Postfire Vegetation Recovery in Highland Pine Forests of the Dominican Republic

Abstract

We surveyed postfire vegetation at five sites at high elevations (> 2000 m) in the Cordillera Central, Dominican Republic. Highlands of the Cordillera Central are dominated by a single pine species, Pinus occidentalis, but plant communities are rich with endemics and conservation and fire management efforts in these systems are ongoing. The burns were 2–7 yr in age and had consumed nearly all shrub crowns. Pines suffered high mortality (> 50%, all sites combined), but shrubs resprouted at high rates (88%, N= 957) after fire. All shrub taxa produced basal resprouts; eight of 11 shrub taxa measured had resprouting rates > 90 percent, while Baccharis myrsinites had the lowest (56%). Most taxa grew to prefire height quickly (within 5–7 yr), with regrowth of stem diameters lagging behind. Patterns and rates of shrub recovery resembled those documented in high elevation shrublands in Costa Rica and Brazil. Pinus occidentalis does not resprout, but larger individuals can survive fire. Survival increases dramatically when trees attain > 13‐cm dbh, when bark becomes thick enough to protect cambial tissue. Overall, pines are regenerating much more slowly than shrubs, but seedling establishment varied considerably between sites. Frequent fires may cause a decline in pines and an increase in shrub‐ or grass‐dominated communities. Succession in these high elevation fire‐dependent pine forests favors taxa already present in the preburn vegetation, with woody composition changing little after fire, in contrast to lower‐elevation cloud forest, where postfire vegetation has been shown to bear little resemblance to mature forest even after several years.

Forest change within and outside protected areas in the Dominican Republic, 2000-2016

“…Efforts to conserve Earth's remaining forests, and to understand the consequences of 39 their disappearance, demand estimates of where, and at what rate, forest loss is occurring 40 [9,10]. Reliable national-level data on forests is urgently needed to inform policies on forest 41 conservation, sustainable development, and climate-change mitigation. A significant contribution 42 to these efforts was made by Hansen et al [9], who provided satellite-based estimates of global 43 forest cover at a relatively fine temporal and spatial scale.…”

“…and their associated understory plants are not only resilient to fire, but depend on it for seed 339 dispersal and germination [41] and thus, absent any additional disturbance, burned pinelands 340 will likely recover [42]. Of concern, however, is evidence of emerging changes in fire regime that 341 may pose a long-term threat to these forests.…”

Size Dependency of Post-Disturbance Recovery of Multi-Stemmed Resprouting Trees

“…Resprout height and diameter are positively correlated with pre-fire stem height and diameter [16], [19], [20], with the relationship between pre- and post-fire size fitting a curvilinear scaling function [18]. This “resprout curve” illustrates the balance between biomass loss and recovery and determines the equilibrium size (i.e., where pre-fire and post-fire size are equal) upon which plants will converge over multiple fire cycles ([18]; Figure 1A).…”

Size-dependent enhancement of water relations during post-fire resprouting

“…Post-fire enhancements in hydraulic efficiency caused by reduction in size (i.e., leaf area and height) of the aboveground stem are particularly noteworthy because their effects should vary predictably across growth forms. Although resprout height is positively correlated with pre-fire stem height (Kennedy andHorn 2008, Dacy andFulbright 2009), small plants tend to recover their pre-burn size more quickly than large plants Solbrig 2003, Grady andHoffmann 2012). Small-statured species should therefore experience less of an increase in K L.p after fire.…”