Resilience of a tropical montane pine forest to fire and severe droughts

Abstract

1. Higher temperatures, declining precipitation, changing cloud cover and increased wildfires threaten tropical montane pine forests by overriding the environmental heterogeneity that typically buffers these systems from catastrophic fires. Severe fires threaten to overwhelm forest resilience and tip this biome into alternate vegetation states.2. This study focused on long-term dynamics of montane Pinus occidentalis forests in the Cordillera Central, Dominican Republic after a ~1000 km 2 fire in 2005, the largest since 1965. We used long-term records to investigate climate before and after the fire, and 19-year dataset of pre-and post-fire vegetation change from a network of 55 permanent plots (20 small 0.05 ha plots and 35 large 0.1 ha plots) established in 1999 to model overstorey and understorey vegetation dynamics.3. The 2005 fire was synchronized with the most extreme drought in the region in over 60 years. The fire burned from <1600 to >3000 m a.s.l. in elevation across windward and leeward slopes, creating a mosaic of low-, moderate-and highseverity patches. Lower elevations, leeward slopes and stands with a higher proportion of smaller pine trees all burned at higher severities. 4. Growth rates of trees that survived the fire remained lower than pre-fire rates 13 years after the fire. The highest post-fire mortality rates were soon after the fire and in the census immediately following subsequent post-fire droughts. Postfire pine seedling abundance was significantly greater in stands with higher basal area of live canopy trees and significantly reduced by increased shrub abundance in the understorey. Understorey composition recovered rapidly to pre-fire states in sites affected by low-and moderate-severity fires, but sites affected by highseverity fires remained dissimilar to pre-fire composition 13 years after the fire.Even though high-severity patches had persistently low pine regeneration, 100% of small plots and 96% of large plots had at least one pine sapling or canopy tree recruit by 2018. Shrub taxa survived the fire in higher numbers and recovered to pre-fire densities much faster than the pine, especially in high-severity burns. Synthesis.Climate change has increased the likelihood of wildfires in tropical montane pine forests, with long-lasting effects on vegetation dynamics. However, this biome may prove resilient to increasingly severe fires in the near future, given the ongoing recovery of Pinus occidentalis forests in Hispaniola despite

Assessment of Biological and Environmental Factors Influence on Fire Hazard in Pine Forests: A Case Study in Central Forest-Steppe of the East European Plain

“…In the context of abiotic [70][71][72][73][74] and phytocenotic conditions [75][76][77][78], it is just expedient to consider the ecological state, landscape functions of pine forests and the possibility of protecting them from fires. Maksimova, Abakumov [79] found the average fire interval is more than 2 times shorter in lichen and grass pine forests on sandy and sandy loamy soils than in grass and green moss pine forests in the Central Forest-Steppe.…”

Integrating plant physiology into simulation of fire behavior and effects

“…4b , Sánchez‐Costa et al ., 2015 ; Martínez‐Vilalta et al ., 2016 ). Topographic variation (microclimates, water availability, and soil resources available for growth) can also modify physiology, and fuel availability and loading, and has been shown to govern fire behavior and effects (Knapp et al ., 1993 ; Krawchuk et al ., 2016 ; Swann et al ., 2022 ). Different functional strategies in relation to seasonal water deficit and disturbance, such as those defined by leaf lifespan (deciduous vs evergreen) and minimum water potential (Ackerly, 2004 ), will determine how these water and carbon dynamics manifest across species.…”