Jurien Bay Dune Chronosequence Floristics and Soil Dataset 

The dataset accompanies the paper by Zemunik et al. (2016), which used the Jurien Bay dune chronosequence to investigate the changes in the plant community diversity and turnover in response to long-term soil development. The Jurien Bay chronosequence is 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 allows all analyses presented in the paper (Zemunik et al. 2016) to be independently investigated. The dataset is an update to that previously supplied for a prior study (Zemunik et al. 2015; DOI 10.4227/05/551A3DDE8BAF8). 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: total and resin soil phosphorus; total nitrogen and dissolved organic nitrogen; soil total and organic carbon; exchangeable calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn) and sodium (Na); Mehlich-III extractable iron, magnesium, copper (Cu) and zinc (Zn); and pH (measured in H20 and CaCl2). 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). The update involved modification to species names due to taxonomic changes and the inclusion of additional soil analyses, not present in Zemunik et al. (2015). The additional soil variables (additional to DOI 10.4227/05/551A3DDE8BAF8) were exchangeable Ca, K, Al, Mg, Mn and Na, measured for all 420 subplots; and Cu, Fe, Mn and Zn, extracted in Mehlich III solution, for each of the 60 plots. References Laliberté, E., Turner, B.L., Costes, T., Pearse, S.J., Wyrwoll, K.H., Zemunik, G. & 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. Walker, T.W. & Syers, J.K. (1976) The fate of phosphorus during pedogenesis. Geoderma, 15, 1-19. Zemunik, G., Turner, B.L., Lambers, H. & Laliberté, E. (2015) Diversity of plant nutrient-acquisition strategies increases during long-term ecosystem development. Nature Plants 1, Article number: 15050, 1-4. Zemunik, G., Turner, B.L., Lambers, H. & Laliberté, E. (2016) Increasing plant species diversity and extreme species turnover accompany declining soil fertility along a long-term chronosequence in a biodiversity hotspot. Journal of Ecology. 

We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging. 

The dataset accompanies the paper "Increasing plant species diversity and extreme species turnover accompany declining soil fertility along a long-term chronosequence in a biodiversity hotspot", in the Journal of Ecology. For this study the author quantified changes in plant species diversity and community composition, and identified the edaphic drivers of these changes, in the Jurien Bay dune chronosequence. The author found large increases in plant alpha diversity and extremely high species turnover associated with declining soil fertility. The results suggest that the interaction of an exceptionally diverse plant species pool and nutrient-impoverished soils provides the basis for the maintenance of such high beta diversity at extremely low soil fertility. 

1. Flora surveys: For full methods see: Zemunik, G., Turner, B.L., Lambers, H. & Laliberté, E. (2016) Increasing plant species diversity and extreme species turnover accompany declining soil fertility along a long-term chronosequence in a biodiversity hotspot. Journal of Ecology, In Press; Zemunik, G., Turner, B.L., Lambers, H. & Laliberté, E. (2015) Diversity of plant nutrient-acquisition strategies increases during long-term ecosystem development. Nature Plants, 1, Article number: 15050, 1-4. In brief, the study used a randomised stratified sampling design, with the three main dune systems of the chronosequence (Quindalup, Spearwood and Bassendean) delineated into six chronosequence stages. Within a digitised region for each stage, 10 (10 × 10 m) plots were randomly located. Within each 10 × 10 m plot, the species name, plant family, the nutrient-acquisition strategy and the growth form of the species were recorded. To estimate canopy cover and the number of individuals for each plant species within the 10 × 10 m plots, seven randomly-located 2 × 2 m subplots were surveyed within each plot. Within each 2 × 2 m subplot, all vascular plant species were identified, the corresponding number of individuals was counted, the vertically projected vegetation canopy cover was visually estimated (yielding both the absolute cover (%), relative cover (%)), and the median width and median height were recorded. 2. Soil sampling and analyses : Seven soil samples per 10x10 m plot (i.e. one in the middle of each of the seven 2x2 m subplots) were taken from the top 20 cm of soil and were analysed for a range of total and available nutrients, and properties. From these subplot samples, soil pH (in water and 10 mM CaCl2), total soil carbon (C) and nitrogen (N) were determined by automated combustion, and dissolved organic N (DON) by KCl extraction. We determined exchangeable cations (aluminium, calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn) and sodium (Na)) by extraction in 0.1 M BaCl2 and detection by inductively coupled plasma optical emission spectrometry (ICP-OES) on an Optima 7300 DV (Perkin Elmer, Inc, Shelton, CT, USA). Key micronutrients (copper, Fe, Mn and zinc) were extracted in Mehlich-III solution (Mehlich 1984) with detection by ICP-OES. Bulked subplot soil samples were used to determine plot-level readily-exchangeable P by extraction with anion-exchange membranes (resin P), and total soil Ca, K, Mg, Mn and P by digestion in concentrated nitric acid and detection by ICP-OES. Carbonate concentrations of the bulked soil samples were determined by mass loss after addition of 3 M HCl.