Biodiversity meets the atmosphere: a global view of forest canopies

The forest canopy is the functional interface between 90% of Earth's terrestrial biomass and the atmosphere. Multidisciplinary research in the canopy has expanded concepts of global species richness, physiological processes, and the provision of ecosystem services. Trees respond in a species-specific manner to elevated carbon dioxide levels, while climate change threatens plant-animal interactions in the canopy and will likely alter the production of biogenic aerosols that affect cloud formation and atmospheric chemistry.     

Broad-leaf species composition in Cryptomeria japonica plantations with respect to distance from natural forest

To address the pressing need to evaluate how conifer plantations can serve biodiversity functions in addition to other economic and social roles they play, we assessed the diversity of broad-leaf seedlings and saplings in Cryptomeria japonica plantations in Ogawa, Ibaraki Prefecture, Japan at increasing distances (0–1000 m) from old growth natural forest edge. For saplings, there was no overall significant trend in the frequency, species richness, and Shannon index with respect to distance. Seedlings on the other hand showed a decrease in frequency and species richness with increasing distance from the old growth forest, implying that should recruitment limitation occur in the plantations, it will be stronger at the seed-to-seedling transition than at the seedling-to-sapling transition. Assigning species into groups based on functional traits that are associated with recruitment and regeneration was more revealing. Relative frequency of species that are moderately shade-tolerant, are shrubs, have small seeds, and are frugivore-dispersed increased in the plantations. In comparison, species that are tall trees, have large seeds and are gravity-dispersed decreased in the plantations. Multi-trait analysis showed that propagule size was the trait that could best explain the difference in the distribution of broad-leaf species in the plantations. Based on our results, we suggest to policy-makers that plantation sizes be kept to within a few hundred meters wide, and should ideally be within dispersal distance of species from natural forests that could potentially be seed sources of broad-leaf species. Otherwise, steps must be taken to drive succession such that potentially recruitment-limited species may be able to overcome barriers to regeneration.     

Beech regeneration research: From ecological to silvicultural aspects

This review describes key regeneration characteristics of the genus Fagus as represented by its four most prominent species: F. crenata (F.c.), F. grandifolia (F.g.), F. orientalis (F.o.) and F. sylvatica (F.s.). Similarities and differences in the relevant life phases of these species are identified. Those are related to natural disturbance regimes and synecological peculiarities of the forests where they grow, thereby establishing a basis for evaluating the likely outcome of different silvicultural measures.     

Interspecific variation in vessel size, growth and drought tolerance of broad-leaved trees in semi-arid regions of Kenya

In semi-arid regions, trees often wither during the dry season. Withering is sometimes manifest as die-back, whereby whithering results in shoot death, which progresses downward from the uppermost part of the crown. In this study, we measured the relationships between height growth and diameter at breast height, die-back frequency and severity, vessel size and specific hydraulic conductivity of four evergreen (Senna siamea (Lamk) H.S. Irwin & Barneby, Jacaranda mimosifolia D. Don, Azadirachta indica A.H.L. Juss and Acacia gerrardii Benth.) and one deciduous (Melia volkensii Gürke) plantation tree species in Kenya, which has a conspicuous dry season. Die-back occurred readily in some species, but not in others. Senna siamea showed the highest specific hydraulic conductivity and the highest growth rate among the five species and was quite susceptible to die-back. Among species, height growth and specific hydraulic conductivity were positively correlated with vessel size and negatively correlated with die-back frequency, suggesting a trade-off between growth rate and drought tolerance. This implies that an adaptation to rapid growth under humid conditions leads to low drought tolerance. However, the deciduous tree Melia volkensii showed high specific hydraulic conductivity and growth, with no symptoms of die-back, implying that a mechanism associated with the deciduous habit results in drought avoidance by reducing the requirement for water during the dry season.     

The change of a satoyama landscape and its causality in Kamiseya,Kyoto Prefecture,Japan between 1970 and 1995

We focused on patterns of land use in a particular satoyama landscape (Japanese traditional rural landscape, comprised of an integral social and ecological network of a village and its surroundings, such as agricultural lands, open forestlands and forests), and the effects of human activities upon them during Japan’s economic growth of the last few decades. Changes of landscape patterns and their probable causes were traced since the beginning of the 1900s to the present, and clarified. Societal, economic and technological changes, especially those that occurred after 1970, were considered the focal points from which major landscape changes developed. We compared the spatial features, patterns of land use and landscape diversities of each land unit, defined in terms of both their natural and man-made conditions for the year 1970, to those of 1995. We found land-use diversity to be strongly related to changes in the patterns of land use, with a decrease in diversity for all land units after 1970. Diversity of forest-age distribution on the other hand, increased. These changes, with the complex, changing patterns of each land unit, could be explained by differences in accessibility from the village and variations in the topography, as well as land ownership of the land units. We selected those land units found to have responded to these factors between 1970 and 1995, and classified them into four types of pattern changes, determined mainly by accessibility and topography.This revised version was published online in May 2005 with corrections to the Cover Date.