**3. Techniques for Remote Sensing Monitoring of Canopy N**

The continuous development of remote sensing technology on ground-based, UAVbased, and satellite-based platforms provides a wide range of modal options for N status monitoring studies. There is the technical focus in the field of N monitoring, including exploring the correlations between remotely sensed information extracted from multisource data and N status, while achieving accurate modeling inversion of N status. To summarize the relevant technologies, three main aspects are discussed: remote sensing monitoring platforms; the correlation between remotely sensed data and N status; and the retrieval methods of canopy N status.
