Monitoring functional traits of alpine vegetation on the Qinghai-Tibet Plateau using multi-sensor remote sensing

Plant functional traits can be used to study the interactions between plants and ecosystem functioning as well as the response of plants to various environmental pressures. Continuous monitoring of plant functional traits dynamics on a large spatial scale is important to understand the mechanisms of ecosystem function degradation, especially on the Qinghai-Tibet Plateau. In this study, we investigated spatiotemporal trends of functional traits (i.e., chlorophyll content, leaf area index proxy of leaf size) in the eastern part of the Qinghai-Tibet Plateau based on the combined analysis of multi-sensor satellite data and field observations at three spatial scales (ground-truth data at 1 m, Landsat at 30 m, MODIS at 500 m). Chlorophyll content was retrieved based on 94 field plots measurements. LAI was analyzed using MCD15A3H product and estimated values using digital hemispherical photographs in the field. The results show that field estimated LAI has better consistency with MCD15A3H product of main algorithm (QC<64). The chlorophyll has significant positive linear trend in 15 years (2001–2015) and has strong increasing trend in the low area, which is correspond to the high chlorophyll content spatial heterogeneity.