A simple survey protocol for assessing terrestrial biodiversity in a broad range of ecosystems

Finding standard cost-effective methods for monitoring biodiversity is challenging due to trade-offs between survey costs (including expertise), specificity, and range of applicability. These trade-offs cause a lack of comparability among datasets collected by ecologists and conservationists, which is most regrettable in taxonomically demanding work on megadiverse inconspicuous taxon groups. We have developed a site-scale survey method for diverse sessile land organisms, which can be analyzed over multiple scales and linked with ecological insights and management. The core idea is that field experts can effectively allocate observation effort when the time, area, and priority sequence of tasks are fixed. We present the protocol, explain its specifications (taxon group; expert qualification; plot size; effort) and applications based on >800 original surveys of four taxon groups; and we analyze its effectiveness using data on polypores in hemiboreal and tropical forests. We demonstrate consistent effort-species richness curves and among-survey variation in contrasting ecosystems, and high effectiveness compared with casual observations both at local and regional scales. Bias related to observer experience appeared negligible compared with typical assemblage variation. Being flexible in terms of sampling design, the method has enabled us to compile data from various projects to assess conservation status and habitat requirements of most species (specifically rarities and including discovery of new species); also, when linked with site descriptions, to complete environmental assessments and select indicator species for management. We conclude that simple rules can significantly improve expert-based biodiversity surveys. Ideally, define (i) a common plot size that addresses multiple taxon groups and management goals; (ii) taxon groups based on field expertise and feasible number of species; (iii) sufficient and practical search time; (iv) a procedure for recording within-plot heterogeneity. Such a framework, combined with freedom to allocate effort on-site, helps utilizing full expertise of observers without losing technical rigor.由于调查成本（含专业资质要求）、特异性与适用范围之间存在权衡，寻找兼具标准性与成本效益的生物多样性监测方法颇具挑战。这些权衡导致生态学家与保护工作者采集的数据集之间缺乏可比性，这在针对物种丰富但难以辨识类群的分类学高要求研究中尤为令人遗憾。我们开发了一种适用于多样固着陆生生物的样地尺度调查方法，该方法可在多尺度下开展分析，并可与生态学认知及管理应用相衔接。其核心思路为：当任务的时间、面积与优先顺序固定时，野外专家可高效分配观测投入。我们详细介绍了该方案，阐释了其适用类群、专家资质、样地面积、调查投入等规范，并基于4个类群的800余份原始调查数据说明了其应用场景；同时通过半寒温带与热带森林中多孔菌的相关数据分析了该方法的有效性。我们证明了该方法在不同生态系统中可得到一致的调查投入-物种丰富度曲线与调查间变异，且在局地与区域尺度上均优于随意观测。相较于典型的群落变异，由观测者经验带来的偏差可忽略不计。由于该方法在抽样设计上具备灵活性，我们得以整合多项目的数据，以评估多数物种（尤其是稀有种，包括新种发现）的保护现状与栖息地需求；同时，若结合样地描述，还可完成环境评估并筛选管理用指示物种。我们得出结论：简单的规则可显著优化基于专家经验的生物多样性调查。理想情况下，应明确：(i) 可兼顾多类群与多重管理目标的统一样地面积；(ii) 基于野外专业能力与可行物种数量划定的调查类群；(iii) 充足且实操性强的搜索时间；(iv) 样地内异质性的记录流程。此类框架结合现场分配调查投入的自由度，可在不损失技术严谨性的前提下，充分发挥观测者的专业能力。