Periodic Reporting for period 3 - GlacialLegacy (Glacial Legacy on the establishment of evergreen vs. summergreen boreal forests)
Reporting period: 2021-11-01 to 2023-04-30
Boreal forests, which make up roughly one‐third of the world's total forested area provide critical ecosystem services including carbon stocks, climate‐feedbacks, permafrost‐stability, biodiversity, and economic benefits. These services differ markedly between the two boreal forest biomes i.e. the evergreen needle‐leaf forests of North America and Europe, and the summergreen needle‐leaf forests covering much of northern Asia. However, the basic mechanisms that control the distributions of boreal biomes remain poorly understood. The potential future changes in boreal ecosystem services are therefore uncertain, which is a matter of local, regional, and global concern. The GlacialLegacy project will aim to answer the timely questions “Why is northern Asia dominated by larch forests?"and “How will these forests change in the future?”. My new hypothesis is that summergreen and evergreen needle‐leaf forests represent alternative quasistable states that occur today under similar climatic conditions, but were triggered by different environmental conditions and gene pools during the Last Glacial. GlacialLegacy used coherent empirical and modelling approaches to investigate this hypothesis across the entire Northern Hemisphere. Eventually, these predictions will aim to anticipate potentially critical future ecosystem service changes on a continental scale, thus providing the knowledge base required for adaptation strategies to be prepared.
The hypothesis of project i.e. a substantial Glacial Legacy on boreal forests was presented to the scientific community in a peer‐reviewed paper and in a palaeodata synthesis study. Field works in Siberia and North America were implemented as well as laboratory works. Furthermore, we investigated synthesized pollen data in terms of climate and ecological change to investigate the trajectories. We set and applied a model that couples forest dynamics and permafrost which can assess Larix forests may self‐stabilize due to complex feedbacks. Furthermore, we implemented of variation and adaptation of traits in this model to investigate whether larches of central Siberia can withstand future drought even if they adapted.
Larix forest functioning is still poorly investigated originates from the lack of data and models specifically from eastern Siberia. We made substantial progress in this respect by publishing unique datasets on the forest structure and forest development in relation with climate change. Also, we investigated the specific feedbacks that stabilize forest in Central Yakutia in two studies focusing on the adaptability of Larix trees to drought and on the biophysical feedbacks between permafrost soils and Larix. This was not addressed before. In addition, we made use of the pollen data synthesized a part of this project, we could perform high level paleoclimate reconstructions. Based on these data we were able to assess two hypotheses about temperature-precipitation relationships in time and space (Herzschuh et al., 2022) as well as temperature variability (Herbert et al., 2022).