The tendency of species richness to increase with patch area is one of the most robust empirical generalisations in ecology and its logic drives conservation actions. Indeed, preference is often given to conserving large, highly connected areas over small isolated patches. However, small habitats have been shown to be important biodiversity refuges in managed landscapes. Field islands are small remnants of natural habitat patches surrounded by cropland. While their island-like position in a species-poor crop field makes them potentially strategic habitats for biodiversity conservation, they have not received much attention in ecological studies. We investigated how local (i.e. field island area and habitat diversity) and landscape factors (i.e. proportion of arable land) affected orthopteran species richness, community mean dispersal and habitat specificity in 71 field islands in central Sweden. We found that despite low numbers of species per field island, due to their intrinsic small size, taken together, a system of small field island increased species richness and included a large proportion of the regional species pool in the arable landscape in central Sweden. Furthermore, we found that patch area and habitat diversity determined orthopteran community composition in field islands. More diverse and, to a lesser extent, larger field islands benefit sedentary and habitat specialist species. This study shows that more care should be taken to incorporate and potentially also prioritize small and permanent habitat patches in the management of agricultural landscapes. The protection of field islands with diverse habitats may be important for the maintenance of sedentary and specialist species.

中文翻译：

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小型野外岛屿系统包括可耕地景观中大部分区域性直翅目物种库

物种丰富度随斑块面积增加的趋势是生态学中最有力的经验概括之一，其逻辑驱动着保护行动。事实上，通常优先考虑保留大的、高度连接的区域而不是小的孤立的补丁。然而，小型栖息地已被证明是管理景观中重要的生物多样性避难所。田野岛屿是被农田包围的自然栖息地小块残余。虽然它们在物种贫乏的农田中的岛状位置使它们成为保护生物多样性的潜在战略栖息地，但它们在生态研究中并未受到太多关注。我们调查了当地（即野外岛屿面积和栖息地多样性）和景观因素（即耕地比例）如何影响直翅目物种丰富度，瑞典中部 71 个野外岛屿的群落平均分布和栖息地特异性。我们发现，尽管每个田地岛的物种数量很少，但由于它们固有的小尺寸，综合起来，小田地岛系统增加了物种丰富度，并在瑞典中部的可耕地景观中包括了大部分区域物种库。此外，我们发现斑块面积和栖息地多样性决定了野外岛屿的直翅目昆虫群落组成。更多样化，在较小程度上，更大的野外岛屿有益于久坐不动和栖息地的专家物种。这项研究表明，在农业景观管理中，应该更加小心地将小型和永久性栖息地斑块纳入其中并可能优先考虑。