Using stone cover patches and grazing exclusion to restore ground-active beetle communities in a degraded pseudo-steppe

The dry grasslands of La Crau, a pseudo-steppe ecosystem located in Southern France, have experienced drastic reduction and degradation due to intensive agricultural activities for the past 50 years, leading to changes in their beetle assemblage. This valuable ecosystem is characterized by 50% stone cover, consisting of remnants from an old riverbed, and centuries-old sheep grazing. However, much of the stone cover has been removed for the purposes of cultivation. With the aim of restoring this ecosystem, we manipulated these two principal ecological factors: sheep grazing (grazing/exclusion) and stone cover (50% stone cover/no large stones). This study was conducted on a former cultivated field and on a pseudo-steppe area. On each of the two areas, 12 experimental units contained four different treatment patches: (1) stones × grazing, (2) no stones × grazing, (3) no stones × no grazing and (4) stones × no grazing, were randomly positioned. Data were obtained from 96 pitfall traps (one on each patch). After 4 years, restored stone cover combined with grazing exclusion significantly improved beetle abundance and increased beetle richness (38 species vs. 22 in the grazed-no-stones treatment), whereas no significant differences were recorded in the three other treatments. Our results therefore suggest that removing grazing for a few years and restoring stone cover is a promising method to restore beetle assemblages in this type of ecosystem.