Abstract Remnant vegetation in agricultural landscapes can play a significant role in supporting farmland biodiversity, especially agriculturally important arthropods such as spiders. Little is known about spider composition in native vegetation remnant patches, or which environmental parameters influence within-patch diversity. Furthermore, data on spider diversity is limited in the Greater Cape Floristic Region (GCFR), a global botanical hotspot of great conservation value. Here we sampled spiders in 12 remnant natural fynbos (sclerophyllous) patches in a fragmented agricultural landscape. Multiple environmental variables were measured at each site (within patch variables and landscape variables), to determine their influence on spider genus richness and assemblage structure. We also did this for ground- and plant-dwelling genera, as well as for their assemblages separately. Overall, natural vegetation remnants supported high spider diversity, even rare and range restricted species. Both patch- and landscape-scale variables influenced spider diversity and assemblage structure. Remnant patch size influenced the assemblage structure of all guilds, and positively influenced overall spider diversity. Similarly, the amount of remnant vegetation in the landscape influenced the assemblage structure of most guilds, as well as positively influencing overall spider diversity, across multiple spatial scales. Additional important variables were rockiness, alien invasive tree species richness and topographic complexity. We show that spider diversity is maintained by remnants of good quality natural vegetation, but also influenced by the complexity of the landscape. Preservation of remnant vegetation patches, regardless of size, throughout the privately-owned farm conservancy landscape maintains spider diversity, and so private land conservation should be promoted.

中文翻译：

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复杂农业景观中的高质量残余斑块维持高蜘蛛多样性

摘要 农业景观中的残余植被可以在支持农田生物多样性方面发挥重要作用，尤其是对农业重要的节肢动物，如蜘蛛。人们对原生植被残余斑块中的蜘蛛组成知之甚少，或者哪些环境参数会影响斑块内的多样性。此外，大开普省植物区 (GCFR) 是具有重要保护价值的全球植物热点，有关蜘蛛多样性的数据有限。在这里，我们在一个支离破碎的农业景观中对 12 个残余的天然 fynbos（硬叶）斑块中的蜘蛛进行了采样。在每个地点测量了多个环境变量（在斑块变量和景观变量内），以确定它们对蜘蛛属丰富度和组合结构的影响。我们也对地面和植物属进行了这项工作，以及分别用于它们的组合。总体而言，自然植被残余支持高蜘蛛多样性，甚至是稀有和范围受限的物种。斑块和景观尺度变量影响蜘蛛多样性和组合结构。残余斑块大小影响所有公会的组合结构，并对整体蜘蛛多样性产生积极影响。同样，景观中残余植被的数量影响了大多数行会的组合结构，并在多个空间尺度上对总体蜘蛛多样性产生了积极影响。其他重要变量是岩石、外来入侵树种丰富度和地形复杂性。我们表明，蜘蛛的多样性是由优质自然植被的残余物维持的，但也受到景观复杂性的影响。