Physical and biological controls on carbon cycling in the equatorial pacific     

Murray JW  Barber RT  Roman MR  Bacon MP  Feely RA 《Science (New York, N.Y.)》1994,266(5182):58-65

The equatorial Pacific is the largest oceanic source of carbon dioxide to the atmosphere and has been proposed to be a major site of organic carbon export to the deep sea. Study of the chemistry and biology of this area from 170 degrees to 95 degrees W suggests that variability of remote winds in the western Pacific and tropical instability waves are the major factors controlling chemical and biological variability. The reason is that most of the biological production is based on recycled nutrients; only a few of the nutrients transported to the surface by upwelling are taken up by photosynthesis. Biological cycling within the euphotic zone is efficient, and the export of carbon fixed by photosynthesis is small. The fluxes of carbon dioxide to the atmosphere and particulate organic carbon to the deep sea were about 0.3 gigatons per year, and the production of dissolved organic carbon was about three times as large. The data establish El Ni?o events as the main source of interannual variability.  相似文献   

Ecological forecasts: an emerging imperative   总被引：1，自引：0，他引：1  

Clark JS  Carpenter SR  Barber M  Collins S  Dobson A  Foley JA  Lodge DM  Pascual M  Pielke R  Pizer W  Pringle C  Reid WV  Rose KA  Sala O  Schlesinger WH  Wall DH  Wear D 《Science (New York, N.Y.)》2001,293(5530):657-660

Planning and decision-making can be improved by access to reliable forecasts of ecosystem state, ecosystem services, and natural capital. Availability of new data sets, together with progress in computation and statistics, will increase our ability to forecast ecosystem change. An agenda that would lead toward a capacity to produce, evaluate, and communicate forecasts of critical ecosystem services requires a process that engages scientists and decision-makers. Interdisciplinary linkages are necessary because of the climate and societal controls on ecosystems, the feedbacks involving social change, and the decision-making relevance of forecasts.  相似文献   

Non-target-site resistance mechanism of barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] to florpyrauxifen-benzyl     

Jeong-In Hwang  Jason K Norsworthy  Fidel Gonzlez-Torralva  Grant L Priess  L Tom Barber  Thomas R Butts 《Pest management science》2022,78(1):287-295

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Clinical characteristics of doxorubicin‐associated alopecia in 28 dogs          下载免费PDF全文

Elizabeth F. Falk  Andrea T. H. Lam  Lisa G. Barber  Lluis Ferrer 《Veterinary dermatology》2017,28(2):207-e48

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Age‐related susceptibility of Eucalyptus species to Phytophthora boodjera          下载免费PDF全文

A. V. Simamora  M. J. C. Stukely  P. A. Barber  G. E. StJ. Hardy  T. I. Burgess 《Plant pathology》2017,66(3):501-512

Phytophthora boodjera is a newly described pathogen causing damping off and mortality of Eucalyptus seedlings in Western Australian nurseries. This study evaluated the age‐related susceptibility of several taxa of mallee Eucalyptus to P. boodjera in sterilized washed river sand‐infestation pot trials. Phytophthora cinnamomi and P. arenaria were included for comparison. Seedlings of Eucalyptus taxa were inoculated at 0, 2, 4, 12 and 88 weeks with individual Phytophthora isolates. Pre‐emergent mortality in the presence of Phytophthora was almost 100%. Post‐emergent mortality was 50–100%, depending on isolate, compared to 0% for the control. Mortality was also high for inoculated 1 month‐old seedlings (46–68%) and root length of surviving seedlings was severely reduced. Death from root infection was not observed for seedlings inoculated at 12 and 88 weeks, but they developed root necrosis and reduced root dry weight compared to non‐inoculated controls. Phytophthora boodjera is a pre‐ and post‐emergent pathogen of mallee eucalypts. These eucalypts are susceptible to P. boodjera at all life stages tested, but the mortality rates declined with plant age. Similar results were obtained for P. cinnamomi and P. arenaria. The events leading to its recent appearance in the nurseries remain unknown and further investigations are underway to determine if this is an introduced or endemic pathogen. The approach used here to understand the impact of a Phytophthora species on multiple hosts at different seedling ages is novel and sets a benchmark for future work.  相似文献   

Immunization with Brucella melitensis Rev 1 against Brucella ovis infection of rams   总被引：1，自引：0，他引：1  

J M Blasco  C M Marín  M Barberán  I Moriyón  R Díaz 《Veterinary microbiology》1987,14(4):381-392

The efficacy of Brucella Melitensis Rev 1 vaccine (Rev 1) for the prophylaxis of Brucella ovis ram epididymitis was evaluated. Twenty-nine 3-month-old rams were vaccinated with 2 X 10(9) Rev 1 and 14 were revaccinated with 5 X 10(8) at 14 months of age. Six rams remained unvaccinated as a control group. All rams were challenged with 5 X 10(8) B. ovis at 21 months of age. Before being slaughtered 8 weeks later, only one vaccinated ram developed epididymitis while four of the six control rams developed testicular alterations. Genital and selected extragenital organs and lymph nodes were removed at slaughter and inoculated on selective media. B. ovis was isolated from 26.6% of the vaccinated rams, 21.4% of the revaccinated rams and 100% of control rams. Portions of epididymis, testes and vesicular glands were also used for pathological studies. More severe lesions were observed in control rams than in vaccinated ones. In conclusion, these results show that vaccination of young lambs, followed or not by revaccination, is a suitable method for the prophylaxis of B. ovis infection of rams.  相似文献   

The rehabilitation of degraded soils in eastern bolivia by subsoiling and the incorporation of cover crops     

R. G. Barber  F. Navarro 《Land Degradation \u0026amp; Development》1994,5(4):247-259

A high proportion of the soils in the central zone of Santa Cruz, eastern Bolivia, are chemically and physically degraded, with low organic matter and N contents, compacted subsoil layers and a propensity to crusting, hardsetting and wind erosion. The aim of the experiment discussed in this paper was to identify suitable cover crops to be used in combination with subsoiling for the rehabilitation of degraded soils and the improvement of crop yields in eastern Bolivia. Fertilizers were not used because of their high cost. An experiment with a split complete block design, with subsoiling and no-subsoiling as the main treatments, 14 cover crops and a continuously cultivated soybean/wheat control as the subtreatments, and four replications, was established on a degraded site comprising a mosaic of two compacted siliceous isohyperthermic soils (a coarse loamy Typic Ustropept and a fine loamy Typic Haplustalf). After a two-year fallow period, the cover crops were incorporated and test crops were sown for five seasons to evaluate the effects of the treatments on subsequent crop yields. Soil samples were taken to measure changes in chemical fertility. The only significant cover crop effect on soil nutrients was an increase in exchangeable K from 0.47 to 0.56 cmol_c kg⁻¹ by Lablab; subsoiling had no effect on chemical fertility. For all treatments there was an average 24 per cent increase in soil organic matter from 13.1 g kg⁻¹ at 3 months after cover crop incorporation to 16.3 g kg⁻¹ at 19 months after incorporation. No significant differences in total N were found during this period. Test crop yields were not influenced by subsoiling, but were significantly increased by some of the cover crops as compared to the soybean/wheat control during the first three seasons only. Evidence from foliar analysis suggests that the effects of the cover crops on soybean yields were not nutritional and so presumably were physical in nature, whereas the benefits on wheat yields were possibly related to increased N availability. Panicum maximum var. Centenario and P. maximum var. Tobiatá gave the highest total yield increases over the first three cropping seasons (101 and 85 per cent, respectively), but these yield increases would not compensate the farmer for the loss of four crop harvests whilst the land was in fallow. These results highlight the difficulties of rehabilitating soil fertility and increasing crop yields through the use of subsoiling and cover crop fallows on compacted, low organic matter soils in eastern Bolivia.  相似文献