Prescribed Burn Effects on Natural Regeneration in Pine Flatwoods: Implications for Uneven-Aged Stand Conversion from a Florida Study

Abstract

Uneven-aged silvicultural approaches are increasingly utilized as efficient management strategies for economic and ecological sustainability of forest resources, including in the southeastern United States where there is interest in converting intensively managed pine plantations to uneven-aged stands. However, success of stand conversion and perpetuation of an uneven-aged forest stand depends on obtaining adequate regeneration of the desired species and its ability to develop into merchantable size classes. In fire-maintained ecosystems, regeneration dynamics can be challenging for species such as slash pine that are not tolerant of fire in the seedling stage. In this study, we examined the survival of slash pine (Pinus elliottii Englm.) regeneration (seedlings and saplings) following prescribed burns in (1) a harvest-created gap (0.4 ha; 70 m diameter) and (2) a mature stand with abundant advanced regeneration at two mesic-hydric flatwoods sites in northwest Florida, USA. We characterized the prescribed burns at the two sites and quantified survival of regeneration of different size classes (<1 m, 1–2 m, 2–3 m, >3 m) at 10 months after the burn. Within the gap, the greatest survival of regeneration was observed at the center (12.5% survival) in comparison to the other positions in the gap (1.92% to 7.14% survival), with all seedlings <3m height killed by the burn. In the stand with advance regeneration, survival ranged between 0% and 50% at different positions, with all regeneration smaller than 2 m killed by fire. Overall, we observed 6.36% and 23.2% survival in the harvest-created gap and the stand with advance regeneration, respectively. Despite these low percent survival values, post-burn slash pine regeneration (seedlings/saplings) density equaled 725 and 4800 per hectare, respectively. Our modeling projections suggest that this level of post-burn regeneration density may be adequate for stand conversion and sustainable uneven-aged silvicultural management of slash pine. These results suggest that seedling size is the preeminent control on slash pine survival after prescribed burn. However, long-term monitoring of stand dynamics following future prescribed burns and cutting cycle harvests will help confirm if slash pine can be sustainably managed using uneven-aged silviculture.

Optimal Forest Management of Even-Aged Longleaf Pine Stands with Nontimber Benefits

“…Longleaf pine forests can produce higher-quality forest products and provide higher rates of carbon sequestration compared to other southern pines (McNulty et al, 2018;Raut et al, 2022). Furthermore, longleaf pine forests are more resilient to natural disturbances and fluctuating climatic conditions (Koontz et al, 2020;Sharma et al, 2020).…”

Using GatorEye UAV-Borne LiDAR to Quantify the Spatial and Temporal Effects of a Prescribed Fire on Understory Height and Biomass in a Pine Savanna

“…With the region-wide suppression of wildfire, land managers now need to use prescribed fire to alter understory biomass and encourage pine regeneration [10]. Thus, knowing the spatial distribution of understory biomass before a fire [11], and the resulting response of understory plants to the prescribed fire [12] could benefit restoration objectives. However, conducting this type of survey of the understory with clipped plots is labor-intensive, and as a result, the provided information is generally limited in spatial and temporal extent.…”

Gestión forestal para la adaptación al cambio global. Evaluación de tratamientos selvícolas para la diversificación y regeneración de masas de repoblación

“…Estas zonas, al encontrarse más lejos del borde del bosquete, disponen de mayor luz, pero esta mayor iluminación supone una mayor competencia inter-específica también (Sharma et al, 2019). La cercanía a los árboles adultos situados en las proximidades del borde de bosquete ha sido identificada como negativa para el desarrollo de las plántulas de regenerado, tanto por sombrear excesivamente a las plántulas de especies intolerantes (Sharma et al, 2020), como por suponer competencia por agua y nitrógeno (Walters et al, 2006). Muscolo et al (2017) revisaron la mayoría de variables implicadas en la gestión vía entresaca por bosquetes, y encontraron que las temperaturas son mayores en el centro del bosquete, lo que hace reducir la humedad y aumentar la evapotranspiración.…”

“…También es una alternativa muy flexible, pues en sucesivas operaciones de apertura de bosquetes se pueden variar los tamaños de bosquete utilizados. Estudios previos (Zhu et al, 2003;Sharma et al, 2020) han destacado cómo esta técnica selvícola puede ser capaz de generar masas irregulares de especies intolerantes a la sombra, indicando que puede ser una alternativa para transformar masas regulares de pino resinero en masas mixtas e irregulares. Otros autores incluso han sugerido la utilización de este tipo de cortas para la diversificación de repoblaciones de pino resinero en España (Carreras y García Viñas, 1998;Solís, 2003), sin embargo, sus recomendaciones no han sido puestas en práctica hasta la fecha.…”

“…Ello se debe a la competencia por la luz, agua y nutrientes con el arbolado adulto circundante (Walters et al, 2006). Y también crecen menos en altura en ambas estaciones (primavera y otoño), por las mismas razones anteriormente expuestas para la supervivencia, como comentan Sharma et al (2020) en su estudio con bosquetes en masas de Pinus elliottii, un pino americano también intolerante a la sombra.…”