Scenarios for global biodiversity in the 21st century   总被引：6，自引：0，他引：6  

Pereira HM  Leadley PW  Proença V  Alkemade R  Scharlemann JP  Fernandez-Manjarrés JF  Araújo MB  Balvanera P  Biggs R  Cheung WW  Chini L  Cooper HD  Gilman EL  Guénette S  Hurtt GC  Huntington HP  Mace GM  Oberdorff T  Revenga C  Rodrigues P  Scholes RJ  Sumaila UR  Walpole M 《Science (New York, N.Y.)》2010,330(6010):1496-1501

Quantitative scenarios are coming of age as a tool for evaluating the impact of future socioeconomic development pathways on biodiversity and ecosystem services. We analyze global terrestrial, freshwater, and marine biodiversity scenarios using a range of measures including extinctions, changes in species abundance, habitat loss, and distribution shifts, as well as comparing model projections to observations. Scenarios consistently indicate that biodiversity will continue to decline over the 21st century. However, the range of projected changes is much broader than most studies suggest, partly because there are major opportunities to intervene through better policies, but also because of large uncertainties in projections.  相似文献   

Productivity and resource use of direct-(drum)-seeded and transplanted rice in puddled soils in rice–rice and rice–wheat ecosystems     

M. Harunur Rashid  M. Murshedul Alam  M. Akhter Hossain Khan  J.K. Ladha   《Field Crops Research》2009,113(3):274-281

Conventional tilled transplanting, a widely practiced method of rice (Oryza sativa L.) establishment in puddled soils in rice–rice and rice–wheat (Triticum aestivum L.) systems in Asia, requires a large amount of labor and water, which are becoming scarce and expensive. Growing more food with the same production costs or even reduced costs and sustaining the quality of the natural resource base are a major concern. On-farm trials were conducted in Chuadanga District of Bangladesh during the wet season as monsoon rice (aman) and during the dry season as winter rice (boro) in 2006–07 to evaluate the effects of establishment methods with improved crop management on productivity, resource (land, water, and labor) use, and economic return. Rice was established by sowing in line with a drum seeder on conventional tilled puddled soils (CT-DrumR) and by transplanting in line on the day of CT-DrumR (CT-TPR1) and 30 and 35 days after CT-DrumR (CT-TPR2) in aman and boro seasons, respectively. Farmers’ usual transplanting time corresponds to the day of CT-TPR2. Grain yields in CT-DrumR and CT-TPR2 were similar but the crop occupied the main field 22–24 days longer in CT-DrumR than in CT-TPR2, resulting in lower productivity (45 kg grain ha⁻¹ day⁻¹ vs. 55 kg grain ha⁻¹ day⁻¹) in both seasons. Drum-seeded rice matured earlier by 8 and 11 days, received 12% and 6% less irrigation water, saved 19 and 24 person-days ha⁻¹, and gave higher gross margins of 6% and 4% but input costs increased by 20% and 12% than CT-TPR2 in aman and boro seasons, respectively. There is a need to examine these benefits of drum-seeded rice in relation to the feasibility of adoption by farmers.  相似文献   

Antimicrobial and cytotoxic activities of Achyranthes ferruginea     

Rahman MM  Alam AH  Sadik G  Islam MR  Khondkar P  Hossain MA  Rashid MA 《Fitoterapia》2007,78(3):260-262

Chloroform extract (CE) of Achyranthes ferruginea and N-trans-feruloyl-4-methyldopamine (1) showed remarkable antimicrobial activities against a wide range of bacteria and fungi. Both crude extract (CE) and compound 1 showed significant cytotoxicity of LC(50) at 16.21 microg/ml and 11.70 microg/ml, respectively.  相似文献   

Short Response of Spring Wheat to Tillage,Residue Management and Split Nitrogen Application in a Rice-Wheat System          下载免费PDF全文

Khalid Usman  Ejaz Ahmad Khan  Fazal Yazdan  Niamatullah Khan  Abdur Rashid  Saleem Ud Din 《农业科学学报》2014,13(12):2625-2633

A field experiment was conducted to study the impact of tillage, crop residue management and nitrogen (N) splitting on spring wheat (Triticum aestivum L.) yield over 2 yr (2010-2012) in a rice (Oryza sativa L.)-wheat system in northwestern Pakistan. The experiment was conducted as split plot arranged in randomized complete blocks design with three replications. Treatments comprised six tillage and residue managements: zero tillage straw retained (ZTsr), zero tillage straw burnt (ZTsb), reduced tillage straw incorporated (RTsi), reduced tillage straw burnt (RTsb), conventional tillage straw incorporated (CTsi), and conventional tillage straw burnt (CTsb) as main plots and N (200 kg ha⁻¹) was applied as split form viz., control (no nitrogen & no splitting, N₀S₀); 2 splits of total N, half at sowing and half at the 1st irrigation (i.e., 20 d after sowing (DAS)) (NS₁); 3 splits of total N, 1/3 at sowing, 1/3 at the 1st irrigation, and 1/3 at the 2nd irrigation (NS₂); 4 splits of total N, 1/4 at sowing, 1/4 at the 1st irrigation, 1/4 at the 2nd irrigation (45 DAS), and 1/4 at the 3rd irrigation (70 DAS) (NS₃); and 4 splits of total N, 1/4 at the 1st irrigation, 1/4 at the 2nd irrigation, 1/4 at the 3rd irrigation, and 1/4 at the 4th irrigation (95DAS) (NS₄) as sub plots. The results showed that the most pikes m⁻², grains/spike, 1000-grain weight, grain yield, and N use efficiency (NUE) were obtained at zero tillage, straw retained and 4 splits application of total N (i.e., at sowing 20, 45 and 70 d after sowing). The results indicated that ZTsr with application of 200 kg N ha⁻¹ in 4 equal splits viz. at sowing 20, 45 and 70 d after sowing is an appropriate strategy that enhanced wheat yield (7436-7634 kg ha⁻¹) and N efficiency (28.6-29.5 kg kg⁻¹) in rice-wheat system.  相似文献   

Improved PCR for identification of members of the genus Xanthomonas     

John Adriko  Ernest Rashid Mbega  Carmen Nieves Mortensen  Ednar Gadelha Wulff  Wilberforce Kateera Tushemereirwe  Jerome Kubiriba  Ole Søgaard Lund 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(2):293-306

A PCR-based system was developed to reliably and robustly identify group I and II members of the genus Xanthomonas. Primer sets developed from three gene targets namely fyuA, ITS and gumD were evaluated in the study. Primer sets were evaluated using DNA extracted from 45 Xanthomonas strains representing 25 species broadly covering the genus. Fifteen non-Xanthomonas strains of plant-associated bacteria including phylogenetically closely related species Stenotrophomonas maltophilia and Xylella fastidiosa were also tested. The primers targeting fyuA amplified DNA from all xanthomonads except X. theicola, while the ITS primers amplified a DNA fragment of 254 bp in all 45 Xanthomonas strains; whereas no amplification was observed for non-xanthomonads. The gumD primers allowed efficient amplification of DNA in 38 out of 39 isolates from Group II, whereas no or very weak amplification occurred with DNA from Group I members. Internal controls of primers targeting bacterial 16S rDNA or plant 26S mitochondrial rDNA were successfully applied in multiplex PCRs for testing bacterial cultures or plant tissue, respectively. The findings give us a PCR based approach that can reliably and effectively differentiate xanthomonads from non-xanthomonads as well as separating the strains belonging to the two described groups of the genus Xanthomonas. The study thus offers valuable tools for disease surveillance and management. It can effectively be applied in rapid assessment of new disease occurrences, for which no specific detection tools could be in place.  相似文献   

Lethal and sublethal effects of cantharidin on the life history traits and population parameters of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)     

Rashid A Khan  Maryam Rashid  Dun Wang  Ya‐Lin Zhang 《Pest management science》2014,70(1):39-45

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Minimizing the impact of fishing          下载免费PDF全文

Rainer Froese  Henning Winker  Didier Gascuel  U Rashid Sumaila  Daniel Pauly 《Fish and Fisheries》2016,17(3):785-802

Minimizing the impact of fishing is an explicit goal in international agreements as well as in regional directives and national laws. To assist in practical implementation, three simple rules for fisheries management are proposed in this study: 1) take less than nature by ensuring that mortality caused by fishing is less than the natural rate of mortality; 2) maintain population sizes above half of natural abundance, at levels where populations are still likely to be able to fulfil their ecosystem functions as prey or predator; and 3) let fish grow and reproduce, by adjusting the size at first capture such that the mean length in the catch equals the length where the biomass of an unexploited cohort would be maximum (L_opt). For rule 3), the basic equations describing growth in age‐structured populations are re‐examined and a new optimum length for first capture (L_{c_opt}) is established. For a given rate of fishing mortality, L_{c_opt} keeps catch and profit near their theoretical optima while maintaining large population sizes. Application of the three rules would not only minimize the impact of fishing on commercial species, it may also achieve several goals of ecosystem‐based fisheries management, such as rebuilding the biomass of prey and predator species in the system and reducing collateral impact of fishing, because with more fish in the water, shorter duration of gear deployment is needed for a given catch. The study also addresses typical criticisms of these common sense rules for fisheries management.  相似文献   

DOES NITROGEN FERTILIZATION ENHANCE DROUGHT TOLERANCE IN SUNFLOWER? A REVIEW     

Rashid Ahmad  Ejaz Ahmad Waraich  M. Y. Ashraf  Shamim Ahmad  Tariq Aziz 《Journal of plant nutrition》2014,37(6):942-963

Water stress is one of the major limitations to the agricultural productivity around the globe, particularly in warm, arid and semi-arid regions of the world. Sunflower (Helianthus annuus L.), being a crop with medium water requirements, has the ability to tolerate a short period of drought. However, water stress in the soil as well as inside the plant influences various physiological and biochemical processes. This may inhibit plant growth, decrease developmental activities of the cells and tissues and cause a variety of morphological, physiological and biochemical modifications. Nitrogen (N) is one of the most important mineral nutrients because of its numerous effects on plant growth and yield. A number of fundamental processes such as water and nutrient uptake, protein metabolism, photosynthesis, carbon partitioning, and enzyme and plant hormonal activities are regulated by N. These responses result in profound changes in growth rate, net photosynthate production, plant development, and yield. It is well documented that nutrient uptake of plants is inhibited in dry soils and with expected nutrient deficiencies the normal functioning of the plants is affected. Different strategies are being practiced in the world to cope with the problem of nutrient deficiency under water stress. Nitrogen application either through soil or through foliar feeding is an important strategy to alleviate the adverse effect of drought. Supplemental application of N as foliar fertilization to soil-applied fertilization is important in situation where nutrient supply through soil is limited. Some of the relevant work available about the effect of water stress and nutrient availability in sunflower is reviewed in this paper.  相似文献   

Microhabitat preferences of fish assemblages in the Udzungwa Mountains (Eastern Africa)     

Rafael Muoz‐Mas  Javier Snchez‐Hernndez  Francisco Martínez‐Capel  Rashid Tamatamah  Shafi Mohamedi  Richard Massinde  Michael E. McClain 《Ecology of Freshwater Fish》2019,28(3):473-484

Environmental flow assessment (EFA) involving microhabitat preference models is a common approach to set ecologically friendly flow regimes in territories with ongoing or planned projects to develop river basins, such as many rivers of Eastern Africa. However, habitat requirements of many African fish species are poorly studied, which may impair EFAs. This study investigated habitat preferences of fish assemblages, based on species presence–absence data from 300 microhabitats collected in two tributaries of the Kilombero River (Tanzania), aiming to disentangle differences in habitat preferences of African species at two levels: assemblage (i.e. between tributaries) and species (i.e. species‐specific habitat preferences). Overall, flow velocity, which implies coarser substrates and shallower microhabitats, emerged as the most important driver responsible of the changes in stream‐dwelling assemblages at the microhabitat scale. At the assemblage level, we identified two important groups of species according to habitat preferences: (a) cover‐orientated and limnophilic species, including Barbus spp., Mormyridae and Chiloglanis deckenii, and (b) rheophilic species, including Labeo cylindricus, Amphilius uranoscopus and Parakneria spekii. Rheophilic species preferred boulders, fast flow velocity and deeper microhabitats. At the species level, we identified species‐specific habitat preferences. For instance, Barbus spp. preferred low flow velocity shallow depth and fine‐to‐medium substratum, whereas L. cylindricus and P. spekii mainly selected shallow microhabitats with coarse substrata. Knowledge of habitat preferences of these assemblages and species should enhance the implementation of ongoing and future EFA studies of the region.  相似文献   

Effect of Nitrogen Rates and Method of Nitrogen Application on Dry Matter Yield and some Characters of Sorghum-Sudangrass Hybrid     

Selahattin Iptas  A. Rashid Brohi 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(2):96-100

In this study, the effect of nitrogen (N) rates (0, 40, 80, 120, 160 and 200 kg N ha -1 ) and methods of N application (A 1 : all N at sowing; A 2 : no N at sowing, half N after the first cutting and the remaining half after the second cutting; A 3 : one-third N at sowing, one-third after the first cutting, and the last third after the second cutting) on dry matter (DM) yield and some characters of the sorghum-sudangrass hybrid was investigated. DM yield increased significantly from 27.0 g pot -1 (0 kg N ha -1 ) to 38.6 g pot -1 (120 kg N ha -1 ). Higher N rates continued to increase the number of tillers per plant -1 (except for 40 and 80 kg N ha -1 ). N rates have significant effect on crude protein (CP) content, and CP content varied from 6.71 to 7.08%. N up to 120 kg N ha -1 rate increased CP yield, but no difference was observed among 80, 120, 160 and 200 kg N ha -1 . There was no significant effect of the method of N application in terms of DM yield, tillering and CP yield. However, the method of N application had a significant effect on CP content, which was 7.09% by A 1 , 6.97% by A 2 and 6.57% by A 3 .  相似文献