Assessing ecosystem services in apple orchard in the Loess Plateau based on STICS model

Apple orchards face the major challenge of ensuring maximal productivity with due consideration for the environment and natural resource. How to balance its ecosystem services is one of the important issues facing the sustainable development of apple orchards. The field experiment and the STICS model were used to study the impacts of agricultural management and climate on the ecosystem services of apple orchards in the Loess Plateau of China. And on this basis, four apple orchard ecosystem services including soil nitrogen availability, climate regulation, water circulation regulation, and fruit production were systematically evaluated in the south semi-humid and north semi-arid regions of the Loess Plateau of China. This model was parameterized by using data collected on two experimental apple orchard sites under irrigating and mulching management in the Loess Plateau. The results showed that:（1） the STICS models could well simulate the ecosystem service indicators such as yield, fruit mass, soil water content, and evapotranspiration of the Baishui and Zizhou experimental orchards.（2） Except for the synergies between carbon sequestration and yield, fruit mass and fruit-related indicators, there is a trade-off relationship among other ecosystem services. The contribution of carbon allocaton to fruit in sequestrated carbon was considerable. Nitrogen absorption, impacted by mulch and irrigation, was a major driver of these ecosystem service relationships.（3） For the average service standard value of the orchard under various management measures, straw mulching（0.67） > film mulching（0.52） > clearing cultivation（0.30）, comfort irrigation（0.56） > low water stress irrigation（0.44） > high water stress irrigation（0.30）. The service profile of the orchard with straw mulching and comfort irrigation were the best. And the service profile of the orchard with film mulching and low water stress irrigation were similar and the most balanced, showing higher yield, fruit mass and soil water content but lower N2O emission.（4） The effect of mitigating trade-offs of straw mulching and low water stress irrigation are better than other management measures, and these two apple orchards are the most ideal orchards. In summary, the STICS model can quantify orchard ecosystem services profiles well, and agricultural management is a powerful driving factor of orchard ecosystem services.