Смещение спектра листовых параметров у двух видов берез вдоль глобального климатического градиента в Северной Евразии

Abstract

Leaf parameters have been studied in Betula pendula and B. pubescens populations from different vegetation zones in North Eurasia. Shifts in morphological leaf parameters depend on ecological properties of species. Leaf size and venation density differed between populations with these parameters in the two species changing in opposite directions along the transect. Two species had similar changes in the mesophyll structural parameters in the gradient of climatic conditions. A linear increase in palisade and spongy cell sizes was found in both species along the transect in the direction from the south to the north. The number of mesophyll cells per unit leaf area decreased along the transect in the northern direction and was strongly influenced by weather conditions in the current year. Changes in three-dimensional organization of mesophyll were also observed in populations from different vegetation zones. In northern populations an increase in the density of cell packing, the total mesophyll surface and the percentage of intercellular contacts was associated with a decrease in the surface-volume ratios of assimilating tissues. The conclusion is drawn that shifts in leaf parameters provide the optimum gas diffusion rate inside the leaf for different climate.