Skip to main content
Research article - Peer-reviewed, 2022

Overstory dynamics regulate the spatial variability in forest-floor CO2 fluxes across a managed boreal forest landscape

Martinez-Garcia, Eduardo; Nilsson, Mats B.; Laudon, Hjalmar; Lundmark, Tomas; Fransson, Johan E. S.; Wallerman, Jorgen; Peichl, Matthias

Abstract

The forest-floor represents an important interface for various carbon dioxide (CO2) fluxes, however, our knowledge of their variability and drivers across a managed boreal forest landscape is limited. Here, we used a three-year (2016-2018) data set of biometric- and chamber-based flux measurements to investigate the net forest-floor CO2 exchange (NEff) and its component fluxes across 50 forest stands spanning different soil types, tree species, and age classes within a 68 km2 boreal catchment in Sweden. We found that the forest-floor acted as a net CO2 source with the 10th-90th percentile (used hereafter for describing reported variations) ranging from 149 to 399 g C m- 2 yr-1. Among the key landscape attributes, stand age strongly affected most NEff component fluxes, whereas tree species and soil type effects were weak and absent, respectively. Specifically, forest-floor net CO2 emissions increased with stand age due to declining understory gross and net primary production, ranging between 77-275 and 49-163 g C m- 2 yr- 1, respectively. Furthermore, we observed higher understory production rates in pine than in spruce stands. Across the 50 stands, the total forest-floor respiration ranged between 340 and 549 g C m- 2 yr-1 and its spatial variation was primarily regulated by its autotrophic components, i.e., understory and tree root respiration, which displayed divergent increasing and decreasing age-related trends, respectively. Furthermore, heterotrophic soil respiration remained within a relatively narrow range (154-290 g C m- 2 yr- 1), possibly owing to compensating gradients in forest-floor properties. We further identified tree biomass as the major driver of the landscape-scale variations of CO2 fluxes, likely attributable to modulating effects on forest-floor resource availability and growing conditions. This implies that tree growth responses to forest management and global change will be particularly important for regulating magnitudes and spatial variations of forest-floor CO2 fluxes in boreal forests.

Keywords

Boreal forest; Forest-floor; Landscape variability; Carbon dioxide exchange; Primary production; Respiration

Published in

Agricultural and Forest Meteorology
2022, volume: 318, article number: 108916
Publisher: ELSEVIER

Authors' information

Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Fransson, Johan
Swedish University of Agricultural Sciences, Department of Forest Resource Management
Fransson, Johan
Linnaeus University
Swedish University of Agricultural Sciences, Department of Forest Resource Management
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management

UKÄ Subject classification

Forest Science
Meteorology and Atmospheric Sciences

Publication Identifiers

DOI: https://doi.org/10.1016/j.agrformet.2022.108916

URI (permanent link to this page)

https://res.slu.se/id/publ/117267