bioRxiv preprint doi: https://doi.org/10.1101/2021.05.16.444370; this version posted May 17, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 1 Title: Hierarchical trait-based model reveals positive and negative effects of land 2 abandonment on butterfly communities across climatic regions in Japan 3 Running title: Land abandonment and butterfly diversity 4 5 Naoki Sugimoto1, Keita Fukasawa2,*, Akio Asahara3, Minoru Kasada4,5, Misako 6 Matsuba2 and Tadashi Miyashita1 7 1 Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, 8 Bunkyo-ku, Tokyo 113-8657, Japan 9 2 Biodiversity Division, National Institute for Environmental Studies, 16-2 Onogawa, 10 Tsukuba, Ibaraki 305-8506, Japan 11 3 Team HEYANEKO, 3-22-18-702 Minami-Urawa, Minami-ku, Saitama, Saitama 12 336-0017, Japan 13 4 Graduate School of Life Sciences, Tohoku University 6-3, Aoba, Sendai 980-8578 14 Japan 15 5 Department of Experimental Limnology, Leibniz-Institute of Freshwater Ecology and 16 Inland Fisheries, Alte Fischerhuette 2, 16775, Stechlin, Germany 17 * Corresponding author 18 Email: [email protected]; [email protected] 19 Tel.: +81-29-850-2676 20 21 1 bioRxiv preprint doi: https://doi.org/10.1101/2021.05.16.444370; this version posted May 17, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 22 Abstract 23 Land abandonment may decrease biodiversity but also provides an 24 opportunity for rewilding. It is therefore necessary to identify areas that may benefit 25 from traditional land management practices and those that may benefit from a lack of 26 human intervention. In this study, we conducted comparative field surveys of butterfly 27 occurrence in abandoned and inhabited settlements in 18 regions of diverse climatic 28 zones in Japan to test the hypotheses that species-specific responses to land 29 abandonment correlate with their climatic niches and habitat preferences. Hierarchical 30 models that unified species occurrence and their habitat characteristics revealed that 31 negative responses to land abandonment were associated with species having cold 32 climatic niches utilizing open habitats, suggesting that traditional land use by human 33 had long mitigated climate warming since the last glacier maximum through creating 34 non-forest open habitats. Maps representing species gains and losses due to land 35 abandonment, which were created from the model estimates, showed similar geographic 36 patterns, but some parts of areas exhibited high species losses relative to gains. A 37 hierarchical trait-based approach presented here revealed to be useful for scaling up 38 local-scale effect of land abandonment to a macro-scale assessment, which is crucial to 39 developing spatial conservation strategies in the era of depopulation. 40 Keywords 41 depopulation, hierarchical model, rewilding, ridge regression, butterfly, trait-based 42 approach 2 bioRxiv preprint doi: https://doi.org/10.1101/2021.05.16.444370; this version posted May 17, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 43 Introduction 44 Traditional agricultural landscapes, with high spatial heterogeneity and 45 moderate levels of disturbance, harbor a variety of organisms worldwide [1]. However, 46 recent social changes, such as depopulation, population aging, and population 47 concentration in urban areas, have resulted in an increase in abandoned fields [2,3]. While 48 land abandonment is expected to decrease biological diversity at the national scale [4,5], 49 it may also provide an opportunity for rewilding by vegetation succession [6,7]. To 50 establish a long-term, broad-scale strategy for biodiversity conservation, it is necessary to 51 identify areas where restoration by human management is effective for enhancing 52 biodiversity as well as areas where rewilding is more effective. 53 Many studies have examined the relationship between land abandonment and 54 biodiversity, but most have targeted a particular region within a nation [8,9]. These results 55 cannot necessarily be extrapolated to other regions with different climates and land cover 56 types because species responses to environmental changes may differ in different 57 climatic zones [10,11]. Moreover, it is generally not possible to predict the responses of 58 species that are not included in a field survey. Meta-analysis may be a promising tool to 59 evaluate the effect of land abandonment [12,13], but it has shortcomings of heterogeneity 60 in study design and inconsistent outcomes [14]. 61 A practical approach to resolve these issues is to collect biodiversity and landuse 62 data that are relevant to the spatial scale of land abandonment, which are taken from 63 multiple climate zones (ecoregions) with a standardized sampling strategy. This makes it 64 possible to evaluate how habitat traits of organisms (i.e., typical habitat types inhabited 65 by particular species) affect the relationship between land abandonment and species 3 bioRxiv preprint doi: https://doi.org/10.1101/2021.05.16.444370; this version posted May 17, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 66 occurrence. Historically, abandoned settlements (or deserted villages) have emerged 67 ubiquitously due to variety of causes such as economic environmental changes and 68 disasters [15–17], and they offer us unique opportunities to evaluate long-term effect of 69 land abandonment and recovery of ecosystems and to compare them among different 70 climate. Species-specific sensitivity to land abandonment is determined by ecological 71 traits [18,19] related to habitat preferences. Such trait-based relationships can be used to 72 estimate the effects of abandonment on species that are not included in census data. 73 Traditional agricultural landscapes have been altered in Japan, with the 74 increases in both urbanization and land abandonment. For instance, semi-natural 75 grasslands areas have decreased by 87% during the last century [20] and agricultural 76 fields have decreased by 26% [21]. These trends will continue in the future; 30–50% of 77 currently inhabited settlements in rural areas are expected to become uninhabited by 2050 78 [22]. Abandonment of agricultural landscapes consisting of various elements, such as 79 paddy field, dry crop field and grassland, has been causing decline in species diversity of 80 various taxa [13,23–26]. As a result, many organisms are expected to become endangered 81 [27], and butterflies are a typical example. In particular, grassland butterfly species are 82 decreasing substantially; they account for approximately 70% of all Red List species of 83 butterflies in Japan [28]. These grassland species were common in the late Pleistocene, 84 when the climate was much cooler than at present and natural grasslands were 85 predominant [29,30]. Thus, the effect of land abandonment is expected to be more severe 86 in northern Japan, since more grassland species are likely included in the regional species 87 pool. Meanwhile, land abandonment may increase forest-inhabiting species during the 88 process of vegetation succession. Although fewer butterfly species are designated as 4 bioRxiv preprint doi: https://doi.org/10.1101/2021.05.16.444370; this version posted May 17, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 89 endangered in forests in Japan, there appears to be a tradeoff in butterfly conservation 90 strategies with respect to whether we should manage abandoned land to maintain open 91 habitats by human intervention or let succession proceed. Thus, the effect of land 92 abandonment should be evaluated for each species across regions, and spatially explicit 93 planning is needed to optimize conservation strategies. For nation-wide evaluations, 94 butterflies are suitable subjects owing to extensive studies of their geographical 95 distributions, preferred habitats, and larval host plants [31]. 96 The aim of this study was to clarify the effect of land abandonment on butterfly 97 communities at a national scale, including different climatic regions, and to determine 98 how responses to land abandonment differ among species with different habitat traits. 99 Here, we chose both inhabited and abandoned settlements in each region across Japan to 100 estimate the effect of land abandonment, defined by inhabitation. We focused on three 101 land use types, dry crop field, paddy field and built-up area (i.e. houses and garden around 102 them), because they can be identified from past terrain map and visual inspection in the 103 field. The hypotheses addressed in this study are (1) species preferring colder 104 temperatures are more likely to show negative responses to land abandonment, and (2) 105 open habitat species (inhabiting grassland/agricultural lands) generally show negative 106 responses to land abandonment, whereas forest-dwelling species exhibit positive 107 responses. Based on parameters related to the responses to land abandonment in 108 butterflies with different habitat traits, we created a nation-wide map for the risks and 109 benefits of land abandonment for butterfly diversity; this map could provide a guideline 110 for identifying regions that may benefit from continuous human intervention.