『Abstract
In this study, we quantified the contribution of mineral tunneling
by fungi to weathering of feldspars and ecosystem influx of K
and Ca. We studied the surface soils of 11 podzols across a Lake
Michigan sand dune chronosequence with soil ages between 450 ad
5000 years. Weathering by tunneling was quantified in thin sections
by image analysis. Total mineral weathering was quantified by
comparing the mineralogy of the surface soil with the underlying
parent material. Mineralogy was characterized using X-ray fluorescence
spectroscopy (XRFS), followed by a normative mineralogical calculation.
Tunnels were observed only in soils older than 1650 years. Throughout
the chronosequence the contribution of tunneling to mineral weathering
in the upper mineral soil, expressed as tunnel volume divided
by volume of weathered feldspar, was less than 1%. Contribution
of tunneling to Na/Ca-feldspar weathering was higher than the
contribution of tunneling to K-feldspar weathering. Feldspar tunneling
equals an average ecosystem influx of 0.4 g ha-1 year-1
for K and 0.2 g ha-1 year-1 for Ca over
5000 years of soil development. Intensity of mineral tunneling,
determined as fraction weathered feldspars, was higher than in
a previously described North Swedish podzol chronosequence. The
presented data suggest that the contribution of tunneling to weathering
becomes more important in older soils, but remains low.
Keywords: Biological weathering; Ca and K biogeochemistry; Chronosequence;
Feldspar; Fungi; Tunneling』
1. Introduction
2. Study area
2.1. The soil chronosequence
2.2. Profile descriptions
2.3. Vegetation
2.4. Texture
2.5. Mineralogy
3. Methods
3.1. Weathering
3.2. Statistics
4. Results
4.1. Tunneling
4.2. Weathering
4.3. Contribution of tunneling to weathering
5. Discussion
5.1. Contribution of tunneling
5.2. Comparison tunnel frequency Michigan-Sweden
Acknowledgements
References