15 Mar 2022
15 Mar 2022
Status: a revised version of this preprint is currently under review for the journal BG.

Tracking vegetation phenology of pristine northern boreal peatlands by combining digital photography with CO2 flux and remote sensing data

Maiju Linkosalmi1, Juha-Pekka Tuovinen1, Olli Nevalainen1, Mikko Peltoniemi3, Cemal Melih Taniş2, Ali Nadir Arslan2, Juuso Rainne1, Annalea Lohila1, Tuomas Laurila1, and Mika Aurela1 Maiju Linkosalmi et al.
  • 1Finnish Meteorological Institute, Helsinki, Climate System Research, 00560 Helsinki, Finland
  • 2Finnish Meteorological Institute, Helsinki, Arctic Space Centre, 00560 Helsinki, Finland
  • 3Natural Resources Institute Finland (LUKE), 00790 Helsinki, Finland

Abstract. Vegetation phenology, which refers to the seasonal changes in plant physiology, biomass and leaf area, is affected by many abiotic factors, such as precipitation, temperature and water availability. Phenology is also associated with the carbon dioxide (CO2) exchange between ecosystems and the atmosphere. We employed digital cameras to monitor the vegetation phenology of three northern boreal peatlands during five growing seasons. We derived a greenness index (Green Chromatic Coordinate, GCC) from the images and combined the results with measurements of CO2 flux, temperature and water table level, and with high-resolution satellite data (Sentinel-2). From the digital camera images it was possible to extract greenness dynamics on the vegetation community and even species level. The highest GCC and daily maximum gross photosynthetic production (GPPmax) were observed at the site with the highest nutrient availability and richest vegetation. The short-term temperature response of GCC depended on temperature and varied among the sites and months. Although the seasonal development and year-to-year variation of GCC and GPPmax showed consistent patterns, the short-term variation in GPPmax was explained by GCC only during limited periods. GCC clearly indicated the main phases of the growing season and peatland vegetation showed capability to fully compensate for the impaired growth resulting from a late growing season start. The GCC data derived from Sentinel-2 and digital cameras showed similar seasonal courses, but a reliable timing of different phenological phases depended upon the temporal coverage of satellite data.

Maiju Linkosalmi et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2022-58', Anonymous Referee #1, 04 Apr 2022
    • AC1: 'Reply on RC1', Maiju Linkosalmi, 18 May 2022
  • RC2: 'Comment on bg-2022-58', Anton Vrieling, 11 Apr 2022
    • AC2: 'Reply on RC2', Maiju Linkosalmi, 18 May 2022

Maiju Linkosalmi et al.

Maiju Linkosalmi et al.


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Latest update: 02 Jul 2022
Short summary
The vegetation phenology was monitored with digital cameras in three northern peatlands during five growing seasons. The greenness index derived from the images was highest at the most nutrient-rich site. Greenness indicated the main phases of phenology and correlated with CO2 uptake, though this was mainly related to the common seasonal cycle. The cameras and Sentinel-2 satellite showed consistent results, but more frequent satellite data are needed for reliable detection of phenological phases.