Rapid responses of root traits and productivity to phosphorus and cation additions in a tropical lowland forest in Amazonia

Laynara F. Lugli*, Jessica S. Rosa, Kelly M. Andersen, Raffaello Di Ponzio, Renata V. Almeida, Maria Pires, Amanda L. Cordeiro, Hellen F.V. Cunha, Nathielly P. Martins, Rafael L. Assis, Anna C.M. Moraes, Sheila T. Souza, Luiz E.O.C. Aragão, Jose L. Camargo, Lucia Fuchslueger, Karst J. Schaap, Oscar J. Valverde-Barrantes, Patrick Meir, Carlos A. Quesada, Lina M. MercadoIain P. Hartley

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Soil nutrient availability can strongly affect root traits. In tropical forests, phosphorus (P) is often considered the main limiting nutrient for plants. However, support for the P paradigm is limited, and N and cations might also control tropical forests functioning. We used a large-scale experiment to determine how the factorial addition of nitrogen (N), P and cations affected root productivity and traits related to nutrient acquisition strategies (morphological traits, phosphatase activity, arbuscular mycorrhizal colonisation and nutrient contents) in a primary rainforest growing on low-fertility soils in Central Amazonia after 1 yr of fertilisation. Multiple root traits and productivity were affected. Phosphorus additions increased annual root productivity and root diameter, but decreased root phosphatase activity. Cation additions increased root productivity at certain times of year, also increasing root diameter and mycorrhizal colonisation. P and cation additions increased their element concentrations in root tissues. No responses were detected with N addition. Here we showed that rock-derived nutrients determined root functioning in low-fertility Amazonian soils, demonstrating not only the hypothesised importance of P, but also highlighting the role of cations. The changes in fine root traits and productivity indicated that even slow-growing tropical rainforests can respond rapidly to changes in resource availability.

Original languageEnglish
Pages (from-to)116-128
Number of pages13
JournalNew Phytologist
Volume230
Issue number1
Early online date20 Dec 2020
DOIs
Publication statusPublished - 1 Apr 2021

Keywords

  • Amazon rainforest
  • arbuscular mycorrhiza
  • fine root productivity
  • large-scale nutrient fertilisation experiment
  • multiple nutrient limitation
  • phosphatase enzyme
  • root morphology

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