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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

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

PathHypothesized 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).