To date, other than the land market, the Russian Federation still does not have an established natural resources market due to restrictions on transactions in the natural resources segment; therefore, the market value of natural resources cannot be calculated using classical evaluation methods, and only cadastral appraisal can be conducted. We propose to assess the resources as a whole, using the evaluation of nature reserves, assessment of the resource’s ecological functions and the environmental damage. However, the existing cadastral appraisal methods take no account of resources functions and consider them separately. Moreover, the information on natural systems used for the assessment of resources is incomplete and inaccurate. Such uncertainty makes it difficult to model using classical statistical tools. Therefore, there is a need to use information processing tools based on data mining. We propose to use the fuzzy modelling techniques in natural resources assessment, as they will allow for the evaluation of nature reserves and environmental monitoring at the same time. This paper contains fuzzy models for a land plot evaluation that include linguistic variables - factors that affect the land plot value, and fuzzy rule bases that define relationships between linguistic variables. The results show that the cadastral value of land plots is 2.5 times lower than the one calculated using the fuzzy model, with regard to the ecological factor. The error between the market value of those land plots and the one calculated using the fuzzy model is 11%. Therefore, the use of proposed tools allows for the calculation of the market value of resources based on their cadastral value with an account of various factors using the comparative approach, and also for adjustments to the market value in order to increase the efficiency of natural resources use. © 2020 Institute of Physics Publishing. All rights reserved.