Table 2 Results of the logistic regressions predicting probability of a cactus to burn, canopy type and growth strategy as explanatory variables. The analysis was conducted with and without Leptocereus quadricostatus and Harrisia portoricensis data. Data were collected in 2014-2015 at El Faro, Puerto Rico. Odds ratio is the probability of being killed by the fire versus surviving the fire (e.g., burned cacti were more than 62 times as likely to die as unburned cacti); Z-value is the regression coefficient divided by its standard error; P-value represents the probability of a Type I error
Parameter | Odds ratio (±SE) | Z-value | P-value |
|---|---|---|---|
Intercept | 0.983 (1.20) | −0.092 | 0.927 |
Open Canopy (Grasses and shrubs) | 4.807 (1.46) | 4.141 | <0.001 |
Globular Cactus | 2.542 (2.39) | 1.089 | 0.276 |
Open Canopy x Globular Cactus | 0.577 (2.61) | −0.574 | 0.566 |
Without Leptocereus quadricostatus and Harrisia portoricencis | |||
Intercept | 0.967 (1.21) | −0.186 | 0.853 |
Open Canopy (Grasses and shrubs) | 4.792 (1.54) | 3.626 | <0.001 |
Globular Cactus | 2.588 (2.36) | 1.109 | 0.267 |
Open Canopy x Globular Cactus | 0.579 (2.66) | −0.556 | 0.578 |