The potential for phosphorus benefits through root placement in the rhizosphere of phosphorus-mobilising neighbours
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PHYSIOLOGICAL ECOLOGY – ORIGINAL RESEARCH
The potential for phosphorus benefits through root placement in the rhizosphere of phosphorus‑mobilising neighbours François P. Teste1,2 · Kingsley W. Dixon1,3 · Hans Lambers1,3,4 · Jun Zhou1,5 · Erik J. Veneklaas1,6 Received: 18 December 2019 / Accepted: 13 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Plants that produce specialised cluster roots, which mobilise large quantities of poorly available nutrients such as phosphorus (P), can provide a benefit to neighbouring plants that produce roots in the cluster rhizosphere, as demonstrated previously in pot studies. To be effective, such roots must be present within the short time of peak cluster activity. We tested if this requirement is met, and quantified potential P benefits, in a hyperdiverse Mediterranean woodland of southwest Australia where cluster-rooted species are prominent. Using minirhizotrons, we monitored root dynamics during the wet season in the natural habitat. We found non-cluster roots intermingling with all 57 of the observed cluster roots of the studied tree species, Banksia attenuata. Almost all (95%) of these cases were observed in a high-moisture treatment simulating the 45-year average, but not present when we intercepted some of the rainfall. We estimate that cluster-root activity can increase P availability to intermingling roots to a theoretical maximum of 80% of total P in the studied soil. Due to their high P-remobilisation efficiency (89%), which results from P rapidly being relocated from cluster roots within the plant, senesced Banksia cluster roots are a negligible P source for other roots. We conclude that, rather than serving as a P source, it is the cluster-root activity, particularly the exudation of carboxylates, that may improve the coexistence of interacting species that are capable of root intermingling, thus potentially promoting species diversity in nutrient-poor habitats, and that this mechanism will be less effective in a drying climate. Keywords Banksia attenuata and B. menziesii · Climate change · Minirhizotron · Phosphorus-mobilisation facilitation · Phosphorus remobilisation
Communicated by Mercedes Bustamante. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00442-020-04733-6) contains supplementary material, which is available to authorized users. * François P. Teste [email protected] 1
School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
2
Present Address: Grupo de Estudios Ambientales, IMASL-CONICET & Universidad Nacional de San Luis, Av. Ejercito de los Andes 950, 5700 San Luis, Argentina
3
School of Molecular and Life Sciences, Curtin University, Kent Street, Bentley, WA 6102, Australia
4
College of Resources and Environmental Sciences, Green Development, Key Laboratory of Plant–Soil Interactions of the Ministry of Education, National Academy of Agriculture, China Agricultural University, B
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