DIFFERENCE IN THE ECOLOGICAL STRATEGIES OF CONIFEROUS TREE SPECIES IN EUROPEAN AND CANADIAN BOREAL FORESTS: A MODELING ANALYSIS

The role of net primary productivity (NPP) allocation to tree organs as a parameter reflecting the ecological strategy of trees is discussed. The application of an individual-based spatially explicit simulation model of the tree-soil system (EFIMOD) to European and North American boreal forests reveals significant differences in ecological parameters (silvics) between, on one hand, North American jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana Mill.) of Canadian boreal forests and, on the other hand, European Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. [Karst.]). A significant difference between these two groups of species was found in the NPP allocation between needles and fine roots. The proportion of annual biomass increment reflected by NPP that is allocated to fine root production is higher in the North American coniferous species than in the European ones. Simulation experiments were performed to investigate the influence of NPP allocation on the components of carbon balance and wood productivity. Additionally, a parameter “turnover capacity” (TC), which is defined as the sum of NPP and soil respiration, was used. North American and European conifers were compared in two sets of simulations. In the first set, simulation was performed upon changes in NPP allocation in tree species ‘growing’ under their native conditions (Canada or Russia). In the second set, the Canadian conifers were simulated under the Russian climate and soil conditions, whereas the European ones, under the respective Canadian conditions. The results showed considerable differences, which depended on the NPP allocation patterns, in tree growth rate, root development, and parameters of carbon balance. Trees with relatively high NPP proportions allocated to fine root production demonstrated lower growth rates even at a high carbon turnover capacity corresponding to the milder climate of European Russia. On the other hand, trees with the European, more uniform, NPP allocation pattern showed higher growth rates compared with the Canadian trees even under the colder continental conditions of Central Canada. The results suggest that wood productivity levels may be significantly different at similar NPP and TC if trees have different NPP allocation patterns. This difference reflects the adaptation of the NorthAmerican coniferous species to harsh soil and climatic conditions, which are very cold in the northern and very dry in the southern part of Central Canadian boreal forests. NPP allocation index (NPP partitioning between leaves and fine roots) is proposed as a measure of tree stress tolerance, adaptation to severe climatic conditions, and ecological strategy.

• Bhatti J.S.
• Bykhovets S.S.
• Chertov O.G.
• Komarov A.S.

• Естественные науки
• Сельское хозяйство. Лесоводство