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61.
Axel Bronstert José-Carlos de Araújo Ramon J. Batalla Alexandre Cunha Costa José Miguel Delgado Till Francke Saskia Foerster Andreas Guentner José Andrés López-Tarazón George Leite Mamede Pedro Henrique Medeiros Eva Mueller Damià Vericat 《Journal of Soils and Sediments》2014,14(12):2001-2018
Purpose
To support scientifically sound water management in dryland environments a modelling system has been developed for the quantitative assessment of water and sediment fluxes in catchments, transport in the river system, and retention in reservoirs. The spatial scale of interest is the mesoscale because this is the scale most relevant for management of water and land resources.Materials and methods
This modelling system comprises process-oriented hydrological components tailored for dryland characteristics coupled with components comprising hillslope erosion, sediment transport and reservoir deposition processes. The spatial discretization is hierarchically designed according to a multi-scale concept to account for particular relevant process scales. The non-linear and partly intermittent run-off generation and sediment dynamics are dealt with by accounting for connectivity phenomena at the intersections of landscape compartments. The modelling system has been developed by means of data from nested research catchments in NE-Spain and in NE-Brazil.Results and discussion
In the semi-arid NE of Brazil sediment retention along the topography is the main process for sediment retention at all scales, i.e. the sediment delivery is transport limited. This kind of deposition retains roughly 50 to 60 % of eroded sediment, maintaining a similar deposition proportion in all spatial scales investigated. On the other hand, the sediment retained in reservoirs is clearly related to the scale, increasing with catchment area. With increasing area, there are more reservoirs, increasing the possibility of deposition. Furthermore, the area increase also promotes an increase in flow volume, favouring the construction of larger reservoirs, which generally overflow less frequently and retain higher sediment fractions. The second example comprises a highly dynamic Mediterranean catchment in NE-Spain with nested sub-catchments and reveals the full dynamics of hydrological, erosion and deposition features. The run-off modelling performed well with only some overestimation during low-flow periods due to the neglect of water losses along the river. The simulated peaks in sediment flux are reproduced well, while low-flow sediment transport is less well captured, due to the disregard of sediment remobilization in the riverbed during low flow.Conclusions
This combined observation and modelling study deepened the understanding of hydro-sedimentological systems characterized by flashy run-off generation and by erosion and sediment transport pulses through the different landscape compartments. The connectivity between the different landscape compartments plays a very relevant role, regarding both the total mass of water and sediment transport and the transport time through the catchment. 相似文献62.
Kloss S Wehrend A Failing K Bostedt H 《Berliner und Münchener tier?rztliche Wochenschrift》2002,115(7-8):247-251
The incidence of dystocia from ewes in nine lambing periods (1992-2000) was recorded at an obstetrical clinic. First we analysed parturition difficulties in normal pregnant sheep (group 1, n = 229). In the second group parturitions of ewes with vaginal prolapse ante partum were investigated (n = 129). In group 1 maternal causes of dystocia occurred more often than fetal ones (50% maternal, 45% fetal). In maternal parturition difficulties ringwomb was the dominating reason (64%), while abnormal presentations, position and/or posture of the lambs occurred most frequently in fetal dystocia (67%). But there was no statistical influence of age and number of parturitions in both groups. The average of the first notice of prolapsed vaginal tissue was 11 days before lambing. There was a predominance in the affection of sheep at first and second pregnancy (52%). Only 26% of the group 2 sheep had a spontaneous delivery. In 58% of the cases a dystocia was diagnosed. A preterm caesarean section had carried out in 12%, five ewes died before parturition because of septicemia (4%). Sheep suffering from vaginal prolapse ante partum showed maternal caused dystocia significant more frequently than members of group 1 (p < 0.001), with ringwomb as dominating reason (70%). The number of born lambs was significant higher in group 2 than in group 1 (p = 0.019). 相似文献
63.
Duncker SC Lorentz A Schroeder B Breves G Bischoff SC 《Veterinary immunology and immunopathology》2006,111(3-4):239-250
Several beneficial effects of probiotics have been described in studies using rodent disease models and in human patients; however, the underlying mechanisms remained mostly unclear. Only a few studies focused on the effects of probiotics on the intestinal mucosal immune system. Here, we studied the effect of the probiotic strain E. coli Nissle 1917 (EcN) administered orally to young pigs at two concentrations (10(9) and 10(11)CFU/d for 21 days) on the gut-associated lymphatic tissue. This probiotic strain was shown recently to reduce recurrence of inflammation in ulcerative colitis patients. We quantified the number and distribution of intestinal immune cells (granulocytes, mast cells, CD4+, CD8+, CD25+, IgA+ lymphocytes) and the mucosal mRNA expression of cytokines (IFN-gamma, TNF-alpha, TGF-beta, IL-10) and antimicrobial peptides (PR-39, NK-lysin, prepro-defensin-beta 1, protegrins). The number and distribution of cells were highly different between small intestinal and colon segments in all groups, but were not influenced by EcN, except high dose EcN fed pigs (10(11) CFU/d) showing an increase in mucosal CD8+ cells in the ascending colon. The mRNA analysis revealed no changes associated with EcN feeding. In conclusion, according to our analyses EcN has only minor effects on the distribution of mucosal immune cells in the gut of healthy individuals. The well-established preventive effects of EcN might therefore be relate to other mechanisms than simple modulation of immune cell distribution. 相似文献
64.
We address the problem of how to integrate risk assessment into forest management and therefore provide a comprehensive review
of recent and past literature on risk analysis and modeling and, moreover, an evaluation and summary on these papers. We provide
a general scheme on how to integrate concepts of risk into forest management decisions. After an overview of the risk management
process and the main hazards in forests (storm, snow, insects, fire), the paper focuses on the principal methods used to assess
risks from these hazards for commercial forestry. We review mechanistic models, empirical models, and expert systems and consider
the needs for different spatial scales of risk assessment, from the regional to the single-tree level. In addition to natural
hazards and their secondary effects, we deal with economic aspects of risk analysis. Monte Carlo simulations to deal with
volatile timber prices and ways to include risk in classical Faustmann approaches are briefly discussed along with the integration
of portfolio theory into forest management decision making and attitude toward risk. Special attention is paid to the implications
for risk modeling under climate change. 相似文献
65.
Axel Klein 《Journal of pest science》1974,47(12):178-183
Summary
View of bird protection measures in Saarland
Bird protection measures are carried out in the public and communal forests of Saarland since many years. From 1971 to 1973 the results of controlling the nest boxes in autumn were evaluated centrally. 12.6% of the boxes were damaged or stolen, 16.9% were unoccupied and 65,1% hatched. The rest were boxes containing died eggs or broods as well as wasps and other inquilines.Titmice were the most frequent breeding birds (68,1%), followed byMuscicapa spec. (14.1%) andSitta europaea (6.7%). This shows that nest boxes are for the benefit of common birds only. They don't show an advancement of rare species. Therefore a reorientation is planned with regard to the advancement of more rare bird species. 相似文献
66.
67.
Natural regeneration measurements are the main silvicultural objective in overaged protective forests of the Bavarian Limestone
Alps. While manifold problems with these stands, especially the impact of browsing, are widely recognised, the regeneration
niches of Norway spruce (Picea abies [L.] Karst.) are insufficiently known. The purpose of this study was to determine favourable combinations of site factors
for the development of spruce in small, unfenced canopy gaps, located on Aposerido-Fagetum caricetosum albae forest sites. We recorded the occurrence of spruce saplings (as dependent variable) and of six site factors (as independent
variables) on 480 0.5 m2-subplots. In addition, we estimated the coverage of six acid adapted plant species to determine correlations with the humus
depth. A binary logistic regression analysis was used to predict the probability of the occurrence of a spruce sapling in
dependency of the different site factors. Supported by other studies, we assumed that the supply of solar radiation was adequate
for the sufficient regeneration of spruce within the canopy gaps. Other site factors significantly determined the regeneration
niches of spruce saplings. More spruce saplings were found near hindrances and on rough surfaces than would be expected from
a random occurrence of saplings. These microsite types may have characteristics, especially protection against snow gliding
that promotes spruce establishment. A calculated “hindrance index”, which accounted for the number, and the distance of surrounding
hindrances might be a good specific value to describe the influence of hindrances on steep slopes. The sapling establishment
decreased on thin humus layers. Our assumption for the sites was that thick organic layers might represent a good seedbed
for spruce. Decayed dead wood was scarce, but was exceedingly favoured by spruce saplings. Results obtained suggest that the
natural regeneration establishment of spruce on steep slopes can be successfully influenced by site factors which inhibit
the influence of snow gliding. According to a “positive microsite” concept, we recommend for artificial regeneration measurements
with spruce, microsites close to hindrances (e.g. stumps, downed trees) and Vaccinium myrtillus as a predictor for thick, acid humus layers. 相似文献
68.
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
69.
Comparison of new foliar nutrient thresholds derived from van den Burg’s literature compilation with established central European references 总被引:1,自引:1,他引:0
In this paper, we suggest new nutrient threshold values and ratios for the major nutrients (N, P, K, Ca, Mg) for four main trees species Pinus sylvestris, Picea abies, Fagus sylvatica and Quercus (Q. robur and Q. petraea) statistically derived from the data collection of van den Burg’s literature compilation (1985, 1990), and compare them with widely used central European literature. The comparison is focused on the normal range of nutrition of major elements. We could show that the new critical foliar nutrient concentrations and ratios do not have the imponderabilities of the established reference systems, like restricted calibration range or data gaps for species in general or some major nutrients in particular. Ranges from the new critical foliar nutrient concentrations are generally smaller, except for broadleaves foliar Ca and Mg values, where another reference provides the narrowest ranges. The practicability of the different systems has been exemplary tested on a foliage data set of Norway spruce from the Bavarian soil survey. This application illustrates that an evaluation based on the new nutrient thresholds is in the majority of cases more cautious than the other reference systems. Moreover, evaluations based on the new concentrations and ratios are quite consistent. Comparisons with nutrient ratios related to the susceptibility to parasite attacks show that the thresholds are close to a general optimum range, indicating health and intact resistance mechanisms of these tree species. Uncertainties of the new threshold values as well as the need to further evaluate and develop reference systems for nutrient status of forest trees are discussed. 相似文献
70.
Bark beetle dispersal and host selection behaviour are a complex and poorly understood process, resulting in specific spatio-temporal infestation patterns in forests. Aerial images from the Bavarian Forest National Park (Germany) provide a high-resolution, that is, tree-scale data set for the period 2001–2010, including information about Ips typographus (Col., Curculio., Scolytinae) infestation, the application of sanitary logging, natural forest edges and the area of living spruce susceptible to bark beetle infestation. We combined methods of GIS and image analysis to investigate the infestation probabilities at three types of forest edges under spatial and temporal aspects and compared them to the corresponding probabilities at the stand interior. Our results showed a pronounced infestation predisposition of such edge trees delimiting infestation patches cleared by sanitary logging measures, in particular at the south-facing edge sector. In contrast, edges adjacent to non-cleared infestation were revealed as less attractive for subsequent infestations, but nonetheless more attractive than permanent forest edges or the stand interior. Additionally, we measured near-bark surface air temperature to determine microclimatic differences at those edge- or non-edge sites and related them to predisposition results. Finally, our study emphasized favourable microclimatic conditions—summarized as the “sun-effect”—as a decisive factor enhancing the local infestation probability at recent forest edges in multiple ways. Both insect- and host tree-related reactions to suddenly altered microclimate are supposed to bias arbitrary colonization behaviour at patch and tree level, thereby mainly explaining observed infestation patterns. From the forester’s point of view, our results may contribute to precise bark beetle risk assessment and thus facilitate decision making in forest management. 相似文献