TY  - JOUR
A1  - Eilmann, Britta
A1  - Rigling, Andreas
ED  - Abrams, Marc
T1  - Tree-growth analyses to estimate tree species' drought tolerance
JF  - Tree Physiology
N2  - Climate change is challenging forestry management and practices. Among other things, tree species with the ability to cope with more extreme climate conditions have to be identified. However, while environmental factors may severely limit tree growth or even cause tree death, assessing a tree species' potential for surviving future aggravated environmental conditions is rather demanding. The aim of this study was to find a tree-ring-based method suitable for identifying very drought-tolerant species, particularly potential substitute species for Scots pine (Pinus sylvestris L.) in Valais. In this inner-Alpine valley, Scots pine used to be the dominating species for dry forests, but today it suffers from high drought-induced mortality. We investigate the growth response of two native tree species, Scots pine and European larch (Larix decidua Mill.), and two non-native species, black pine (Pinus nigra Arnold) and Douglas fir (Pseudotsuga menziesii Mirb. var. menziesii), to drought. This involved analysing how the radial increment of these species responded to increasing water shortage (abandonment of irrigation) and to increasingly frequent drought years. Black pine and Douglas fir are able to cope with drought better than Scots pine and larch, as they show relatively high radial growth even after irrigation has been stopped and a plastic growth response to drought years. European larch does not seem to be able to cope with these dry conditions as it lacks the ability to recover from drought years. The analysis of trees' short-term response to extreme climate events seems to be the most promising and suitable method for detecting how tolerant a tree species is towards drought. However, combining all the methods used in this study provides a complete picture of how water shortage could limit species.
Y1  - 2012
U6  - http://dx.doi.org/10.1093/treephys/tps004
SN  - 0829-318X (Print)
SN  - 1758-4469 (Online)
VL  - 32
IS  - 2
SP  - 178
EP  - 187
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Rigling, Andreas
A1  - Bigler, Christof
A1  - Eilmann, Britta
A1  - Feldmeyer-Christe, Elisabeth
A1  - Gimmi, Urs
A1  - Ginzler, Christian
A1  - Graf, Ulrich
A1  - Mayer, Phillip
A1  - Vacchiano, Giorgio
A1  - Weber, Pascal
A1  - Wohlgemuth, Thomas
A1  - zweifel, Roman
A1  - Dobbertin, Matthias
T1  - Driving factors of a vegetation shift from Scots pine to pubescent oak in dry Alpine forests
JF  - Global Change Biology
N2  - An increasing number of studies have reported on forest declines and vegetation shifts triggered by drought. In the Swiss Rhone valley (Valais), one of the driest inner-Alpine regions, the species composition in low elevation forests is changing: The sub-boreal Scots pine (Pinus sylvestris L.) dominating the dry forests is showing high mortality rates. Concurrently the sub-Mediterranean pubescent oak (Quercus pubescens Willd.) has locally increased in abundance. However, it remains unclear whether this local change in species composition is part of a larger-scale vegetation shift. To study variability in mortality and regeneration in these dry forests we analysed data from the Swiss national forest inventory (NFI) on a regular grid between 1983 and 2003, and combined it with annual mortality data from a monitoring site. Pine mortality was found to be highest at low elevation (below 1000 m a.s.l.). Annual variation in pine mortality was correlated with a drought index computed for the summer months prior to observed tree death. A generalized linear mixed-effects model indicated for the NFI data increased pine mortality on dryer sites with high stand competition, particularly for small-diameter trees. Pine regeneration was low in comparison to its occurrence in the overstorey, whereas oak regeneration was comparably abundant. Although both species regenerated well at dry sites, pine regeneration was favoured at cooler sites at higher altitude and oak regeneration was more frequent at warmer sites, indicating a higher adaptation potential of oaks under future warming. Our results thus suggest that an extended shift in species composition is actually occurring in the pine forests in the Valais. The main driving factors are found to be climatic variability, particularly drought, and variability in stand structure and topography. Thus, pine forests at low elevations are developing into oak forests with unknown consequences for these ecosystems and their goods and services.
Y1  - 2012
U6  - http://dx.doi.org/10.1111/gcb.12038
SN  - 1354-1013 (Print)
SN  - 1365-2486 (Online)
VL  - 19
IS  - 1
SP  - 229
EP  - 240
PB  - Wiley-Blackwell
CY  - Oxford
ER  -