Earth's well-being depends mainly on the conservation of ecosystem goods and services. However, biodiversity is extensively threatened in agricultural landscapes. Since farmers' decisions and practices are the main determinant factors of on-farm biodiversity conservation, this study was conducted to clarify the underlying constructs of farmers' intention to preserve biodiversity. The Theory of Planned Behavior was applied to investigate the intention of a sample of 274 Iranian farmers towards on-farm biodiversity conservation. In order to increase the predictive power of this theory, the new constructs of knowledge, moral norm and perceived threats of intensified agriculture were added to the model. The results indicated that farmers have a moderate level of knowledge about the value and strategies of biodiversity conservation. Also, they have a favorable attitude toward preserving biodiversity. However, they do not perceive enough control to engage in biodiversity conservation practices. Furthermore, the findings revealed that attitude, perceived threats of intensified agriculture, knowledge, social norms and moral norms are the most relevant factors explaining the farmers' intentions toward biodiversity conservation. In general, the results presented evidence about effectiveness of the Theory of Planned Behavior and the extended model of planned behavior on assessing the farmers' intention to preserve biodiversity. Also, the findings reinforced the available evidence regarding the significance of moral norm and knowledge in development of environmental intention. Accordingly, a number of considerations about improving farmers' intention to preserve on-farm biodiversity are recommended.
