Ecosystem services valuation: a review of concepts, systems, new issues, and considerations about pollution in ecosystem services.

Managers can determine the function of ecosystem services in decision-making processes through valuation. Ecological functions and processes that benefit people lead to ecosystem services. Valuing ecosystem services mean finding values for the benefits of ecosystem services. For the concepts related to ecosystem services and their valuation, categories in different articles have been presented. One of the most important issues is providing a suitable grouping for different methods and concepts of valuing ecosystem services. In this study, the most recent topics related to ecosystem service valuation methods were compiled and categorized by using the system theory. The aim of this study was to introduce some of the most important classical and modern methods and concepts of valuing ecosystem services. For this aim, a review of articles related to ecosystem service valuation methods, content analysis, and categorization of their contents was used to provide definitions, concepts, and categorization of different methods. To summarize, valuation methods are classified into two types: classical and modern methods. Classical approaches include the avoided cost method, the replacement cost method, the factor income method, the travel cost method, hedonic pricing, and contingent value. Modern methods include the basic value transfer method, deliberative ecosystem service valuation, valuation of climate change risks, and other cases that evolve every day in the world of science. Findings of the paper have the potential to be beneficial in comprehending the definitions and ideas of ecosystem services in ecosystem management, particularly in protected areas, participatory management, and pollutant research. This research can add to the worldwide literature on the valuing of ecosystem services while also determining the most pressing issues and difficulties of today, such as climate change, pollution, ecosystem management, and participatory management.

Contribution of agricultural land conversion to global GHG emissions: A meta-analysis.

Greenhouse gases (GHG) have extensive environmental effects by trapping heat and causing climate change and air pollution. Land plays a key role in the global cycles of GHG (i.e., carbon dioxide (CO2), methane (CH4), and nitrogen oxide (N2O)), and land use change (LUC) can lead to the release of such gases into the atmosphere or the removal of them from the atmosphere. One of the most common forms of LUC is agricultural land conversion (ALC) where agricultural lands are converted for other uses. This study aimed to review 51 original papers from 1990 to 2020 that investigate the contribution of ALC to GHG emissions from a spatiotemporal perspective using a meta-analysis method. The results of spatiotemporal effects on GHG emissions showed that the effects were significant. The emissions were affected by different continent regions representing the spatial effects. The most significant spatial effect was relevant to African and Asian countries. In addition, the quadratic relationship between ALC and GHG emissions had the highest significant coefficients, showing an upward concave curve. Therefore, increasing ALC to more than 8 % of available land led to increasing GHG emissions during the economic development process. The implications of the current study are important for policymakers from two perspectives. First, to achieve sustainable economic development, policymaking should prevent the conversion of more than 90 % of agricultural land to other uses based on the turning point of the second model. Second, policies to control global GHG emissions should take into account spatial effects (e.g., continental Africa and Asia), which show the highest contribution to GHG emissions.