Boreal coniferous forest density leads to significant variations in soil physical and geochemical properties
At the northernmost extent of the managed forest in Quebec, Canada, the boreal forest is currently undergoing an ecological transition between two forest ecosystems. Open lichen woodlands (LW) are spreading southward at the expense of more productive closed-canopy black spruce–moss forests (MF)....
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-07-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/14/3445/2017/bg-14-3445-2017.pdf |
| Summary: | At the northernmost extent of the managed forest in Quebec, Canada,
the boreal forest is currently undergoing an ecological transition between
two forest ecosystems. Open lichen woodlands (LW) are spreading southward at
the expense of more productive closed-canopy black spruce–moss forests (MF).
The objective of this study was to investigate whether soil properties could
distinguish MF from LW in the transition zone where both ecosystem types
coexist. This study brings out clear evidence that differences in vegetation
cover can lead to significant variations in soil physical and geochemical
properties.<br><br>Here, we showed that soil carbon, exchangeable cations, and iron and
aluminium crystallinity vary between boreal closed-canopy forests and open
lichen woodlands, likely attributed to variations in soil microclimatic
conditions. All the soils studied were typical podzolic soil profiles
evolved from glacial till deposits that shared a similar texture of the C
layer. However, soil humus and the B layer varied in thickness and chemistry
between the two forest ecosystems at the pedon scale. Multivariate analyses
of variance were used to evaluate how soil properties could help distinguish
the two types at the site scale. MF humus (FH horizons horizons composing the O layer) showed significantly
higher concentrations of organic carbon and nitrogen and of the main
exchangeable base cations (Ca, Mg) than LW soils. The B horizon of LW sites
held higher concentrations of total Al and Fe oxides and particularly
greater concentrations of inorganic amorphous Fe oxides than MF mineral
soils, while showing a thinner B layer. Overall, our results show that MF
store three times more organic carbon in their soils (B+FH horizons, roots
apart) than LW. We suggest that variations in soil properties between MF and
LW are linked to a cascade of events involving the impacts of natural
disturbances such as wildfires on forest regeneration that determines the
vegetation structure (stand density) and composition (ground cover type) and
their subsequent consequences on soil environmental parameters (moisture,
radiation rate, redox conditions, etc.). Our data underline significant
differences in soil biogeochemistry under different forest ecosystems and
reveal the importance of interactions in the soil–vegetation–climate
system for the determination of soil composition. |
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| ISSN: | 1726-4170 1726-4189 |