Effects of landscape corridors on seed dispersal by birds   总被引：1，自引：0，他引：1  

Levey DJ  Bolker BM  Tewksbury JJ  Sargent S  Haddad NM 《Science (New York, N.Y.)》2005,309(5731):146-148

Habitat fragmentation threatens biodiversity by disrupting dispersal. The mechanisms and consequences of this disruption are controversial, primarily because most organisms are difficult to track. We examined the effect of habitat corridors on long-distance dispersal of seeds by birds, and tested whether small-scale (<20 meters) movements of birds could be scaled up to predict dispersal of seeds across hundreds of meters in eight experimentally fragmented landscapes. A simulation model accurately predicted the observed pattern of seed rain and revealed that corridors functioned through edge-following behavior of birds. Our study shows how models based on easily observed behaviors can be scaled up to predict landscape-level processes.  相似文献   

Functional interaction between beta-catenin and FOXO in oxidative stress signaling     

Essers MA  de Vries-Smits LM  Barker N  Polderman PE  Burgering BM  Korswagen HC 《Science (New York, N.Y.)》2005,308(5725):1181-1184

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Forensic submissions in a diagnostic pathology practice: A 10-year review     

P. Nick Nation 《The Canadian veterinary journal. La revue veterinaire canadienne》2021,62(4):384

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Quantifying the water budget of irrigated rice in the Shepparton Irrigation Region, Australia   总被引：3，自引：0，他引：3  

Matthew Bethune  Nick Austin  Sheridan Maher 《Irrigation Science》2001,20(3):99-105

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Long-term trends in lobster populations in a partially protected vs. no-take Marine Park     

Nick T. Shears  Roger V. Grace 《Biological conservation》2006,132(2):222-231

Increasing the level of protection afforded to the marine environment requires assessment of the efficacy of existing marine protected areas (MPAs) in protecting exploited species. Long-term data from before and after the establishment of MPAs provide a rare but valuable opportunity to assess these effects. In this study we present long-term data (1977-2005) from before and after park establishment, on the abundance of spiny lobster Jasus edwardsii from fixed sites in a no-take marine park and a recreationally fished marine park, to assess the efficacy of no-take vs. partial protection. Lobster densities were comparable between both marine parks prior to park establishment, but the response of lobster populations differed markedly following protection. On average, legal-sized lobster were eleven times more abundant and biomass 25 times higher in the no-take marine park following park establishment, while in the partially protected marine park there has been no significant change in lobster numbers. Furthermore, no difference was found in densities of legal-sized lobster between the partially protected marine park and nearby fully-fished sites (<1 per 500 m²). Long-term data from fully fished and partially protected sites suggest long-term declines in lobster populations and reflect regional patterns in catch per unit effort estimates for the fishery. The long-term patterns presented provide an unequivocal example of the recovery of lobster populations in no-take MPAs, but clearly demonstrate that allowing recreational fishing in MPAs has little benefit to populations of exploited species such as J. edwardsii.  相似文献   

Identification of groups of metabolically-active rhizosphere microorganisms by stable isotope probing of PLFAs     

Amy M. Treonis  Nick J. Ostle  Ruth Primrose  Philip Ineson 《Soil biology & biochemistry》2004,36(3):533-537

We combined microbial community phospholipid fatty acid (PLFA) analyses with an in situ stable isotope ¹³CO₂ labelling approach to identify microbial groups actively involved in assimilation of root-derived C in limed grassland soils. We hypothesized that the application of lime would stimulate more rapid ¹³C assimilation and turnover in microbial PLFAs. Four and 8 d after label application, 18:1ω9, 18:2ω6,9 (fungal biomarkers) and 16:1ω7, 18:1ω7, 19:0cy (Gram-negative bacterial biomarkers) showed the most ¹³C enrichment and rapid turnover rates. This suggests that these microorganisms were assimilating recently-photosynthesized root C inputs to soils. Contrary to our hypothesis, liming did not affect assimilation or turnover rates of ¹³C-labelled C. ¹³C stable isotope pulse-labelling technique paired with analyses of PLFA microbial biomarkers shows promise for in situ investigations of microbial function in soils.  相似文献   

Root parasite induced nitrogen transfer between plants is density dependent     

Karsten M. Dromph  Nick J. Ostle 《Soil biology & biochemistry》2006,38(8):2495-2498

Recent studies point to the importance of soil borne parasites as agents of vegetation change via their negative effect on host plants. Here we show that these soil organisms can influence vegetation characteristics by increasing the transfer of the plant growth-limiting nutrient nitrogen (N) from their host, a N-fixing legume, to neighbouring grass species, thereby benefiting the growth of the neighbour. Furthermore, the amount of N transferred from the legume to the neighbour, and its consequent effect on the neighbours growth, was dependant on the density of root infestation. This mechanism of N transfer from legumes to neighbouring plant species is likely to be an important agent of vegetation change.  相似文献   

Iron deficiency stress responses amongst citrus rootstocks     

Michael Treeby  Nick Uren 《植物养料与土壤学杂志》1993,156(1):75-81

Seedlings of citrus rootstocks differing in lime tolerance were grown in nutrient solution with and without Fe. Proton efflux, release of phenolic compounds and Fe reducing substances and root-mediated reduction of Fe^III in FeEDTA and freshly precipitated Fe(OH)₃ in response to Fe deficiency were determined. Sweet orange, Carrizo citrange and trifoliate orange, the three least tolerant rootstocks used in the study, did not decrease nutrient solution pH in response to Fe deficiency. The more lime tolerant rootstocks, rough lemon, Cleopatra mandarin and sour orange, did decrease nutrient solution pH. But in CaSO₄ solution only sour orange increased H⁺ efflux significantly under Fe deficiency. In response to Fe deficiency, the release of phenolic compounds was increased significantly in rough lemon and Cleopatra mandarin seedlings, while the release of reducing substances was increased significantly in rough lemon, sour orange and trifoliate orange. Rough lemon was the only rootstock to respond to Fe deficiency with an increase in root-mediated reduction of chelated Fe^III at pH 6.5. At pH 8.0, both Fe-deficient rough lemon and Cleopatra mandarin roots reduced higher amounts of Fe^III from freshly precipitated Fe(OH)₃ than Fe-sufficient seedlings. Iron reduction by detached roots of Fe-deficient and Fe-sufficient rough lemon did not follow Michaelis-Menten kinetics at high substrate concentrations. Rates of Fe reduction at low substrate concentrations were inconsistent with the existence of an inducible ferric reductase in response to Fe deficiency.  相似文献   

Tillage and surface moisture effects on bare-soil albedo of a tropical loamy sand   总被引：1，自引：0，他引：1  

Philip G. Oguntunde  Ayodele E. Ajayi  Nick van de Giesen 《Soil & Tillage Research》2006,85(1-2):107-114

Effects of four tillage systems on the albedo of a tropical loamy sand were studied under dry and moist surface conditions. The aim was to determine whether tillage-induced roughness and soil wetness significantly affected soil albedo. Changes in smooth reference surface albedo with respect to four roughness conditions were used to assess tillage effects. Surface albedo (), soil moisture content (θ_m) and soil surface roughness (δ) were measured. Two types of pyranometers used for albedometers are CM 3 and SP LITE. Mean albedo of a reference smooth surface (<2 mm sieved soil) was 0.16 and 0.20 for CM 3 and SP LITE under moist condition, and 0.29 and 0.28 under dry condition, respectively. Bare-soil shortwave albedo generally increased with an increase in solar zenith angle, whereas albedo decreased with an increase in surface roughness and soil wetness. Linear relationships of albedo with surface roughness and soil moisture content indicated that albedo was more sensitive to surface roughness under dry condition. The goodness-of-fit of a multiple linear regression model combining the effects of roughness and wetness on surface albedo was 0.96 with a standard error of 0.01. This simple model could be used to estimate albedo of bare soil similar to the tropical loamy sand reported in this study. This study provides useful information for modelling tillage effects on the energy budget at the soil surface.  相似文献   

Association between anesthesia duration and outcome in dogs with surgically treated acute severe spinal cord injury caused by thoracolumbar intervertebral disk herniation     

Joe Fenn  Hongyu Ru  Nick D. Jeffery  Sarah Moore  Andrea Tipold  Franz J. Soebbeler  Adriano Wang-Leandro  Christopher L. Mariani  Peter J. Early  Karen R. Muñana  Natasha J. Olby 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2020,34(4):1507-1513

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