Monitoring post-fire regeneration of Pinus brutia in North Lebanon

Abstract

Forest fires represent a major threat to Lebanons forests which include Pinus brutia forests, among others. Pinus brutia forests occupy a relatively large area in Lebanon and they are constantly impacted by fire events. The understanding of the post-fire response of Pinus brutia is crucial and falls under Lebanons National Strategy for forest fire management, which emphasized on adapting the best management strategies at the highest level of social, economic and environmental sustainability. The monitoring of post-fire regeneration of Pinus brutia should support national efforts in restoring healthy ecological conditions of burnt forest lands by providing useful and insightful information about the status of natural regeneration after fire and help to avoid expensive reforestation campaigns. This study aimed at monitoring the natural regeneration of burnt Pinus brutia forests throughout the past 20 years in North Lebanon. In this context, the specific objectives of this study were to 1) map the extent of large burnt areas in Lebanon from 2000 to 2012, as well as 1992, using satellite remote sensing data and delineate Pinus brutia fire affected areas, 2) assess fire severity of recently burnt areas using the Composite Burn Index (CBI), 3) evaluate Pinus brutia regeneration dynamics and vegetation recovery of untreated burnt forests, and 4) investigate the relationship between regeneration rate and various biophysical factors. The Geographic Object Based Image Analysis (GEOBIA) was applied to Landsat images. A shapefile containing information on the classified fires was extracted and data on the extent of burnt Pinus brutia forests were withdrawn. Field assessments were conducted and forest fire affected areas of Pinus brutia were sampled on 18 different plots across North Lebanon in the year 2013. The selected plots represented areas that were affected by only one fire event in 1993, 2004, 2006, 2007, 2008, 2009 and 2012, consecutively. Using the belt transect sampling method, 30 samples of 1x1m² were taken along the plotted area on three various positions within each plot (top, middle, bottom). A total of 540 samples of 1x1m² were collected. The number of seedlings was recorded for each sample and the regeneration density for each plot was calculated. The vegetative recovery was assessed visually and an overall cover percentage for regenerated shrubs on burnt sites was obtained. The severity test was conducted on the selected regeneration plots using the Composite Burn Index (CBI) field protocol. The CBI of the assessed sites was calculated using the protocols guidance. A set of descriptive, correlation regression analysis in addition to ANOVA tests were conducted to investigate the relationship between regeneration rate and various bio-physical factors. The obtained results highlighted the need to implement efficient post-fire management measures within the first four years after a fire event to decrease the mortality rate of young seedlings. Furthermore, the need to further understand post fire recovery dynamics and burn severity as important factors in burnt forests restoration was revealed by the study.