关键词: 亚高山/高山森林, 土壤线虫, 群落结构, 营养类群

Abstract: As an important tree species with high economic and ecological values, Sorbus pohuashanensis (Hance) Hedl. is naturally distributed in the alpine forest ecosystems in North China. Growth traits and physiological parameters in field were measured and heat tolerance of 1-year-old seedlings of six provenances were evaluated by subordinate function in order to select superior provenances at the earlier stage, which could well adapt to the habitats at low altitudes in North China. The results indicated that seedlings of the different provenances showed different adaptability to hot summer. Annual height increment of seedlings from Shandong Laoshan was the largest (34.99 cm), and annual ground diameter increment  of seedlings of Hebei Wuling  mountain provenance was the largest (6.90 mm). Net photosynthetic rate and transpiration rate of seedlings of Hebei Tuoliang moutain provenance were the highest (12.1 μmol CO₂·m^-2·s^-1 and 6.28 μmol H₂O·m^-2·s^-1, respectively), and those of Shanxi Pangquangou provenance were the lowest (8.03 μmol CO₂·m^-2·s^-1 and 4.39 μmol H₂O·m^-2·s^-1, respectively). Leaf damage of seedlings from Shanxi Pangquangou provenance was the greatest with the leaf damage index of 46.53%, while that from Shandong Taishan provenance was the least with the leaf damage index of 17.75%. Comprehensive evaluation results indicated that the 1-year-old seedlings originally coming from Shandong Province (Taishan and Laoshan) adapted better  to the conditions of hot summer in Beijing Plain than those from other provinces.

Key words: community structure, subalpine and alpine forest., trophic group, soil nematode