Relationship between fuel and solar radiation in a Pinus hartwegii Lindl. forest and a grassland at the Iztaccihuatl-Popocatepetl Park

Abstract

Introduction. Fuel studies provide information on fire danger, fire behavior, greenhouse gas emissions, and fuel management. Objective. To establish relationships between fuel variables, leaf area index, and solar radiation to estimate fuel loads in a Pinus hartwegii Lindl. forest and subalpine grassland at the Iztaccíhuatl-Popocatépetl National Park. Materials and methods. Fuels (load, cover, height, or depth), forest stand (tree measurement variables), and solar radiation (diffuse, direct, total area and clearing) were sampled. Relationships between variables were determined using linear regression using the coefficient of determination, significance, normality, homoscedasticity, multicollinearity, and autocorrelation. Results and discussion. In the forest, the average load was 27.9 Mg∙ha-1, with nearly 60 % of leaflitter and fermentation layer. There are direct relationships between grass cover and clearing; woody material load and leaf area index; and total fuel load with leaflitter depth and fermentation layer. Conditions with higher radiation promote greater grass load, while low radiation facilitates the accumulation of woody materials, leaflitter, and the fermentation layer. In the grassland, the load reached 6.8 Mg∙ha-1, and there was a direct relationship between total fuel load and cover. Conclusions. In the P. hartwegii forest and grassland, statistical models were found that relate forest fuel loads with radiation variables or with variables specific to the fuels, which expedites estimates and supports decisions for fuel management.