Photosynthetic advantages of conifers in the boreal forest.

Abstract

Boreal conifers - the 'Christmas trees' - maintain their green needles over the winter by retaining their chlorophyll. These conifers face the toughest challenge in February and March, when subzero temperatures coincide with high solar radiation. To balance the light energy they harvest with the light energy they utilise, conifers deploy various mechanisms in parallel. These include, thylakoid destacking, which facilitates direct energy transfer from Photosystem II (PSII) to Photosystem I (PSI), and excess energy dissipation through sustained nonphotochemical quenching (NPQ). Additionally, they upregulate alternative electron transport pathways to safely reroute excess electrons while maintaining ATP production. From an evolutionary and ecological perspective, we consider these mechanisms as part of a comprehensive photosynthetic alteration, which enhances our understanding of winter acclimation in conifers and their dominance in the boreal forests.