Present and forecasted xeric climatic limits of beech and sessile oak distribution at low altitudes in Central Europe

Table 2 Parameters of each of the ten bootstrapped decision tree models on the xeric limits of beech and sessile oak-dominated zonal forest stands calculated without (“basic”) or with (“extended”) aridity indices (see details in text)

a) Beech (Fagus sylvatica)					Basic
	Tree depth	Tree width	κ	ROC/AUC	Root split
1	3	5	0.35	0.77	P₀₅ (76.8 mm)
2	6	8	0.39	0.83	T₀₅ (13.4°C)
3	5	7	0.38	0.82	T₀₅ (13.7°C)
4	5	8	0.40	0.82	T₀₅ (13.7°C)
5 ^a	4	7	0.34	0.79	T₀₅ (14.0°C)
6	4	7	0.35	0.80	T₀₅ (14.1°C)
7	5	9	0.43	0.82	T₀₅ (13.7°C)
8	4	7	0.36	0.81	T₀₅ (13.6°C)
9	6	9	0.45	0.84	T₀₅ (13.7°C)
10	5	8	0.38	0.82	T₀₅ (13.6°C)
b) Beech (Fagus sylvatica)					Extended
1	3	6	0.41	0.81	EQ (26.2)
2 ^a	3	5	0.40	0.83	EQ (26.1)
3	5	6	0.41	0.81	EQ (26.4)
4	4	6	0.47	0.83	EQ (25.8)
5	4	7	0.36	0.80	T₀₅ (14°C)
6	5	6	0.41	0.80	EQ (26.2)
7	4	7	0.41	0.80	T₀₅ (13.7°C)
8	2	4	0.47	0.84	EQ (26.0)
9	4	6	0.45	0.83	T₀₅ (13.7°C)
10	3	5	0.43	0.83	EQ (26.9)
c) Sessile oak (Quercus petraea)					Basic and extended
1	5	8/7	0.37	0.76	P₀₅ (60.2 mm)
2	4	7	0.39	0.76	P₀₅ (60.8 mm)
3	6	10	0.35	0.74	P₀₅ (58.8 mm)
4 ^a	4	6	0.37	0.75	P₀₅ (58.8 mm)
5	4	8	0.40	0.76	P₀₅ (58.9 mm)
6	4	9/8	0.35	0.71	T₀₈ (19.4°C)
7	4	9	0.31	0.74	P₀₅ (65.6 mm)
8	3	7	0.33	0.73	T₀₈ (19.2°C)
9	4	7	0.32	0.72	P₀₅ (61.6 mm)
10	3	7/6	0.33	0.73	T₀₈ (19.5°C)

Tree depth the maximum number of nested levels (partitions); tree width the number of terminal nodes (“leaves”); κ maximum of Cohen’s kappa; ROC/AUC area under the receiver operating characteristics curve of the model projections on the evaluation data set; root split the splitting variable and the corresponding split value selected for the first partition
^aThe marked models are shown in detail in Fig. 1

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