Short‐ and long‐term effects of fire in subtropical cloud forests on an oceanic island

Abstract

The recurrence of fires has increased considerably due to human activity, affecting even forests where traditionally fire is uncommon. In this study, we verify the effects of degradation caused by fire in the Canarian laurel forests, which is a subtropical forest formation restricted to the humid montane areas of these Macaronesian islands. We evaluated the effect of fire by comparing a series of burned plots corresponding to fires from 1960, 1984, 1995, to 2012 with geographically proximate and comparable unburned plots in the Garajonay National Park (La Gomera Island, Spain). We focused on three aspects that are immediately altered by fire: forest structure, floristic composition, and microclimate. These aspects have been quantified using (a) tree density, the Pielou index using tree height classes, and DBH for the vertical structure of the forest; (b) DCA, the Bray Curtis dissimilarity index, and a species indicator analysis for the floristic composition; and (c) temperature and relative humidity for microclimate under three canopy cover conditions. Our results reveal that, overall, structural complexity and its composition in the burned areas have barely reached 40% and 35%, respectively, when compared with unburned areas, and recovery mainly depends on time since fire. Additionally, burned plots presented more pioneer species, a higher density of trees, and climatic variables tend to have a wider range throughout the day. These data reveal the long time span that this ecosystem needs for recovery to a prefire state and how it may be more prone to subsequent fire events.

Wildfire impacts on forest microclimate vary with biophysical context

“…Further, reduced evapotranspiration decreases latent heat flux and increases sensible heating in recently burned forests (Liu 2005, Chambers 2005, Liu et al 2019). While we cannot directly infer the mechanisms through which wildfires alter microclimates because we did not fully characterize the surface energy budget, our results are consistent with studies documenting increased air temperature or VPD after fires (Ripley and Archibold 1999, Ma et al 2010, Bello‐Rodríguez et al 2019), and studies that examined the influence of canopy cover on microclimate independent of fire (e.g., Davis et al 2019 b ).…”

“…Further, albedo tends to increase with total vegetation cover after fire (Tsuyuzaki et al 2009), suggesting that greater reflectance in sites with more understory vegetation regulated temperature extremes. These results imply that microclimate extremes will attenuate over time as vegetation reestablishes, although the microclimatic buffering capacity of structurally complex stands may take decades to develop (Frey et al 2016, Kovács et al 2017, Bello‐Rodríguez et al 2019).…”

“…temperature extremes. These results imply that microclimate extremes will attenuate over time as vegetation reestablishes, although the microclimatic buffering capacity of structurally complex stands may take decades to develop (Frey et al 2016, Kovács et al 2017, Bello-Rodríguez et al 2019.…”

Climate controls plant life‐form patterns on a high‐elevation oceanic island

“…subtropics or tropics) seems obvious. However, other seasonally occurring unfavourable conditions such as drought or heat can likewise restrict plant growth (Bello‐Rodríguez et al., 2019). Taxonomy independent classifications for plant strategies in ecosystems are particularly useful for large‐scale comparisons and for answering evolutionary questions related to species functioning (like convergent evolution; Chave et al., 2009; Diaz et al, 2016; Lavorel & Garnier, 2002; Reich, 2014; Wright et al., 2004).…”

Analyzing the Joint Effect of Forest Management and Wildfires on Living Biomass and Carbon Stocks in Spanish Forests

“…The frequency of wildfires in the Canary Islands has risen since the arrival of the human population to the islands [55] and the number of anthropogenic related fires quadrupled between 1970 and 2010 [56]. Burned subtropical cloud forests are more prone to increased wildfire events due to a greater presence of pioneer species, a higher density of trees, climatic variables which tend to range more widely throughout the day, and the long time span needed for recovery to a pre-fire state [57]. However, the Canary Island pine, which accounts for more than 30% of Macaronesian forest area, is characterized by its fire adaptation strategies [58].…”