Photosynthetic functions of cembran pines and dwarf pines during winter at timberline as regulated by different temperatures, snowcover and light.

摘要: Trees at timberline in the high Alps are exposed to a variety of climatic conditions. Most stresses occur during winter and spring, when frost, occasionally low snow cover, irradiation interact. In this study, we follow reactions photosynthesis from spring two dominating tree species alpine timberline, which may indicate status stress response changing environment. The results level physiological stability trees, important for stabilising natural mountain ecosystems. Pinus cembra mugo were selected altitudes between 1850 m a.s.l. 1950 near innsbruck, Austria. At six sampling times January May, fast chlorophyll fluorescence was measured field twigs collected further investigation laboratory. following measurements taken: photosynthetic oxygen formation, needle carotenoid determination, kinetic studies xanthophyll cycle. general, both showed similar most parameters studied. P. seems have some advantages if precipitation is high, when, because its growth habitus, needles will be covered. Primary photochemistry (trapping per reaction centre) PS II does not change with dates despite fact that temperature light changing. However, first events electron transport whole strongly affected by conditions days before sampling. kinetics cycle only light, but also strong effects. higher under weather. Both well prepared start winter, favourable conditions, like foehn events, occur.