|The cyclic dynamics of northern trees photosynthetic capacity
P.A.Kashulin, N.V.Kalacheva, V.K. Zhirov
Polar-Alpine Botanical Garden-Institute, Apatity, Russia
The contemporary approaches to registration means of the local biological responses on global biosphere changes simultaneously with possible cosmic fine effects on terrestrial biota life suggest the wide use of remote-sensing and noninvasive, but sensitive methods. Such state-of-the-art technique provides an investigator by current data with minimal disturbance of the living objects.
Long-term monitoring for photosynthetic capacity of indicator flora species was carried out in terms of noninvasive optical method which have been included chlorophyll fluorescence measurements in situ emitted up the surface of native foliage. The pulse amplitude modulated PAM-2100 portable chlorophyll fluorometer from Heinz Walz Effetrich (Germany) was used. The parallel daily PAR, UV, temperature and humidity measurements for the plant vegetation local points were carried out also. The ran current data were as follows: Fo and Fm – minimal dark and maximal chlorophyll fluorescence, respectively; derivative parameter Fv/Fm which is a measure of the maximal quantum yield of photosystem II and some other indices.
The midday and evening chlorophyll fluorescence measurements of Salix caprea L., Populus tremula L., Betula pendula Roth, Lonicera edulis Turcz. Ex Freyn., Lonicera tatarica L., Syringa josikaea Jacq. fil arboreal deciduous plants were carried out daily, starting of June to October/ Both 2014 yr and 2015 yr seasons are considered.
The photosynthesis capacities of the plants throughout whole vegetation season were compared between different biological species and with UV, PAR, temperature. A number of cycles in Fo, Fm and Fv/Fm seasonal dynamics were revealed in terms of spectral analysis for the rows obtained. The most robust periods registered were as follows: circaseptan (about 7-day) and circasemiceptan (about 3,5-day), the cycles about 14-day, a number of larger period cycles were found also. The relation of the plant photosynthesis capacity with climatic, geophysical indices and plausible cosmic provenance of the cycles found are discussed.