Understory plant diversity and biomass in hybrid poplar riparian buffer strips in pastures     

Julien Fortier  Daniel Gagnon  Benoit Truax  France Lambert 《New Forests》2011,42(2):241-265

Understory plant biomass, species richness and canopy openness were measured in six-year old hybrid poplar riparian buffer strips, in the understory of two unrelated clones (MxB-915311 and DxN-3570), planted along headwater streams at three pasture sites of southern Quebec. Canopy openness was an important factor affecting understory biomass in hybrid poplar buffers, with lower understory biomass observed on sites and under the clone with lower canopy openness. Although tree size was an important factor affecting canopy openness, relationships between total stem volume and canopy openness, for each clone, also support the hypothesis of a clonal effect on canopy openness. Understory biomass and canopy openness as low as 3.6 g m⁻² and 7.6% in 1 m² microplots were measured under clone MxB-915311 at the most productive site. This reduction of understory plant growth could compromise important buffer functions for water quality protection (runoff control, sediment trapping and surface soil stabilisation), particularly were concentrated runoff flow paths enter the buffer. On the other hand, tree buffers that maintain relatively low canopy openness could be interesting to promote native and wetland plant diversity. Significant positive relationships between canopy openness and introduced species richness (R ² = 0.46, p < 0.001) and cover (R ² = 0.51, p < 0.001) were obtained, while no significant relationship was observed between canopy openness and native (wetland) species richness and cover. These results suggest that planting riparian buffer strips of fast-growing trees can rapidly lead to the exclusion of shade-intolerant introduced species, typical colonisers of disturbed habitats such as riparian areas of pastures, while having no significant effect on native (wetland) diversity. Forest canopy created by the poplars was probably an important physical barrier controlling introduced plant richness and abundance in agricultural riparian corridors. A strong linear relationship (R ² = 0.73) between mean total species richness and mean introduced species richness was also observed, supporting the hypothesis that the richest communities are the most invaded by introduced species, possibly because of higher canopy openness, as seen at the least productive site (low poplar growth). Finally, results of this study highlight the need for a better understanding of relationships between tree growth, canopy openness, understory biomass and plant diversity in narrow strips of planted trees. This would be useful in designing multifunctional riparian buffer systems in agricultural landscapes.  相似文献   

Outcomes of cats undergoing surgical attenuation of congenital extrahepatic portosystemic shunts through cellophane banding: 9 cases (2000-2007)     

Cabassu J  Seim HB  MacPhail CM  Monnet E 《Journal of the American Veterinary Medical Association》2011,238(1):89-93

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Zinc toxicity in two dogs associated with the ingestion of identification tags     

Adam F  Elliott J  Dandrieux J  German A  Blackwood L 《The Veterinary record》2011,168(3):84-85

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Impact of concentration of ellagitannins in oak wood on their levels and organoleptic influence in red wine     

Michel J  Jourdes M  Silva MA  Giordanengo T  Mourey N  Teissedre PL 《Journal of agricultural and food chemistry》2011,59(10):5677-5683

Some wood substances such as ellagitannins can be extracted during wine aging in oak barrels. The level of these hydrolyzable tannins in wine depends of some parameters of oak wood. Their impact on the organoleptic perception of red wine is poorly known. In our research, oak staves were classified in three different groups according to their level of ellagitannins estimated by NIRS (near infrared spectroscopy) online procedure (Oakscan). First, the ellagitannin level and composition were determine for each classified stave and an excellent correlation between the NIRS classification (low, medium and high potential level of ellagitannin) and the ellagitannin content estimated by HPLC-UV was found. Each different group of NIRS classified staves was then added to red wine during its aging in a stainless tank, and the extraction and evolution of the ellagitannins were monitored. A good correlation between the NIRS classification and the concentration of ellagitannins in red wine aging in contact with the classified staves was observed. The influence of levels of ellagitannins on the resulting wine perception was estimated by a trained judge's panel, and it reveals that the level of ellagitannins in wine has an impact on the roundness and amplitude of the red wine.  相似文献   

Plant species extinction debt in a temperate biodiversity hotspot: Community, species and functional traits approaches   总被引：1，自引：0，他引：1  

Julien Piqueray  Emmanuelle Bisteau  Sara Cristofoli  Rodolphe Palm  Peter Poschlod  Grégory Mahy 《Biological conservation》2011,(5):1619-1629

Destruction and fragmentation of (semi-) natural habitats are considered the main causes of biodiversity loss worldwide. Plant species may exhibit a slow response to fragmentation, resulting in the development of an extinction debt in fragmented plant communities. The detection of extinction debt is of primary importance in habitat conservation strategies. We applied two different approaches proposed in the literature to identify extinction debt in South-East Belgium calcareous grasslands. The first method compared species richness between stable and fragmented habitat patches. The second explored correlations between current species richness and current and past landscape configurations using multiple regression analyses. We subsequently examined results generated by both methods. In addition, we proposed techniques to identify species that are more likely to support extinction debt and associated functional traits. We estimated a respective extinction debt of approximately 28% and 35% of the total and specialist species richness. Similar results were obtained from both methods. We identified 15 threatened specialist species under the current landscape configuration. It is likely the landscape configuration no longer supports the species habitat requirements. We demonstrated that non-clonal species are most threatened, as well as taxa that cannot persist in degraded habitats and form only sparsely distributed populations. We discussed our results in light of other studies in similar habitats, and the overall implications for habitat conservation.  相似文献   

Baseflow control on sediment flux connectivity: Insights from a nested catchment study in Central Mexico   总被引：1，自引：0，他引：1  

Clément Duvert  Nicolas Gratiot  Roberto Anguiano-Valencia  Julien Némery  Manuel E. Mendoza  Teodoro Carlón-Allende  Christian Prat  Michel Esteves 《CATENA》2011

In order to assess the extent of sediment connectivity between uplands and lowlands and to quantify the processes of in-channel deposition and remobilization, measurements of suspended sediment fluxes were conducted in a nested rural catchment of the Mexican Volcanic Belt. Data were collected over one year at three upland sites (3 to 12 km²) and two downstream stations (390–630 km²). Our results show that a structural discontinuity in the catchment (i.e. abrupt slope decrease at the junction between piedmonts and the alluvial plain from 2 to 10% to < 0.1%) could be compensated by functional continuity during floods. Direct conveyance of fine sediment to the outlet occurred when a high stream transport capacity was reached. Erosion of the streambed was observed on various occasions and accounted for up to 50% of the flux leaving the catchment during one event. Conversely, temporary in-channel storage was apparent on other occasions, amounting to up to 52% of the flux recorded upstream during one storm. These two distinct behaviours were approximately equally distributed along the rainy season and strongly driven by the extent of coupling between surface and subsurface water. This work indeed highlights the role of baseflow spatial variations in determining the extent of lowland sediment conveyance. Riverbed erosional processes occurred when large differences in pre-event baseflow values (i.e. at least a twofold longitudinal increase) were observed between the 5-km distant lowland stations. Our findings outline the importance of systematically taking into consideration the baseflow parameter in research focusing on fine sediment transport across scales.  相似文献   

The Effect of Hyperbaric Oxygen Treatment on a Compromised Axial Pattern Flap in the Cat     

SHARON C. KERWIN dvm  GISELLE HOSGOOD bvsc  ms  facvsc  dipiomate acvs  GEORGE M. STRAIN phd  CAROL C. VICE dvm  CLAUDE E. WHITE dvm  R. KELLY HILL mo  facm 《Veterinary surgery : VS》1993,22(1):31-36

A pedicle skin flap based on the caudal superficial epigastric artery was created in 12 cats. The artery was ligated and the vein left intact. Six cats were treated with hyperbaric oxygen at 2 atm absolute for 90 minutes daily for 14 days, starting the day after surgery. Skin flap color was significantly better in the treated cats on days 1, 2, and 3. The amount of exudate was significantly less in the treated cats on day 3. There was no difference in the amount of swelling between treated and nontreated control cats. Although five of six of the treated cats had 100% skin flap survival, there was no significant difference in total flap survival between treated and nontreated control cats.  相似文献   

Isolation of Streptococcus suis from a young wild boar.     

R Higgins  A Lagac  S Messier    L Julien 《The Canadian veterinary journal. La revue veterinaire canadienne》1997,38(2):114

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Splenic vasculitis,thrombosis, and infarction in a febrile dog infected with Bartonella henselae          下载免费PDF全文

Steven G. Friedenberg DVM  MS  DACVECC  Nandhakumar Balakrishnan PhD  Julien Guillaumin DVM  DACVECC  DECVECC  Edward S. Cooper VMD  MS  DACVECC  Kristin Lewis DVM  Duncan S. Russell BVMS  DACVP  Edward B. Breitschwerdt DVM  DACVIM 《Journal of Veterinary Emergency and Critical Care》2015,25(6):789-794

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Cortical constriction during abscission involves helices of ESCRT-III-dependent filaments   总被引：1，自引：0，他引：1  

Guizetti J  Schermelleh L  Mäntler J  Maar S  Poser I  Leonhardt H  Müller-Reichert T  Gerlich DW 《Science (New York, N.Y.)》2011,331(6024):1616-1620

After partitioning of cytoplasmic contents by cleavage furrow ingression, animal cells remain connected by an intercellular bridge, which subsequently splits by abscission. Here, we examined intermediate stages of abscission in human cells by using live imaging, three-dimensional structured illumination microscopy, and electron tomography. We identified helices of 17-nanometer-diameter filaments, which narrowed the cortex of the intercellular bridge to a single stalk. The endosomal sorting complex required for transport (ESCRT)-III co-localized with constriction zones and was required for assembly of 17-nanometer-diameter filaments. Simultaneous spastin-mediated removal of underlying microtubules enabled full constriction at the abscission site. The identification of contractile filament helices at the intercellular bridge has broad implications for the understanding of cell division and of ESCRT-III-mediated fission of large membrane structures.  相似文献