北京昌平区农业景观野生蜂多样性的时空动态分布

近年来,由于生境质量的下降和生境丧失,野生蜂多样性急剧下降,严重威胁传粉服务和农业的可持续发展。为揭示野生蜂在农业景观镶嵌体中的时空分布格局及不同生境对野生蜂保护的重要性,本研究于2016年4—9月采用网捕法调查了北京昌平农业景观4种主要生境类型(人工林、自然灌木林、荒草地和桃园)中的野生蜂,分析不同生境类型中野生蜂多样性及其时间动态变化特征。结果表明:野生蜂及其中的大体长蜂和独居蜂的物种数和个体数,以及中体长蜂的个体数均在自然灌木林中最高,人工林中小体长蜂个体数最多,野生蜂总个体数和总物种数均在桃园中最低。在不同月份,所有功能群野生蜂均在自然或半自然生境中最高,5月桃园中最低,原因可能与桃园中对地表杂草的集约化管理有关。多度最大的4个优势物种依次为黄胸彩带蜂、铜色隧蜂、黄芦蜂和隧淡脉隧蜂,其在生境间的时间动态特征不同。调查的4种生境均为野生蜂提供了可利用资源,但自然生境和半自然生境的作用更大;其中,自然灌木林维持了较多具有较高潜在传粉效率的中体长和大体长野生蜂,具有更高的保护价值。为了促进该地区农业景观中不同功能群野生蜂多样性及传粉服务,需提高生境类型的多样性,同时在野生蜂活动高峰季节采取低集约化的生境管理方式。

Temporal-spatial dynamics of wild bee diversity in agricultural landscapes in Changping District, Beijing

Pollination is one of the most important ecosystem services provided mainly by bees for crops and wild plants. The universality, adaptability and diversity of wild bees are driven more as reliable pollinators than honey makers. However, the diversity of wild bees had significantly reduced in recent years due to the loss of habitat and the erosion of habitat quality, which potentially threaten pollination service and agricultural sustainability supported by bees. The functional group diversity of wild bees is also the important component of diversity, which is a better predictor of pollination than species diversity. Wild bee species with different functional traits need different resources and respond to environmental changes differently. However, there is little knowledge on the response of different functional groups of wild bees to habitat types. To determine the spatio-temporal dynamics of wild bees in different habitats and the importance of different habitats for wild bee conservation in agricultural landscape mosaics, netting-catching was used to collect wild bees in four habitats (planted woodland, natural shrub forest, wasteland and peach orchard) during the period from April to September 2016. The temporal dynamics of diversity of wild bees and their functional groups in different habitats were analyzed. The results showed that natural shrub forest had the highest individual numbers and species richness of wild bees, large bees, solitary bees; and highest individual number of medium-sized bees. While planted woodland had more individuals of small bees, peach orchard had the lowest individuals number and species richness of wild bees. Natural shrub forest, planted woodland and peach orchard all had similar temporal dynamics of wild bee diversity, with one peak in spring and the other in summer. Overall, all functional groups of wild bees had the highest diversity in natural or semi-natural habitats across the sampling seasons. Peach orchard had the lowest wild bee diversity in May, which was attributed to intensive management of groundcover in peach orchards. Similarly, there were more unique species solely in natural shrub forest because of high resource availability and low human disturbance. Other habitat types also had some unique species which contributed to the overall bee diversity in the region. The four most abundant species were respectively Nomia thoracica, Halictus aerarius, Ceratina flavipes and Lasioglossum halictoides, which had different temporal dynamics in the habitat types. The species N. thoracica and C. flavipes were distributed in all the habitat types, except for wasteland. While N. thoracica was active in June through August, C. flavipes was active throughout all the sampling seasons. H. aerarius and L. halictoides existed in all habitat types, with the former active from May through September and the latter from April through July. Therefore, the four habitat types all had essential resources for wild bees, but the natural and semi-natural habitats were more important. In particular, natural shrub forest sustained more bees and had greater pollination efficiency. It was concluded that habitat diversity (especially natural and semi-natural habitat diversity) and less intensive management during active seasons of wild bees were critical for improving wild bee diversity and pollination services.