Introduction

Both intensification and abandonment of traditional agricultural practices are known to be major threats to biodiversity worldwide. Land abandonment, in particular, has a negative effect on the diversity of both plant and insect communities, although few studies have analysed the effects on the interactions between both groups. Given the importance in maintaining mutualistic interactions between plants and pollinators, it is essential to know how the structure of pollination networks changes in the process of abandonment of traditionally managed habitats and also to determine to what extent it is re-established when such habitats are restored.

Methods

We monitored a butterfly-plant network over a long period (22 years) in habitats where land abandonment and restoration had taken place. This has allowed to analyse the long-term effects of such processes on both plant and butterfly communities and the interactions between them.

Results and discussion

Abandonment led to significant reductions in the cover of typical grasslands plants, resulting in changes in butterfly assemblages and plant-butterfly interactions. Specifically, it caused a replacement of multivoltine by monovoltine species, increasing thus network specialization as the latter established interactions with fewer plants. A grassland restoration combining mowing and grazing promoted a quick return to the pre-abandonment situation in the butterfly community. Moreover, such restoration practice increased network generalization and nestedness, network descriptors known to enhance community stability.

Implications for insect conservation

Maintaining traditional management practices in these semi-natural meadows is an effective way to preserve their biodiversity, understood not only as the number of species but also as the number of interactions that butterflies establish with nectar sources.

中文翻译：

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废弃和恢复地中海草甸对蝴蝶植物相互作用的长期影响

介绍

众所周知，传统农业做法的强化和摒弃都是对世界范围内生物多样性的主要威胁。土地遗弃对植物和昆虫群落的多样性都具有负面影响，尽管很少有研究分析了对这两个群体之间相互作用的影响。考虑到维持植物与授粉媒介之间相互互动的重要性，必须了解授粉网络的结构在放弃传统管理的栖息地的过程中如何变化，并确定在恢复这些栖息地时将其重建到何种程度。

方法

在很长一段时间（22年）内，我们在发生土地遗弃和恢复的生境中监测了一个蝴蝶植物网络。这使得可以分析此类过程对植物和蝴蝶群落以及它们之间的相互作用的长期影响。

结果与讨论

抛弃导致典型草原植物的覆盖面积显着减少，从而导致蝴蝶组合和植物与蝴蝶之间的相互作用发生变化。具体而言，它导致单伏物种取代了多伏，从而增加了网络的专业化程度，因为后者建立了与较少植物的相互作用。割草和放牧相结合的草地恢复措施迅速恢复了蝴蝶群落被遗弃前的状况。而且，这样的恢复实践增加了网络的泛化性和嵌套性，已知网络描述符可增强社区稳定性。

对昆虫保护的意义

在这些半天然草地上维持传统的管理方法是保护其生物多样性的有效途径，这不仅理解为物种的数量，而且还理解为蝴蝶与花蜜来源建立的相互作用的数量。