Supervisors: Asst/Prof Etienne Laliberté

W/Prof Hans Lambers

Patrick Hayes School of Plant Biology, The University of Western Australia

Conversion to poorly available forms

Occlusion

Leaching

Erosion

Plant uptake

2-million year Jurien Bay dune chronosequence

Provide model system for strong fertility gradient with soil age

Increasingly

P-limited

Increase P use efficiency (NUE) – the amount of carbon fixed per unit nutrient

Leaf [P] and P resorption

Influenced by soil nutrient availability

Important on P-poor soils

Primary AIM: To assess how leaf [P] and resorption were influenced by soil age over a 2-million year dune chronosequence

Range of strategies to improve P-acquisition:

2nd AIM: To investigate differences in leaf [P] and resorption between contrasting nutrient-acquisition strategies across a 2-million year chronosequence

Lambers et al (2008) Trends Ecol Evol

⇐ P ‘scavengers’ Arbuscular mycorrhizal(AM) and Ectomycorrhizal(EM)

P ‘miners’ ⇒Non-mycorrhizal (NM)

(e.g. Cluster, dauciformand sand-binding roots)

Non-mycorrhizal strategies very successful in

P-poor soils

Combined specialised structure and metabolism

Commonly release carboxylates, mobilising occluded phosphate

Also mobilises metals,

such as Mn

(Lambers et al. 2008)

This mobilised Mn is taken up and when not regulated can be accumulated

Occurs in Proteaceae (e.g Hakea prostrata)

Linked with increased carboxylate release

3rd AIM: To assess Mn accumulation across a range of contrasting nutrient-acquisition strategies including different NM strategies along a chronosequence

(Shane et al. 2011)

Dauciform Proteoid

Sand-binding

1) Community level leaf [P] ⇩ and resorption⇧ with soil age

2) NM strategies will consistently show ⇩ leaf [P] and ⇧ P resorption, regardless of soil age

3) Mn accumulation will be consistently higher in all NM strategies compared to the other nutrient-acquisition strategies

JurienBay

Perth

0-7 ky

120-500 ky

>2000 ky

Laliberté et al. (2012)

Soil P decreases strongly with soil age

Laliberté et al. (2012) Experimental assessment of nutrient limitation along a 2-million-year dune chronosequence in the south-western Australia biodiversity hotspot.

Stage 5: Bassendean(>2,000,000 years)

-Mature leaf [P] showed an incredible range: 229 – 1173 µg P g-1

- Mature and senesced leaf [P] ⇩ while leaf P resorptionefficiency ⇧ with soil age

- NM species consistently showed the lowest leaf [P] regardless of soil age- Variation between strategies was highest in the youngest dunes - All strategies converged on similarly very low leaf [P] in the oldest soils: mean = 229 µg P g-1

- Similar pattern for senesced leaf [P] and resorption efficiency

-Mn accumulation is highest in NM species compared to other strategies- Interestingly, leaf [Mn] increased with soil age for all strategies

-All of the different NM strategies showed higher leaf [Mn] compared to other strategies

- This suggests that all these NM strategies may be releasing large amounts of carboxylates into the rhizosphere

Extreme range of mature leaf [P]

Leaf [P] ⇩ with soil age

Leaf P resorption ⇧ with soil age

Leaf P traits differed strongly between nutrient-acquisition strategies in younger soils

Converged on older soils

Leaf Mn was highest in all the NM strategies surveyed, suggesting they all release large amounts of carboxylates, associated with P-acquisition

Model system: Nutrient dynamics across a diverse range of species and nutrient-acquisition strategies

Nutrient-acquisition strategies: considered when assessing leaf nutrient traits, particularly across soil fertility gradients

Leaf Mn accumulation: Occurs in a range of NM strategies

Many thanks to my supervisors: Etienne and Hans

And to everybody who helped me this year, including:Ben TurnerGraham Zemunik, OsmarinaMarinho and Troy Alwright (field work)Greg Cawthray and Elizabeth Halladin (Lab assistance)

Many photos were taken while on fieldwork, by Troy AlwrightPhotography (TAP) and are not to be copied