title: Codominant water control on global interannual variability and trends in land surface phenology and greenness.
abstract: Identifying the relative importance of climatic and other environmental controls on the interannual variability and trends in global land surface phenology and greenness is challenging. Firstly, quantifications of land surface phenology and greenness dynamics are impaired by differences between satellite data sets and phenology detection methods. Secondly, dynamic global vegetation models (DGVMs) that can be used to diagnose controls still reveal structural limitations and contrasting sensitivities to environmental drivers. Thus, we assessed the performance of a new developed phenology module within the LPJmL (Lund-Potsdam-Jena managed Lands) DGVM with a comprehensive ensemble of three satellite data sets of vegetation greenness and ten phenology detection methods, thereby thoroughly accounting for observational uncertainties. The improved and tested model allows us quantifying the relative importance of environmental controls on interannual variability and trends of land surface phenology and greenness at regional and global scales. We found that start of growing season interannual variability and trends are in addition to cold temperature mainly controlled by incoming radiation and water availability in temperate and boreal forests. Warming-induced prolongations of the growing season in high latitudes are dampened by a limited availability of light. For peak greenness, interannual variability and trends are dominantly controlled by water availability and land-use and land-cover change (LULCC) in all regions. Stronger greening trends in boreal forests of Siberia than in North America are associated with a stronger increase in water availability from melting permafrost soils. Our findings emphasize that in addition to cold temperatures, water availability is a codominant control for start of growing season and peak greenness trends at the global scale.
authors.affiliation: Department for Biogeochemical Integration, Max-Planck-Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.
authors.forename: Matthias
authors.identifier: http://orcid.org/0000-0003-0363-9697
authors.initials: M
authors.lastname: Forkel
authors.affiliation: Department for Biogeochemical Integration, Max-Planck-Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.
authors.forename: Mirco
authors.initials: M
authors.lastname: Migliavacca
authors.affiliation: Potsdam Institute for Climate Impact Research, Earth System Analysis, Telegraphenberg A31, 14473, Potsdam, Germany.
authors.forename: Kirsten
authors.identifier: http://orcid.org/0000-0001-5283-4937
authors.initials: K
authors.lastname: Thonicke
authors.affiliation: Department for Biogeochemical Integration, Max-Planck-Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Reichstein
authors.affiliation: Potsdam Institute for Climate Impact Research, Earth System Analysis, Telegraphenberg A31, 14473, Potsdam, Germany.
authors.forename: Sibyll
authors.initials: S
authors.lastname: Schaphoff
authors.affiliation: Department for Biogeochemical Integration, Max-Planck-Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Weber
authors.affiliation: Department for Biogeochemical Integration, Max-Planck-Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.|Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Carvalhais
mesh_terms: D057231:Climate Change; D004777:Environment; D008962:Models, Theoretical; D063245:Plant Development; D012621:Seasons; D013696:Temperature; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water
keywords: browning; dynamic global vegetation model; greening; land-use and land-cover change; model evaluation; phenology; remote sensing; vegetation dynamics