Ecological patterns of plant diversity in a plantation forest managed by clearfelling

摘要

1. Commercial forests represent an important but often neglected biological resource. This study related the understorey plant species composition of a coniferous plantation forest managed by clearfelling to environmental factors (stand structure, soil pH and previous land use) and ecological patterns (abundance-occupancy relationships, species dispersal and life history). 2. Plant species richness and composition were recorded in 326 managed stands of different ages, soil types and land-use histories in a 185-km(2) lowland forest planted onto heath and arable land. 3. Stands replanted in the last 10 years had the greatest species richness, typically containing in the order of 18 plant species. Stands on soils of high pH had greater plant species richness, as did those on previously arable land. 4. Less than a quarter (23%) of all species persisted in the above-ground vegetation throughout the growth cycle. The majority recolonized forest stands during the cycle, by physical dispersal or from the seed bank, largely after canopy opening in mature stands (26%) or after felling (47%). Annual species and species with plumed seeds were most abundant in early growth stages, while shrubs with berries were more abundant in mature stands. 5. We found a strong positive interspecific relationship between frequency of stand occupancy and mean abundance within occupied stands. For species not persisting above-ground throughout the forestry cycle (i.e. patch colonizers), the slope of the abundance-occupancy relationship was steeper for those with a long-distance dispersal mechanism than for those lacking such a mechanism. 6. Synthesis and applications. Rotational clearfelling of plantations may be an appropriate form of forest and conservation management in forests planted on former open areas such as heaths, where the conservation interest is not in old-growth species but in earlier successional species. Maximizing representation of young growth stages will help maximize plant diversity in such cases. These prescriptions contradict guidance for sustainable forestry; however, it is appropriate to vary guidelines according to land-use history and species composition. Our findings confirm the importance of dispersal to species persistence within landscapes comprising successional patch networks.