A large database supports the use of simple models of post-fire tree mortality for thick-barked conifers, with less support for other species

Cansler, C. Alina; Hood, Sharon M.; van Mantgem, Phillip J.; Varner, J. Morgan

doi:10.1186/s42408-020-00082-0

Fire Ecology

Table 1 Classification table of model predictions and model performance statistics calculated based on predicted and true conditions, from this study of post-fire tree mortality models from the USA, from fires occurring from 1981 to 2016. Managers may wish to use models or classification thresholds that perform optimally for different scenarios

From: A large database supports the use of simple models of post-fire tree mortality for thick-barked conifers, with less support for other species

		True condition		Model performance statistics
		Positive (P) = Dead	Negative (N) = Live	Model performance statistics
Predicted condition	Positive (P) = Dead	True Positive (TP) Dead trees that were predicted to be dead	False Positive (FP) Live trees that were predicted to be dead	*Positive predictive value (PPV**) \( \boldsymbol{PPV}=\frac{\boldsymbol{TP}}{\boldsymbol{TP}+\boldsymbol{FP}} \) Dead trees that were predicted to be dead divided by predicted dead trees Example use: Prescribed fire planning where there is a need to kill small shade-tolerant trees to reduce future fire risk.*
Predicted condition	Negative (N) = Live	False Negative (FN) Dead trees that were predicted to be live	True Negative (TN) Live trees that were predicted to be live	*Negative predictive value (NPV**) \( \boldsymbol{NPV}=\frac{\boldsymbol{TN}}{\boldsymbol{TN}+\boldsymbol{FN}} \) Live trees that were predicted to be live divided by predicted live trees Example use: Prescribed fire planning where there is a need to avoid killing large or old trees.*
Model performance statistics		*Sensitivity (Sens**) \( \boldsymbol{Sens}=\frac{\boldsymbol{TP}}{\boldsymbol{TP}+\boldsymbol{FN}} \) Dead trees that were predicted to be dead divided by total dead trees Example use: Post-fire salvage in campground, where there is a need to remove any trees that may die and become a hazard.*	*Specificity (Spec**) \( \boldsymbol{Spec}=\frac{\boldsymbol{TN}}{\boldsymbol{TN}+\boldsymbol{FP}} \) Live trees that were predicted to be live divided by total live trees Example use: Post-fire salvage where there is a need to avoid harvesting large trees that may survive (e.g., potential seed trees or large wildlife trees.)*	*Accuracy (ACC**) \( \boldsymbol{ACC}=\frac{\boldsymbol{TP}+\boldsymbol{TN}}{\boldsymbol{TP}+\boldsymbol{TN}+\boldsymbol{FP}+\boldsymbol{TN}} \) Correctly classified live and dead trees divided by total trees Example use: Need to optimize multiple objectives.*

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