Response of belowground communities to short-term phosphorus addition in a phosphorus-limited woodland
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- Nielsen, U.N., Prior, S., Delroy, B. et al. Plant Soil (2015) 391: 321. doi:10.1007/s11104-015-2432-6
Soil biota regulate essential ecosystem processes but our understanding of how soil fertility constrains biotic interactions remains limited. We investigated belowground responses to short-term phosphorus (P) fertilization in a P-limited woodland.
Ten Eucalyptus tereticornis were randomly selected and five fertilized with superphosphate equivalent to 50 kg P ha−1 over 6 months. We estimated aboveground (understory) and belowground plant biomass, and collected samples for soil chemistry, arbuscular mycorrhizal (AM) root colonization, soil fungal abundance and community composition, and extraction of nematodes and microarthropods.
P-fertilization increased root biomass, abundance of non-AM fungi, and abundances of Collembola, and altered fungal community structure, but was associated with a decrease in predatory nematodes. Structural equation modelling indicated that effects on Collembola and fungal abundances were mediated by direct effects of the fertilizer treatment and/or indirect effects via root biomass responses. However, fungal community compositional changes and reductions in predatory nematodes resulted primarily due to fertilization-mediated changes in soil pH.
Our study shows that understory plant communities and soil biota are P-limited at the study site but that some biotic groups appear to be more sensitive to changes in soil pH than to increases in P availability.