Data from: Small-scale restoration in intensive agricultural landscapes supports more specialized and less mobile pollinator species

1. Agriculture now constitutes 40–50% of terrestrial land use globally. By enhancing habitat suitability and connectivity, restoration within agricultural landscapes could have a major influence on biodiversity conservation. However, habitat management within intensive agricultural landscapes may primarily boost abundances of common, highly mobile generalists, rather than vulnerable or endangered species. We studied pollinator community response to small-scale habitat restoration in the intensively farmed Central Valley of California to determine whether restoration could also promote more specialized, less common, and/or less mobile species. 2. Composition of pollinator communities was assessed in five experimental and 10 control (unrestored) sites before and after restoration of native plant hedgerows over an 8-year period, using a before-after-control-impact design. 3. We characterized bee and fly species based on functional response traits [floral specialization, habitat specialization, abundance, body size, and sociality (bees only)] known to influence the response to habitat change. 4. We modelled how species occurrences changed with habitat restoration over time as modulated by their response traits. 5. We found that hedgerows not only significantly enhanced occurrences of native bee and syrphid fly species, but that as hedgerows matured, they had a greater positive effect on species that were more specialized in floral and nesting resources and smaller (less mobile). 6. Synthesis and applications. Unlike previous studies that suggest habitat restoration in agricultural landscapes only benefits mobile, generalist species, our results suggest that small-scale habitat restoration can promote species whose traits likely render them particularly vulnerable to habitat degradation. Thus, even within highly intensive agricultural landscapes, small-scale habitat restoration can be a conservation management tool. However, tailoring habitat enhancements to promote certain species or guilds may be critical for their success as a conservation intervention in agricultural landscapes.

1. 当前全球农业用地占陆地土地利用总面积的40%~50%。通过提升栖息地适宜性与连通性，农业景观内的生境修复可对生物多样性保护产生重要推动作用。然而，集约化农业景观中的生境管理，往往仅能提升常见、高流动性广食性物种的种群丰度，而非易危或濒危物种。本研究以集约化耕作的美国加利福尼亚州中央谷为研究区域，探究小型生境修复对传粉者群落（pollinator community）的响应效应，旨在明确生境修复是否同样能够促进特化程度更高、种群更为稀有、流动性更低的物种。
2. 本研究采用对照前后影响设计（Before-After-Control-Impact design, BACI），在为期8年的时间序列中，于5个实验样地与10个对照（未修复）样地内，对本土植物绿篱（native plant hedgerow）修复前后的传粉者群落组成开展了调查评估。
3. 研究基于已知会影响物种对生境变化响应的功能响应性状（functional response trait），对蜂类与蝇类物种进行了特征刻画，这些性状包括花部特化程度、栖息地特化程度、种群丰度、体型大小，以及社会性行为（仅针对蜂类）。
4. 本研究构建统计模型，分析了物种存在情况随生境修复的时间变化规律，以及该变化如何受其功能响应性状的调控。
5. 研究结果表明，本土植物绿篱不仅显著提升了本土蜂类与食蚜蝇（syrphid fly）物种的出现率，且随着绿篱逐渐成熟，其对那些在花部与筑巢资源上特化程度更高、体型更小（流动性更低）的物种产生的正向效应更为显著。
6. 综合与应用（Synthesis and applications）：过往研究认为农业景观中的生境修复仅能使流动性强的广食性物种获益，但本研究结果表明，小型生境修复可促进那些因功能性状而易受生境退化威胁的物种。因此，即便在高度集约化的农业景观中，小型生境修复亦可作为一种有效的保护管理工具。不过，若要使生境改善措施作为农业景观中的保护干预手段取得成功，针对特定物种或功能群（guild）定制化优化生境提升方案或为关键所在。