Ecosystem service mapping in soybean agroecosystems

Abstract

Depending on the type and intensity of use of agroecosystems, they provide important goods and ecosystem services (ES) to human. This study assesses supporting, regulating, provisioning and cultural services in 48 Iranian soybean fields under conventional and conservation cropping systems. We hypothesize that the present agricultural soybean land use in Gorgan County is the reason for a reduced performance of ES. We updated the Millennium Ecosystem Assessment (MEA) framework for mapping of ES and included new indicators like insect biodiversity, biodiversity indexes according to Shannon-Wiener, Simpson, Inverse Simpson and Margalef, soil microbial respiration, and quantification of soil conservation by using the Universal Soil Loss Equation (USLE). To quantify carbon sequestration and microbial respiration, soil samples were taken at depths of 0–30 cm before cultivation start in late May 2017 and after soybean harvest in early October 2017. Oxygen production was estimated based on net primary production. Various types of supporting services were evaluated in two general groups, including insect communities and plant biodiversity. The results show that conservation cropping systems in general provide better performing ES than conventional cropping systems. Soil microbial respiration was significantly higher in conservation fields. The average oxygen production on conventional fields was 79.9 ton per ha, compared to 59.9 ton per ha in conservation fields. The biodiversity assessment showed that species richness and all diversity indexes in conservation fields were higher than conventional agroecosystems. From a soil conservation point of view, the rates of soil erosion according to USLE were estimated at an average of 996.64 and 417.63 kg per ha under conventional and conservation fields, respectively. In a spatial distinction, the eastern part of the county exposes the highest soil erosion. Regulating services for carbon sequestration were high in the southern region and on fields close to forest ecosystems. Provisioning services of soybean yield, oil and protein contents were highest in the western and central parts and lowest in the northern part of the study area. As the first report of ecosystem services mapping in conservation and conventional cropping systems in Iran, we confirm that conservation cropping systems in general provide better performing ES than conventional cropping systems.