorporation of these xenobiotics is located preferentially in the membrane structures. 相似文献
4.
The causes of linear relationships between local species richness and the size of the actual species pool in closed subalpine
meadow communities and open plant communities of the alpine stony substrate (the Greater Caucasus Mountains) were analyzed
using a computer simulation model. The results demonstrated that this relationship is insufficient evidence for the variation
of local species richness among communities is wholly or partly determined by regional processes (the species-pool hypothesis).
A relatively proportional ratio between these variables can also arise where local species richness and the size of the species
pool both depend on local processes, or where local species richness is determined by local factors alone while the size of
the species pool is determined by both local and regional factors. 相似文献
5.
J. Robert Macey Yuezhao Wang Natalia B. Ananjeva Allan Larson Theodore J. Papenfuss 《Molecular phylogenetics and evolution》1999,12(3):1399-332
A well-supported phylogenetic hypothesis is presented for gekkonid lizards of the genus Teratoscincus. Phylogenetic relationships of four of the five species are investigated using 1733 aligned bases of mitochondrial DNA sequence from the genes encoding ND1 (subunit one of NADH dehydrogenase), tRNA(Ile), tRNA(Gln), tRNA(Met), ND2, tRNA(Trp), tRNA(Ala), tRNA(Asn), tRNA(Cys), tRNA(Tyr), and COI (subunit I of cytochrome c oxidase). A single most parsimonious tree depicts T. przewalskii and T. roborowskii as a monophyletic group, with T. scincus as their sister taxon and T. microlepis as the sister taxon to the clade containing the first three species. The aligned sequences contain 341 phylogenetically informative characters. Each node is supported by a bootstrap value of 100% and the shortest suboptimal tree requires 29 additional steps. Allozymic variation is presented for proteins encoded by 19 loci but these data are largely uninformative phylogenetically. Teratoscincus species occur on tectonic plates of Gondwanan origin that were compressed by the impinging Indian Subcontinent, resulting in massive montane uplifting along plate boundaries. Taxa occurring in China (Tarim Block) form a monophyletic group showing vicariant separation from taxa in former Soviet Central Asia and northern Afghanistan (Farah Block); alternative biogeographic hypotheses are statistically rejected. This vicariant event involved the rise of the Tien Shan-Pamir and is well dated to 10 million years before present. Using this date for separation of taxa occurring on opposite sides of the Tien Shan-Pamir, an evolutionary rate of 0.57% divergence per lineage per million years is calculated. This rate is similar to estimates derived from fish, bufonid frogs, and agamid lizards for the same region of the mitochondrial genome ( approximately 0.65% divergence per lineage per million years). Evolutionary divergence of the mitochondrial genome has a surprisingly stable rate across vertebrates. 相似文献
6.
This study investigates the role of climate in determining phytogeographic regions, focusing particularly on the Irano-Turanian floristic region in SW and Central Asia. A set of simple climatic variables and bioclimatic indices were used to prepare climate-space scatter plots and climate diagrams. The climate data were also subjected to multivariate analyses (PCA and Regression tree) in order to develop a bioclimatic characterization of the Irano-Turanian region in comparison with the adjacent Mediterranean, Saharo-Sindian, Euro-Siberian, and Central-Asiatic regions. Phytogeographic regions of SW and Central Asia display distinct bioclimatic spaces with small overlaps. The Irano-Turanian region is differentiated from surrounding regions by continentality, winter temperature, and precipitation seasonality. Continentality is the most important bioclimatic factor in differentiating it from the Mediterranean and Saharo-Sindian regions and is responsible for floristic differences among sub-regions of the Irano-Turanian region. In our case study, the Irano-Turanian region is a nearly independent bioclimatic unit, distinct from its surrounding regions. Hence, it is suggested that the term “Irano-Turanian bioclimate” be used to describe the climate of most of the continental Middle East and Central Asia. Among different sub-regions, the west-central part of this floristic region (“IT2 sub-region”) is a major center of speciation and endemism. Our case study demonstrates that climate is a primary determinant of phytogeographic regionalization. Although modern climate and topography are strong control parameters on the floristic composition and geographical delimitation of the Irano-Turanian region, the complex paleogeographic and paleoclimatic history of SW Asia has also influenced the Tertiary and Quaternary evolution of the Irano-Turanian flora, with additional impacts by the long-lasting historic and present land-use in this region. Many Irano-Turanian montane species are threatened by global warming, and particular conservation measures are needed to protect the Irano-Turanian flora in all sub-regions. 相似文献
7.
We determined the climate-sensitive zones along an altitudinal gradient in a low mountain range forest, the Bavarian Forest National Park in south-eastern Germany, and studied which vascular plant species are likely to respond to climate change. Plants were recorded on 273 plots along four straight transects. The composition of the plant species and their environmental correlates were detected using unconstrained correspondence analysis (DCA) with post-hoc correlation of axes against site variables. We tested the effect of site variables on species composition using maximally selected rank statistics, which allow the simultaneous identification of a threshold and assessment of its significance. Species turnover within the vascular plant community along the altitudinal gradient was assessed using the same method on the basis of the DCA sample scores. Using geostatistical models of local temperature and Bayesian methods with binomial errors that account for spatial structure, we tested the influence of temperature on selected single vascular plant species and assessed the suitability of the species as climate change indicators. Temperature was the most important factor explaining the variability in vascular plant community composition, which changed discretely along the altitudinal gradient, with a climate-sensitive zone found between 1,100 and 1,200 m a.s.l. The distribution of ten species with their lower or upper altitudinal limit in this zone was significantly driven by temperature. To track vegetation responses to climate change effectively, we suggest a three-level monitoring program, flexible with regard to the volume of required sampling effort. 相似文献
8.
Diaphanosoma macrophthalma sp.nov. is described based on material (parthenogenetic females and males) obtained from a number of water bodies of Uzbekistan,
Kazakhstan and China. Intra- and interpopulation morphological variability, size range, sex structure and geographical distribution
are analyzed. 相似文献
9.
Abstract
The Mediterranean red coral (Corallium rubrum, L. 1758) is a slow-growing longevous gorgonian that produces a red calcium carbonate skeleton, which is in high demand by
the jewellery industry. Its long history of intensive commercial harvesting has resulted in a well-documented decline of its
stocks throughout the Mediterranean, becoming especially apparent during the last two decades. Based on the extensive ecological
data from the Costa Brava (NE Spain) stocks, this study reviews, for the first time, socioeconomic aspects and the impact
of current fishing practices on the red coral population structure and reproductive biology. A comparison of the intensively
harvested populations in shallow water with that of the infrequently harvested ones in deep water, along with a population
in a marine reserve as well, reveals that 98% of all shallow water colonies show a juvenile size and branching pattern as
a result of harvesting. Recent data on the reproductive biology of the species show that 91% of the colonies in shallow water
populations (<60 m depth) are not 100% sexually mature. These populations are clearly at the limit of their recoverability
potential. The maximum sustainable yield (estimated using the Beverton-Holt model) is reached at an age of first capture of
98 years, although the current regulations allow harvesting of approximately 11-year-old colonies (corresponding to a basal
diameter of 7 mm). The presented data reveal how this renewable resource is being exploited in a clearly non-sustainable and
inefficient way, changing significantly the underwater landscape of the Mediterranean coast. The review of all available data
suggests that the shallow water stocks are depleted. Furthermore, recent trends in poaching of juvenile colonies and mass
mortality events threaten the survival of the shallow water populations. A ban on reconstituted coral from the market appears
to be the only option to control this form of poaching. 相似文献
10.
Celestino Ordóñez Javier Roca-Pardiñas Fernando Castedo-Dorado José R. Rodríguez-Pérez 《人类与生态风险评估》2013,19(1):254-267
In lightning-induced fire risk prediction models, the number of potential predictors is usually high, with some redundancy among them. It is therefore important to select the best subset of predictors that obtain models with the greatest discrimination capacity. With this aim in mind, the logistic generalized linear model was used to estimate lightning-induced fire occurrence using a case study of the province of León (northwest Spain). A bootstrap-based test was used to obtain the optimal number of predictors and to model this optimal number of predictors displaying the largest area under the receiver operating characteristics curve. The results show that of the 16 variables initially considered, only three were necessary to obtain the model with the best discriminatory capacity for estimating lightning-induced fire occurrence. Moreover, this model can be considered equivalent to another nine alternative models with three covariates. Both the optimal and the equivalent models are useful in the spatially explicit assessment of fire risk, the planning and coordination of regional efforts to identify areas at greatest risk, and the design of long-term wildfire management strategies. The methodology used for this case study can be applied to other wildfire risk assessment situations where multiple and interconnected covariates are available. 相似文献
11.
Developing and Communicating a Taxonomy of Ecological Indicators: A Case Study from the Mid-Atlantic
Denice Heller Wardrop Carl Hershner Kirk Havens Kent Thornton Donna Marie Bilkovic 《EcoHealth》2007,4(2):179-186
To ensure indicators of ecosystem health are integrated into environmental decision-making, it is imperative to provide a comprehensive framework for indicator selection and use. The same framework can also be used to evaluate the utility of any given indicator. The Atlantic Slope Consortium (ASC) has developed such a framework, based upon three primary elements: 1) The specific questions to be answered (the type of indicator), recognizing the following types of questions/indicators: Condition assessment: snapshot of the current state of the system; Stressor diagnosis: identification of causative factors of condition; Communication to the public: encouraging comprehension of condition in its most elementary or integrated form; Futures assessment: estimating the probable trajectory of condition, or assessing the vulnerability of any system to a stochastic event; Evaluation: a subset of condition indicators that evaluate the effectiveness of management actions. 2) The spatial and/or temporal scale of the issue being addressed (the spatial/temporal scale over which the indicator is valid). 3) The context of the question, using categories of surrounding land use as surrogates for social choices. A Fish Community Index (FCI) developed for the ASC will provide an example of utilizing the framework to select an indicator, as well as using the framework to judge the utility of the indicator. 相似文献
12.
Synopsis The Andean and preandean regions are characterized by the presence of several endorheic drainage basins, each of which has
evolved a characteristic fish fauna, some of which are poorly known or hitherto inaccessible. We describe here a new species
of Trichomycterus from Aguarague National Park, Bolivia. Trichomycterus aguarague is considered to belong to a species assemblage comprised of T. alterus, T. boylei, T. ramosus, and T. belensis, a group diagnosed by three putative apomorphic conditions: (1) base of the maxillary barbel wide and engrossed like a skin
flap or fold, (2) premaxillary bone smaller than maxilla, and (3) odontodes embedded in thick integument that covers interopercle.
Alternatively, T. aguarague and T. alterus share an unusual number of five or fewer abdominal vertebrae, which is a synapomorphy for the group composed of Scleronema, Ituglanis, and the Stegophilinae+Tridentinae+Vandelliinae+Glanapteryginae+Sarcoglanidinae clade. The new species differs from all congeners
in having the following combination of characters: caudal peduncle depth 13.5 – 16.0% SL, 15 or 16 pairs of ribs, 15 dorsal
procurrent rays, 12 ventral procurrent rays, 8 pectoral fin rays; 9 anal fin rays; barbels and skin of trunk with numerous,
minute thread-like papillae. 相似文献
13.
Spatial and Social Boundaries and the Paradox of Pastoral Land Tenure: A Case Study from Postsocialist Mongolia 总被引:1,自引:0,他引:1
Mobile pastoralists are subject to potentially conflicting needs for secure resource tenure and socially and spatially flexible patterns of resource use. This paradox of pastoral land tenure poses problems for the application of common property theory to the management of pastoral commons. The vagueness, permeability, and overlap of boundaries around pastoral resources and user groups complicate the implementation of formal tenure regimes designed to address insecure pastoral tenures and unsustainable land use patterns. A case-study from postsocialist Mongolia is used to illustrate the problem of spatial and social boundaries for managing pastoral commons. Three solutions to the paradox are evaluated: tenure formalization, rangeland comanagement, and regulation of herders' seasonal movements. An approach that develops and tests institutions to coordinate pastoral movements is recommended over formal tenure for pasturelands, which should be approached with caution in Mongolia. 相似文献
14.
M. F. CLARIDGE J. DEN HOLLANDER J. C. MORGAN 《Biological journal of the Linnean Society. Linnean Society of London》1988,35(1):79-93
Populations of the morphological species, Nilaparvata lugens (Stål), were found to breed and feed on the grass, Leersia hexandra Schwartz, at six sites in Queensland, Australia. They differ from sympatric rice-feeding populations in characters of pulse repetition frequencies of male and female acoustic courtship signals. The two host-derived populations hybridize freely in the laboratory, but in mate choice experiments show very significant preferences for homogametic matings. No indication of field hybridization has been found, so that the two morphologically inseparable populations represent sympatric biological species in Australia.
Populations from L. hexandra are also reported from four localities in Sri Lanka and one in Orissa, India. These resemble previously studied populations from the Philippines. They differ significantly in courtship call characters, both from sympatric rice-associated populations and from allopatric Leersia -associated populations from Australia.
The geographical variation reported for acoustic signals is not consistent with Paterson's recognition concept of species, but may be interpreted in terms of theories of allopatric speciation involving sexual selection for mate recognition signals. 相似文献
Populations from L. hexandra are also reported from four localities in Sri Lanka and one in Orissa, India. These resemble previously studied populations from the Philippines. They differ significantly in courtship call characters, both from sympatric rice-associated populations and from allopatric Leersia -associated populations from Australia.
The geographical variation reported for acoustic signals is not consistent with Paterson's recognition concept of species, but may be interpreted in terms of theories of allopatric speciation involving sexual selection for mate recognition signals. 相似文献
15.
A phytosociological study was conducted in the National Park of Alta Murgia in the Apulia region (Southern Italy) to determine the adverse effects of metal contamination of soils on the distribution of plant communities. The phytosociological analyses have shown a remarkable biodiversity of vegetation on non-contaminated soils, while biodiversity appeared strongly reduced on metal-contaminated soils. The area is naturally covered by a wide steppic grassland dominated by Stipa austroitalica Martinovský subsp. austroitalica. Brassicaceae such as Sinapis arvensis L. are the dominating species on moderated contaminated soils, whereas spiny species of Asteraceae such as Silybum marianum (L.) Gaertn. and Carduus pycnocephalus L. subsp. pycnocephalus are the dominating vegetation on heavily metal-contaminated soils. The presence of these spontaneous species on contaminated soils suggest their potential for restoration of degraded lands by phytostabilization strategy. 相似文献
16.
Hans Sanderson William Greggs Christina Cowan-Ellsberry Paul DeLeo Richard Sedlak 《人类与生态风险评估》2013,19(4):999-1013
The human and environmental safety of chemicals in formulated consumer products has for decades been important for product manufacturers and ingredient suppliers. However, prior to the mid-1990s, the underlying product safety data were largely not publicly available. The U.S. Environmental Protection Agency's Chemical Right-to-Know Program and a related program of the Organization of Economic Cooperation and Development have since been the catalysts for the broad dissemination of standardized hazard datasets for thousands of high production volume (HPV) chemicals in commerce around the globe. The formulated consumer products industry took the additional step of developing and summarizing the science around exposure to their products, largely cleaning products and personal care products, in order to be able to characterize and communicate the safety of their products. Perhaps even more significant was the collection and circulation of information surrounding the habits and practices of product use, and ingredient concentrations in products. The objective of this article is to detail the methods used for collection of this information by the American Cleaning Institute (ACI), and the process by which hazard and exposure information may be used in screening-level risk assessments. These data and methods appear in a number of ACI's publications (http://www.aciscience.org). 相似文献
17.
The Ahníkov (Miocene, Czech Republic) site represents a concentration of vertebrate skeletal remains in a swamp setting. Autochthonous bone deposits were strongly altered by sedimentary processes and early diagenesis. Biting and gnawing traces recognized on hard animal tissues (bones, teeth, antlers, turtle thoraces) represent seven recurring morphotypes. The following ichnotaxa are erected: Nihilichnus nihilicus n. igen. et n. isp., Nihilichnus mortalis n. isp., Machichnus regularis n. igen. et n. isp., Machichnus multilineatus n. isp., Machichnus bohemicus n. isp., and Brutalichnus brutalis n. igen. et n. isp. Each kind of bones or similar substrates bears a specific proportion of various bite traces but no observed morphotype is specific for a single substrate. Ethologically, traces of sharpening of teeth are principally different from predation traces. The beavers Steneofiber eseri and Steneofiber depereti, the carnivore Amphicyon sp. and the crocodiles are presumed as the tracemakers. 相似文献
18.
19.
Shankar Aswani 《Human ecology: an interdisciplinary journal》1999,27(3):417-453
In recent decades, Pacific Region indigenous sea tenure regimes have received considerable attention from social scientists who believe thatmarine-localized common entitlements and fishing practices can aid modern littoral fisheries management. The endorsement of sea tenure institutions as managerial tools, however, has proceeded without adequate consideration of their vulnerability to social and economic changes. The general view held by researchers is that Pacific Island sea tenure regimes are generally undermined by the influence of exogenous forces resulting in an open-access commons. In this article, it is argued that the contemporary transformation of sea tenure regimes emerges not only from exogenous agency, but from a complex set of autochthonous processes. A case study from New Georgia, Solomon Islands, is presented to show how sea tenure regimes can vary within an ethnically and culturally homogeneous region. Three tenure models are presented to show how different pre- and post-European contact regional settlement patterns, localized processes of political expansion and contraction, and dynamic indigenous sociocultural principles have resulted in institutional differences between each sea tenure model. The effect of the market economy on the organizational structure and managerial outcomes of each model also is discussed. 相似文献
20.
Estimating Invasion Probabilities: A Case Study of fire Blight Disease and the Importation of Apple Fruits 总被引:4,自引:0,他引:4
A statistical method is proposed for the estimation of the probability of invasion of fire blight disease via the importation of apple fruits, by considering that the proportion of infected fruits varies depending on the production area and the year. The following three assumptions, which might be applicable to biological invasions of several diseases of plants and animals, are used: (1) A beta distribution approximately describes the probability distribution of the proportion of infected fruits in the production area of a given consignment, (2) every consignment contains fruits that were drawn at random from the infinite population of the production area, and (3) each infected fruit causes infection of fire blight in the importing country by an independent constant probability. The estimate of the expected time required for invasion is 1707 years if we ignore the variability of infection, whereas the estimate is 334 years if we consider the variability. Thus, it is suggested that the estimation of the risk of invasion might be quite biased if we ignore the variability of infection. 相似文献