『Abstract
Recently it was hypothesized that ectomycorrhizas hyphae are
involved in mineral tunneling. We evaluated the role of ectomycorrhizas
in mineral weathering and the ecosystem influx of basic cations
by correlating mineral tunnel density to ectomycorrhizas density
in two forest productivity gradients. The gradients, two gentle
slopes in northern Sweden, are the result of groundwater movement
and are characterized by reduced productivity upslope due to lower
nitrogen availability. As expected, ectomycorrhizas density in
the O horizon was higher upslope, where nitrogen availability
was lower and where the vegetation was dominated by ectomycorrhizas
plant species. We consistently found that tunnel formation in
mineral grains was more intense in nutrient-poor sites, indicating
a higher contribution of fungi to ecosystem influx of potassium
and calcium. Ectomycorrhizas density was positively correlated
with feldspar tunnel density in the upper 2 cm of the E horizon.
This suggests that ectomycorrhizas are involved in mineral tunneling.
We discuss the possible involvement of ericoid mycorrhizas and
saprotrophic fungi in feldspar tunneling and the role of the weathering
status of mineral grains as additional factors controlling mineral
funneling.
Key words: boreal forest; ectomycorrhiza; ericoid mycorrhiza;
feldspar tunneling; productivity gradient; weathering.』
『最近、外生菌根菌糸が鉱物穿孔に関係しているという仮説がたてられた。鉱物風化における外生菌根の役割と塩基陽イオンの生態系への流入について、２つの森林生産性勾配で外生菌根密度に対して鉱物穿孔密度を関連づけることにより、我々は評価を行った。スウェーデン北部の２つの緩い斜面の勾配は、地下水移動の結果であり、利用できる窒素の低下のため斜面上方で生産性が減少することで特徴づけられる。予期されるように、O層での外生菌根密度は斜面上方で高く、そこでは利用できる窒素は低く、植生は外生菌根植物種が優勢だった。鉱物粒子の穿孔形成は栄養に乏しい場所ほど激しくて、このことは菌類がカリウムとカルシウムの生態系への流入に大きな貢献をしていることを示すことを、我々は絶えず見出した。外生菌根密度はE層の上部2cmで長石穿孔密度と正の相関を示した。このことは、外生菌根は鉱物穿孔と関係していることを示す。長石穿孔におけるツツジ型菌根と腐生菌類の考えられる関係、および鉱物穿孔をコントロールする別の要因としての鉱物粒子の風化状態の役割について、我々は検討している。』
Introduction
Materials and methods
Study sites
Soil sampling
Ectomycorrhizal density and root length
Mineralogy and texture
Micromorphology: Tunneling and weathering status
Statistics
Results
Tunnel formation and weathering along the gradients
Ectomycorrhizal density
Relationship of ectomycorrhizas density to tunnel density
Discussion
Tunnel formation and weathering along productivity gradients
Relationship between ectomycorrhizas density and tunnel formation
Conclusions
Acknowledgements
References