Publications

Shen, RQ; Lu, HB; Yuan, WP; Chen, XZ; He, B (2021). Regional evaluation of satellite-based methods for identifying end of vegetation growing season. REMOTE SENSING IN ECOLOGY AND CONSERVATION, 7(4), 685-699.

Abstract
Autumn phenology plays an important role in regulating ecosystem carbon and water cycling, but it has received less attention than spring phenology. Satellite-based methods have been widely applied in monitoring autumn phenology at large spatial scales. However, few studies have evaluated and compared the performance of different satellite-based methods in autumn phenology identification. Here, we compared the spatiotemporal variations of end of vegetation growing season dates (EOS) as determined from eight prevailing satellite-based methods against long-term field observations at 31 sites in China. We found that field-based observations in forest and grassland sites, respectively, had rates of EOS delay of 2.11 and 3.85 days per 1 degrees C increase in mean annual temperature (MAT) during 2001-2014. However, nearly all the eight satellite-based methods underestimated these delay rates compared with the ground observations over all sites. We also found that the eight methods weakly agreed with the field-observed interannual variations of EOS. At the regional scale, the identified average EOS differed up to 38 and 40 days among the investigated satellite-based methods in forest and grassland ecosystems respectively. The delayed rate of identified EOS with the increase of MAT ranged from 0.77 to 3.51 days degrees C-1 for forests and from 0.41 to 2.95 days degrees C-1 for grasslands. The identified EOS by most of the eight methods had delayed temporal trends in forests during 2001-2014 while we found advanced trends in grassland ecosystems. The large discrepancy in EOS identification among the prevailing satellite-based methods highlight the need for more accurate satellite-based methods in data gap-filling and phenometrics detection, and more extensive, multi-species based field observations that can be used to constrain and validate the satellite-based methods.

DOI:
10.1002/rse2.223

ISSN: