Economic valuation of ecosystem services in canola agroecosystems

Ecosystem service values are divided into three categories: direct use values, indirect use values, and non-use values. In this research, the economic value of ecosystem services in canola (Brassica napus L.) fields was investigated during 2020-2021. These fields are located in Gorgan County (Sorkhankalateh region) north of Iran. We calculated the carbon sequestration by the carbon emission tax policy as shadow value of carbon, and to estimate some ecosystem services including the oxygen supply, grain yield and soil conservation, we applied the substitute cost methods, direct market method and replacement cost, respectively. Also, the value of pollination service was estimated along with the effect of pollinators on yield production, and the value of agrotourism estimated based on contingent valuation method. In this research, the logit model was used by the maximum likelihood method to investigate the influencing factors on people's willingness to pay. The required data for each of these variables were collected through field methods, questionnaires and face-to-face interviews with 117 visitors from the mentioned region. The results showed that the average total value of ecosystem services was equal to 3,685.91$ ha-1 yr-1. In this research, the value of the provisioning service was equal to 1,720.81$ ha-1. Also, the grain yield had the highest value among ecosystem services and accounted as 46.69 percent of all the ecosystem services. While, atmospheric services (oxygen production and carbon sequestration) included 1,155.12$ (31.34%), pollination 516.24$ (14.01%) and soil conservation 292.19$ (7.93%) of the total economic value. The share of agrotourism service from the total value of services was about 1.53$ (0.04%). In general, canola fields are more important in terms of provisioning services (grain yield) than regulating services such as oxygen production, carbon sequestration, soil conservation and pollination, as well as agrotourism services. Therefore, maintaining and enhancing market and non-market services in the canola fields of the study area is crucial for both the human and economic aspects.