Table 1 Analysis of age- and height-related changes in W i for different life stages

From: Tree height strongly affects estimates of water-use efficiency responses to climate and CO2 using isotopes

Species

W i vs. age trends ppm (100 yr −1 )

 

Full age range

Age > 25 yrs

>50 yrs

>75 yrs

>100 yrs

>200 yrs

Pinus sylvestris a

3***

2.9***

2.4***

2.2***

2.0***

2.6**

Quercus robur

43.1***

27.7*

65.3*

   

Fagus sylvatica

69.5***

99.4***

185*

   

Cedrela odorata

39.1***

26.1***

14.3*

15.2NS

12.9NS

 
 

W i vs. height trends, ppm (10 m) −1

     
 

Full height range

Height > 1 m

>2.5  m

>5  m

>10 m

>20  m

Pinus sylvestris b

−0.41NS

1.74

8.42*

9.94*

14.7

 

Quercus robur

17.43***

20.22***

20.84***

14.94***

13.95**

 

Fagus sylvatica

18.41***

18.08***

18.16***

23.04***

26.10***

52.28**

Cedrela odorata

19.37***

17.28***

15.81***

16.27***

15.72***

16.10**

  1. Linear trends in W i vs. age or height for full range of data, and excluding earlier life stages (e.g., first 25 years, 50 years, etc, or first metre, first 2.5 m, etc). Results show that age trends in Quercus and Fagus remain strong, while Cedrela and Pinus show slight decreases in the slope of the trends with age. Trends with tree height remain strong throughout the full height range Significance levels are indicated as follows: NS not significant; *p < 0.05; **p < 0.01; ***p < 0.001
  2. aUsing the data set of sub-fossil pine trees from Helama et al.39
  3. bUsing the data set of Pinus trees with height measurements from the UK (see Methods section)
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