2025/02/21 by Charlotte Angove, Guido L. B. Wiesenberg, Marco M. Lehmann +6 · 1 voice
Earth and Planetary Sciences · Environmental Science · #Geology and Paleoclimatology Research #Isotope Analysis in Ecology #Plant Water Relations and Carbon Dynamics
paper · pdf · doi:10.1111/nph.20448
openalex publication_date 2025/02/21 · openalex created_date 2025/02/22 · openalex updated_date 2026/07/30
Summary Reliable insights from key δ 2 H bioindicators, n ‐alkanes and carbohydrates, are hindered by our limited understanding of isotope fractionation processes related to leaf water and primary assimilates. We addressed this with the first study to investigate time‐integrated intra‐annual δ 2 H signals of n ‐alkanes and carbohydrates in a natural forest. We sampled 1‐yr‐old needles (1N) and current‐year needles (0N) from five Scots Pine trees in a coniferous forest in Hyytiälä, Finland, biweekly during 2019. The δ 2 H of their n ‐alkanes (δ 2 H alkane ), water‐soluble carbohydrates (δ 2 H WSC ) and starch (δ 2 H starch ) were evaluated for time‐integrated physiological (gas‐exchange) and environmental (hydrological) signals. Time integration was critical for interpreting δ 2 H WSC and δ 2 H alkane . Time‐integrated net assimilation rate ( T : A n ), the strongest signal in δ 2 H WSC , correlated negatively with 1N δ 2 H WSC (early season) and positively with 0N δ 2 H WSC (late season). Unexpectedly, δ 2 H alkane exhibited stronger environmental signals in 1N than in 0N, with the most pronounced being physiologically mediated hydrological signals. T : A n is a major signal in intra‐annual δ 2 H WSC in a boreal forest, subject to seasonal interactions with needle age and δ 2 H starch . There could be enough de novo n ‐alkane synthesis in situ to enhance the reliability of δ 2 H alkane as a hydrological indicator, bringing promise to interpretations of the n ‐alkane palaeohydrological record.