1. Long-term pedogenesis leads to important changes in the availability of soil nutrients, especially nitrogen (N) and phosphorus (P). Changes in the availability of micronutrients can also occur, but are less well understood. We explored whether changes in leaf nutrient concentrations and resorption were consistent with a shift from N to P limitation of plant productivity with soil age along a >2-million year dune chronosequence in south-western Australia. We also compared these traits among plants of contrasting nutrient-acquisition strategies, focusing on N, P and micronutrients. 2. The range in leaf [P] for individual species along the chronosequence was exceptionally large for both green (103–3000 μg P g-1) and senesced (19–5600 μg P g-1) leaves, almost equalling that found globally. From the youngest to the oldest soil, cover-weighted mean leaf [P] declined from 1840 to 228 μg P g-1, while P-resorption efficiency increased from 0% to 79%. All species converged towards a highly conservative P-use strategy on the oldest soils. 3. Declines in cover-weighted mean leaf [N] with soil age were less strong than for leaf [P], ranging from 13.4 mg N g-1 on the youngest soil to 9.5 mg N g-1 on the oldest soil. However, mean leaf N-resorption efficiency was greatest (45%) on the youngest, N-poor soils. Leaf N:P ratio increased from 8 on the youngest soil to 42 on the oldest soil. 4. Leaf zinc (Zn) concentrations were low across all chronosequence stages, but mean Zn-resorption efficiency was greatest (55–74%) on the youngest calcareous dunes, reflecting low Zn availability at high pH. 5. N2-fixing species had high leaf [N] compared with other species. Non-mycorrhizal species had very low leaf [P] and accumulated Mn across all soils. We surmise that this reflects Mn solubilisation by organic acids released for P acquisition. 6. Synthesis. Our results show community-wide variation in leaf nutrient concentrations and resorption that is consistent with a shift from N to P limitation during long-term ecosystem development. High Zn resorption on young calcareous dunes supports the possibility of micronutrient co-limitation. High leaf [Mn] on older dunes suggests the importance of carboxylate release for P acquisition. Our results show a strong effect of soil nutrient availability on nutrient-use efficiency, and reveal considerable differences among plants of contrasting nutrient-acquisition strategies.
Jurien Bay leaf nutrient data
Description
Leaf nutrient concentration and C/N stable isotope data for 18 plant species across five dune chronosequence stages along the Jurien Bay chronosequence.
Format
A data frame with 508 observations on the following 22 variables:
plot
factor with names of 50 10x10-m plots
stage
factor indicating chronosequence stage (1 = youngest, 5 = oldest)
species
factor with full plant species names
state
factor with leaf state: mature or senesced
date
sampling date
ICP
factor stating whether nutrients other than C and N were analysed with a radial or axial ICP equipment for each sample
C
leaf carbon concentration (%)
Ca
leaf calcium concentration (microg g^-1)
Cd
leaf boron concentration (microg g^-1)
Cu
leaf copper concentration (microg g^-1)
Fe
leaf iron concentration (microg g^-1)
K
leaf potassium concentration (microg g^-1)
Mg
leaf magnesium concentration (microg g^-1)
Mn
leaf manganese concentration (microg g^-1)
Mo
leaf molybdenum concentration (microg g^-1)
Na
leaf sodium concentration (microg g^-1)
P
leaf phosphorus concentration (microg g^-1)
S
leaf sulfur concentration (microg g^-1)
Zn
leaf zinc concentration (microg g^-1)
N
leaf nitrogen concentration (microg g^-1)
d15N
delta-N-15 (permil Air)
d13C
delta-C-13 (permil VPDB)
Details
For leaf sampling, we used 50 plots (10 m x 10 m each) from five chronosequence stages where vegetation had been characterised previously.
Using the vegetation survey data, we ranked species in each of the five chronosequence stages from the most to the least abundant, based on canopy cover estimates. We then selected 5–7 species from each stage, targeting the most abundant species for each of four contrasting nutrient-acquisition strategies: arbuscular mycorrhizal (AM), ectomycorrhizal (EM), N-fixing (NF) and non-mycorrhizal (NM) (see juriensp for strategies). Ericoid mycorrhizal species were not considered because they were not among the most abundant species. We note that N-fixing species are generally AM and/or EM, but we considered them as a separate group because they often show high foliar [N]. Species were selected from the ten most-abundant species per stage, with the exception of stage 4 where the 18 most-abundant species were considered. The selected species accounted for between 38% (stage 5) and 65% (stage 1) of the total canopy cover of each stage. A total of 18 species were selected for leaf sampling.
All leaf material was collected over a two-month period between late March and early May 2012, near the end of the dry summer season. In each of the 50 plots, only healthy mature individuals were selected for sampling. In general, mature and senesced leaves were sampled from one individual plant per species in each plot. A species was considered absent from a plot if it could not be found within ~30 m of its centre. The number of individual collections (one collection = both mature and senesced leaves) per species in each chronosequence stage ranged from five to ten. In each case, representative samples of mature and senesced leaves were collected using nitrile gloves in order to minimise sample contamination. Leaves were not washed prior to nutrient analyses but we consider dust contamination to be highly unlikely, given the sandy nature of the soils.
Mature leaves were undamaged, fully expanded and exposed to full sunlight. In most cases, senesced leaves were collected directly from the plant by gently shaking the plant and collecting fallen leaves. Senesced leaves were easily distinguished from green leaves, since they were yellow or brown and detached easily from the plant. However, for a few species it was not possible to collect senesced leaves from live plants, in which case senesced leaves were collected directly beneath the plant from recently fallen litter. In all cases, there was no visible degradation of senesced leaves collected from this litter, which had predominantly fallen during the summer and had not been exposed to any significant rain between litter fall and collection. Therefore, we assumed that losses of nutrients through leaching or decomposition were minimal, although some photodegradation may have occurred. A total of 508 leaf samples (mature and senesced) were collected for nutrient analyses.
Each leaf sample was oven-dried (70 degrees C, 48 h) and finely ground using a Teflon-coated stainless steel ball mill. A subsample was analysed for carbon (C) and nitrogen (N) concentrations using a continuous-flow system consisting of a SERCON 20-22 mass spectrometer connected with an automated nitrogen/carbon analyser (Sercon, Crewe, UK). Stable isotopes of C and N were analysed using a continuous flow system consisting of a SERCON 20-22 mass spectrometer connected with an automated N/C analyser (Sercon, Crewe, UK). These analyses were done at the Western Australian Biogeochemistry Centre, located at the University of Western Australia.
A second subsample was acid-digested using concentrated HNO3:HClO4 (3:1) and analysed for Ca, Cd, Cu, Fe, K, Mg, Mn, Mo, Na, P, S and Zn concentrations using inductively coupled plasma-atomic emission spectrometry (ICP-AES; ChemCentre, Perth, Australia). All digests were first analysed using a simultaneous Varian Vista Pro (Australia), radially configured ICP-AES equipment fitted with a charge-coupled device (CCD) detection system and an A.I. Scientific AIM-3600 auto-sampler. Samples with P concentrations close to minimum reporting limit were re-run on more sensitive axially-configured ICP-AES equipment. The ICP analyses were done at the WA Chemcentre.
jurienleafnut.csv
