1
Supplementary Information
2
S1: data descriptions
3
1. Biomass measurements
4
In all three studies sample trees were excavated on measurement days. Immediately after
5
excavation, leaves, stem, branches and roots were separated from each individual tree and
6
weighed on scales. The length, and maximum and minimum diameter of stem, branches and roots
7
were measured. Various samples in different size classes were selected and returned to the
8
laboratory to determinant the dry/fresh weight ratios of leaves, stems, branches and roots. In the
9
study by Zeng et al. (2000), the dry mass of different organs was calculated using the dry/fresh
10
weight ratios. In the studies by Fang (1999) and Yang et al. (2001), biomass was calculated by the
11
allometric equations developed by them.
12
2. Respiration measurements
13
Respiration measurements of sample leaves or sample segments of woody organs (for details see
14
below) were made in a customized chamber connected to an infrared CO2 analyzer under field
15
conditions and completed within a short period of time after the sample tree was dug out and
16
sectioned. Respiration rates of these sample tissues were calculated by the following equation:
17
r
18
where t is the measurement period (s), w is the fresh weight (g) of the sample, C 2 and
19
C1 are CO2 concentrations (ppm) inside the chamber at the end and begin of the measurement,
20
respectively, Vc and Vt are volumes (ml) of the chamber and the sample, respectively, and
21
is the mean temperature inside the chamber.
22
2.1. Leaf respiration measurements
23
Since leaf dark respiration has been demonstrated to vary with leaf crown position and leaf age,
24
leaf subsamples representing the whole crown were taken for leaf respiration measurements of
25
each sample tree. Briefly, in the study by Yang et al. (2001), leaf dark respiration was separately
26
determined on leaves from different crown positions and with differing leaf ages, using the
27
CD-510 portable photosynthetic system and cuvette operating in an open configuration. In studies
28
by Fang et al. (1999) and Zeng et al. (2000), at least three composite leaf samples were collected,
29
each composed of several thoroughly-mixed subsamples from different leaf crown positions. Dark
3.6 1
273 44
(C2  C1 )(Vc  Vt )
t w
273   22.4

1
respiration of each composite sample was measured in a customized chamber using an infrared
2
CO2 analyzer. These data were used to calculate the average leaf dark respiration, which was
3
further used to estimate total leaf respiration per plant by multiplying it by total leaf fresh weight.
4
2.2 Woody organs respiration measurements
5
Stem was segmented at 1-m intervals, and the central diameter and fresh weight of each segment
6
measured. For the segment of < 1 m, the actual length was measured. The length, basal diameter
7
and fresh weight of each branch and root were measured; branches and roots were then classified
8
into different diameter classes, respectively. These diameters were used to establish the diameter
9
frequency distribution of stem, branch and root to estimate afterwards their respective total
10
respirations. For stem respiration measurement, a subsegment of ca. 20-cm length was cut from
11
the base of each stem segment. The fresh weight of each stem subsegment was weighed and its
12
accurate diameters at both cut ends were measured. Similarly, a branch or root segment was
13
collected from each diameter class of branches or roots for their respiration measurements; the
14
fresh weight as well as the diameter was measured. Woody segments more than 1 cm in diameter
15
were sealed with a thin layer of Vaseline at both cut ends to minimize CO2 emission due to wound
16
respiration. Dark respiration was determined in the customized chamber. These data were used to
17
fit the respiration versus diameter relations of woody organs and obtain their respective
18
coefficients required for the scaling up of the whole organ respiration.
19
Direct measurement of the total respirations of woody organs of a mature tree poses a challenge
20
due to its big size and the technical limitations. The early attempt to measure the total
21
aboveground wood respiration of a tree was reported by Möller et al. (1954), who did so by
22
sorting all shoot parts into diameter classes and multiplying the biomass in each class with the
23
average respiration rate for that class. Because mass-based respiration rates of woody organs (root,
24
stem and branch) are size dependent and decline with increasing diameter, in the follow-up
25
research work, Yoda et al. (1965) established a numerical relationship between the diameters of
26
woody organs and their respiration rates, and incorporated such relationship into the whole tree
27
respiration calculations to achieve a relatively more reliable estimate of wood respiration. The
28
method used in the three original publications (Fang 1999; Yang et al.2001; Zeng et al. 2000) to
29
scale up the sample segment respiration to the whole woody organ respiration was derived from
30
the one developed by Yoda et al.
1
Generally, estimates of total respirations of woody organs were obtained based on the
2
respiration-diameter relations and the frequency distributions of diameters (Yoda et al. 1965; see
3
also Kim et al. 2007). Details run as follows. Firstly, the respiration-diameter relations of specific
4
organs of a sample tree were established by fitting the following reciprocal or power equation to
5
the data from sample segments:
6
r ( x) 
7
where r ( x ) is the respiration rate of a woody segment of a given size, x is its diameter, and
8
A and B are coefficients specific to woody organs.
9
As predicted by the pipe model theory (Shinozaki et al., 1964), when a woody organ (stem, branch
10
or root) is sectioned into different diameter classes, the frequency, f ( x ) , of a certain diameter
11
class of a woody organ (stem, branch or root) is expressed as a power function of the
12
corresponding diameter x , i.e.
13
1
Ax  B
f ( x)  kx  a
(1)
(2)
14
where k and a are coefficients specific to woody organs. Empirical data indicate that a
15
varies between 1.5 and 2.5 for both branches and roots, but approximately equals zero for stem in
16
that it can be roughly considered as a cone in shape.
17
The weight of a certain segment of a woody organ, dw( x ) , within a range in diameter from x
18
to x  dx is given as follows:
19
dw( x)  kk x 2a dx ,
20
where k  is a coefficient related to wood density. The total weight W of a woody organ is then
21
obtained by integrating Eq. (3) over the whole range of diameters from the minimum diameter,
22
xmin , to the maximum diameter, xmax , provided that wood density remain constant across the
23
whole woody organ:
24
x
x
kk  3a
3 a
W   max dw( x)  kk  max x 2a dx 
( xmax  xmin
)
xmin
xmin
3 a
25
Eq. (4) can be further transformed as follows:
(3)
(4)
W (3  a )
3 a
3 a
xmax
 xmin
1
kk  
2
On the other hand, the total respiration R of a woody organ is obtained by the integration of the
3
whole range from xmin to xmax :
4
x
R   max r ( x)dw( x)
xmin
5
Inserting Eqs. (1) and (3) into Eq (6) gives:
6
x kk x 2 a
R   max
dx
xmin Ax  B
7
Substituting Eq. (5) into Eq. (7) gives:
8
W (3  a) xmax x 2a
R  3 a
dx
3 a x
xmax  xmin
min Ax  B
9
Eq. (8) shows that the total respiration of a specific woody organ (stem, branch or root) can be
10
estimated using its fresh weight W , maximum diameter xmax and minimum diameter xmin
11
only if coefficients a , A , B are known. All these parameters can be calculated using available
12
data.
13
2.3 Temperature adjustments
14
The three data sets were obtained at temperatures near to each other. Data from Fang (1999) were
15
measured at temperature of about 18℃, those from Zeng et al. (2000) at 25℃, and those from
16
Yang et al. (2001) at 28℃. Here we used a published temperature model (Alkin & Tjoelker 2003)
17
to adjust all respiration rates at measurement temperatures to a common temperature of 24 ℃, as
18
did by Reich et al. (2006).
(5)
(6)
(7)
(8)
19
20
References:
21
Kim, M.H., Nakane, K., Lee, J.T., Bang, H.S. & Na, Y.E. 2007 Stem/branch maintenance
22
23
respiration of Japanese red pine stand. For. Ecol. Manage., 243, 283–290.
Möller, C.M., Müller, D. & Nielsen, J. 1954 Respiration in stem and branches of beech. Det
1
Forstlige Forsoegsvaesen I Danmark 21, 273–301.
2
Shinozaki, K., Yoda, K., Hozumi, K. & Kira, T. 1964 A quantitative analysis of plant form. The
3
pipe model theory II. Further evidence of the theory and its application in forest ecology.
4
Jpn. Ecol. 14, 133–139.
5
Yoda, K., Shinazaki, K., Ogawa, H., Hozumi, K. & Kira, T. 1965 Estimation of the total amount
6
of respiration in woody organs of trees and forest communities. J. Biol. Osaka City Univ.,
7
16, 15–26.
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
1
2
S2: Tables
3
4
Table 1. The main geographical and climatic conditions of the three studies in China.
Study
Parameters
Fang (1999)
Zeng et al. (2000)
Yang et al. (2001)
Latitude
39°58' N
22°41′ N
27°23' N
Longitude
115°26' E
112°54′ E
111°53' E
Annual mean temperature (°C)
4.5
21.7
19.6
Annual mean precipitation (mm)
612
1700
1744
Table 2. Data of respiration and biomass used in the present paper.
DBH
height
log RA
log RT
log MAf*
log MA
log MTf*
log MT
citation
species
(cm)
(m)
(24 ℃)
(24 ℃)
Fang
Pinus tabulaeformis Carr.
6.1
6.5
3.912521
3.972828
4.181844
3.859659
4.274158
3.920065
Fang
Pinus tabulaeformis Carr.
14.3
8.8
4.575309
4.614302
5.087781
4.64263
5.186956
4.728983
Fang
Pinus tabulaeformis Carr.
14.2
9.8
4.663489
4.701116
5.056142
4.679757
5.156549
4.767426
Fang
Pinus tabulaeformis Carr.
10.6
7.9
4.341014
4.37883
4.690196
4.364201
4.770115
4.440873
Fang
Pinus tabulaeformis Carr.
16.6
8.2
4.528545
4.565354
5.082067
4.733048
5.187521
4.822614
Fang
Pinus tabulaeformis Carr.
12.5
7.8
4.523884
4.562756
4.867467
4.488695
4.965202
4.569649
Fang
Pinus tabulaeformis Carr.
8.6
7
4.215283
4.27103
4.549003
4.153871
4.632457
4.223527
Fang
Betula platyphylla Suk.
9.4
8.5
4.054915
4.17689
4.549003
4.212376
4.646404
4.363028
Fang
Betula platyphylla Suk.
14.2
11.2
4.438125
5.058805
4.666161
Fang
Betula platyphylla Suk.
13.9
9.8
4.404709
4.469997
4.966611
4.593379
5.097951
4.749569
Fang
Betula platyphylla Suk.
13.1
11.6
4.369302
4.415219
4.989005
4.614051
5.080626
4.770533
Fang
Betula platyphylla Suk.
8.6
8.7
3.945019
4.008719
4.487138
4.148786
4.605305
4.29849
Fang
Betula platyphylla Suk.
16.8
14.3
4.610242
4.663815
5.206826
4.906379
5.319938
5.066873
Fang
Betula platyphylla Suk.
5.8
6.1
3.496431
3.603543
3.986772
3.679736
4.120574
3.822341
Fang
Quercus liaotungensis Koidz.
23.8
11
4.987553
5.051783
5.517855
5.249017
5.654273
5.34885
Fang
Quercus liaotungensis Koidz.
14.6
9.8
4.535241
4.632987
5.109579
4.751407
5.230704
4.886851
Fang
Quercus liaotungensis Koidz.
9.9
7
4.085742
4.240096
4.549003
4.262208
4.737193
4.438511
Fang
Quercus liaotungensis Koidz.
19.8
11.1
4.747394
4.855349
5.296665
5.083448
5.471585
5.194424
Fang
Quercus liaotungensis Koidz.
12.4
8.9
4.414198
4.490236
4.895975
4.563658
5.009876
4.714132
Fang
Quercus liaotungensis Koidz.
8
7.2
3.887571
4.275354
4.298853
4.090953
4.622214
4.282814
Fang
Quercus liaotungensis Koidz.
16.4
10.3
4.713925
4.799721
5.222976
4.878138
5.325721
5.003917
Zeng et al.
Acacia mangium Willd.
24.1
12.3
5.006955
5.054182
5.441901
5.245002
5.564022
5.361987
Zeng et al.
Acacia mangium Willd.
21.9
13.3
4.805962
4.868661
5.404455
5.207756
5.524427
5.322625
Zeng et al.
Acacia mangium Willd.
18.1
12.1
4.791201
4.849818
5.247755
5.05186
5.358940
5.158096
Zeng et al.
Acacia mangium Willd.
14.2
12.5
4.508175
4.575959
5.099357
4.904177
5.202545
5.002588
Zeng et al.
Acacia mangium Willd.
12.7
14
4.414457
4.478927
5.063427
4.868414
5.164731
4.964985
Zeng et al.
Acacia mangium Willd.
12.4
12.8
4.410175
4.508705
5.018575
4.823766
5.117555
4.918071
Zeng et al.
Acacia mangium Willd.
10.8
11.1
4.182282
4.279107
4.882244
4.688031
4.974364
4.775659
Zeng et al.
Acacia mangium Willd.
6.4
6.7
4.095066
4.141215
4.381256
4.188949
4.450949
4.254893
Zeng et al.
Acacia mangium Willd.
3.7
4.4
3.45359
3.510383
3.896238
3.705415
3.948441
3.754598
Yang et al.
Pinus massoniana Lamb.
30.2
20
5.092232
5.156075
5.810367
5.454204
5.913125
5.545605
Yang et al.
Pinus massoniana Lamb.
26
19
4.96663
5.033281
5.671543
5.313403
5.775683
5.406055
Yang et al.
Pinus massoniana Lamb.
52
30
5.668912
5.714116
6.416524
6.053195
6.513404
6.139437
Yang et al.
Pinus massoniana Lamb.
45
23
5.458397
5.50944
6.200495
5.830472
6.29942
5.918601
Yang et al.
Pinus massoniana Lamb.
32
20.2
5.157934
5.218012
5.879325
5.504674
5.981366
5.59563
Yang et al.
Pinus massoniana Lamb.
18
18.3
4.688686
4.765133
5.355834
5.003136
5.463146
5.098601
*: the subscript ‘f’ refers to fresh biomass.