ABOVE- AND BELOWGROUND INTERACTIONS ARE MEDIATED BY NUTRIENT AVAILABILITY
Citation
Martin Schädler, Stefan Scheu, Josephine Haase, and Roland Brandl, ABOVE- AND BELOWGROUND INTERACTIONS ARE MEDIATED BY NUTRIENT AVAILABILITY: .
Summary
By influencing nutrient mineralization in the soil, decomposers may affect the performance of plants and their associated herbivores. The strength of above–belowground linkages may therefore depend on the availability of nutrients in ecosystems. We investigated the dependency of decomposer- and leaf-herbivore-mediated changes in plant performance on soil nutrient availability in microcosm systems. In separate treatments, Poa annua was used as host plant for the herbivore and was grown in combination with different herb species: Plantago lanceolata, Trifolium repens, and Sanguisorba minor. At three different levels of nutrient availability, the impact of Collembola (Folsomia candida) and aphids (Rhopalosiphum padi), as well as their [...]
Summary
By influencing nutrient mineralization in the soil, decomposers may
affect the performance of plants and their associated herbivores. The
strength of above–belowground linkages may therefore
depend on the availability of nutrients in ecosystems. We investigated
the dependency of decomposer- and leaf-herbivore-mediated changes in
plant performance on soil nutrient availability in microcosm systems. In
separate treatments, Poa annua was used as host plant for the herbivore
and was grown in combination with different herb species: Plantago
lanceolata, Trifolium repens, and Sanguisorba minor. At three different
levels of nutrient availability, the impact of Collembola (Folsomia
candida) and aphids (Rhopalosiphum padi), as well as their interacting
effects on plant performance, were investigated. We further assessed the
effects of Collembola on the performance of aphids and vice versa, as
well as the effects on element contents in P. annua and soil nutrients.
Collembola increased total aboveground biomass and biomass of single
plant species (except T. repens) only at low and moderate nutrient
availability, whereas the negative effects of aphids on P. annua and
total aboveground biomass were highest at high nutrient availability.
Collembola decreased relative root allocation. The negative effect of
aphids on plant biomass was more pronounced in the presence of
Collembola. Nitrogen concentration in shoots of P. annua was increased
by Collembola. Aphids decreased the nitrogen concentration in grass
shoots only when Collembola were present. These interacting effects can
be related to indirect effects of decomposers on herbivore performance.
At low and moderate nutrient availability, aphid numbers strongly
increased due to decomposers, whereas at high nutrient availability this
effect was much weaker. In turn, aphid herbivory increased the number of
Collembola only at high nutrient availability. We conclude that the
role of both below- and aboveground food webs for the dynamics of
vegetation depend on each other and the availability of nutrients in
ecosystems. This suggests that nutrient enrichment of ecosystems may
have important consequences for above–belowground
linkages and their effects on natural communities. Published in Ecology,
volume 89, issue 11, on pages 3072 - 3081, in 2008.