Environmental factors determining the distribution of highland plants at low-altitude algific talus sites

Algific talus is a micro-scale habitat type where highland plants (subalpine and alpine species) are found, disjunct from their typical range, in lowland forests. On algific talus, cold airflows from the interstices between talus fragments create a local microclimate colder than surrounding forests. Despite of the widely-known occurrence of unique vegetation on algific talus, critical environmental factors determining the distribution of highland species in this habitat type are unclear. In order to reveal the environmental factors enabling highland species to inhabit algific talus, we investigated the vegetation and environments of 26 algific talus sites and four reference (non-algific talus) sites in Hokkaido, northern Japan. Several algific talus sites were dominated by highland species, while some algific talus sites and all non-algific talus sites were dominated by lowland species. Community analysis based on detrended correspondence analysis (DCA) and canonical corresponding analysis (CCA) revealed that the algific talus sites dominated by highland species had lower ground temperature, more acidic soil, larger canopy openness, and less diverse vegetation than the sites dominated by lowland species. Highland plants might be maintained under conditions stressful for lowland plants, resulting in less competitive situation. Generalized linear models (GLM), used to evaluate the response of individual highland species to environmental factors, revealed that preferable environmental conditions for highland plants are highly species specific. These results indicate that the maintenance of diverse environments is crucial for the conservation of the unique vegetation and local populations of highland species in algific talus areas

Habitat-specific responses of shoot growth and distribution of alpine dwarf-pine (Pinus pumila) to climate variation

Alpine dwarf-pine (Pinus pumila) in dominant in the alpine regions of Japan, and often forms the krummholz zone of stunted alpine forest. The distribution of P. pumila is strongly related to the distribution of snow, and shoot growth is also sensitive to weather conditions. Changes in temperature and snowmelt regimes may well affect the distribution patterns of the krummholz zone. P. pumila usually occupies the habitat between the fellfield and snowbed communities, and responses to climate change may differ depending on whether plants are close to the fellfield or the snowbed. We compared the distribution and shoot growth patterns of P. pumila close to both surrounding ecosystems in the Taisetsu Mountains, northern Japan. P. pumila has expanded its distribution area by 14 % toward both edges over the last 32 years. Annual shoot growth was positively affected by summer temperature and sunshine duration, but negatively related to spring temperature toward the fellfield side. Shoot growth was greater at the southeastern edge of patches, where snowdrifts were formed. The results indicated that shoot growth and distribution area increased in warm summers. However, warm springs might have a negative influence on shoot growth, probably because the earlier reduction in cold-resistance enhances the risk of frost damage in spring close to the fellfield side. This study suggests the importance of understanding the site-specific responses of shrubs to predict the impacts of climate change on alpine ecosystems