Jurien Bay Dune Chronosequence Data 

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).

References: [1] 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 ; [2] 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 ; [3] Laliberté, E., Turner, B.L., Costes, T., Pearse, S.J., Wyrwoll, K.H., Zemunik, G. & Lambers, H. (2012); [3] 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.x.; [4] 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 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. 

Soil fertility strongly influences plant communities, but its effects on diversity of belowground strategies by which plants obtain nutrients are poorly known. As soil fertility declines, plants with nutrient-conserving traits are favoured, leading to functional convergence. This led to generalisations that environmental filtering dominates plant community assembly at low fertility. By contrast, our study along an exceptionally-strong fertility gradient in a biodiversity hotspot showed increasing diversity of nutrient-acquisition strategies with declining fertility. Our results demonstrated that fundamentally-different community-assembly processes operate above- and belowground. As such, it emphasises the importance of belowground traits to predict how vegetation will respond to environmental changes such as eutrophication. 

Flora surveys: In brief, 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. Nutrient-acquisition strategies were identified from the literature, where known, and from roots sampled from species in the field, where unknown. The file contains the following: stage: the chronosequence stage number plot: three-part code name for the plot species: Binomial (sometimes with the common name in brackets) of the species family: The species' family cover: Absolute cover (%) in the plot. This usually will sum to <100% relativecover: Relative cover (%) in the plot. This sums to 100% strategy: The nutrient-acquisition strategy, as determined from the literature and root sampling of selected species. Can be a combination of the following: "AM", "Carnivorous", "Cluster roots", "Dauciform", "Ectomycorrhizal", "Ericoid", "Hemiparasite", "Holoparasite", "Non-mycorrhizal", "Orchid mycorrhizal", "Sand-binding", "Thysanotus mycorrhizal, Sand-binding", "Unspecialised" growthform: the species' growth form. Can be one of: "annual grass" , "annual herb", "annual sedge", "geophytic herb", "grass", "perennial herb", "rush", "sedge", "shrub", "tree"