Effect of climate on decomposing coarse woody debris along a north- and
a south-facing elevational transect in Val di Sole (Eastern Alps, Italy)
Marta Petrillo
1,2, Paolo Cherubini
2, Giacomo Sartori
3, Samuel Abiven
1, Judith Ascher
4,5, Daniela Bertoldi
6, Alice Barbero
6, Roberto Larcher
6, Markus Egli
1
1 Department of Geography, University of Zurich, Switzerland (martapetrillo@geo.uzh.ch)
2 WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland 3 Museo delle Scienze, Trento, Italy
4 Department of Agrifood and Environmental Science, University of Florence, Italy 5 Institute of Microbiology, University of Innsbruck, Austria
6 IASMA, Fondazione Edmund Mach, San Michele all’Adige, Italy
Introduction
-
Coarse woody debris (CWD) plays an important role in carbon and nutrient dynamics-
In the Alpine region air and soil temperature are major drivers of decomposition-
Few studies have been carried out to disentangle the different factors of CWD decay-
Global carbon models oversimplify CWD decay dynamicsResults & Conclusions
•
A strong negative correlation was found between the content of cellulose and lignin
•
Lignin and nutrient concentrations were higher at south-facing sites
•
Biochemical differences tended to be reduced in late decay stages
•
∂
13C is changing according to elevation/exposition but not with decay stage
Research Question & Aim
Are chemical characteristics (cellulose, lignin, carbon, ∂13C and nutrient content) of CWD
affected by different elevation/exposition and decay stage in subalpine forests?
Our objective is to compare wood at different decay stages in Alpine forests at different sites having different elevation and exposition
Methods
Decay classes
Chemical characterization
•
α-cellulose•
Klason lignin•
carbon•
∂13C isotopic ratio•
nutrients: N-P-K-Ca-Mg1 2 3 4 5
Figure 5 Sample preparation. After drying at 50°C
until constant mass, samples were milled to powder using a planetary ball mill
Figure 4 Logs at different decay stages, from left to right: decay class 1, 2, 3, 4, 5
Site descripton
Figure 1 The study area is located
in the Eastern Italian Alps Figure 2 Val di Sole (Trentino, Italy)
• Mean annual temperature from 8.2 °C
in the valley floor to 0 °C at 2400 m asl
• Mean precipitation 800-1300 mm per year • Geological substrate paragneiss debris • Soil units Cambisols, Umbrisols, Podzols • Dominant tree species European larch
and Norway spruce
R = 0.63 p < 0.05 0 20 40 60 80 0 10 20 30 40 50 Li gn in (% ) Cellulose (%) 10 20 30 40 1 5 cellulose lignin 10 20 30 40 cellulose lignin 1 5 North-facing South-facing % %
decay class decay class
35 40 45 50 55 60
Carbon (%)
10 20 30 40 50 60Cellulose (%)
North facing South facing10 20 30 40 50 60
Lignin (%)
-28 -27 -26 -25 -24 -23 Decay classδ
13C (‰)
(‰
)
1 2 3 4 5}
-24 -25 -26 N S δ13C elevation exposition}
Climosequence
North-facing South-facing N4 - 2000 m N3 - 1600 m N2 - 1400 m N1 - 1200 m S9 - 2000 m S8 - 1600 m S7 - 1400 m S6 - 1200 mFigure 3 Schematic representation of the eight plots at different elevation/exposition. Soil physical and chemical properties were
investigated in a previous study (Egli et al., 2006)
25 30 35 40 45
Weeks
Lignin content Maximum density
Ring width
Jul Aug Sep Oct
• Lignin is depleted in13C
• Microbial derived
compounds can induce 13C enrichment
Counteracting effect of different factors that
influence δ13C
Gindle et al., 2000 (modified)
Lignin content could be mainly influenced by the temperatures of September and October
N and P increase with increased decay stage
References
Egli M., Mirabella A., Sartori G., Zanelli R., Bischof S., 2006. Effect of north and south exposure on weathering rates and clay mineral formation in Alpine soils. Catena 67, 155-174.
Gindl W., Grabner M., Wimmer R., 2000. The influence of temperature on
latewood lignin content in treeline of Norway spruce compared with maximum density and ring width. Trees 14, 409-414.
Alpine tundra
Subalpine forest belt
2 4 6 North South 0 0.1 0.2 0.3
Total Nitrogen Total Phosphorus
0 1 2 3 4 5 Decay class mg/g mg/g 1 2 3 4 5 Decay class Acknowledgements
This study is part of the DecAlp DACH project no. 205321L_141186.
We thank F. Angeli and his team of foresters from the “Ufficio distrettuale forestale of Malé” for their support in the field. We also thank D. Asensio for her help in performing elemental and isotopic analysis and all the laboratory technicians of the WSL and the University of Zurich.
