Contribution of runoff to incomplete off season soil water refilling in a Mediterranean vineyard

The dynamics of soil water was investigated in a Mediterranean vineyard during the 2003-2007 period in order to identify the inter-seasonal modification of water storage due to intercropping. The intercrop was a mixture of tall fescue and rye grass. Soil water content was measured on 3 m soil profiles (plus one 5 m profile) as was runoff from local stands.Great variations in soil refilling were observed over the years, for both the bare soil and intercrop treatments. The complete refilling occurred once and it was associated with a rise of the water table up to less than 2 m from the soil surface in the low part of the field. During the other years, the wetting front was identified between 1 m and 2.3 m at spring in the bare soil treatment, deeper in the lowest part of the field. The available soil water content at bud-break was influenced by the topography. A higher infiltration was observed in the intercropped treatment. Runoff kinetics was compared to rainfall kinetics in a selection of three rain events differing by duration and intensity. The curve number method was used to perform the analysis of runoff at a 1-day time-step rather than the quarter of an hour time-step of the registrations. With this method, the time limitation of water balance studies for Mediterranean vineyards would be partially removed.     

Resource landscapes and movement strategy shape Queensland Fruit Fly population dynamics

Context

Animal population dynamics are shaped by their movement decisions in response to spatial and temporal resource availability across landscapes. The sporadic availability and diversity of resources can create highly dynamic systems. This is especially true in agro-ecological landscapes where the dynamic interplay of insect movement and heterogeneous landscapes hampers prediction of their spatio-temporal dynamics and population size.

Objectives

We therefore systematically looked at population-level consequences of different movement strategies in temporally-dynamic resource landscapes for an insect species whose movement strategy is slightly understood: the Queensland Fruit Fly (Bactrocera tryoni)

Methods

We developed a spatially-explicit model to predict changes in population dynamics and sizes in response to varying resources across a landscape. We simulated the temporal dynamics of fruit trees as the main resource using empirical fruiting dates. Movement strategies were derived from general principles and varied in directedness of movement and movement trigger.

Results

We showed that temporal continuity in resource availability was the main contributing factor for large and persistent populations. This explicitly included presence of continuous low-density resources such as fruit trees in urban areas. Analysing trapping data from SE Australia supported this finding. We also found strong effects of movement strategies, with directed movement supporting higher population densities.

Conclusions

These results give insight into structuring processes of spatial population dynamics of Queensland Fruit Fly in realistic and complex food production landscapes, but can also be extended to other systems. Such mechanistic understanding will help to improve forecasting of spatio-temporal hotspots and bottlenecks and will, in the end, enable more targeted population management.

     

The risk of ignoring fear: underestimating the effects of habitat loss and fragmentation on biodiversity

Landscape Ecology - Habitat loss and fragmentation threaten species not only through structural landscape changes and resource reduction, but also through modifications to species’...     

Studies of Escherichia Coli in Gnotobiotic Pigs: V. Evaluation of the Effects of Orål and Parenteral Administration of Immune Serum

The effects of orally and/or parenterally administered immune serums were evaluated in 36 gnotobiotic pigs infected with an enteropathogenic strain of Escherichia coli. Pigs were euthanatized at predetermined time intervals between 6 and 48 hours prostinfection. The results were evaluated on the basis of: 1) clinical observations, 2) necropsy observations, 3) counts of viable E. coli in segments of the small intestine, 4) attempts to isolate E. coli from the heart, liver, and bile, 5) microscopic examination of fixed intestinal sections to determine the location of E. coli and morphologic evidence of the host response, and 6) determination of the pH of the various portions portions of the gastrointestinal tract.     

Analgesic effect of butorphanol and levomethadone in detomidine sedated horses

The analgesic potency of butorphanol 25 microg/kg bodyweight (BW) and levomethadone 100 microg/kg BW, administered together with detomidine 10 microg/kg BW, was measured in twelve Warmblood horses in a randomized, blinded cross-over study. Detomidine with saline 10 ml 0.9% was used as placebo. The nociceptive threshold was determined using a constant current and a pneumatic pressure model for somatic pair Detomidine alone and in combination with butorphanol or levomethadone caused a significant temporary increase (P < 0.05) of the nociceptive threshold with a maximum effect within 15 min and a return to baseline levels within 90 min. Butorphanol and levomethadone increased the nociceptive threshold and prolonged the duration of anti-nociception significantly from 15 to 75 min (P < 0.05) after drug administration compared with detomidine alone to both test methods. No significant difference between butorphanol and levomethadone was registered. It is concluded that the addition of butorphanol or levomethadone to detomidine increases the nociceptive threshold to somatic pain and prolongs the analgesic effect of detomidine in the horse.     

To What Extent Can Silviculture Enhance Sustainability of Forest Sites under the Immission Regime in Central Europe?

Stand structure and tree species composition influence not only the volume flux of soil water but also the concentration of dissolved minerals in the soil solution. We found much higher element fluxes under spruce than under beech stands. This is mainly caused by different activities of nitrate in the soil solution and by different deposition rates of nitrogen and acids from the atmosphere which were ±60% lower in beech stands than in spruce stands. In old spruce stands, the acid output with the seepage water was more or less equal to the input, whereas in beech stands most of the acid deposition was buffered. The nitrogen balance in beech stands was characterized by a net uptake of about 60% to 75% of the input. In spruce stands only 40% of the nitrogen input was incorporated. In a clear-cut, a high mobilization rate of nitrate was found in the first 5 years, resulting in nitrate concentrations above the threshold for drinking water quality. The cutting of even a single tree in a spruce stand caused heavy mineralization and nitrification for at least 2 years, which indicates that the system is near nitrogen saturation.