Background and aims Start and end of the growing season determine important ecosystem processes, but their drivers may differ above-and belowground, between autumn and spring, and between ecosystems. Here, we compare above-and belowground spring and autumn phenology, and their abiotic drivers (temperature, water level, and soil moisture) in four temperate ecosystems (beech forest, alder carr, phragmites reed, and sedge reed). Methods Root growth was measured in-situ with minirhizotrons and compared with aboveground phenology assessed with dendrometer data and NDVI. Results Synchrony of above- and belowground phenology depended on ecosystem. Onset of root growth was later than shoot growth in all three peatlands (12-33 days), but similar in the beech forest. The growing season ended earlier belowground in the two forested ecosystems (beech forest: 27 days, understory of the alder carr: 55 days), but did not differ in the phragmites reed. Generally, root production was correlated with soil temperature (especially in spring) and water level in the peatlands, while abiotic factors were less correlated with leaf activity or root production in either spring or autumn in the beech forest. Conclusions Root production on organic soils was ten times higher compared to the zonal broadleaf deciduous forest on mineral soils, highlighting the importance of peatlands. Belowground phenology cannot be projected from aboveground phenology and measuring root phenology is crucial to understand temporal dynamics of production and carbon fluxes.
