Tree seedling performance in microhabitats along an elevational gradient on Mount Koma, Japan
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Questions: How do biological invasion patterns of larch (Larix kaempferi) seedlings change with different microhabitats along an elevational gradient on a volcano? How are seedling attributes such as establishment, competitive ability and morphological plasticity, advantageous to the invasion of stressful disturbed areas?Location: Mount Koma, Hokkaido, Japan.Methods: Seed-sowing experiments and natural-seedling censuses were conducted with L. kaempferi and the dominant native tree Betula ermanii. Seed germination, seedling survival and allocation were investigated on three microhabitats (bareground, Salix reinii patch, and Larix understory) in three elevational zones for three years.Results: For the two species, seed germination was higher in Larix understories than in bareground and Salix patches, but did not differ between elevations. Survival rates were not different between elevations and microhabitats. Larix had a higher survival rate than Betula. Larix showed the highest natural-seedling density in Salix patches, independent of elevational differences, while Betula density was nearly zero. Larix seedlings changed allocations between microhabitats, while the ratio of leaf to total biomass was constant. In bareground Larix became more stunted and branched and increased its allocation to the roots. This form is adaptive to windy, nutrient-poor environments. Larix seedlings became more tall and slender in Salix patch, indicating that the priority was light acquisition in shaded habitats. Little change in Betula allocation was detected.Conclusion: Invasive species establish themselves more efficiently than native species in every microhabitat especially at higher elevations by having higher survival and growth rates derived from superior seedling performance. Plant communities on and above treeline are modified by the biological invasion.
- International Association for Vegetation Scienceの論文