Stable isotopes in tree rings record physiological trends in Larix gmelinii after fires.

Tree Physiol

Beijing Key Laboratory of Forest Resources and Ecosystem Process, Beijing Forestry University, 35 East Qinghua Road, Beijing 100083, China.

Published: July 2023

Fire is an important regulator of ecosystem dynamics in boreal forests, and in particular has a complicated association with growth and physiological processes of fire-tolerant tree species. Stable isotope ratios in tree rings are used extensively in eco-physiological studies for evaluating the impact of past environmental (e.g., drought and air pollution) factors on tree growth and physiological processes. Yet, such studies based on carbon (δ13C) and oxygen (δ18O) isotope ratios in tree rings are rarely conducted on fire effect, and are especially not well explored for fire-tolerant trees. In this study, we investigated variations in basal area increment and isotopes of Larix gmelinii (Rupr.) Rupr. before and after three moderate fires (different fire years) at three sites across the Great Xing'an Mountains, Northeastern China. We found that the radial growth of L. gmelinii trees has significantly declined after the fires across study sites. Following the fires, a simultaneous increase in δ13C and δ18O has strengthened the link between the two isotopes. Further, fires have significantly enhanced the 13C-derived intrinsic water-use efficiency (iWUE) and largely altered the relationships between δ13C, δ18O, iWUE and climate (temperature and precipitation). A dual-isotope conceptual model revealed that an initial co-increase in δ13C and δ18O in the fire year can be mainly attributed to a reduction in stomatal conductance with a constant photosynthetic rate. However, this physiological response would shift to different patterns over post-fire time between sites, which might be partly related to spring temperature. This study is beneficial to better understand, from a physiological perspective, how fire-tolerant tree species adapt to a fire-prone environment. It should also be remembered that the limitation of model assumptions and constraints may challenge model applicability and further inferred physiological response.

Download full-text PDF

Source
http://dx.doi.org/10.1093/treephys/tpad033DOI Listing

Publication Analysis

Top Keywords

tree rings
12
δ13c δ18o
12
larix gmelinii
8
fires fire
8
growth physiological
8
physiological processes
8
fire-tolerant tree
8
tree species
8
isotope ratios
8
ratios tree
8

Similar Publications

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!