Authors:G. Koncz, P. Török, M. Papp, G. Matus, and B. Tóthmérész
Intensification of land use in the last few decades resulted in an increased rate of fragmentation of natural forest habitats. With decreased patch size but increased total borderline length the influence of the surroundings also increased. The extent of influence is especially crucial where the forest stands are adjacent to agricultural lands. We studied the vegetation (cover) and seed bank (soil samples, seedling emergence) along adjacent stands of an abandoned vineyard and edge and interior of an oak forest community (Quercetum petraeae-cerris) widespread in Central-Europe, using five transects (16 m2 plots along each transect). We asked the following questions: (i) How do vegetation and seed bank composition differ between the vineyard and forest interior and (ii) which weeds are able to penetrate into the forest herbaceous understorey vegetation and seed banks from the vineyard? In total, 15 phanaerophytes and 147 herbs were detected. Negatively associated with canopy shading, herb cover proved the lowest in the forest inferior. Few weeds and other ruderals recorded in vineyard penetrated into the forest interior. Mean seed density decreased one order of magnitude from the vineyard to the forest interior (from 20,831 to 2,159 seed/m2). The seed banks of the abandoned vineyard and edge and forest interior were dominated by ruderals, but decreasing proportion of weeds was detected from the vineyard to the forest interior. Characteristic forest herbs possessed at most sparse seed banks. Our results suggest that high canopy cover mitigates the negative impact of surrounding weedy vegetation on the forest herb layer. Therefore, the effect of surroundings is detectable mostly in the seed banks. We can assume that the formation of an increased ruderal herb cover can be foreseen if canopy opens, because the local propagule sources of forest species are missing from vegetation and soil seed banks.
Authors:F. Tóth, L. Horváth, J. Komáromi, J. Kiss, and E. Széll
The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is a new pest of corn in Europe. Future management may include the use of natural enemies. Our study focused on the determination of density and species composition of spiders in corn fields, as well as in the adjacent corn field margins, during the peak flight period of WCR adults. An additional objective was to test different sampling methods, used for spider collecting, in corn fields and in adjacent corn field margins. The field study was conducted in July and August, 1999, in experimental corn plots, as well as in the adjacent field margins, owned by the Cereal Research Institute, Szeged, in Southern Hungary. Spiders were collected by individual plant search and by sweep nets. Number of spiders /m2 was significantly higher, whereas /m3 was significantly lower in the corn plots compared to the adjacent field margins. Remnants of WCR adults were found in theridiid [Theridion impressum L. Koch, T. pictum (Walckenaer), Enoplognatha latimana Hippa and Oksala] and agelenid (Agelena sp.) webs. We observed that individuals of both families were able to kill 1-5 adult beetles within 90 minutes.
Burgio, G., Ferrari, R., Boriani, L., Pozzati, M. and Lenteren, J. van (2006): The role of ecological infrastructures on Coccinellidae (Coleoptera) and other predators in weedy fieldmargins within northtern Italy agroecosystems. Bulletin of Insectology