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See detailInvasion by Fallopia japonica increases topsoil mineral nutrient concentrations
Dassonville, Nicolas; Vanderhoeven, SONIA ULg; Gruber, Wolf et al

in Ecoscience (2007), 14(2), 230-240

Fallopia japonica is one of the most troublesome alien invasive plants across temperate regions, with large negative impacts on plant species diversity. We examined its impacts on topsoil chemistry and ... [more ▼]

Fallopia japonica is one of the most troublesome alien invasive plants across temperate regions, with large negative impacts on plant species diversity. We examined its impacts on topsoil chemistry and nutrient stocks in standing biomass at 6 sites with contrasting resident plant communities in Belgium. Topsoil and biomass were sampled in invaded and closely adjacent uninvaded plots. Standing biomass and mineral nutrient concentrations in soil (ammonium acetate exchangeable cations and P, total C, and N) and plants were determined. Soil under F. japonica generally had higher exchangeable nutrient concentrations (Cu: +45%, K: +34%, Mg: +49%, Mn: +61%, P: +44%, Zn: +75%). Standing biomass was 3- to 13-fold higher depending on site. Despite lower nutrient concentrations in aboveground biomass, invaded stands had 3.2- to 5.4-fold larger nutrient stocks in aboveground biomass compared to the resident vegetation. We conclude that F. japonica enhances nutrient cycling rates and topsoil fertility, probably due to nutrient uplift. The impacts were greatest in sites with low nutrient concentrations in uninvaded plots, suggesting that F. japonica may contribute to soil homogenization in invaded landscapes. [less ▲]

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See detailTerrestrial versus aquatic foraging in juvenile Alpine newts (Triturus alpestris)
Denoël, Mathieu ULg

in Ecoscience (2004), 11(4), 404-409

Many species of newts and salamanders forage in both terrestrial and aquatic environments during their life. However, the relative benefits of the two foraging patterns remain unknown because all previous ... [more ▼]

Many species of newts and salamanders forage in both terrestrial and aquatic environments during their life. However, the relative benefits of the two foraging patterns remain unknown because all previous studies have focused on only one habitat. The aim of this study was to find out which foraging tactic is the most successful in terms of energy intake. To this end, I analyzed trophic habits in metamorphosed juveniles in the Alpine newt, Triturus alpestris veluchiensis, inhabiting an alpine lake (Drakolimni) and the surrounding lands (Tymphi Mountains, northern Greece). The diet of the newts reflected the range of prey available in the two habitats, but aquatic newts also foraged on invertebrates that fell on the water surface. The two lifestyles have different energy outcomes. Terrestrial invertebrates provided high energy gains mainly to terrestrial juveniles because of the low number of this prey type in the lake. However, terrestrial juveniles are expected to suffer higher mortality (freezing on land is more probable than in deep waters) and a lower energy intake when air temperature is low, i.e., the main pattern in high-elevation sites, except during mid-summer. Persistence of the aquatic foraging tactics in the population may depend on a trade-off between costs and benefits. [less ▲]

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