The International Phenological Garden network (1959 to 2021): its 131 gardens, cloned study species, data archiving, and future

Collaborative networks that involve the compilation of observations from diverse sources can provide important data, but are difficult to maintain over long periods. The International Phenological Garden (IPG) network, begun in 1959 and still functioning 60 years later, has been no exception. Here we document its history, its monitored 23 species (initially all propagated by cloning), and the locations and years of data contribution of its 131 gardens, of which 63 from 19 countries contributed data in 2021. The decision to use clones, rather than multiple, locally adapted individuals, was based on the idea that this would “control” for genetic effects, and it affects the applicability of the data and duration of the network. We also describe the overlap among the IPG network, the Pan-European Phenology network (PEP725), and the phenological data offered by the German Weather Service. Sustainable data storage and accessibility, as well as the continued monitoring of all 23 species/clones, are under discussion at the moment, as is the fate of other phenological networks, despite a politically mandatory plant-based climate-change monitoring.

Meteorological and Salix species (S. acutifolia, S. smithiana, S. viminalis) phenological trends in central Italy

Plant phenology, through opportune observing and interpreting techniques can be useful to interpret the eventual plant vegetative and reproductive adaptation to climate changes. Some plants of Salix acutifolia Willd., S. smithiana Willd. and S. viminalis L. were considered in a phenological garden in central Italy for analysing their phenological growth stages according to the International gardens network indications during a 10-year period (2008-2017) which allowed us to realize some preliminary trend analyses. The 3 Salix species showed different behaviours in the same cultivation area. S. acutifolia manifested no trend for spring and autumnal phases, S. viminalis presented low significant trends while S. Smithiana was that with the more evident tendencies for all the considered vegetative phases during the study period. The reproductive phase (BBCH 65) showed no significant trend for any Salix species during the study period not being influenced by the different meteorological variables and suggesting that photoperiod in this case may play an important role. The more evident phenological trends were represented for 2 Salix species by the advance of the leaf development during spring and by the progressive delay of the senescence during the last part of the summer, with the fallen leaves phase that was recorded averagely 2 weeks later during the last years of the study period.