Introduction

Most Central European grasslands crucially depend on land use, and thus there is a need to comparatively analyse the impacts of different types of land use management on grassland biota.

Aims and methods

We use grasshoppers (Orthoptera), which are the most important insect herbivores in grasslands, and assess the differences of grazing (sheep) and mowing on species abundance, richness, and composition. We use a river embankment in the National Park Donau Auen as study site, where we have established 28 transects. Orthoptera abundance was surveyed 13 times between May and September 2019 in each transect.

Results

We recorded 24 Orthoptera species, of which 12 species are listed in the national Red List. The most abundant non-threatened species is Pseudochorthippus parallelus in mown transects, while in grazed transects Euchorthippus declivus is most abundant. Eight of the ten most abundant Orthoptera species differed significantly in abundance between mown and grazed transects. Total abundance of Orthoptera was higher in mown transects, while grazed transects had higher species richness. Most xero-thermophilic species were more abundant in grazed transects, while some species of mesic grassland were more abundant in mown transects. These species-level differences resulted in clearly separated Orthoptera species assemblages between grazed and mown transects. Our findings suggest that the less dense vegetation in grazed transects better fulfilled the habitat requirements of xero-thermophilic species compared to mown transects

Discussion

Given that mown and grazed transects are located adjacent to each other, that the complete study site was mown for many decades and grazing was only started one year before field data collection, the scale of differences in species richness, composition and abundances between grazed and mown transects is surprising. Thus, our findings indicate that grasshoppers respond rapidly to changing land use.

Implications for insect conservation

We conclude that river embankments can be important secondary habitats for species-rich grasshopper communities. We recommend that grazing should be continued at the river embankment, ideally as rotational pasture as currently done. Mowing should be changed towards mowing parts of the river embankment at different times and leaving small strips of vegetation unmown.

中文翻译：

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吃草还是割草？草地管理对蚱蜢（直翅目）对多瑙-奥恩国家公园（奥地利）防洪堤的影响

介绍

大多数中欧草原严重依赖土地利用，因此需要比较分析不同类型的土地利用管理对草原生物群的影响。

目标和方法

我们使用蚱蜢（Orthoptera），它们是草原中最重要的昆虫食草动物，并评估放牧（绵羊）和割草对物种丰度、丰富度和组成的差异。我们使用 Donau Auen 国家公园的河堤作为研究地点，在那里我们建立了 28 条横断面。2019 年 5 月至 2019 年 9 月期间，对每个断面的直翅目丰度进行了 13 次调查。

结果

共记录直翅目24种，其中12种被列入国家红色名录。在已割断的断面中数量最多的未受威胁物种是Pseudochorthippus parallelus，而在放牧的断面中为Euchorthippus declivus是最丰富的。十种最丰富的直翅目物种中有八种在割草和放牧横断面之间的丰度存在显着差异。直翅目总丰度在割下的样带中较高，而放牧样带中的物种丰富度更高。大多数干旱嗜热物种在放牧样带中更丰富，而中性草原的一些物种在割下样带中更丰富。这些物种水平的差异导致在放牧和割下的横断面之间明显分离的直翅目物种组合。我们的研究结果表明，与割下的样带相比，放牧样带中密度较低的植被更好地满足了干旱嗜热物种的栖息地要求

讨论

鉴于割草和放牧的横断面彼此相邻，整个研究地点被割草了几十年，放牧仅在田间数据收集前一年才开始，放牧和割草之间物种丰富度、组成和丰度的差异规模横断面令人惊讶。因此，我们的研究结果表明，蚱蜢对土地利用的变化反应迅速。

对昆虫保护的影响

我们得出结论，河堤可能是物种丰富的蚱蜢群落的重要次生栖息地。我们建议在河堤上继续放牧，最好是像目前那样轮流放牧。修剪应改为在不同时间修剪河堤的部分，并留下小条植被未修剪。