Estimating fine root production of Scots pine stands

Abstract

Photosynthesis, allocation and consumption of photosynthate are the main processes in many recently developed models for trees and stands (Zhang, 1994). A substantial part of the tree’s overall carbon economy is represented by the root system. A thorough investigation of root requirements must include tissue synthesis, maintenance costs of the roots and costs of the symbionts over the lifetime of the roots (Eissenstat, 1992). A considerable proportion of the total costs of the root system can be quantified by the annual tissue synthesis in fine root production (Agren et al., 1980). Additional maintenance costs are relevant in coarse roots, but in short living very fine and fine roots most of the required photosynthates for life are stored with the root formation as initial starch concentration (Persson, 1992). Marshall and Waring (1985) have shown that fine roots of seedlings die when all their stored carbohydrates are respired. Schneider et al. (1989) found nonstructural carbohydrates in dead Spruce roots and concluded that fine roots died from causes other than shortage of carbohydrates. That means a proper estimation of fine root production (FRP) contains both, the tissue synthesis and the later maintenance costs. For the carbon allocation to the mycorrhizal fungi only rough estimates exists. The lack of adequate methods for quantifying mycorrhizal mycelium impedes an accurate estimation (Finlay and Söderström, 1992).