Filters

20183

More filters

2020 - 20233
Reset filters

Settings

End date: 2018 × Start date: 2018 × DDC: 590 × Version: publishedVersion ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Off-grid: solar powered LED illumination impacts epigeal arthropods
    (Oxford [u.a.] : Wiley- Blackwell, 2018) Eccard, Jana A.; Scheffler, Ingo; Franke, Steffen; Hoffmann, Julia
    Advances in LED technology combined with solar, storable energy bring light to places remote from electricity grids. Worldwide more than 1.3 billion of people are living off-grid, often in developing regions of high insect biodiversity. In developed countries, dark refuges for wildlife are threatened by ornamental garden lights. Solar powered LEDs (SPLEDs) are cheaply available, dim, and often used to illuminate foot paths, but little is known on their effects on ground living (epigeal) arthropods. We used off-the-shelf garden lamps with a single ‘white’ LED (colour temperature 7250 K) to experimentally investigate effects on attraction and nocturnal activity of ground beetles (Carabidae). We found two disparate and species-specific effects of SPLEDs. (i) Some nocturnal, phototactic species were not reducing activity under illumination and were strongly attracted to lamps (>20-fold increase in captures compared to dark controls). Such species aggregate in lit areas and SPLEDs may become ecological traps, while the species is drawn from nearby, unlit assemblages. (ii) Other nocturnal species were reducing mobility and activity under illumination without being attracted to light, which may cause fitness reduction in lit areas. Both reactions offer mechanistic explanations on how outdoor illumination can change population densities of specific predatory arthropods, which may have cascading effects on epigeal arthropod assemblages. The technology may thus increase the area of artificial light at night (ALAN) impacting insect biodiversity. Measures are needed to mitigate effects, such as adjustment of light colour temperature and automated switch-offs.
  • Thumbnail Image
    Item
    Sensor-based detection of the severity of hyperkeratosis in the teats of dairy cows
    (Basel : MDPI AG, 2018) Demba, S.; Hoffmann, G.; Ammon, C.; Rose-Meierhöfer, S.
    The aim of this study was to evaluate whether the severity of hyperkeratosis (HK) in the teats of dairy cows can be assessed by a dielectric measurement. The study focused on surveying the occurrence of hyperkeratosis in a total of 241 teats of lactating dairy cows. A scoring system consisting of four categories was used to macroscopically assess the severity of HK. Additionally, the dielectric constant (DC) of all teats with milkability was measured in a double iteration with the MoistureMeterD (Delfin Technologies, Kuopio, Finland) on four different days. The Spearman rank correlation coefficient revealed a negative correlation between the DC and HK score (rs = −0.55 to −0.36). The results of the regression analysis showed that the DC values differed significantly between healthy teat ends (≤2) and teat ends with HK (≥3). Thus, the non-invasive measurement of DC provides a promising method of objectively assessing the occurrence and severity of HK.
  • Thumbnail Image
    Item
    Farm water productivity in conventional and organic farming: Case studies of cow-calf farming systems in North Germany
    (Basel : MDPI AG, 2018) Vellenga, L.; Qualitz, G.; Drastig, K.
    The increase of organic agriculture in Germany raises the question of how water productivity differs from conventional agriculture. On three organic and two conventionally farming systems in Germany, water flows and water related indicators were quantified. Farm water productivity (FWP), farm water productivity of cow-calf production (FWPlivestock), and farm water productivity of food crop production (FWPfood crops) were calculated using the modeling software AgroHyd Farmmodel. The FWP was calculated on a mass and monetary basis. FWPlivestock showed the highest productivity on a mass basis occurring on a conventional farm with 0.09 kg m-3Winput, whereas one organic farm and one conventional farm showed the same results. On a monetary basis, organic cow-calf farming systems showed the highest FWPlivestock, with 0.28 € m-3Winput. Since the productivity of the farm depends strongly on the individual cultivated plants, FWPfood crops was compared at the level of the single crop. The results show furthermore that even with a precise examination of farm water productivity, a high bandwidth of temporal and local values are revealed on different farms: generic FWP for food crops and livestock are not within reach.