Recovery of the herbaceous layer in the young silver birch and black alder stands that developed spontaneously after a forest fire

The studies, which were conducted in southern Poland, focused on the recovery of the herb layer in 17-year-old post-fire silver birch and black alder forests. Although both types of stands, which are of the same age, developed spontaneously, the alder stands occupied damper sites (with thicker A horizons that survived the fire) than those in the birch forests. We surveyed the migration rates of 44 woodland species, primarily ancient woodland indicators, into both forests and the potential differences in these rates depending on their moisture regime and the community type represented by unburned forests, which were treated as the source of the woodland species pool. Additionally, the role of local depressions with high humidity that were covered by post-fire alder woods in the colonization process, as well as species survivorship and recolonisation, were estimated. Woodland species showed diverse migration paces among the sites; most of them migrated faster on more fertile sites with a higher humidity. Small patches of post-fire alder woods contributed to the recolonisation process since many woodland species in the herb layer survived the fire due to its high humidity, which inhibited the intensity of the forest fire. The recovery of woodland species in post-fire woods is the combined effect of regeneration, which relies on autochthonic propagules, and secondary succession, which is based on allochthonic propagules. Local depressions, which provide refuges for fire-sensitive, dispersal-limited species, contribute to their survivorship and thus to the successive recovery of herbaceous layers after a fire

Dispersal timing, palatability and caching of acorns of Aesculus turbinata Bl.

Aesculus turbinata acorns were dispersed earlier than other acorn-producing species and are removed completely by rodents, although the acorns are unpalatable. The dispersal timing and low palatability to rodents on A. turbinata acorns promote the seed caching by rodents, facilitating the seedling emergence is possible even in lower-seeding years

Roadside grassland vegetation in an oak forest, Oak Creek Wildlife Area, the Cascade Range, USA

Roadside grassland vegetation in a Quercus garryana forest, that is one of the dominant species in west Cascade, on the Oak Creek Wildlife Area, Naches, Washington, USA, was investigated to determine the patterns of human impact on the vegetation along mountain trails. Vegetation and environmental data were collected on forty-eight 50 cm × 50 cm plots. Plot cover ranged from 3 to 100% (1 to 8 species) and most of the cover was from exotic species. In order to explore vegetation patterns the following environmental variables were measured: slope, tree canopy area, bare area, distance from road, and litter thickness. The vegetation data and environmental variables were examined using Canonical Correspondence Analysis (CCA). CCA showed that canopy area played important roles in vegetation development. Litter thickness and soil firmness also seemed to be related to the vegetation pattern. Distance from the road affected plant cover but was not related to canopy area, and litter thickness, suggesting that the distance was not a prime determinant on the vegetation pattern a priori. Species richness was the highest in mid-vegetation cover plots, i.e., 40-60%. An exotic plant, Sisymbrium officinale, increased in frequency with a decrease in vegetation cover, and two exotic plant species, Achillea millefolium and Anthoxanthum odoratum, occurred with S. officinale. S. officinale may be a good indicator for evaluating environmental deterioration. The preservation of canopy cover is of prime importance for nature conservation in forested recreational areas