Moths and management of a grassland reserve: regular mowing and temporary abandonment support different species

Abstract

Although reserves of temperate seminatural grassland require management interventions to prevent succesional change, each intervention affects the populations of sensitive organisms, including insects. Therefore, it appears as a wise bet-hedging strategy to manage reserves in diverse and patchy manners. Using portable light traps, we surveyed the effects of two contrasting management options, mowing and temporary abandonment, applied in a humid grassland reserve in a submountain area of the Czech Republic. Besides of Macrolepidoptera, we also surveyed Microlepidoptera, small moths rarely considered in community studies. Numbers of individiuals and species were similar in the two treatments, but ordionation analyses showed that catches originating from these two treatments differed in species composition, management alone explaining ca 30 per cent of variation both for all moths and if split to Marcolepidoptera and Microlepidoptera. Whereas a majority of macrolepidopteran humid grassland specialists preferred unmown sections or displayed no association with management, microlepidopteran humid grassland specialists contained equal representation of species inclining towards mown and unmown sections. We thus revealed that even mown section may host valuable species; an observation which would not have been detected had we considered Macrolepidoptera only. Our results highlight the necessity of diversified management, including temporary abandonment, to conserve the biodiversity of grassland reserves and grasslands in general.