Effect of climate change‐induced increases on the range of rice‐barley double cultivation on the intermediate egret

Abstract Intensification of cultivation methods and land‐use types, particularly in the face of climate change, has steadily weakened the habitat function of rice fields for waterbirds. Intermediate egrets ( Ardea intermedia ) are highly dependent on rice field habitats. Here, we examine the effect of a shift from rice monoculture to rice–barley double cultivation on the use of rice fields by intermediate egrets in South Korea. Rice–barley double cultivation has been increasing steadily in the southern region of South Korea due to changes in the rice growth period under climate change and maximization of economic benefits. We studied rice fields to determine the effect of the rice–barley double cultivation area on the abundance of intermediate egrets on the regional scale and their potential distribution pattern in response to double cultivation in relation to climate change using national‐scale climate, altitude and land cover data from 1 May to 23 June 2018. Compared to the irrigation practices used for rice monoculture, irrigation was stopped for some time in rice–barley double cultivation prior to planting, compromising the role of rice fields as a food ground for intermediate egrets. The potential abundance of intermediate egrets rapidly decreased by half when the double cultivation area increased to >40% of the total rice‐field area, and was less than one individual if the area increased to >80%. Furthermore, according to climate change projections, by 2100, the double cultivation area would account for 75.74% of the predicted range of intermediate egret foraging ground. Synthesis and applications. Double cultivation areas should be <40% of existing rice fields to minimize the impact of the change in cultivation practices. This approach can also convert rice fields to other types of land use. Consequently, appropriate conservation and management measures may be developed to maintain suitable habitats despite rapidly changing cultivation practices resulting from climate change.