Underplanted silver fir and common beech cause changes in root stratification and morphology in mature spruce stands

抄録

In this study we analysed changes in distribution and morphological properties of fine roots caused by underplanting of a 110-year-old Norway spruce monoculture by silver fir and common beech. Three different stand structures were investigated: mature spruce underplanted by beech (S/b), by fir (S/f) and mature spruce with natural regeneration of spruce (S/s). We established 3 sample plots per each structure and took 5 soil cores per sample plot (45 cores in total). Soil cylinders of 5 cm diameter were taken up to 40 cm depth. Fine roots (diameter ≤ 2 mm) were extracted from the soil, classified according to tree species, weighted and scanned; their length and surface were quantified and specific root length (SRL) and specific surface area (SSA) were calculated. Root-to-root interaction of spruce and underplanted species led to differences in vertical distribution of roots towards the more homogenous root density in investigated profile with clear shifting of beech and fir roots into deeper soil layers. Cumulative root fractions of fir and beech in upper 20 cm were lower than those of Norway spruce. The share of spruce roots in depth under 20 cm never exceeded 20%. The co-occurrence of beech and spruce in small spots was about twice as frequent as the co-occurrence of spruce with fir. We found differences in SRL and SSA between broadleaves (beech) and conifers, while the values of beech morphological parameters increased significantly, when mixed with spruce. We assume that the competitive strategy of beech is based in changing its root morphology, whereas silver fir is inclined to extend its biomass.