Restoration of semi-natural grasslands, a success for phytophagous beetles (Curculionidae)

Abstract

Semi-natural pastures have rich plant and animal communities of high conservation value which depend on extensive management. As the area of such land decreases, abandoned semi-natural grasslands have been restored to re-establish biodiversity. Restoration schemes, which include thinning of woody plants and reintroduction of grazing, are mainly designed according to the responses of well-studied groups (such as vascular plants and birds). Weevils (Curculionidae) are a very diverse phytophagous beetle family. Here, we evaluated the restoration success of pastures for weevils (Curculionidae), by comparing their species diversity in abandoned, restored, and continuously grazed seminatural pastures on 24 sites in central Sweden. Weevils were sampled by sweep-netting. We recorded 3019 weevil individuals belonging to 104 species. There was no statistically significant difference in species numbers between the pasture management treatments. However, weevil species composition of abandoned pastures differed from those in restored and continuously managed pastures, but there was no significant difference in community composition between restored and continuously grazed pastures. The abandoned sites tended to be dominated by polyphagous species, whereas the grazed sites contained more monophagous and oligophagous species. The number of weevil species was positively related to understory vegetation height and connectivity to other seminatural grasslands and negatively related to the cover of trees and shrubs in the pastures. We conclude that restoration of abandoned semi-natural pastures is a good approach to restore weevil communities. To maintain a species rich weevil community, pastures should be managed to be relatively open, but still have patches of tall field-layer vegetation.Restoration and conservation measures should primarily be targeted on regions and landscapes where a high proportion of semi-natural grassland still remains.

Contrasting beetle assemblage responses to cultivated farmlands and native woodlands in a dynamic agricultural landscape

“…We also found higher abundance of herbivorous Curculionidae in fallow fields than other land uses during spring, which suggests that fallow fields provide optimal levels of springflowering weed or host plant resources for this family (Hangay and Zborowski 2010). This result is consistent previous studies which found high abundance of specialist Curculionidae species in grazed pastures (Bat ary et al 2007, Steiner et al 2016, with the probability of occurrence for certain species increasing with grassland cover (Bat ary et al 2007). More research is needed to identify plant-species associations that may be driving high Curculionidae abundance when fallowing farmlands.…”

“…, Steiner et al. ), with the probability of occurrence for certain species increasing with grassland cover (Batáry et al. ).…”

Plant community recovery from intense deer grazing depends on reduction of graminoids and the time after exclosure installation in a semi-natural grassland

“…The sika deer ( Cervus nippon ) population, which has increased since the 1980s in Japan, has caused a decrease due to grazing in grassland specialist species in grassland communities (Otsu, Hoshino & Matsuzaki, 2011). Furthermore, the total grassland area, which had covered 50% to 70% of Japan’s total land area in the 1650s, decreased to less than 1% by the early 2000s (Ogura, 2006) because of abandonment and conversion in land use, which are common with European regions (Steiner et al, 2016). Such grassland decrease in Japan had never been occurred during past 100, 000 years (Yamaura et al, 2019).…”

Peer Review #2 of "Plant community recovery from intense deer grazing depends on reduction of graminoids and the time after exclosure installation in a semi-natural grassland (v0.1)"

“…The sika deer (Cervus nippon) population, which has increased since the 1980s in Japan, has caused a decrease due to grazing in grassland specialist species in grassland communities (Otsu, Hoshino & Matsuzaki, 2011). Furthermore, the total grassland area, which had covered 50% to 70% of Japan's total land area in the 1650s, decreased to less than 1% by the early 2000s (Ogura, 2006) because of abandonment and conversion in land use, which are common with European regions (Steiner et al, 2016). Such grassland decrease in Japan had never been occurred during past 100000 years (Yamaura et al, 2019).…”