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Despite a growing number of national-scale ecosystem service (ES) assessments, few studies consider the impacts of ES use and consumption beyond national or regional boundaries. Interregional ES flows ecosystem services imported from and exported to other countries are rarely analyzed and their importance for global sustainability is little known. Here, we provide a first multi-ES quantification of a nation's use of ES from abroad. We focus on ES flows that benefit the population in Germany but are supplied outside German territory. We employ a conceptual framework recently developed to systematically quantify interregional ES flows. We address four types of interregional ES flows with: (i) biophysical flows of traded goods: cocoa import for consumption; (ii) flows mediated by migratory species: migration of birds providing pest control; (iii) passive biophysical flows: flood control along transboundary watersheds; and (iv) information flows: China's giant panda loan to the Berlin Zoo. We determined that: (i) Ivory Coast and Ghana alone supply around 53% of Germany's cocoa while major negative consequences for biodiversity occurred in Cameroon and Ecuador; (ii) Africa´s humid and sub-humid climate zones are important habitats for the majority of migratory bird species that provide natural pest control services in agricultural areas in Germany; (iii) Upstream watersheds outside the country add an additional 64% flood regulation services nationally, while Germany exports 40% of flood regulation services in neighboring, downstream countries; (iv) Information flows transported by the pandas were mainly related to political aspects and - contrary to our expectations - considerably less on biological and natural aspects. We discuss the implications of these results for international resource management policy and governance. (c) 2020 The Authors Thomas Kastner was supported by the Vienna Science and Technology Fund (WWTF), project no. ESR17-014. Laura Lopez-Hoffman acknowledges the support of the National Science Foundation (NSF) awards DEB-1118975 and DEB-1518359. Support for Liu's time was provided by US National Science Foundation and Michigan AgBioResearch. Javier Martínez-López acknowledges the support of the Spanish Government through María de Maeztu excellence accreditation 2018-2021 (Ref. MDM-2017-0714). Sarah Wolff was supported by the European Research Council grant GLOLAND (grant no. 311819)

We introduce an explicit indicator and the Land Use Management Support System to assess the resource-use efficiency of land use (RUE) at the landscape scale. To estimate RUE, we relate land-use performance with regard to ecosystem services indicators to the maximum possible land-use performance based on an optimised land-use configuration. The test application of the RUE assessment in the Haean catchment, South Korea, shows that the land-use system's RUE could be increased by 11% for both nitrate and sediment loss. The estimated headroom could indicate whether potential contaminant reduction targets for the downstream water reservoir Lake Soyang could be achieved with the current land-use system. The recurring RUE assessment for a given region might indicate the effectiveness of spatial planning and policy measures to improve the RUE in that region. Future work should address the integration of RUE into a participatory spatial planning or resource-management framework.

In mountainous watersheds, agricultural land use cause changes in ecosystem services, with trade-offs between crop production and erosion regulation. Management of these watersheds can generate environmental land use conflicts among regional stakeholders with different interests. Although several researches have made a start in mapping land use conflicts between human activities and conservation, spatial assessment of land use conflicts on environmental issues and ecosystem service trade-offs within agricultural areas has not been fully considered. In this study, we went further to map land use conflicts between agricultural preferences for crop production and environmental emphasis on erosion regulation. We applied an agricultural land suitability index, based on multi-criteria analysis, to estimate the spatial preference of agricultural activities, while applying the Revised Universal Soil Loss Equation (RUSLE) to reflect the environmental importance of soil erosion. Then, we classified the agricultural catchment into four levels of land use conflicts (lowest, low, high and highest) according to preference and importance of farmland areas, and we compared the classes by crop type. Soil loss in agricultural areas was estimated as 45.1thayr, and agricultural suitability as 0.873; this indicated that land use conflicts in the catchment could arise between severe soil erosion (environmental importance) and agricultural suitability (land preferences). Dry-field farms are mainly located in areas of low land use conflict level, where land preference outweighs environmental importance. When we applied farmland management scenarios with consideration of services, conversion to highest-conflict areas (Scenario 1) as 7.5% of the total area could reduce soil loss by 24.6%, while fallow land management (Scenario 2) could decrease soil loss 19.4% more than the current scenario (Business as usual). The result could maximize land management plans by extracting issues of spatial priority and use-versus-conservation conflicts as ecosystem service trade-offs from arguments over land use policy.

Summary The linkage between hydrologic dynamics and the delivery of nitrate and DOC (dissolved organic carbon) to streams was studied in the Haean catchment, a mixed land-use mountainous catchment in South Korea. Three monsoonal precipitation events were analyzed, which varied in total rainfall amount (39–70 mm) and intensities (mean: 1.6–5.6 mm h −1 ), by high-resolution (2–4 h interval) stream water-quality sampling along the topographic elevation gradient of the catchment, from an upland deciduous forest stream, over areas intensively used for agriculture (dryland farming and rice paddies) down to the catchment outlet. The dynamics of river-aquifer exchange were investigated at two piezometer transects at mid and lower elevations. DOC and nitrate sources and their transport pathways to the receiving surface waters differed between the forested and the agricultural stream site. In the forest stream, elevated DOC concentrations (max: 3.5 mgC l −1 ) during precipitation events were due to hydrologic flushing of soluble organic matter in upper soil horizons, with a strong dependency on pre-storm wetness conditions. Nitrate contributions to the forested stream occurred along shallow subsurface transport pathways. At the agricultural sites stream DOC concentrations were considerably higher (max: 23.5 mgC l −1 ) supplied from adjacent rice paddies. The highest in-stream nitrate concentrations (max: 4.1 mgN l −1 ) occurred at river reaches located in the lower agricultural part of the catchment, affected by groundwater inputs. Groundwater nitrate concentrations were high (max: 7.4 mgN l −1 ) owing to chemical fertilizer leaching from dryland fields forced by monsoonal rainfalls. Overall, this study demonstrates that the hydrologic dynamics resulting from the monsoonal climate drive the in-stream DOC dynamics in the forested 1st-order catchment whereas sources and mobilization of DOC in downstream agricultural areas are mainly controlled by the prevailing land-use type and irrigation management. Nitrate dynamics in higher order agricultural streams and their connected aquifers reflect combined effects of land-use type and monsoonal hydrology.

Plastic-covered ridge-furrow cultivation (plastic mulch) can substantially influence runoff and soil erosion on agricultural land. However, the impact of this management practice in combination with complex farmland topography has not been thoroughly investigated. The goal of this study was to identify how topography influences runoff patterns and erosion rates of plastic mulch cultivation. We measured runoff and sediment transport on two mountainous fields in South Korea, one with a concave topography and one with a convex topography, during monsoonal rain events. We used the EROSION 3D model to compare flow and sediment transport between plastic mulch, uncovered ridges, and a smooth soil surface. We found the highest runoff and erosion rates from both of the fields with plastic mulch due to the impermeable surface. For the uncovered ridges, we identified 140% higher erosion compared to the smooth surface on the concave field, but 20% lower erosion on the convex field. The simulated sediment transport patterns showed that the ridge-furrow system concentrated overland flow on the concave field, resulting in high erosion rates. On the convex field, the ridge-furrow system prevented flow accumulation and erosion. Our results demonstrate that the effect of ridge-furrow systems on erosion is controlled primarily by the topography. These results have practical consequences for watershed conservation planning and the application of large-scale erosion models. Nevertheless, further research is needed to fully understand the impact of this management system on runoff and erosion on mountainous farmland.

Dryland farming practices in mountainous regions of South Korea are dominated by cultivation of vegetables with plastic film covered ridges (plastic mulch). Primarily, furrows are oriented perpendicular to the main slope of the field site. In terms of soil erosion, this cultivation strategy could be regarded as a contour tillage conservation practice because it diminishes surface runoff along the steepest slopes. Contour farming is expressed in the Universal Soil Loss Equation with the P-Factor. The effectiveness of contouring depends primarily on slope angle and slope length, which results in P-Factors between zero (maximum efficiency) and one (no effect). Alternatively, tillage in mountainous areas of South Korea is typically at an angle to the contour lines, and runoff flows along the furrows, although not parallel to the steepest flow path. Therefore the erosion reduction efficiency is reduced with angle from contour. The contouring effectiveness depends not only on the slope angle and flow distance, but also on the field site morphology. On fields with a straight or concave surface, runoff flows along the ridges from the field to its edge with sediment only derived from the corresponding furrow. On field sites with a convex surface, runoff is focused along the furrows to the steepest point where flow accumulation occurs. During intense monsoonal events, the accumulated runoff can induce ridge breakovers resulting in increased erosion rates. Additional erosion can occur due to the plastic cover, which inhibits infiltration and accelerates runoff generation in the inter-rows. This results in both, loss of ridge conservation effectiveness, and higher field site total erosion. In this case P-Factors larger than one are necessary to describe the erosive effect of this cropping system. The objective of this study was to verify and quantify the impact of this cultivation strategy on soil erosion rates from mountainous farmland areas in South Korea.