This is the Honours presentation of Patrick Hayes. It describes his work on leaf nutrient concentration and resorption along the 2-million year Jurien Bay dune chronosequence. Patty gave an excellent talk!
1. Patrick Hayes
School of Plant Biology,
The University of Western Australia
Supervisors: Asst/Prof Etienne Laliberté
W/Prof Hans Lambers
2. Conversion to poorly available forms
Occlusion
Leaching
Erosion
Plant uptake
3. Provide model 2-million year Jurien Bay
system for strong dune chronosequence
fertility gradient
with soil age
Increasingly
P-limited
4. 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
5. Range of strategies to improve P-acquisition:
⇐ P ‘scavengers’
Arbuscular mycorrhizal
(AM) and Ectomycorrhizal
(EM)
P ‘miners’ ⇒
Non-mycorrhizal (NM)
(e.g. Cluster, dauciform
and sand-binding roots)
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
6. 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)
7. 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
Dauciform Proteoid
Sand-binding
(Shane et al. 2011)
8. 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
9. Jurien
0-7 ky Bay
120-500 ky
Perth
>2000 ky
Laliberté et al. (2012)
10. 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.
16. -Mature leaf [P] showed an incredible range:
229 – 1173 µg P g-1
- Mature and senesced leaf [P] ⇩ while leaf P resorption
efficiency ⇧ with soil age
17. - 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
18. -Mn accumulation is highest in NM species compared to other
strategies
- Interestingly, leaf [Mn] increased with soil age for all strategies
19. -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
20. 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
21. 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
22. Many thanks to my supervisors:
Etienne and Hans
And to everybody who helped me
this year, including:
Ben Turner
Graham Zemunik, Osmarina
Marinho and Troy Alwright (field
work)
Greg Cawthray and Elizabeth
Halladin (Lab assistance)
Many photos were taken while on
fieldwork, by Troy Alwright
Photography (TAP) and are not to be
copied
Notes de l'éditeur
Define P resorption: the reallocation of P from senescing leaves back to the plant for further growth.
you don’t need to go as far as Hawaii to find similar long-term soil age sequencesin fact you’re sitting on one right nowall across the Swan Coastal Plain you find systems of dune that range from very young to very old, around 2 million yearsthis is what I use in my current research
