Aims There is a time lag between loss of semi‐natural grassland and a reduction of population size that leads to the extinction of grassland plant specialists; thus, current species richness in the grassland may include an ‘extinction debt’. However, previous studies have not tried to detect the presence of an extinction debt from individual species loss and colonization rates in an assemblage of plant species. In addition, few researchers have studied extinction debt using factors other than landscape changes [e.g. the impacts of management (mowing or burning), habitat use by large herbivores or climate factors]. In the present study, we examined an extinction debt for vascular plant species by monitoring their survival and colonization dynamics. Location Abandoned and managed semi‐natural grasslands, central Japan, where the area of grasslands has decreased considerably. Methods We re‐surveyed species compositions in the 2000s in plots that had been surveyed in the 1980s, and estimated the impacts of the past (1910s) and recent (1980s–2000s) proportion of the total grassland area and the abovementioned factors on species dynamics during the past 20 yrs using hierarchical Bayesian models. Results In abandoned grasslands, the past grassland proportion was significantly positively associated with the probabilities of survival of 96% of the grassland specialists and of colonization by 21% of these specialists. The effects of the past grassland proportion on the specialists were much stronger than those of recent grassland proportion and the other factors studied (i.e. herbivores, climate). In managed grasslands, however, the past grassland proportion had little effect on survival of and colonization by specialists from the result that few specialists were significantly affected by past grassland proportion. Conclusions We found higher probabilities of both survival of and colonization by grassland specialists at sites with larger past habitat areas, which suggests that there is a time lag after habitat loss before the loss of specialists. In addition, we found that continuous management inhibits payment of the extinction debt created by the habitat loss.

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Exclosures that exclude large herbivores are effective tools for the protection and restoration of grazed plant communities. However, previous studies have shown that the installation of an exclosure does not ensure plant community recovery. Our study aimed to determine the effects of the domination of unpalatable plants and the timing of exclosure installation on the plant community recovery process in montane grassland overgrazed by sika deer (Cervus nippon) in Japan. In this study we compared plant species composition and their cover with inside and outside exclosures installed at different times. Furthermore, we also compared them with those in 1981, when density of sika deer was very low. We used quadrats inside and outside fenced areas established in 2010 and 2011 to record both the cover and the height of species in each quadrat between 2011 and 2015. Plant cover, with the exception of graminoid species, increased in later years in all treatments. Non-metric multidimensional scaling (NMDS) plots showed significantly differentiated treatment trends. The species composition within the 2010 fenced area gradually shifted to greater similarity with the species composition reported in 1981. The plant community in the 2011 fenced area was slower to recover. Compositions of plant communities outside the fenced areas hardly changed from 2011 to 2015. Chao’s dissimilarity index decreased over time between the plant community surveyed between 2011 and 2015 and the past plant community in 1981 within the exclosures, and was higher in the 2011 fenced area than in the 2010 fenced area. In conclusion, we show that the reduction of graminoids and the time after exclosure installation were important for plant community recovery from deer grazing damage. A delay in exclosure installation of one year could result in a delay in plant community recovery of more than one year.

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To determine the factors contributing to both the control of erosion and the establishment of indigenous species dispersed from vegetation surrounding slopes in the early stages, we investigated the influence of location and construction methods on the occurrence of erosion and indigenous species cover at 293 sites located on slopes, which had been constructed within the past five years in Yamanashi prefecture, using a generalized linear mixed model. Erosion of the surface layer was observed in 37% of the study sites. The mean plant cover at all sites was relatively high, although there were few slopes where indigenous species were observed. Sites sprayed with a soil seed cultivation base and located in valleys had a greater coverage by indigenous species and were considered to have established indigenous species faster than the other sites studied. In contrast, the use of a thick cultivated base spraying method and revegetation mats helped to control erosion, while both methods suppressed the establishment of indigenous species. The results suggest that either the control of erosion or the establishment of indigenous species on the slopes should be prioritized when selecting which revegetation method to use. To create favorable conditions for both slope stability and the establishment of an indigenous species community on cut slopes, it is important to consider the selection of revegetation methods, the composition of plant species introduced, and the control of wildlife damage.