Seminatural grasslands are important biodiversity hotspots, but they are increasingly degraded by intensive agriculture. Grassland restoration is considered to be promising in halting the ongoing loss of biodiversity, but this evaluation is mostly based on plant communities. Insect herbivores contribute substantially to grassland biodiversity and to the provisioning of a variety of ecosystem functions. However, it is unclear how they respond to different measures that are commonly used to restore seminatural grasslands from intensively used agricultural land. We studied the long‐term success of different restoration techniques, which were originally targeted at reestablishing seminatural grassland plant communities, for herbivorous insect communities on taxonomic as well as functional level. Therefore, we sampled insect communities 22 yr after the establishment of restoration measures. These measures ranged from harvest and removal of biomass to removal of the topsoil layer and subsequent seeding of plant propagules. We found that insect communities in restored grasslands had higher taxonomic and functional diversity compared to intensively managed agricultural grasslands and were more similar in composition to target grasslands. Restoration measures including topsoil removal proved to be more effective, in particular in restoring species characterized by functional traits susceptible to intensive agriculture (e.g., large‐bodied species). Our study shows that long‐term success in the restoration of herbivorous insect communities of seminatural grasslands can be achieved by different restoration measures and that more invasive approaches that involve the removal of the topsoil layer are more effective. We attribute these restoration successes to accompanying changes in the plant community, resulting in bottom‐up control of the herbivore community. Our results are of critical importance for management decisions aiming to restore multi‐trophic communities, their functional composition and consequently the proliferation of ecosystem functions.

中文翻译：

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半天然草原昆虫食草动物群落的长期恢复成功：一种功能性方法。

半天然草原是重要的生物多样性热点地区，但由于集约化农业而日益退化。草地恢复被认为在阻止生物多样性的持续丧失方面很有前途，但是该评估主要基于植物群落。食草动物极大地促进了草地的生物多样性和各种生态系统功能的提供。然而，目前尚不清楚它们如何应对通常用于从集约化耕地恢复半自然草原的不同措施。我们研究了不同恢复技术的长期成功经验，这些恢复技术最初旨在重建半天然草原植物群落，无论是在分类学还是功能水平上，都是草食性昆虫群落。因此，在制定恢复措施后的22年，我们对昆虫群落进行了采样。这些措施的范围从收获和去除生物量到去除表土层以及随后播种植物繁殖体。我们发现，与集约化管理的农业草原相比，恢复的草原上的昆虫群落具有更高的分类学和功能多样性，并且其组成与目标草原更为相似。事实证明，包括表土清除在内的恢复措施更为有效，特别是在恢复以集约化农业为特征的功能性状（例如大物种）的物种时。我们的研究表明，通过不同的恢复措施可以在半天然草原的草食性昆虫群落恢复中取得长期成功，并且涉及去除表土层的更具侵入性的方法更为有效。我们将这些恢复成功归因于植物群落的伴随变化，从而导致对草食动物群落的自下而上的控制。我们的结果对于旨在恢复多营养群落，其功能组成并进而恢复生态系统功能扩散的管理决策至关重要。