Response of belowground communities to short-term phosphorus addition in a phosphorus-limited woodland
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.
KeywordsCumberland plain woodland Fungi Microarthropods Nematoda Phosphorus fertilization pH
Dr Kaushal Tewari and Sarah Beck provided technical assistance with sample processing. This work was supported by the Australian Reseach Council Discovery Grants scheme (DP110105102 and DP130102501). EucFACE is supported by the Australian Commonwealth government in collaboration with the University of Western Sydney. This is part of a TERN Super-site facility. EucFACE was built as an initiative of the Australian government as part of the Nation-building Economic Stimulus Package.
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