Table 1 Components of hypothesized relationships (Fig. 1) represented by initial structural equation model. The model represents post-fire plant community dynamics in southern California, USA, chaparral communities one year and twelve years after the 2003 Old and Simi fires
Path | Hypothesized relationship |
|---|---|
1 | (+) Fire severity increases with fuel moisture (Parks et al. 2014b). |
2 | (+) Precipitation increases the number of fires at a site by increasing site productivity and thus fuel loads (Davis and Michaelsen 1995). |
3 | (−) Wetter sites are less likely to burn with a short time interval between fires (Meng et al. 2014). |
4 | (+) Resource fluctuations, particularly increases in precipitation, lead to increases in plant diversity (Keeley et al. 2005b). |
5 | (+) Leaf area index increases with increases in antecedent precipitation conditions (McMichael et al. 2004). |
6 | (+) Rocky topography provides favorable microsites for young shrub stands (Schlesinger and Gill 1978). |
7 | (−) Persistent negative relationships between introduced species richness and rock cover were found over five years (Keeley et al. 2005d). |
8 | (+) Fire severity is high where plant cover is high (Grace and Keeley 2006). |
9 | (−) The relationship between dNBR and non-native cover is negative (Lentile et al. 2007). |
10 | (+) Burn severity increases with the length of time since the last burn (Parks et al. 2014a). |
11 | (−) Fire severity is significantly lower when fires burn within a previously recorded fire perimeter (i.e., it reburned; Parks et al. 2015). |
12 | (−) Fire frequency (<12 yr) limits shrub recruitment (Jacobsen et al. 2004). |
13 | (−) Sites that burn twice in four years have higher introduced cover then sites that burn once in four years (Keeley and Brennan 2012). |
14 | (+) Shorter fire intervals increase gap size and decrease shrub cover, negatively effecting shrub cover (Jacobsen et al. 2004). |
15 | (−) Introduced cover increases with younger pre-fire stand age (Keeley et al. 2005d). |
16 | (−) A direct negative relationship exists between woody plant canopy and introduced species dominance (Keeley et al. 2005d). |