Heard Island Vegetation Survey 1986-1987 and 1987-1988

Vegetation surveys were conducted on Heard Island during the 1986/87 and 1987/88 Australian National Antarctic Research Expeditions (ANARE). A stratified sampling approach was adopted. Given the limited time available for sampling, quadrats were placed to sample the bryophytic component of Hughes (1987) six visually recognizable broad vascular plant community categories as well as sampling distinct landscape features such as coastal areas, moraines, scoria cones, and lava fields. Ideally, this stratification would have ensured that the major environmental gradients on the island were detected. A total of 475, 1 x 1 m quadrats were surveyed during the 8-wk 1986/87 field period. Two hundred and fifty quadrats were randomly selected within 25 (10 x 10 m) sites. One hundred and eighty quadrats were positioned on transects over distinct landscape features. The remaining 45 quadrats were randomly located in visually different areas in isolated localities.Access to Heard Island is logistically difficult. Field time for our survey was short. Travel by foot was slow due to rough terrain and the use of helicopters was restricted by unfavorable weather conditions. Field work was conducted in three major ice-free areas on the island: the northwest areas encompassing Laurens Peninsula, Azorella Peninsula, and Mt. Drygalski; the eastern Spit Bay area; and the southern Long Beach area. The number of quadrats in each area reflects the time available (Laurens Peninsula, 119; Azorella Peninsula, 40; Mt. Drygalski, 10; Spit Bay, 250; Long Beach, 45; other areas 11.In each quadrat the following habitat characteristics were noted: location (mapped); geomorphological features (sand, moraine, clinker lava, and lava flow), and general notes on topography; altitude; general slope of the quadrat (irregularities in clinker lava sites made slope difficult to assess); aspect; unconsolidated substrate depth to bedrock or a maximum of 100 cm, using a 1-cm-diameter metal probe (this may be an organic base such as peat or an inorganic substrate such as moraine); availability of water, rated on a subjective five-point exponential scale ranging from 1 (very dry) to 5 (surface free water); exposure to wind, rated on a subjective five-point scale ranging from 1 (very exposed) to 5 (very protected); availability of light, rated on a five-point subjective scale ranging from 1 (exposed to full light conditions) to 5 (deep shade).In each quadrat, cover values using the Braun-Blanquet (1932) scale were recorded for all vascular plants, bryophytes (as a collective unit), bare ground, and rock. Notes on individual cover values for major bryophyte taxa were taken, and samples of bryophyte taxa were collected for identification.This work now falls under the auspices of the RiSCC project (ASAC_1015).The fields in this dataset are:RegionSiteFormationEnvironAltitude (m)Species

本数据集源自1986/87及1987/88年度澳大利亚国家南极研究探险队（ANARE）在赫德岛开展的植被调查工作。本次调查采用分层抽样方法。鉴于采样可用时长有限，样方布设需覆盖Hughes（1987）所划分的6类目视可辨的大型维管植物群落大类中的苔藓植物组分，同时兼顾海岸、冰碛物、火山渣锥及熔岩场等典型景观特征。理想状态下，该分层策略可确保捕获该岛的主要环境梯度。

1986/87年度的8周野外调查期间，共布设475个1×1m样方：其中250个样方随机设置于25个10×10m的样地内；180个样方沿覆盖典型景观特征的样线布设；剩余45个样方随机设置于孤立区域内目视差异显著的地段。

赫德岛的后勤通行条件极为严苛，本次调查的野外作业时长有限。受崎岖地形影响，步行行进速度缓慢，且直升机作业受恶劣天气制约。本次野外工作集中开展于岛上3处主要无冰区：涵盖劳伦斯半岛、阿佐雷拉半岛及德加尔斯基山的西北部区域；东部的斯皮特湾区域；以及南部的朗比奇区域。各区域的样方数量与可支配的作业时长相匹配（劳伦斯半岛119个、阿佐雷拉半岛40个、德加尔斯基山10个、斯皮特湾250个、朗比奇45个，其余区域11个）。

每个样方均记录以下生境特征：点位信息（已完成测绘）、地貌特征（砂质、冰碛、渣状熔岩及熔岩流）、地形概况、海拔高度、样方所在区域的坡度（渣状熔岩区域的地形起伏导致坡度评估存在难度）、坡向、未固结基质至基岩的深度（采用直径1cm的金属探针测定，最大测量深度为100cm，基质可为泥炭类有机质或冰碛物类无机基质）、水分条件（采用1（极干燥）至5（地表自由水）的五级主观指数量表评定）、风力暴露程度（采用1（极暴露）至5（极遮蔽）的五级主观量表评定）、光照条件（采用1（全光照）至5（重度遮阴）的五级主观量表评定）。

针对每个样方，采用Braun-Blanquet（1932）盖度等级法记录所有维管植物、苔藓植物（以类群为统计单位）、裸地及岩石的盖度。同时记录主要苔藓植物类群的单种盖度，并采集苔藓植物类群标本用于物种鉴定。

本研究工作现隶属于RiSCC项目（ASAC_1015）。

本数据集包含以下字段：区域（Region）、样点（Site）、群系（Formation）、生境环境（Environ）、海拔（米，Altitude (m)）、物种（Species）。