AB
Fig.3 Contribution of CO2 flux at deep
layers(80-200cm)to the total CO2 flux of
soil-atmosphere interface in different use-land types (crop land, CH10a,
CH20a,CH30a,CH40a). Violin plot represents proportion of
CO2 flux at deep profile (80-200cm) to the total flux at
soil-atmosphere interface in growing seasons and non-growing seasons
(A ) . Box plot represents proportion of CO2flux at deep profile (80-200cm) to the total flux at soil-atmosphere
interface in whole season (B ). Columnar plot represents the
accumulated variance contribution of soil CO2 flux at
deep profile (80-200cm) to the total flux at soil-atmosphere interface
in whole season of different land- use type (B ).
Fig.4 The content of soil organic carbon(g
kg-1) at different soil profiles
depth(0-5cm,5-20cm,20-80cm,80-140cm,140-200cm) in crop land andRobinia pseudoacacia of four kinds of stand age(CH10a, CH20a,
CH30a, CH40a). Values are means of three replicates (n=3) and error
bars are standard errors of means. The letters in a column represent a
significant difference(p<0.01) between means (n=3) of different soil
profiles depth within a land-use type.
Fig.5 Regression parameters and statistics equations for index
model between soil CO2 flux (F) and soil temperature (T)
in different profiles.The parameters (mean) are defined in Eqs.
(F=a×ebT). Q10, the proportional
increase in soil CO2 flux with a 10℃ increase in
temperature,Q10=e10b, where, b is
parameter in Eqs. (F=a×ebT); R2,
coefficient of determination; P-value, parameter testing regression
significant.** Significant at the 0.01 probability level.
Fig.6 Regression parameters and statistics equations for
quadratic Objective function model between soil CO2 flux
(F) and soil moisture (M) in different profiles.The parameters (mean)
are defined in Eqs. ((F=aM2+bM+c)).
R2, coefficient of determination; P-value, parameter
testing regression significant. * Significant at the 0.05 probability
level,** Significant at the 0.01 probability level.
Fig.7 Correlation analysis between soil CO2flux, temperature, moisture, and soil organic carbon in
Shallow
layer (5-20cm) (Heat map: A ). Correlation analysis between soil
CO2 flux, temperature, moisture, and soil organic carbon
in
layer(80-200cm)
(Heat map: B ). P-value, parameter testing correlation
significant.
* Significant at the 0.05 probability level.
** Significant at the 0.01 probability level.
Fig.8 The CO2 flux at different soil
temperature, moisture, and organic carbon . 3D-scatter diagram(a) presents the CO2 flux in shallow layers
(5-20cm). 3D-scatter diagram (b) presents the
CO2 flux in deep layers(80-200cm).
Fig.9 Observed and modeled CO2 flux in
different ecosystems with the T&M&C-model. (a) , (b) ,(c) , (d) , (e) and (f) represent
temperate forests,subtropical forests,neotropical rain
forests,mediterranean arable land,fir plantation,coniferous and
broad-leaved forests, respectively; statistics are shown inAppendix A .
Fig.10 observed and modeled CO2 flux in
different ecosystems with the T&M-model. (a) , (b) ,(c) , (d) , (e) and (f) represent
temperate forests,subtropical forests,neotropical rain
forests,mediterranean arable land,fir plantation,coniferous and
broad-leaved forests, respectively; statistics are shown inAppendix A .
Fig.11 Contribution rates of T&M&C model to the
CO2 flux estimation improvement compared with T&M
model.
Table 1 Description
of sample plot used in the study.