Spatial and temporal variations in soil respiration in relation to stand structure and soil parameters in an unmanaged beech forest   总被引：1，自引：0，他引：1  

Søe AR  Buchmann N 《Tree physiology》2005,25(11):1427-1436

Soil CO2 efflux (soil respiration) plays a crucial role in the global carbon cycle and efflux rates may be strongly altered by climate change. We investigated the spatial patterns of soil respiration rates in 144 measurement locations in a 0.5-ha plot and the temporal patterns along a 300-m transect in the 0.5-ha plot. Measurements were made in an unmanaged, highly heterogeneous beech forest during 2000 and 2001. We investigated the effects of soil, roots and forest stand structure on soil respiration, and we also assessed the stability of these spatial patterns over time. Soil temperature alone explained between 68 and 95% of the temporal variation in soil respiration; however, pronounced spatial scatter of respiration rates was not explained by soil temperature. The observed spatial patterns stayed remarkably stable throughout the growing season and over 2 years. The most important structural parameter of the stand was the mean diameter at breast height of trees within a distance of 4 m of the measurement locations (m-dbh4), which explained 10-19% of the variation in soil respiration throughout the growing season. Among the soil chemical parameters, carbon content (bulk as well as dissolved) and magnesium content explained 62% of the spatial variation in soil respiration. The final best model combining soil, root and stand structural parameters (fine root biomass, soil carbon content, m-dbh4 and soil water content) explained 79% of the variation in soil respiration, illustrating the importance of both biotic and abiotic factors.  相似文献   

Physical activity, diet and gene-environment interactions in relation to body mass index and waist circumference: the Swedish young male twins study     

Karnehed N  Tynelius P  Heitmann BL  Rasmussen F 《Public health nutrition》2006,9(7):851-858

OBJECTIVE: The aim of the present study was to examine the relationships between genetic susceptibility to obesity, physical activity (PA), dietary fibre, sugar and fat intakes and 4-year changes in body mass index (BMI) and attained waist circumference (WC) in a cohort of 287 monozygotic and 189 dizygotic young adult male twin pairs. Increased knowledge about interactions between genes and environment may provide insight into why some individuals are more prone to obesity than others. DESIGN: Information about PA, BMI, dietary habits, WC and potential confounders was collected by questionnaire in 1998 and 2002. The cohort data were analysed by mixed linear models. RESULTS: Twins with low PA attained larger WC than twins with high PA (difference 2.5 cm; 95% confidence interval (CI) 1.3, 3.6). The twins with the lowest fibre intake were found to have attained the highest WC and to have increased most in BMI (difference between highest and lowest fibre intakes: 1.6 cm, 95% CI 0.4, 2.9 and 0.45 kg m(-2), 95% CI 0.15, 0.76, respectively). Furthermore, our results suggested the presence of interactions so that twins with genetic susceptibility to obesity were more prone to have larger WC if sedentary than twins without genetic susceptibility. CONCLUSION: PA and a diet rich in fibre may be protective against weight gain among younger adult men. An interaction between PA, genes and attained WC is a novel finding which needs confirmation by other studies.  相似文献   

Debating sexual selection and mating strategies     

Dall SR  McNamara JM  Wedell N  Hosken DJ 《Science (New York, N.Y.)》2006,312(5774):689-97; author reply 689-97

  相似文献   

Treatment for fear of fireworks in dogs     

Mills D  Cracknell N 《The Veterinary record》2006,159(16):536

  相似文献   

Common Kibra alleles are associated with human memory performance   总被引：1，自引：0，他引：1  

Papassotiropoulos A  Stephan DA  Huentelman MJ  Hoerndli FJ  Craig DW  Pearson JV  Huynh KD  Brunner F  Corneveaux J  Osborne D  Wollmer MA  Aerni A  Coluccia D  Hänggi J  Mondadori CR  Buchmann A  Reiman EM  Caselli RJ  Henke K  de Quervain DJ 《Science (New York, N.Y.)》2006,314(5798):475-478

Human memory is a polygenic trait. We performed a genome-wide screen to identify memory-related gene variants. A genomic locus encoding the brain protein KIBRA was significantly associated with memory performance in three independent, cognitively normal cohorts from Switzerland and the United States. Gene expression studies showed that KIBRA was expressed in memory-related brain structures. Functional magnetic resonance imaging detected KIBRA allele-dependent differences in hippocampal activations during memory retrieval. Evidence from these experiments suggests a role for KIBRA in human memory.  相似文献   

Retrospective. Norton Zinder (1928-2012)     

Lodish H  Fedoroff N 《Science (New York, N.Y.)》2012,335(6074):1316

  相似文献   

Do different breeding lines show unequal problem-solving strategies at an early age of life?—A comparison of two labrador retriever breeding lines at week 8 of life     

Nina Reitz  Franzsika Kuhne  Rainer Struwe 《Journal of Veterinary Behavior: Clinical Applications and Research》2009,4(2):52

  相似文献   

Factors affecting piglet mortality in loose farrowing systems on commercial farms   总被引：1，自引：0，他引：1  

Roland Weber  Nina M. Keil  Max Fehr  Ren Horat 《Livestock Science》2009,124(1-3):216-222

Crating sows in farrowing systems greatly restricts their normal behaviour (e.g. movement, nest-building, leaving the nest site for defecation), which is usually justified by the assumption that piglet mortality is higher with loose-housed sows. Based on experiments showing that this is not the case, farrowing crates were banned in Switzerland in 1997, with a 10-year transitional period. Since then, many farms have introduced loose farrowing systems, enabling an analysis of risk factors for piglet mortality in crateless farrowing systems based on a large sample size. Data from a Swiss sow recording scheme (UFA2000) were analysed using generalised linear mixed-effects models with an underlying Poisson distribution. Average total piglet mortality for the years 2002 and 2003 on 99 farms (N = 12457 litters) with loose farrowing systems amounted to 1.36 liveborn piglets per litter. The number of crushed piglets was 0.64 piglets per litter, whereas the number of piglets that died for other reasons was 0.72 piglets per litter.Herd size, pen size, possibility of confinement of the sow, presence of piglet protection bars and year of data collection did not significantly influence total piglet losses, losses due to crushing and losses due to reasons other than crushing. With greater litter size at birth, significantly more losses occurred due to all reasons (total, crushed, others). Total piglet mortality and losses for reasons other than crushing were significantly higher in older sows. Losses were therefore mainly attributable to sow-related characteristics rather than to the design of the farrowing pen.  相似文献   

Concomitant exposure of rainbow trout fry to Gyrodactylus derjavini and Flavobacterium psychrophilum: effects on infection and mortality of host     

Busch S  Dalsgaard I  Buchmann K 《Veterinary parasitology》2003,117(1-2):117-122

Although rainbow trout fry mortality syndrome caused by the bacterium Flavobacterium psychrophilum is widespread in fish farms it is difficult to reproduce infection of rainbow trout in the laboratory using immersion exposure with bacterial suspensions. It has therefore been speculated that ectoparasites could act as enhancers of bacterial infections under natural conditions. In the present study rainbow trout fry were exposed to infections with F. psychrophilum (immersion for 30 min or 10 h) alone, exposed to the ectoparasitic monogenean Gyrodactylus derjavini alone or exposed to both pathogens in combination. Infection levels and host mortality were subsequently monitored to elucidate if the ectoparasitic monogeneans could enhance infection of fish with the bacterium. Immersion of fish in bacterial suspensions alone did not result in infection. Only one fish became infected with the bacterium and this fish belonged to the combination exposure group. The parasite populations increased differently in the various groups and it was found that host mortality was correlated to gyrodactylid infection levels (r=0.94) but not to bacterial exposure. The results emphasise the pathogenicity of the parasite G. derjavini, the relative resistance of intact fish to direct exposure to F. psychrophilum but provide only a weak indication of a possible enhancement of bacterial invasion due to ectoparasitic infections. It cannot be excluded that higher parasite burdens and/or prolonged immersion (more than 10 h) in bacterial suspensions may result in bacterial invasion.  相似文献   

Dermatophytosis in three colony-born spotted hyenas     

Hahn NE  Jenné KJ  Diggs HE 《Journal of the American Veterinary Medical Association》2003,223(12):1809-11, 1779

An adult female hyena and her two 4-month-old cubs were found to have multifocal areas of alopecia and dermatitis. Dermatophyte culture of hair and skin samples collected from the lesions yielded Trichophyton mentagrophytes. None of 10 other animals in the colony that were tested were found to have dermatophytes. Lesions were treated twice, at 3-week intervals, with thorough cleansing with chlorhexidine scrub followed by topical application of antifungal agents. Lesions resolved, and dermatophyte culture of samples collected 6 weeks after the initiation of treatment did not yield growth.  相似文献