Mini-round box as standardized sampling method for orthopterans in alpine and subalpine grasslands: a field study to highlight strengths and weaknesses

Abstract

Orthopterans are known as suitable ecological indicators in grassland habitats, with their community composition providing useful information about the environmental consequences of management actions, ecological processes, or climate change. However, community studies often require the collection of both species richness and abundance data, which are difficult to obtain for these insects without a proper sampling strategy in certain environmental and population density conditions. In general, box quadrats with high sides (≥ 1 m2) represent a valuable method to assess orthopteran assemblages in open habitats, although their big size might be inappropriate for challenging environments, such as high-elevation alpine grasslands. For this reason, in this paper the effectiveness of a smaller (0.16 m2) and handy (circular-shaped) version of the box quadrat sampling device (hereafter called “mini-round box”) is tested in the field. Then, through a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis, the positive and negative features of this sampling method are highlighted, focusing in particular on the alpine and subalpine grassland context. Overall, the mini-round box strategy showed a good potential as a handy, easy, cheap, and standardized sampling method, but serious shortcomings in species detection have been observed (i.e. 47% of species undetected in average). A number of valuable strengths and interesting opportunities are counteracted by serious weaknesses and significant threats, which need to be carefully evaluated when planning a sampling design involving orthopterans as indicators. Some solutions to improve the mini-round box accuracy are suggested, perhaps encouraging the performance of biodiversity monitoring and ecological studies on orthopterans in even challenging grassland ecosystems.