Abandonment and intensified use of agricultural land decrease habitats of rare herbs in semi-natural grasslands Yuta Uematsu a, *, Tatsuro Koga a , Hiromune Mitsuhashi b , Atushi Ushimaru a a Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Kobe 657-8501, Japan b Museum of Nature and Human Activities, Hyogo, Yayoigaoka, Sanda 669-1546, Japan 1. Introduction Land-use changes have a large impact on biodiversity globally (Sala et al., 2000). Agriculture alters natural terrestrial ecosystems to human-managed landscapes (Vitousek et al., 1997; Mock, 2000). Although traditional low-impact agricultural land use maintains biodiversity (Tscharntke et al., 2005), recent land-use changes have rapidly reduced the biodiversity of agricultural landscapes (McNeely et al., 1995). These changes in agricultural land use are bidirectional, involving land abandonment and land-use intensification (Meeus, 1995). Either change leads to biodiversity loss in traditional agricultural landscapes in the temperate zone (e.g., Farina, 1997; Bakker and Berendse, 1999; Robinson and Sutherland, 2002; Selmi and Boulinier, 2003; Fukamachi et al., 2005). However, organisms living in agricultural landscapes are unlikely to respond in the same manner to land-use changes: some may decline rapidly, whereas others do not. Comparing plant species diversity among 130 grasslands and 141 arable fields in six European countries, Kleijn et al. (2009) found that plant species richness is significantly negatively related to land- use intensification (N input) in both field types and that this is largely the result of the responses of rare species. In an East Asian agricultural ecosystem called Satoyama (Tabata, 1997; Kato, 2001), interspecific differences in susceptibility to land-use changes occur even among closely related species. Some Satoyama species are now threatened or have decreased distributions, whereas others remain common (Table 1). Exam- ining the causes of interspecific differences in rarity is important for long-term conservation strategies (Kunin and Gaston, 1993). However, few studies have focused on interspecific differences in susceptibility to land abandonment and land-use intensifica- tion in agricultural landscapes (Kleijn et al., 2009). In particular, how land abandonment asymmetrically decreases the abun- dance of rare species has not been examined in agricultural landscapes. Paddy abandonment and consolidation are major drivers of a decrease in herb diversity in semi-natural grasslands around paddy fields (hereafter referred to as Satokusachi) in Japan (Yamaguchi et al., 1998; Iiyama et al., 2002; Fukamachi et al., Agriculture, Ecosystems and Environment 135 (2010) 304–309 ARTICLE INFO Article history: Received 1 June 2009 Received in revised form 15 October 2009 Accepted 16 October 2009 Available online 17 November 2009 Keywords: Abandoned field Consolidated field Distribution characteristics Grassland species Paddy terrace Species rarity ABSTRACT Although traditional agricultural land use maintains biodiversity, recent land-use changes involving abandonment or use intensification have rapidly reduced the biodiversity of agricultural landscapes. Organisms living in agricultural landscapes are likely to respond differently to these changes, with some species declining rapidly and others remaining unchanged. However, few studies have focused on this interspecific difference in susceptibility to land abandonment and intensification in agricultural landscapes. We hypothesize that rarer herb species are more susceptible to both abandonment and intensification than are common herbs due to habitat preferences in the semi-natural grasslands of agricultural landscapes. To test this hypothesis, we examined the distributions of two pairs of congeneric grasslands species on abandoned and consolidated (production-intensified) paddy fields to assess differences in vulnerability to paddy abandonment and consolidation between the rarer and the more common species in an agricultural landscape. We found that higher, steeper fields farther from roads in the upper areas of paddy terraces were more frequently abandoned in our study area. The two rarer species had significantly more overlap with the distribution of fields at risk of abandonment than did the two more common congeneric species. In addition, the two rarer species were significantly less widely distributed in consolidated fields. Thus, both land abandonment and intensification appear to asymmetrically decrease habitats of rarer species. In light of our findings, we also discuss biodiversity conservation in agricultural landscapes with changing land use. ß 2009 Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +81 078 803 7746; fax: +81 078 803 7761. E-mail addresses: 087d404d@stu.kobe-u.ac.jp (Y. Uematsu), gako19840721@yahoo.co.jp (T. Koga), hiromune@hitohaku.jp (H. Mitsuhashi), ushimaru@kobe-u.ac.jp (A. Ushimaru). Contents lists available at ScienceDirect Agriculture, Ecosystems and Environment journal homepage: www.elsevier.com/locate/agee 0167-8809/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.agee.2009.10.010