Geographical, Climatological, and Biological Characteristics of Tree Radial Growth Response to Autumn Climate Change

Shunsuke Tei,Nagai Shin,Ayumi Kotani,Atsuko Sugimoto

doi:10.3389/ffgc.2021.687749

Abstract

Terrestrial forest ecosystems are crucial to the global carbon cycle and climate system; however, these ecosystems have experienced significant warming rates in recent decades, whose impact remains uncertain. This study investigated radial tree growth using the tree-ring width index (RWI) for forest ecosystems throughout the Northern Hemisphere to determine tree growth responses to autumn climate change, a season which remains considerably understudied compared to spring and summer, using response function and random forest machine learning methods. Results showed that autumn climate conditions significantly impact the RWI throughout the Northern Hemisphere. Spatial variations in the RWI response were influenced by geography (latitude, longitude, and elevation), climatology, and biology (tree genera); however, geographical and/or climatological characteristics explained more of the response compared to biological characteristics. Higher autumn temperatures tended to negatively impact tree radial growth south of 40° N in regions of western Asia, southern Europe, United State of America and Mexico, which was similar to the summer temperature response found in previous studies, which was attributed to temperature-induced water stress.

Highlights

Forest ecosystems play a vital role in the global carbon cycle (Pan et al, 2011) and climate systems (e.g., Bonan, 2008)
We investigated the spatial distribution of tree radial growth responses to autumn climate change and obtained results corresponding with those of the summer
These results indicate that tree radial growth responses to climate change may differ with the season, and the impact of the genus is less critical compared to other geographic and climatological factors, we did show that some characteristics of the ring width index (RWI) response to autumn climate change were due to genera differences (Table 3)

Summary

Introduction

Forest ecosystems play a vital role in the global carbon cycle (Pan et al, 2011) and climate systems (e.g., Bonan, 2008). The warming rates across northern high-latitude regions are higher than anywhere else on earth, a phenomenon known as Arctic amplification (e.g., Serreze and Barry, 2011). Understanding spatial variations in the forest ecosystem response to climate change over a vast biome or region with significant gradients in geographic, climatological, and biological characteristics are crucial for accurate projections of the terrestrial carbon cycle and global climate

Methods

Discussion

Conclusion