Fine Root Biomass of Temperate Forests in Relation to Soil Acidity and Fertility, Climate, Age and Species
Root growth represents an important component of ecosystem carbon cycling because, in a global perspective, belowground carbon storage is more important than aboveground storage (Schlesinger 1997 ). Together with above-ground litter fall, root production
- PDF / 3,223,885 Bytes
- 34 Pages / 439 x 666 pts Page_size
- 72 Downloads / 236 Views
---"'-'--
- - - --
-
Fine Root Biomass of Temperate Forests in Relation to Soil Acidity and Fertility, Climate, Age and Species Christoph Leuschner and Dietrich Hertel
1 Introduction Root growth represents an important component of ecosystem carbon cycling because, in a global perspective, belowground carbon storage is more important than aboveground storage (Schlesinger 1997). Together with above-ground litter fall, root production provides the primary input of organic carbon to soils. Due to methodological problems, only slow progress in our understanding of ecosystem belowground processes has occurred and, as a consequence, carbon storage in, and carbon flow through the root system is only poorly represented in most models on plant and ecosystem carbon turnover. However, prediction of the effects of global warming, nitrogen deposition or soil acidification on plant growth and carbon sequestration remains questionable if root processes are not adequately covered. In forest ecosystems, roots 2 mm form the coarse root fraction (Bohm 1979). Because of their role in water and nutrient absorption, fine roots represent the functionally most important component of tree root systems. Although this root diameter class may contribute less than 2% of tree biomass in mature forests, fine root growth can consume up to 75% of the carbon fixed by the canopy (Fogel and Hunt 1983). Tree fine roots are organs with a rapid turnover not only of water and nutrients, but also of carbon because their life expectancy ranges from weeks to a few years, depending on species and environmental conditions (Hendrick and Pregitzer 1993; Bloomfield et al. 1996). Fine root growth and root mortality are, in part, controlled by soil temperature, moisture and nutrient availability (Nadelhoffer et al. 1985; Pregitzer et al. 1993; Burton et al. 2000). Drought and elevated concentrations of aluminium, hydrogen ions or other potentially harmful elements in the soil solution may act as stressors that can increase fine root mortality of trees (e.g., Marsha1l1986; Murach and Ulrich 1988). There is increased interest in estimating the fine root biomass of forests because of (1) its prominent role in the ecosystem carbon budget,
Progress in Botany, Vol. 64 © Springer-Verlag Berlin Heidelberg 2003
406
Ecology - - - - - - - - - -- - - -- - - - - - - - - - -----""-
(2) its importance in the uptake of water and the cycling of nutrients, and (3) a possible indicator function of fine root vitality for the physical and chemical state of the soil and its change over time (Polomski and Kuhn 1998). In this review we synthesise fine root biomass data of temperate forests and relate them to soil chemical parameters (pH, soil fertility), tem perature, rainfall, elevation and stand age. The data were analysed with the aim (1) to compare fine root biomass of temperate broad-leaved and coniferous forests, (2) to detect differences among important temperate tree genera (Fagus, Quercus, Acer, Pinus, Picea, Pseudotsuga), and (3) to investigate relationships between ro
Data Loading...
