Tree regeneration characteristics in limestone forests of the Cat Ba National Park, Vietnam

Table 3 Linear mixed effect model results of tree regeneration density and the first three principal components

Variables	Value	Standard Error	df	t-value	p-value
Intercept	3220.53	363.098	80	8.870	< 0.001
PC1	− 88.09	54.555	80	− 1.615	0.110
PC2	− 127.70	71.060	80	− 1.797	0.076
PC3	− 75.87	81.576	80	− 0.930	0.355
PC1:PC2	10.77	32.874	80	0.328	0.744
PC1:PC3	− 79.89	41.627	80	− 1.919	0.058
PC2:PC3	7.55	42.768	80	0.177	0.860
PC1:PC2:PC3	− 0.90	21.475	80	− 0.042	0.966

PC1 = light availability gradient, PC2 = soil fertility, rock surface, soil moisture, and pH gradient; PC3 = soil texture gradient. Given are the estimates (Value) and the respective standard error, the degrees of freedom (df), the t-value of each variable, and its significance (p-value). Significance was assumed with p < 0.05

ISSN: 2730-7182