Climate variability, vegetation productivity and people at risk     

Cristina Milesi  Hirofumi Hashimoto  Steven W. Running  Ramakrishna R. Nemani 《Global and Planetary Change》2005,47(2-4):221

Human domination of ecosystems has been pervasive over the last century, with nearly half of Earth's surface transformed by human actions. It is widely accepted that humans appropriate up to 50% of global net primary production (NPP), the energy base of all the trophic levels on the land surface. Yet, despite the important role of vegetation productivity for defining Earth habitability, the covariation of NPP and human population distribution has not been analyzed in depth. We used recently available satellite-based NPP estimates, along with gridded population at 0.5° resolution, first, to identify the global distribution of human population with reference to average NPP and to the various climatic constraints (temperature, water and cloud cover) that limit NPP, second, to analyze recent trends in global NPP in relation to population trends, and third, to identify populations that are vulnerable to changes in NPP due to interannual variability in climate. Our results indicate that over half of the global human population is presently living in areas with above the average NPP of 490 g C m⁻² year⁻¹. By 1998, nearly 56% of global population lived in regions where water availability strongly influences NPP. Per capita NPP declined over much of Africa between 1982 and 1998, in spite of the estimated increases in NPP over the same period. On average, NPP over 40% of the total vegetated land surface has shown significant correlations with ENSO-induced climate variability affecting over 2.8 billion people.  相似文献   

Crustal growth of the central-eastern Paleoproterozoic domain,SW Amazonian craton: Juvenile accretion vs. reworking     

Moacir José Buenano Macambira  Marcelo Lacerda Vasquez  Daniela Cristina Costa da Silva  Marco Antonio Galarza  Carlos Eduardo de Mesquita Barros  Julielson de Freitas Camelo 《Journal of South American Earth Sciences》2009,27(4):235-246

The Trans-Amazonian cycle was an important rock-forming event in South America, generating voluminous juvenile and reworked fractions of continental crust. The Bacajá domain, in the southern sector of the Maroni-Itacaiúnas Province in the Amazonian craton, is an example of the Trans-Amazonian terranes adjacent to the Archean Carajás block. Zircon Pb-evaporation and whole-rock Sm–Nd analyses were carried out on representative samples of six lithological units, and allowed the proposal of a comprehensive tectonic-magmatic evolutionary sequence for the central and eastern parts of this domain, from the Neoarchean to the Rhyacian. Gneisses with ages of ca. 2.67 and 2.44 Ga are the oldest rocks recorded in the region, and probably represent remnants of island and continental arcs. The Três Palmeiras succession, emplaced between 2.36 and 2.34 Ga, hosts gold deposits and represents the first record of Siderian supracrustal rocks in the Amazonian craton. It was probably part of an island arc/ocean floor accreted to a craton margin. Rhyacian granitogenesis lasted for ca. 140 My (2.22–2.08 Ga), marking different stages of the Trans-Amazonian cycle. The first stage is represented by continental arc granitoids formed by melting of Archean crust at 2.22–2.18 Ga. The second is characterized by the production of juvenile material between 2.16 and 2.13 Ga. The third and final stage at ca. 2.08 Ga is represented by a large volume of granitoids originated from either juvenile material or reworked crust during compressive stresses. Nd isotopes reveal that juvenile rocks dominated in the northern part of the domain, whereas those formed from reworked crust predominate in the south. The present-day configuration of the Bacajá domain results from collision against the Archean Carajás block at the end of the Trans-Amazonian cycle.  相似文献   

Crystal size distributions of plagioclase in lavas from the July–August 2001 Mount Etna eruption     

Alessandro Fornaciai  Cristina Perinelli  Pietro Armienti  Massimiliano Favalli 《Bulletin of Volcanology》2015,77(8):1-15

  相似文献   

Population structure and conservation status of the red gorgonian Paramuricea clavata (Risso, 1826) in the Eastern Adriatic Sea          下载免费PDF全文

Silvija Kipson  Cristina Linares  Hrvoje Čižmek  Emma Cebrián  Enric Ballesteros  Tatjana Bakran‐Petricioli  Joaquim Garrabou 《Marine Ecology》2015,36(4):982-993

Gorgonians are important structuring species of the Mediterranean hard‐bottom communities that are threatened by disturbances such as increasing seawater temperature, mucilaginous events and destructive fishing, among others. In this study we assessed for the first time the population structure and conservation status of one of the most common gorgonians in the Eastern Adriatic Sea, the red gorgonian Paramuricea clavata. During late spring 2009, nine populations dwelling between 30 and 50 m depth were examined by SCUBA diving along 200 km of the Croatian coastline. The density ranged between 7 and 20 colonies·m^?2. The mean and maximum colony heights were 31.2 ± 22.7 cm (±SD) and 138 cm, respectively. Two main patterns of P. clavata size frequency distributions were observed: the first one with a higher proportion of juveniles (~30%) observed mostly in the northernmost populations, and the second one with a higher proportion of larger colonies (>25% of colonies >40 cm in height). Regarding the disturbance impact level, the proportion of healthy colonies (with <10% of injured surface) was high in almost all of the studied populations (>60%) and the mean extent of injury (i.e. denuded axis or epibiosis) was 9.7 ± 4% (±SD), indicating low impacts. Contrasting population size structures with high recruitment in mature populations provides new insights into the demographic structure of the Mediterranean gorgonian forests dwelling in their upper bathymetric range (<50 m depth). Furthermore, these size structures and the low impact levels suggest a current favorable conservation status of the studied populations in the Eastern Adriatic Sea and provide a baseline for their monitoring in the future.  相似文献   

Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations     

Mariano Poisson  Marcelo López Fuentes  Cristina H. Mandrini  Pascal Démoulin 《Solar physics》2015,290(11):3279-3294

  相似文献   

Evaluation of the applicability of a fuzzy index of ecosystem integrity (FINE) to characterize the status of Tyrrhenian lagoons     

Munari C  Mistri M 《Marine environmental research》2007,64(5):629-638

The new index FINE, a multimetric, fuzzy-based index for the evaluation of environmental quality for Mediterranean transitional waters, was calculated using biotic data gathered between 2000 and 2006 at 15 stations in 4 Tyrrhenian transitional water ecosystems (Orbetello Lagoon, Padrongiano Delta, Stagno di S. Teodoro, and Stagno di Tortolì), i.e. in a different biogeographic sub-province respect to the one in which the index was developed and validated. The rationale of FINE is that certain attributes, selected on the basis of established principles of benthic ecology, are fundamental for lagoon ecosystem function. A set of other indices (Simpson's 1-lambda', the W-statistics, AMBI, and BOPA) was also calculated and compared to FINE outputs. FINE, 1-lambda', and the W-statistics were significantly correlated with sedimentary organic matter content. Some stations were unequivocally assigned to the same ecological status, independently from the index used; for others, some discrepancies were evident. Mediterranean transitional waters probably share ecosystem complexities which are not yet fully captured by indices developed and validated elsewhere.  相似文献   

A two-color CCD survey of the North Celestial Cap: I. The method     

Evgeny Gorbikov  Noah Brosch  Cristina Afonso 《Astrophysics and Space Science》2010,326(2):203-217

We describe technical aspects of an astrometric and photometric survey of the North Celestial Cap (NCC), from the Pole (δ=90°) to δ=80°, in support of the TAUVEX mission. This region, at galactic latitudes from ∼17° to ∼37°, has poor coverage in modern CCD-based surveys. The observations are performed with the Wise Observatory one-meter reflector and with a new mosaic CCD camera (LAIWO) that images in the Johnson–Cousins R and I bands a one-square-degree field with sub-arcsec pixels. The images are treated using IRAF and SExtractor to produce a final catalogue of sources. The astrometry, based on the USNO-A2.0 catalogue, is good to ∼1 arcsec and the photometry is good to ∼0.1 mag for point sources brighter than R=20.0 or I=19.1 mag. The limiting magnitudes of the survey, defined at photometric errors smaller than 0.15 mag, are 20.6 mag (R) and 19.6 (I). We separate stars from non-stellar objects based on the object shapes in the R and I bands, attempting to reproduce the SDSS star/galaxy dichotomy. The completeness test indicates that the catalogue is complete to the limiting magnitudes.  相似文献   

Technological study of “ghiara” mortars from the historical city centre of Catania (Eastern Sicily, Italy) and petro-chemical characterisation of raw materials     

Cristina M. Belfiore  Mauro F. La Russa  Paolo Mazzoleni  Antonino Pezzino  Marco Viccaro 《Environmental Earth Sciences》2010,61(5):995-1003

This paper presents new petro-chemical data on some typical mortars found in many buildings in the historic city centre of Catania (Eastern Sicily). Extensively used in the architecture of the city from the second half of the nineteenth century until the mid-twentieth century, these mortars are characterised by a particular aggregate locally known as “agghiara” or “ghiara”. This is the product of thermal transformation induced by the heating undergone by palaeo-soils, originally rich in organic matter, covered by lava flows, which change their colour to reddish nuances. The volcanic origin of ghiara is a peculiar feature of the Etnean area. Mixed with lime, it gives to mortars an intense reddish colour, as well as hydraulic properties, which are comparable with those of the historically used pozzolana. This work aimed at complete characterisation of these ghiara mortars, for providing information on several important technological aspects. In order to get information on used raw materials, sampling of some ancient underground quarries, located both in the historic city centre and at the periphery, was also performed. Results led to the complete characterisation of the selected ghiara mortars and yielded information on some technological features and the composition of both newly formed and secondary phases, these latter due to alteration processes. The hydraulic properties of mortars have been related to the occurrence of amorphous phases within the ghiara aggregate, which were identified by means of SEM morphological observations. These phases, formed during the “firing” process of palaeo-soils, react with lime producing hydraulic compounds (C–S–H and C–A–H), which are responsible for the mortars durability.  相似文献   

Influence of sample and terrain unit on landslide susceptibility assessment at La Pobla de Lillet,Eastern Pyrenees,Spain   总被引：2，自引：2，他引：0  

Cristina Baeza  N. Lantada  J. Moya 《Environmental Earth Sciences》2010,60(1):155-167

The reliability of susceptibility maps depends largely on the quality of the information used for its evaluation. This study seeks to analyze the influence of sample size and type on the results of discriminant analysis applied to shallow landslide susceptibility assessment. The study also assesses the role of the terrain unit in discriminant analysis. To this end, two databases based on fieldwork (slope unit) and GIS with 15- and 45-m grid cells (grid cell-based unit), were compared in the same zone at La Pobla de Lillet, Spanish Eastern Pyrenees. The results show that although there is no significant influence of the type of sample, it is necessary to use at least half of the individuals of the sample in order to obtain good results from discriminant analysis. It is the terrain unit that exerts the biggest influence on the result of susceptibility. Some morphometric parameters related to landslides were compared in the databases. The slope unit of the fieldwork database better reflects the land characteristics than the regular grid used by GIS. The values of the variables obtained by GIS procedures are smooth, obtaining mean errors for the slope angle variable of 19.5 and 33.5% for the grids of 15 and 45 m, respectively, in the study area. One-way and T tests demonstrate that the smoothness of the values exerts a decisive influence on the discriminant results. Kappa’s analysis shows that there is no significant equivalence between some of the categorical variables used in both databases. The use of these variables demand the application of clearly defined criteria. The cell size should match the dimensions of the phenomenon analyzed given the unsuitability of the grid of 45 m in this study.  相似文献   

Butyltin compounds,sterility and imposex assessment in Nassarius reticulatus (Linnaeus, 1758), prior to the 2008 European ban on TBT antifouling paints,within Basque ports and along coastal areas     

J. Germán Rodríguez  Itziar Tueros  Ángel Borja  Javier Franco  J. Ignacio García Alonso  Joxe Mikel Garmendia  Iñigo Muxika  Cristina Sariego  Victoriano Valencia 《Continental Shelf Research》2009,29(8):1165-1173

Levels of imposex (superimposition of male characters, upon females) and the presence of sterile females are assessed in the gastropod Nassarius reticulatus (L.), at 35 locations in the Basque Country. At 18 of these localities, organotin bioaccumulation (tributyltin (TBT); dibutyltin; monobutyltin) was evaluated, using isotope dilution GC–ICP–MS. Higher imposex levels and TBT body burden were found in confined harbours, with large vessel traffic or the presence of an offshore fleet. The highest values were found for the port of Pasaia, near to a shipyard (a relative penis size index of up to 92%, and TBT body burden up to 405 ng g^?1 – given on a dry weight basis as Sn). Imposex effects were evaluated also in parasitized females, at some of the sampling sites. The percentage of presence of c-type Vas Deferens sequence stages (i.e., with vas deferens beginning at the oviduct opening) was higher in parasitized females. In turn, there was an absence of highly convoluted oviduct in parasitized females.  相似文献