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Fig. 1. Sampling design for the two sites at Salgesch and Jeizinen. Wood cores were sampled eight times in 2003 to estimate intra-annual growth of the current year and tree rings of the past years. Stem radius (
R) and sap flow measurements were recorded at 10 min intervals and led to intra-annual growth and tree water deficit (W) (Zweifel et al., 2005). The ratio between actual and potential transpiration (T PET–1) of tree crowns was calculated for the corresponding periods from sap flow rates, canopy surface properties, and microclimate according to Zweifel et al. (2002). Climate data for Salgesch of the years 1998 to 2001 were linearly transformed from the data from Sion.
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Fig. 2. Intra-annual radial growth of individual trees of Quercus pubescens, Pinus sylvestris, and Picea abies at the two sites Salgesch (a–d) and Jeizinen (e–j) in the year 2003. Growth was approached directly by counting new cells of the current tree ring in the wood cores (triangles) and measuring the size (black dots with range of variation), and indirectly by detrending stem radius measurements (R) for water-related changes according to Zweifel et al. (2005) (grey lines). The difference between the grey line and the stem radius measurements represents the actual tree water deficit W. Numbers in brackets indicate tree labels as listed in Table 3.
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Fig. 3. Intra-annual radial growth of tree individuals of Quercus pubescens (grey symbols), Pinus sylvestris (black symbols), and Picea abies (open/dashed symbols) deduced from eight wood cores sampled over the vegetation period 2003 (a) at Salgesch and (b) Jeizinen. Arrows point to the time of budburst and the corresponding time of reaching full physiological activity.
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Fig. 4. Radial growth and mean daily (6–20 h) ratio between actual and potential transpiration (T PET–1) of (a) Quercus pubescens and (b) Pinus sylvestris at Salgesch and of (f) Q. pubescens, (g) P. sylvestris, and (h) Picea abies at Jeizinen for the years 2002 to 2004. (c) and (i) The species-specific courses of tree water deficit (W) for Q. pubescens (grey line), P. sylvestris (black line), and P. abies (broken line). (d) and (e) The growth periods (90% of the yearly increment) of the respective species. The vertical dotted lines indicate the date of full leaf expansion of Q. pubescens. Intra-annual radial growth of individual trees was deduced from stem radius measurements (R). The species-specific course of T PET–1 is depicted as a running mean of the daily values.
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Fig. 5. Annual radial growth of Quercus pubescens (a–c) and Pinus sylvestris (d–f) compared with the mean daily (6–20 h) ratio between actual and potential transpiration (T PET–1), sum of rain and mean tree water deficit (W) during the growing period (25 March to 10 July when not labelled differently). Regressions for data points from Salgesch only (squares), Jeizinen (open circles).
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Fig. 6. Intra-annual radial growth of Quercus pubescens (grey symbols), Pinus sylvestris (black symbols), and Picea abies (open or dotted symbols) over 10 d periods compared with the corresponding sum of rain at (a) Jeizinen and (b) Salgesch.
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Fig. 7. Stem radius changes (R) including the water-related and growth-related component (Quercus pubescens = grey line, Pinus sylvestris = black line) compared with rain, vapour pressure deficit (VPD) and soil water potential (
Soil) in 2003.
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