Tree-ring isotopes capture interannual vegetation productivity dynamics at the biome scale

Mathieu Levesque,Brady W Allred,Laia Andreu-Hayles,Neil Pederson,William Kolby Smith,A Park Williams,Martina L Hobi

doi:10.1038/s41467-019-08634-y

Abstract

Historical and future trends in net primary productivity (NPP) and its sensitivity to global change are largely unknown because of the lack of long-term, high-resolution data. Here we test whether annually resolved tree-ring stable carbon (δ13C) and oxygen (δ18O) isotopes can be used as proxies for reconstructing past NPP. Stable isotope chronologies from four sites within three distinct hydroclimatic environments in the eastern United States (US) were compared in time and space against satellite-derived NPP products, including the long-term Global Inventory Modeling and Mapping Studies (GIMMS3g) NPP (1982–2011), the newest high-resolution Landsat NPP (1986–2015), and the Moderate Resolution Imaging Spectroradiometer (MODIS, 2001–2015) NPP. We show that tree-ring isotopes, in particular δ18O, correlate strongly with satellite NPP estimates at both local and large geographical scales in the eastern US. These findings represent an important breakthrough for estimating interannual variability and long-term changes in terrestrial productivity at the biome scale.

Highlights

Historical and future trends in net primary productivity (NPP) and its sensitivity to global change are largely unknown because of the lack of long-term, high-resolution data
Supporting our hypothesis, we found significant correlations between annually resolved Δ13C and δ18O tree-ring data and annual NPP data across large geographical regions with differing hydroclimatic conditions
Despite distinct environmental conditions and diverging trends in climate, these results indicate a strong agreement between tree-ring δ18O and space-based NPP

Summary

Introduction

Historical and future trends in net primary productivity (NPP) and its sensitivity to global change are largely unknown because of the lack of long-term, high-resolution data. We test whether annually resolved tree-ring stable carbon (δ13C) and oxygen (δ18O) isotopes can be used as proxies for reconstructing past NPP. We show that tree-ring isotopes, in particular δ18O, correlate strongly with satellite NPP estimates at both local and large geographical scales in the eastern US. These findings represent an important breakthrough for estimating interannual variability and long-term changes in terrestrial productivity at the biome scale. Decadal to centennial trends in historical NPP have been difficult to characterize because of the lack of high-resolution and long-term data. The potential of tree-ring isotopes for inferring regional to continental terrestrial vegetation productivity has never been tested

Methods

Results

Conclusion