Disentangling Intra-annual Tree Growth Responses to Hydro-Climatic Conditions: Insights from Quantitative Wood Anatomy in Peatlands

Silvia Piccinelli ¹, Johannes Edvardsson ², Christophe Corona ³, Lenka Slamova ³, Veiko Lehsten ², Markus Stoffel ³

Franklin University Switzerland ¹, Lund University, Sweden ², University of Geneva, Switzerland ³

Peatland dynamics, influenced by climatic and hydrological fluctuations, play a crucial role in regulating carbon storage capacity and methane emissions, thereby affecting feedback processes on climate change. Persistent draining conditions driven by increasing air temperature, drought and evapotranspiration, promote soil aeration and peat mineralization boosting tree establishment, which further lower water-table levels, and eventually cause an increase in greenhouse gas emissions. Conversely, peatland tree growth is hindered by either excessively dry or waterlogged conditions, which lead to water stress in trees or limit nutrient uptake due to anoxia and soil acidity, respectively. Despite recent research efforts, dendroecological studies focused on peatland trees remain scarce, impairing a successful application in hydro-climatic reconstructions. To address this gap, we sampled and analyzed 13 Pinus sylvestris trees at Mycklemossen peatland in southern Sweden, selecting three 63-year-long chronologies: ring width (RW), radial cell-wall thickness (CWTrad) and radial diameter (Drad). While daily air temperature, precipitation and estimated water-table data were correlated with RW, xylem traits were assessed at an intra-seasonal resolution, by dividing each ring into five equal-width sectors and computing five chronologies per trait. Our results provide significant, albeit variable, hydro-climatic responses among wood parameters, with the strongest signal detected for temperature in CWTrad and Drad, resulting in i) a positive correlation during the beginning of the growing season for CWTrad (March-May, S3-4), and ii) a negative correlation during spring and summer for Drad (March-August, S4). While growth responses to water-table were absent in RW chronologies, a significant influence was observed in the earlywood formation of both Drad and CWTrad during summer of the previous year of ring formation (July-August, S1-3), with negative and positive correlations, respectively. Moreover, a variable but significant positive effect of precipitation was detected in CWTrad, though not visible in RW. Our novel findings offer a crucial advancement in dendroecological research, confirming the value of QWA analyses over RW, allowing for more accurate hydro-climatic reconstruction models in peatland environments, extremely needed in the actual context of global change.

Main author career stage: Professor / Permament researcher

Contribution type: Talk

First choice session: 4. Structure, physiology, and development

Second choice session: 2. Ecology