Extreme drought triggers parallel shifts in wood anatomical and physiological traits in upper treeline of the Mediterranean Andes

Ecological Processes

Table 1 Descriptive statistics for ring width chronologies and wood vessel traits across three populations of K. angustifolia (ring width and vessels features) in the Mediterranean Andes of central Chile

Variables	Sites
Variables	North	Central	South
Tree size
DBH ± SD (cm)	13.98 ± 4.56	16.97 ± 5.45	14.11 ± 3.80
Height ± SD (m)	3.75 ± 0.85	4.00 ± 0.55	3.77 ± 0.98
Ring width chronology
Total trees sampled	15	30	32
Total trees in chronology (radii)	15 (24)	26 (43)	26 (49)
Mean ring width ± SD (mm)	1.61 ± 1.01	2.06 ± 1.06	1.40 ± 0.76
Chronology span	1948–2020	1979–2020	1948–2020
Mean age (max–min)	50 (29–73)	28 (24–37)	56 (18–74)
Mean sensitivity	0.564	0.391	0.408
Series intercorrelation	0.568	0.530	0.556
RBar	0.340	0.280	0.305
Expressed population signal	0.941	0.880	0.942
Vessel traits
Total trees studied	15	15	15
Mean vessel area ± SD (µm²)	2650 ± 789a	3144 ± 1007b	3038 ± 978b
Mean vessel frequency ± SD (ind mm^–²)	22.212 ± 6.750a	22.996 ± 7.650a	25.358 ± 8.468b
Mean hydraulic diameter (µm)	61.062 ± 9.264a	67.305 ± 11.270b	66.063 ± 11.274b
Mean K_p (kg m MPa^–1 s^–1)	2.814 ± 2.399a	3.817 ± 2.506b	5.738 ± 3.503c
Total vessel measured	18,755	19,644	18,238
Vulnerability index	1.4E⁻⁵ ± 1.0E⁻⁶a	9.3E⁻⁶ ± 1.2E⁻⁶b	0.9E⁻⁵ ± 2.0E⁻⁶b
Chronology span	2000–2020	2000–2020	2000–2020
Mean ring width ± SD (mm)	1.96 ± 1.04b	1.92 ± 1.00b	1.29 ± 0.80a

*Different letters indicate statistically significant differences between study sites, based on Kruskal–Wallis tests (p < 0.05)