Influence of land consolidation on aquatic invertebrate communities and their distribution patterns in Korean rice fields

Abstract

Rice fields, the major cropland in South Korea, provide an important wetland habitat for a diverse wildlife and contribute to biodiversity conservation. On the other hand, land consolidation conducted to increase agricultural production since the 1960s on a nationwide scale in South Korea has frequently been suggested to be one of the factors in the decline of biodiversity in agricultural ecosystems. Negative effects of habitat manipulation such as land consolidation would have influenced paddy field biodiversity, but the degree has not been clearly measured in South Korea. This study evaluated the impacts of land consolidation on the aquatic invertebrate biodiversity and investigated their patterns across the nation. Field sampling for biodiversity and environmental variables were made from 290 sites of paddy field over the country. Aquatic invertebrate communities were clustered into four major clusters showing land consolidation as the main factor and geographic location as the second factor. Species richness and abundance were significantly lower in the land consolidation fields (mean ± s.e., 12.80 ± 0.28 vs 88.89 ± 0.89 and 2027.15 ± 150.84 vs 2573.54 ± 572.16). Shannon diversity index was also significantly lower in land consolidation fields. Our results suggest that land consolidation and spatial location are important for biodiversity and conservation of the aquatic invertebrate assemblages in Korean rice fields.

Can landscape level semi-natural habitat compensate for pollinator biodiversity loss due to farmland consolidation?

“…The lower richness and evenness of wild pollinator communities in landscapes with consolidated farmland as compared to traditional farmland is in line with our first hypothesis, and aligns with findings for aquatic invertebrate in Korean rice systems (Nam et al, 2019) and plant communities in Japan (Osawa et al, 2016). The relatively low pollinator diversity in consolidated fields might be associated with the deterioration of the fine-scale network of vegetation on the edges between fields, as the management of the oilseed rape crops was similar, i.e., based on farmer's own practice.…”

“…Thus, in consolidation, finely interwoven semi-natural habitats in farmland is lost. While negative impacts of land consolidation have been reported on aquatic invertebrates (Nam et al, 2019) and wild plants (Osawa et al, 2016), the effect of land consolidation on wild pollinators has not been studied.…”

Land consolidation impacts the abundance and richness of natural enemies but not pests in small‐holder rice systems

“…In line with our hypothesis #1, we found that the abundance and richness of natural enemies were lower in rice fields in consolidated farmlands than in traditional farmlands. This finding aligns with previous studies reporting negative effects of land consolidation on pollinator communities (Shi et al., 2021), aquatic arthropods (Nam et al., 2019), and birds (Denac & Kmecl, 2021). The main reason might be that land consolidation eliminated natural vegetation cover on the field margins, while these field margins can provide nesting habitat and food sources for natural enemies (Marshall & Moonen, 2002; Vickery et al., 2009).…”

“…During the consolidation process, the removal of linear habitats may result in biodiversity loss (Li et al., 2019; Shi et al., 2021; Zhang et al., 2012). Compared to traditional lands, consolidated farmlands have a lower diversity of pollinators, probably due to the removal of flowering plants in field margins (Shi et al., 2021), and a lower diversity of aquatic arthropods due to the reduction of small irrigation ponds and ditches (Nam et al., 2019). Therefore, while farmland consolidation may increase agricultural efficiency (General Administration of Quality Supervision, 2014; Ministry of Natural Resources of the People's Republic of China, 2021), the potential impacts on biodiversity need to be evaluated (Zou, 2024).…”