How post-fire succession shapes psammophilous ground-dwelling assemblages: effect of wildfire and alteration in food composition.

Psammophilous beetles, a group endangered in temperate ecosystems, are mainly threatened by habitat loss. These beetles thrive in areas formed by the weathering of marine or fluvial sediments. Historically, practices such as slash-and-burn method or litter raking have exposed and destabilized sediments. In Central Europe, the Scots pine ( Pinus sylvestris ) has been used to stabilize sand dunes, improve soil composition and create shadier environments. This has led to the degradation of psammophilous communities and a decline in biodiversity. Our study examines whether fire can help restore and maintain psammophilous beetle populations. Our research focused on two aspects: (i) the long-term effects of wildfire in 2012 on beetles (Coleoptera: Carabidae) in the "Moravská Sahara–Bzenec district" of South Moravia (period 2013–2021), and (ii) the effects of environmental factors, influenced by the aforementioned wildfire on the distribution of these beetles in the period 2016 to 2021. The study compared species composition, life-history traits, and functional diversity between three forest stages: (i) newly disturbed areas with Coarse Wood Debris (CWD) left to naturally decay; (ii) semi-decayed mid-aged stands and (iii) reference mid-aged stands. Our findings indicate that fire was important factor influencing species assemblages. Interestingly, post-fire changes in food availability emerged as the second important factor, leading to the formation of two distinct species clusters: granivorous species thrived on site dominated by graminoids, and site with accumulated CWD was attracted predominantly by carnivorous species. Implications for insect conservation: We suggest that fire management is an effective strategy for conserving and enhancing the diversity of post-fire early-successional beetle assemblages in areas where these species exist. Consequently, the increase in forest canopy closure in these habitats should not be solely regarded as regeneration or a return to a natural state. Instead, it should be considered a potential threat to their richness and diversity.