Bigler Christof
Tree Mortality in Peatbogs in Central Switzerland
Project Number: Parcs Data Center 50171 / 4D CH-7162
| Project Type: |
Master |
| Project Duration: |
01/01/2021 - 08/12/2021 project completed |
| Funding Source: |
other , |
| Leading Institution: |
ETH Zürich |
| Project Leader: |
Prof. Christof Bigler
Forest Ecology
Dept. Umweltsystemwissenschaften (D-USYS)
ETH Zürich
CHN G77
Universitätstrasse 22
8092 Zürich
Phone: +41 (0) 44 632 52 05
e-Mail: christof.bigler(at)env.ethz.ch
http://www.usys.ethz.ch/ |
Research Areas:
Disciplines:
Abstract:
Increasing mortality of mountain pine (Pinus montana) and Norway spruce (Picea abies) have been detected in the recent years in the peatbogs of the Entlebuch biosphere reserve. Using dendrochronological methods, 150 mountain pines and Norway spruces were sampled in five plots where abundant tree mortality was observed. Prior to this study, it was unclear, first, how the temperature and precipitation affected tree growth in that region, second, when these trees died, third, what influenced the lifespan of the dead trees, and fourth, why some trees are dead while others are alive.
First, the analyses have shown that mountain pines grew better if snow accumulation in the current January were high and precipitation in the current September low. For the future growth of the mountain pine, it is therefore necessary to maintain cold winters with high snow accumulation and warm end-of-summer months with little precipitation. For the growth of Norway spruces in plot 4 to 5, no common pattern was identified. Second, it was found that the majority of the mountain pines and Norway spruces died between 2001 and 2006. However, as a result of the summer drought in 2003, most of the mountain pines died in the years 2003 and 2004 and most of the Norway spruces in the year 2003. Third, these analyses showed that over 80% of both dead tree species had a lifespan between 100 and 200 years. For the mountain pines, an increasing DBH (diameter at breast height, i.e., 130 cm above the ground) also increased the lifespan, whereas an increasing early growth decreased the lifespan. For the Norway spruces, an increasing DBH, higher number of neighbouring trees and a medium sphagnum cover increased the lifespan, whereas an increasing early growth and low and high sphagnum cover decreased the lifespan. The slow-growing dead trees of both tree species reached a higher lifespan than the fast-growing dead trees. Forth, the analyses revealed that the mortality probability of the mountain pines decreased with increasing height and increasing neighbouring trees. The mortality probability of the Norway spruces decreased with increasing recent growth as well as increasing sphagnum cover and increased with decreasing neighbouring trees.
Overall, the tree mortality appeared to be a result from a combination of the species specific morphology, growth, competition with neighbouring trees, and their environmental surrounding such as sphagnum cover. However, the summer drought of 2003 has led to the highest mortality of both tree species. As the climate-induced tree mortality is expected to increase in Switzerland in the future, summer droughts may further increase tree mortality in peat moss forests.
Publications:
Catoja, M. (2021): Tree mortality in peatbogs in central Switzerland. Masterarbeit, ETH Zürich.
PDF Masterarbeit
Last update: 2/20/24
Source of data: ProClim- Research InfoSystem (1993-2024)
Update the data of project: CH-7162
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