Natural and anthropogenic influences on photosynthesis in trees of alpine forests.

Coniferous trees in alpine forests have to cope with harsh natural life conditions, which nowadays are superimposed by anthropogenic stresses via changes in soil chemistry or air pollution with ozone as the key compound. Studies on spruce and cembran pine conducted in the course of different research projects in the Alps used several photosynthetic parameters to describe seasonal and altitude - related metabolic changes and to recognise possible stress symptoms. Chlorophyll fluorescence and oxygen formation in photosynthesis revealed characteristic values of growth site, season and needle ages, which came up to be in the same order of magnitude for the two species and for samples from the Northern Limestone Alps and those from the Central Alps. The successful separation and analysis of chlorophyll protein complexes (CPK) from purified thylakoids allowed a deeper insight into photosynthetic units and mainly mirrored seasonal influences. Parameters raised from photosynthetic pigments could be used to discriminate needle samples of trees of less polluted forests and of trees suffering from high ozone loads plus nutritional deficiencies. Photosynthesis appeared to be a highly protected mechanism because of its prime importance for plant life, but increasing loads of ozone, as observed in the alpine environment in combination with alpine climate, can affect even photosynthesis in the long run, because ozone effects remain measurable in plants for months