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The dataset accompanies the paper by Zemunik et al. (2015), which used the Jurien Bay dune chronosequence to investigate the changes in the community-wide suite of plant nutrient-acquisition strategies in response to long-term soil development. The study was located in the Southwest Australian biodiversity hotspot, in an area with an extremely rich regional flora. The dataset consists of both flora and soil data that not only allow all analyses presented in the paper (Zemunik et al. 2015) to be independently investigated, but also would allow further exploration of the data not considered or presented in the study. The study used a randomised stratified design, stratifying the dune system of the chronosequence into six stages, the first three spanning the Holocene (to ~6.5 ka) and oldest spanning soil development from the Early to Middle Pleistocene (to ~2 Ma). Floristic surveys were conducted in 60 permanent 10 m × 10 m plots (10 plots in each of six chronosequence stages). Each plot was surveyed at least once between August 2011 and March 2012, and September 2012. To estimate canopy cover and number of individuals for each plant species within the 10 m × 10 m plots, seven randomly-located 2 m × 2 m subplots were surveyed within each plot. Within each subplot, all vascular plant species were identified, the corresponding number of individuals was counted and the vertically projected vegetation canopy cover was estimated. Surface (0-20 cm) soil from each of the 420 subplots was collected, air dried and analysed at the Smithsonian Tropical Research Institute in Panama, for a range of chemical and physical properties, the main ones of which were considered in this paper being total and resin soil phosphorus, total nitrogen and dissolved organic nitrogen, soil total and organic carbon, and pH (measured in H20 and CaCl2). However, other soil data are also presented in the dataset. Nutrient-acquisition strategies were determined from the literature, where known, and from mycorrhizal analyses of root samples from species with poorly known strategies. Most of the currently known nutrient-acqusition strategies were found in the species of the chronosequence. Previous studies in the Jurien Bay chronosequence have established that its soil development conforms to models of long-term soil development first presented by Walker and Syers (1976); the youngest soils are N-limiting and the oldest are P-limiting (Laliberté et al. 2012). However, filtering of the regional flora by high soil pH on the youngest soils has the strongest effect on local plant species diversity (Laliberté et al. 2014). <br></br> References:  Zemunik, G., Turner, B., Lambers, H. et al. Diversity of plant nutrient-acquisition strategies increases during long-term ecosystem development. Nature Plants 1, 15050 (2015). https://doi.org/10.1038/nplants.2015.50 ;  T.W. Walker, J.K. Syers. The fate of phosphorus during pedogenesis Geoderma, 15 (1) (1976), pp. 1-19, 10.1016/0016-7061(76)90066-5 ;  Laliberté, E., Turner, B.L., Costes, T., Pearse, S.J., Wyrwoll, K.H., Zemunik, G. & Lambers, H. (2012);  Laliberté, E., Turner, B.L., Costes, T., Pearse, S.J., Wyrwoll, K.-H., Zemunik, G. and Lambers, H. (2012), Experimental assessment of nutrient limitation along a 2-million-year dune chronosequence in the south-western Australia biodiversity hotspot. Journal of Ecology, 100: 631-642. https://doi.org/10.1111/j.1365-2745.2012.01962.;  Laliberté E, Zemunik G, Turner BL. Environmental filtering explains variation in plant diversity along resource gradients. Science. 2014 Sep 26;345(6204):1602-5. doi: 10.1126/science.1256330.
We investigated recovery of soil chemical properties after restoration in semi-arid Western Australia, hypothesising that elevated nutrient concentrations would gradually decline post planting, but available phosphorus (P) concentrations would remain higher than reference conditions. We used a space-for-time substitution approach, comparing 10 planted old field plots with matched fallow cropland and reference woodlands. Sampling on planted old fields and reference woodland plots was stratified into open patches and under tree canopy to account for consistent differences between these areas. Soil samples to 10 cm depth were collected at 20 points across 30 plots. Ten samples were randomly collected and combined from locations beneath trees and a further 10 samples collected in gaps and combined, resulting in one soil sample for beneath tree canopy and another one for gap areas. Sampling occurred in autumn 2017 to capture potentially high concentrations of soil nitrate following the seasonal die-back of exotic annual plants typical of this Mediterranean-climate region. Samples were stored at 4 °C in plastic zip-lock bags until delivery to the CSBP Limited (Bibra Lake, WA) laboratories. Chemical parameters measured were plant available P (Colwell), plant available N (nitrate and ammonium), total N, plant available potassium (Colwell) and plant available sulphur (KCl 40). Lastly, electrical conductivity, pH (H2O, CaCl2), and soil texture were quantified as differences among plots could affect nutrient availability and soil chemistry. Soil available nutrients were also measured using Plant Root Simulator (PRS)TM resin probes (Western Ag Innovations, 2010, https://www.westernag.ca/inn). Probes contain anion or cation exchange membranes within a plastic stake. The membranes act as a sink for collecting nutrients and continuously absorb ions during deployment. Four anion and cation probes were placed vertically in the top 15 cm of soil at each stratification. Probes were left in the ground for three months during the growing season, from August to November 2017. This period was deemed suitable for semi-arid regions to achieve sufficient nutrient uptake but not too long to saturate probes. After removal, probes were cleaned with deionized water and sent to Western Ag Innovations (Canada) for analysis. All soil chemical analyses were conducted under laboratory conditions using standard test procedures. PRS probe nutrients are reported as micrograms/10cm2/time.
This data contains soil physico-chemical characteristics collected at the Warra Tall Eucalypt site in 2012.