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.

本数据集配套Zemunik等人（2015）发表的研究论文，该研究依托朱里恩湾沙丘年代序列（Jurien Bay dune chronosequence），探究植物群落整体养分获取策略组合随长期土壤发育的演变规律。研究区域位于澳大利亚西南部生物多样性热点地区，该区域拥有极为丰富的本土植物区系。本数据集涵盖植物区系与土壤两类数据，不仅可独立复现Zemunik等（2015）论文中的全部分析内容，还支持对研究未涉及或未展示的数据集进行进一步挖掘。

研究采用随机分层设计，将年代序列覆盖的沙丘系统划分为6个发育阶段：前3个阶段属于全新世（至约6.5 ka），最老阶段的土壤发育始于早更新世至中更新世（至约2 Ma）。研究共设置60个永久10 m × 10 m样地，6个年代序列阶段各设10个样地。每个样地于2011年8月至2012年3月，以及2012年9月期间至少完成1次野外调查。

为估算10 m × 10 m样地内各植物物种的冠层盖度与个体数量，每个样地内额外布设7个随机定位的2 m × 2 m小样方。在每个小样方中，调查人员完成所有维管植物物种的鉴定、个体数量统计以及植被垂直投影盖度估算。

研究人员从全部420个小样方中采集0~20 cm表层土壤样品，经风干处理后，交由巴拿马史密森尼热带研究所（Smithsonian Tropical Research Institute）开展一系列理化性质检测。本论文重点关注的土壤指标包括：全磷与树脂提取态磷、全氮与可溶性有机氮、土壤总碳与有机碳，以及pH值（分别在纯水与氯化钙溶液中测定）。数据集同时包含其他未在论文中重点展示的土壤理化数据。

植物养分获取策略的判定依据为公开文献，对于策略尚不明确的物种，则通过其根系样品的菌根分析（mycorrhizal analyses）完成判定。本年代序列的植物物种涵盖了当前已知的绝大多数养分获取策略类型。

朱里恩湾年代序列的前期研究已证实，其土壤发育过程符合Walker与Syers（1976）提出的长期土壤发育模型：最年轻的土壤受氮限制，而最古老的土壤受磷限制（Laliberté等，2012）。此外，最年轻土壤的高pH值对区域植物区系的环境过滤作用，是驱动本地植物物种多样性变化的最主要因素（Laliberté等，2014）。

参考文献：
[1] Zemunik, G., Turner, B., Lambers, H. et al. 植物养分获取策略的多样性随长期生态系统发育而增加. 《自然-植物》（Nature Plants）1, 15050 (2015). https://doi.org/10.1038/nplants.2015.50 ;
[2] T.W. Walker, J.K. Syers. 成土过程中磷的归宿. 《土壤学进展》（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), 澳大利亚西南部生物多样性热点地区200万年沙丘年代序列沿资源梯度的养分限制实验评估. 《生态学杂志》（Journal of Ecology）100: 631-642. https://doi.org/10.1111/j.1365-2745.2012.01962.x.;
[4] Laliberté E, Zemunik G, Turner BL. 环境过滤解释沿资源梯度的植物多样性变化. 《科学》（Science）2014 Sep 26;345(6204):1602-5. doi: 10.1126/science.1256330.