Reforestation of ex-arable land in temperate regions increases the area of potential habitat for forest plants. However, the herbaceous plant layer of these plantations contains fewer forest species than comparable plantations at continuously forested sites. One of the reasons for this might be differences in recruitment. The present study addresses post-dispersal seed predation, mainly of woody plants, as the factor limiting the recolonization of young oak plantations in southern Sweden. Our objectives were to investigate differences in dispersal and post-dispersal seed predation between first-generation forest plantations on ex-arable land and re-planted clear-cuts on continuously forested land. Therewas no recruitment following the experimental sowing of six commonwoody species (Alnus glutinosa, Betula pendula, Frangula alnus, Sambucus nigra, Sorbus aucuparia and Sorbus intermedia). Thus, the colonization of forest plantations by native shrubs and trees appears to be habitat-limited; the only exception being Rhamnus catharticus, for which poor dispersal ability may be more important. Post-dispersal seed predation of forest shrubs and trees was marked, especially in relatively small and isolated plantations on ex-arable land. There was a high seed predation of Crataegus monogyna, Sorbus aucuparia and Viburnum opulus on ex-arable land, while that of Frangula alnus and Sambucus racemosa was not associated with site placement and landuse history. Seed predation is probably a more important factor limiting restoration of near-natural forests than previously thought.
Information on the dispersal ability of flightless insect species associated with woodlands is severely lacking. Therefore, a study was conducted examining the dispersal ability of wood cricket (Nemobius sylvestris) juveniles (nymphs) and adults in a wooded landscape on the Isle of Wight, UK, to further our understanding of the ecology and management of this and other flightless insects. A series of experiments were conducted where nymphs and adults were released and observed at a range of spatial-temporal scales within different habitat environments. The results of this investigation indicated no difference in the dispersal ability of wood cricket nymphs and adults. However, adult females moved less than adult males. Adult males were found to spread twice as fast as females, and males were found capable of traversing up to 55 m away from woodland habitat through semi-natural and grazed grassland. Additionally, rates of population spread of both wood cricket nymphs and adults (males and females) were found to be accurately described by the inverse-power function, predicting only few individuals dispersing over time. Together this indicates that overall colonization success and rate of population spread, being female dependent, is likely to be low for this species. Wood crickets were found to live in and able to move along mature woodland edges directly bordering agricultural land. This indicates that conservation initiatives focusing on creating woodland corridors and developing woodland habitat networks have the potential to facilitate the spread and population viability of wood crickets, if the woodland edges are given enough time to develop. However, long-term monitoring is needed to evaluate the overall effectiveness of such approaches. and Niels C. BROUWERS, Adrian C. NEWTON, Sallie BAILEY.
Viticulture is one of the most intensively managed agricultural ecosystems in Europe. Therefore, the conservation problems of vineyards and the ecological benefits of increasing the amount of fallow land are addressed using butterflies as a model group. We established 43 transects, each 100 m long, in a vineyard region in the vicinity of Trier (Rhineland-Palatinate, Germany) and recorded the butterflies observed along these transects on 20 occasions from late May to early August 2003. Transects crossed vineyards, fallow land and transitional areas of land. 4041 individuals of 34 species showed the typical pattern of relative abundance with few common and many relatively rare species. Fallow land had more individuals and species and a higher Shannon species diversity index than vineyards. Community evenness and average butterfly dispersal ability were highest in the vineyards. Principal Factor Analyses and UPGMA cluster analysis distinguished between fallow land and vineyards. The difference between early meadow and late forest fallow land areas was not strong, but the former tended to have a higher diversity than the latter. Vineyards thus might act as a sink for butterflies. Therefore, a clear separation between vineyards and fallow land is best for nature conservation. As young fallow land tends to have a higher diversity than older fallow land in this study, it is likely that the conservation value of vineyards for butterflies could be increased by active management of fallow land areas.