کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5770256 | 1629415 | 2017 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Altitude affects the quality of the water-extractable organic matter (WEOM) from rhizosphere and bulk soil in European beech forests Altitude affects the quality of the water-extractable organic matter (WEOM) from rhizosphere and bulk soil in European beech forests](/preview/png/5770256.png)
- Beech rhizosphere effect on WEOM was evaluated at 800Â m and 1000Â m a.s.l.
- Rhizosphere WEOM had larger amounts of sugars than that of bulk soil.
- Organic C and phenols contents were higher in rhizosphere than in bulk soil WEOM at 1000Â m.
- Higher tannins diversity occurred in rhizosphere than in bulk soil WEOM at 1000Â m.
- Environmental constraints enhanced the rhizosphere effect on WEOM quality.
Water-extractable organic matter (WEOM) is the most dynamic and bioavailable fraction of the soil organic matter pool. Although the litter floor is considered the main source of WEOM, roots also release a great amount of labile organic compounds through rhizodeposition processes. This makes the rhizosphere, the small soil volume in proximity to the roots, a soil compartment relatively enriched in WEOM. Since both the rhizosphere and the labile organic C pool are highly sensitive to the environmental conditions we evaluated the characteristics of WEOM from rhizosphere and bulk soil collected from the A horizons of European beech (Fagus sylvatica L.) forest soils of Apennines mountains (central Italy) at two altitudes (800 and 1000Â m), using elevation as a proxy for temperature change. Specifically, we tested if i) the rhizosphere contains higher amounts of WEOM with a greater diversity of compounds with respect to the bulk soil, and ii) this effect is more pronounced at higher altitude. At both 800Â m and 1000Â m above sea level, the main distinction between WEOM from rhizosphere and bulk soil was the larger amounts of sugars in the soil close to the roots. Further, our results indicated an influence of altitude on rhizospheric processes as suggested by the larger concentrations of organic C and soluble phenols, and richness of tannins in the rhizosphere WEOM than in the bulk soil at 1000Â m. We attributed this influence to environmental constraints which enhanced the release of labile organics and secondary metabolites by rhizodeposition and humification processes in the rhizosphere. As a whole, our data draw a picture where the roots are able to affect the characteristics of WEOM and environmental constraints enhance the differentiation between rhizosphere and bulk soil. This view confirms the influence of the rhizosphere on the soil C cycle, and the importance of the rhizospheric processes when environmental conditions become harsher.
Journal: Geoderma - Volume 302, 15 September 2017, Pages 6-13