Below-ground hydraulic constraints during drought-induced decline in Scots pine

Table 1 Summary of the linear mixed-effects models with predawn (ψ_PD), midday (ψ_MD) leaf water potentials and their difference (Δψ) as response variables

Parameter	ψ _PD	ψ _MD	Δψ
Parameter	R²(m) = 0.82	R²(m) = 0.50	R²(m) = 0.87
Intercept	− 1.33 ± 0.05***	− 2.14 ± 0.06***	− 0.95 ± 0.08***
Non-defoliated	ni	0.30 ± 0.09*	0.55 ± 0.12**
Summer	− 0.48 ± 0.07***	ni	0.81 ± 0.11***
Non-defoliated: summer	ni	ni	− 0.63 ± 0.17*

The coefficients indicate the difference between each level of a given variable and the corresponding reference level (‘defoliated’ for defoliation class and ‘spring’ for season). The values are the coefficient estimates ± 1 SE. Only marginal R², R²(m), is reported as the variance associated to the ‘tree’ random effect was estimated as near zero
ni not included in the model
*0.01 < P < 0.05; **0.001 < P < 0.01; ***P < 0.001

ISSN: 1297-966X