Belowground competition in a broad-leaved temperate mixed forest: pattern analysis and experiments in a four-species stand

Abstract

We investigated fine root biomass and distribution patterns in a species-rich temperate CarpinusQuercus-Fagus-Tilia forest and searched for experimental evidence of symmetry or asymmetry in belowground competition. We conducted extensive root coring and applied the recently introduced in situ-root growth chamber technique for quantifying fine root growth under experimentally altered intra-and interspecific root neighbourhoods in the intact stand. In 75% of all soil cores, fine roots of more than two tree species were present indicating a broad overlap of the root systems of neighbouring trees. Quercus trees had more than ten times less fine root biomass in relation to aboveground biomass or productivity (stem growth) and a much higher leaf area index/root area index ratio than Carpinus, Fagus and Tilia trees. The root growth chamber experiments indicated a high belowground competitive ability of Fagus in interspecific interactions, but a low one of Quercus. We conclude that (1) interspecific root competition is ubiquitous in this mixed stand, (2) root competition between trees can be clearly asymmetric, and (3) tree species may be ranked according to their belowground competitive ability. Fagus was found to be the most successful species in belowground competition which matches with its superiority in aboveground competition in this forest community.

No evidence of spatial root system segregation and elevated fine root biomass in multi-species temperate broad-leaved forests

“…While six studies compared one-and two-species stands, the study by Rewald and Leuschner (2009) together with the present one are the only studies, which referred to species-rich stands with more than four tree species. These eight studies produced inconsistent results with respect to 'belowground overyielding'.…”

“…Brandtberg et al (2000) and Leuschner et al (2001), on the other hand, observed a similar fine root mass in one-and two-species stands (spruce/birch and beech/oak, respectively). The study by Rewald and Leuschner (2009) compared forest patches, where roots of one to four tree species (beech/ hornbeam/oak/lime) coexisted in the soil, and provided only weak evidence of the existence of a higher fine root mass in mixed patches. By comparing monospecific stands with stands of three to five species, our study similarly found no conclusive evidence of higher root biomass in the species-rich stands.…”

“…While Hölscher et al (2002) found a maximum horizontal extension of only ca. 8 m for fine roots of Fagus and Tilia, Hertel (1999) reported a maximum horizontal distance of Quercus fine roots from the nearest stem of [12 m, and Rewald and Leuschner (2009) found a maximum root extension of even 30 m in the case of Tilia trees.…”

Analyzing size-symmetric vs. size-asymmetric and intra- vs. inter-specific competition in beech (Fagus sylvatica L.) mixed stands

“…Some studies concerning belowground competition in mixed stands found that F. sylvatica displays greater competitive ability than oak in inter-specific interactions (Leuschner et al, 2001;Rewald and Leuschner, 2009), which might result in a negative effect of beech on oak. However, the reduction in size-asymmetric competition for both species suggests some degree of complementarity in aboveground niche occupation, probably due to their different shade tolerance and crown architecture (Ruiz de la Torre and Ceballos, 1979).…”

Differences in fine root traits between Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) - A case study in the Kysucké Beskydy Mts

“…In fact, only a few studies have been conducted on this problem, for instance comparing Norway spruce (Picea abies [L.] Karst. ) and European beech (Fagus sylvatica L.; Schmid 2002), Norway spruce, Scots pine (Pinus sylvestris L.) and European beech (Finér et al 2007), Scots pine and Pedunculate oak (Quercus robur L., Konôpka et al 2005), among a variety of broadleaves (Rewald, Leuschner 2009). Most studies have a limited possibility to generalize their findings because of including only few features of fine roots and/or site-specific results (an exception can be found in Finér et al 2007).…”