Tree mortality and regeneration of Euphrates poplar riparian forests along the Tarim River, Northwest China

Forest Ecosystems

Table 2 Analysis of population structure dynamics of gap makers under different volumes of runoff water

Years	Runoff (10⁸ m⁻³)	V₁	V₂	V₃	V₄	V_pi	P	V_pi′	P′	V_pi′′
1957–1966	33.34	−0.92	0.75	0.69	−0.67	− 0.073	0.0095	− 0.0040	0.2670	−0.0180
1967–1976	31.05	−0.77	0.55	0.25	0.00	−0.060	0.0040	−0.0019	0.1430	−0.0300
1977–1986	27.85	−0.84	0.78	0.71	−0.60	0.000	0.0080	0.0025	0.5000	0.0600
1987–1996	21.83	0.87	0.80	0.33	−0.33	0.040	0.0039	0.0071	0.6350	0.0970
1997–2006	22.84	0.00	0.40	1.00	−1.00	0.200	0.0133	0.0057	0.5600	0.0400
2007–2016	8.10	−0.57	0.57	0.13	0.33	0.460	0.0154	0.0084	0.6599	0.0554

V₁ I–II dynamic index value of I–II class sizes, V₂ II–III dynamic index value of II–III class sizes, V₃ III–IV dynamic index value of III–IV class sizes, V₄ IV–V dynamic index value of IV–V class sizes, V_pi dynamic index value under no external disturbance, V_pi′ dynamic index value under completely random disturbance, V_pi″ dynamic index value of non-random disturbance, P maximum risk value under completely random disturbance, P′ maximum risk value under non-random disturbance