Got shrubs? Precipitation mediates long-term shrub and introduced grass dynamics in chaparral communities after fire

Fire Ecology

Table 3 Results from structural equation model of mediating variables affecting chaparral ecosystem recovery one and twelve years after the southern California, USA, Old and Simi fires of 2003. Direct relationships with P < 0.05 in bold and italics; P < 0.10 in italics; dNBR = differenced Normalized Burn Ratio

Independent variable	Mediating variable	Dependent variable	Model estimate	Standard error	Z-value	P-value
*Mean annual precipitation*	*dNBR 2003*	*Introduced cover 2004*	*−0.35*	*0.13*	*−2.65*	*0.01*
Mean annual precipitation	Time between fires 2015	Shrub cover 2015	0.15	0.08	1.84	0.07
*Mean annual precipitation*	*Number of reburns 2004*	*Shrub cover 2004*	*−0.10*	*0.04*	*−2.71*	*0.01*
*Mean annual precipitation*	*Number of reburns 2015*	*Shrub cover 2015*	*−0.17*	*0.09*	*−1.91*	*0.05*
*dNBR 2003*	*dNBR 2008*	*Introduced cover 2015*	*−0.05*	*0.01*	*−3.65*	*<0.001*
Time between fires 2015	Shrub cover 2015	Introduced cover 2015	−0.13	0.08	−1.72	0.09
Number of reburns 2004	Shrub cover 2004	Introduced cover 2004	−0.76	0.46	−1.63	0.10
Number of reburns 2015	Shrub cover 2015	Introduced cover 2015	−2.88	1.58	−1.82	0.07