Belowground interspecific competition in mixed boreal forests: fine root and ectomycorrhiza characteristics along stand developmental stage and soil fertility gradients

Kalliokoski, Tuomo; Pennanen, Taina; Nygren, Pekka; Sievänen, Risto; Helmisaari, Heljä-Sisko

Belowground interspecific competition in mixed boreal forests: fine root and ectomycorrhiza characteristics along stand developmental stage and soil fertility gradients

2010

Kalliokoski, Tuomo | Pennanen, Taina | Nygren, Pekka | Sievänen, Risto | Helmisaari, Heljä-Sisko

We studied fine roots and ectomycorrhizas in relation to aboveground tree and stand characteristics in five mixed Betula pendula Roth, Picea abies (L.) H. Karst., and Pinus sylvestris L. stands in Southern Finland. The stands formed gradients of developmental stage (15-, 30-, and 50-year-old stands) in the stands of medium fertility, and of site fertility in the young stands (30-year-old fertile, medium fertile, and least fertile stands). The biomass of the external hyphae of ectomycorrhizas (ECM) was the highest, and the diversity of the fungal community the lowest, in the most fertile stand. The vertical distributions of fine roots of the three tree species were mostly overlapping, indicating high inter-specific belowground competition in the stands. We did not find any clear trends in the fine root biomass (FRB) or length across the stand developmental stages. The FRB of the conifers varied with site fertility, whereas in B. pendula it was almost constant. In contrast to the conifers, the specific root length (SRL) of B. pendula clearly increased from the most fertile to the least fertile stand. This indicates differences in the primary nutrient acquisition strategy between conifers and B. pendula.

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