Silva Fennica

Fig. 1. Daily sum of precipitation (bars) over two growing seasons and mean soil temperature (open circles) with standard deviation on dates of soil CO₂ efflux measurements.

Fig. 2. Mean soil water content (±SD) in the studied plots: M-mature stand, C_U-unthinned coppice stand, C_T-thinned coppice stand, C_UR-coppice stand with reduced throughfall, and C_TR-thinned coppice stand with reduced throughfall.

Fig. 3. Mean gap fraction and leaf area index above soil CO₂ efflux measurement positions in the individual plots: M-mature stand, C_U-coppice stand, C_T-thinned coppice stand, C_UR-coppice stand with reduced throughfall, and C_TR-thinned coppice stand with reduced throughfall. For calculation of mean LAI in C_UR and C_TR positions shaded by the drainage channels were excluded, while for calculation of mean gap fraction all positions were included.

Table 1. Q₁₀ values and the parameters the coefficient of determination (R²) of the sigmoid fit of the relationships between soil CO₂ efflux normalised for temperature of 10 °C (R₁₀) and soil water content (SWC) from Fig. 5 [R₁₀ = a/(1+exp(–(SWC–x₀)/b))] for individual plots: M-mature stand, C_U-coppice stand, C_T-thinned coppice stand, C_UR-coppice stand with reduced throughfall, and C_TR-thinned coppice stand with reduced throughfall.
	M	CU	CT	CUR	CTR
Q₁₀	1.85	2.27	2.29	2.56	2.43
a	2.53	2.39	2.42	1.99	1.98
b	1.68	1.64	2.38	2.68	4.17
x₀	7.18	6.85	6.39	6.81	5.74
R²	0.68	0.79	0.84	0.91	0.82

Fig. 4. Mean soil CO₂ efflux normalised for temperature of 10 °C (R₁₀; ±SD) in the studied plots: M-mature stand, C_U-coppice stand, C_T-thinned coppice stand, C_UR-coppice stand with reduced throughfall, and C_TR-thinned coppice stand with reduced throughfall.

Fig. 5. Relationship between soil water content and R₁₀ in individual plots: M-mature stand, C_U-coppice stand, C_T-thinned coppice stand, C_UR-coppice stand with reduced throughfall, and C_TR-thinned coppice stand with reduced throughfall.

Fig. 6. Percentage differences in soil water content (SWC) between selected plots: M-mature stand, CU-coppice stand, CT-thinned coppice stand, CUR-coppice stand with reduced throughfall, and CTR-thinned coppice stand with reduced throughfall.

Fig. 7. Percentage differences in R₁₀ (soil CO₂ efflux normalised for temperature of 10 °C) between selected plots: M-mature stand, C_U-coppice stand, C_T-thinned coppice stand, C_UR-coppice stand with reduced throughfall, and C_TR-thinned coppice stand with reduced throughfall.

Table 2. Results of statistical analyses (p-values of t-tests) comparing soil water content (SWC) and R₁₀ between plots on individual dates: M-mature stand, C_U-coppice stand, C_T-thinned coppice stand, C_UR-coppice stand with reduced throughfall, and C_TR-thinned coppice stand with reduced throughfall. Asterisks indicate significant difference in the level α = 0.05.
		2015					2016
		14 Jul	4 Aug	8 Sep	30 Sep	23 Oct	14 Apr	7 Jun	29 Jun	5 Aug	25 Aug	21 Sep
SWC	M × C_U	0.056	0.247	0.276	0.216	0.353	0.095	0.050	0.004*	0.039*	0.028*	0.586
	C_U × C_T	0.282	0.444	0.104	0.005*	0.583	0.102	0.009*	0.203	0.388	0.369	0.363
	C_U × C_UR	0.243	0.273	0.610	0.883	0.578	0.778	0.024*	0.650	0.139	0.138	0.861
	C_T × C_TR	0.096	0.048*	0.096	0.184	0.265	0.447	0.920	0.167	0.041*	0.061	0.497
R10	M × C_U	0.161	0.017*	0.595	0.953	0.273	0.065	0.462	0.009*	0.223	0.879	0.547
	C_U × C_T	0.429	0.650	0.833	0.120	0.575	0.102	0.787	0.258	0.982	0.598	0.743
	C_U × C_UR	0.012*	0.002*	0.026*	0.776	0.325	0.134	0.068	0.010*	0.933	0.152	0.106
	C_T × C_TR	0.040*	0.046*	0.095	0.197	0.139	0.125	0.164	0.016*	0.626	0.099	0.357

Fig. 8. Linear regressions describing the relationship of soil water content (SWC) and soil CO₂ efflux normalised for temperature of 10 °C (R₁₀) between selected pairs of the plots: M-mature stand, C_U-coppice stand, C_T-thinned coppice stand, C_UR-coppice stand with reduced throughfall, and C_TR-thinned coppice stand with reduced throughfall.

Table 3. Statistics of the linear regressions from Fig. 8 describing the relationship of soil water content (SWC, %) and R₁₀ (μmolCO₂ m^–2 s^–1) between selected pairs of the plots: M-mature stand, C_U-coppice stand, C_T-thinned coppice stand, C_UR-coppice stand with reduced throughfall, and C_TR-thinned coppice stand with reduced throughfall. y₀ and a are the parameters of the linear regression (y = y₀ + a*x); F and p are the parameters of the F-test of the regressions, statistically significant regression corresponds to p < 0.05.
		y₀	a	R2	F	p
SWC	M × C_U	3.09	0.86	0.9	87.4	<0.0001
	C_U × C_T	0.68	1.02	0.95	188	<0.0001
	C_U × C_UR	–0.41	0.92	0.9648	246.4	<0.0001
	C_T × C_TR	–0.63	0.85	0.9519	178.1	<0.0001
R10	M × C_U	0.95	0.55	0.63	15.6	0.0034
	C_U × C_T	0.69	0.71	0.79	34.1	0.0002
	C_U × C_UR	0.41	0.59	0.50	9.0	0.0150
	C_T × C_TR	0.41	0.59	0.50	9.0	0.0148