Table 1 Net primary productivity and its fractional distribution

From: Enhanced woody biomass production in a mature temperate forest under elevated CO2

 

Q. robur

bole + branch

Q. robur

coarse root

Understory wood

Total wood

Fine root

Exudation

Reprod.

tissue

Leaves

Total NPP

2021

   

NPP (g m−2)

   

Ambient

755 ± 95

83 ± 12

12 ± 7

849 ± 103

203 ± 28

76 ± 20

124 ± 13

501 ± 9

1,753 ± 114

Elevated

835 ± 166

88 ± 21

15 ± 7

938 ± 183

201 ± 11

124 ± 15

133 ± 31

529 ± 49

1,924 ± 263

E/A

1.106

1.060

1.269

1.104

0.989

1.633

1.075

1.054

1.097

2022

Ambient

534 ± 67

58 ± 8

16 ± 1

608 ± 74

154 ± 8

83 ± 8

72 ± 1

562 ± 22

1,479 ± 78

Elevated

621 ± 87

67 ± 10

17 ± 10

706 ± 87

156 ± 15

118 ± 25

95 ± 28

575 ± 88

1,650 ± 140

E/A

1.164

1.141

1.087

1.161

1.014

1.426

1.318

1.023

1.115

2021

   

Fractional distribution (%)

   

Ambient

   

48.1 ± 2.7

11.6 ± 1.7

4.2 ± 0.8

7.2 ± 1.1

28.8 ± 1.9

 

Elevated

   

47.8 ± 4.7

10.8 ± 1.5

6.5 ± 0.4

6.9 ± 1.2

27.9 ± 1.6

 

E/A

   

0.995

0.929

1.542

0.967

0.967

 

2022

Ambient

   

40.8 ± 2.8

10.5 ± 0.9

5.6 ± 0.3

4.9 ± 0.3

38.2 ± 2.2

 

Elevated

   

42.7 ± 3.8

9.5 ± 1.0

7.2 ± 1.6

6.1 ± 2.0

34.5 ± 2.5

 

E/A

   

1.045

0.908

1.174

1.243

0.904

 
  1. All data are the means of three plots in ambient CO2 and three plots in elevated CO2 ±s.e., expressed as grams dry matter per m2. None of the differences within year are statistically significant (P > 0.20); repeated measures analysis across years indicated an effect of CO2 on NPP at P = 0.099, F1,4 = 4.56. Wood production by plot was adjusted to account for the average pretreatment BAI for 2011–2015 as determined by tree-ring analysis. Leaf mass production was assumed to be 14% greater than litter mass based on the amount of nitrogen resorbed from senescing leaves and the assumption that nitrogen was exported as glutamine30. Plot-level leaf mass production was normalized to the pretreatment (2016) values. Production of fine roots (<2 mm diameter) was determined from in-growth cores installed to 30 cm depth and scaled to 1 m depth on the basis of the relative depth distribution of fine-root standing crop in core samples. E/A is the ratio of the measure in eCO2 to the measure in aCO2.
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