scholarly journals Patchy Fires Promote Regeneration of Longleaf Pine (Pinus palustris Mill.) in Pine Savannas

Forests ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 367 ◽  
Author(s):  
Kevin M. Robertson ◽  
William J. Platt ◽  
Charles E. Faires
Keyword(s):  
Fire Severity ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Fire Spread ◽  
Tree Regeneration ◽  
Prescribed Fires ◽  
Pine Needle ◽  
Canopy Tree ◽  
Canopy Trees ◽  
Pine Savannas

Research Highlights: Spatial patterns of fire spread and severity influence survival of juvenile pines in longleaf pine savannas. Small areas that do not burn during frequent fires facilitate formation of patches of even-aged longleaf pine juveniles. These regeneration patches are especially associated with inner portions of openings (gaps) and where canopy trees have died in recent decades. Patterns of prescribed fire can thus have an important influence on stand dynamics of the dominant tree in pine savannas. Background and Objectives: Savannas are characterized by bottlenecks to tree regeneration. In pine savannas, longleaf pine is noted for recruitment in discrete clusters located within gaps away from canopy trees. Various mechanisms promoting this pattern have been hypothesized: light limitations, soil moisture, soil nutrients, pine needle mulching, competition with canopy tree roots, and fire severity associated with pine needle litter. We tested the hypothesis that regeneration patches are associated with areas that remain unburned during some prescribed fires, as mediated by gaps in the canopy, especially inner portions of gaps, and areas re-opened by death of canopy trees. Materials and Methods: We mapped areas that were unburned during prescribed fires applied at 1–2 year intervals from 2005–2018 in an old-growth pine savanna in Georgia, USA. We compared the maps to locations of longleaf pine juveniles (<1.5 m height) measured in 2018 and canopy cover and canopy tree deaths using a long-term (40 year) tree census. Results: Logistic regression analysis showed juveniles to be associated with unburned areas, gaps, inner gaps, and areas where canopy trees died. Conclusions: Patterns of fire spread and severity limit survival of longleaf pine juveniles to patches away from canopy trees, especially where canopy trees have died in recent decades. These processes contribute to a buffering mechanism that maintains the savanna structure and prevents transition to closed canopy forest or open grassland communities.

Longleaf Pine (Pinus palustris Mill.) Branch Pruning by Prescribed Fire

2021 ◽  
Author(s):  
John P McGuire ◽  
John S Kush ◽  
J Morgan Varner ◽  
Dwight K Lauer ◽  
J Ryan Mitchell
Keyword(s):  
Prescribed Fire ◽  
Longleaf Pine ◽  
Wood Quality ◽  
Pinus Palustris ◽  
Planting Density ◽  
Prescribed Fires ◽  
Pine Tree ◽  
Southeastern Us ◽  
Tree Survival ◽  
The Impact

Abstract Efforts to restore longleaf pine (Pinus palustris Mill.) in the southeastern US require substantial artificial regeneration. Once established, important questions remain about when to introduce fire. We investigated the impact of initial planting density on tree branching and how prescribed fire might interact with tree architecture and survival. A particular focus was on how prescribed fires could “prune” lower branches. Lower density plantings (897 trees ha−1) had more and larger live lower branches than higher density plantings (2,243 trees ha−1). Fire was effective in pruning lower branches regardless of season burned, but fire in the growing season was more effective at pruning. Branches up to a height of 1.5 to 2 m were killed by fire. Fire applied in August caused greater damage with more needles scorched and/or consumed and more stem char. Prescribed fire did not impact longleaf pine tree survival. In general, fire applied to longleaf pine facilitated pruning lower branches that affect long-term wood quality, an additional argument for its utility in restoration and management of these ecosystems.

Measuring moisture dynamics to predict fire severity in longleaf pine forests

2002 ◽  
Vol 11 (4) ◽  
pp. 267 ◽  
Author(s):  
Sue A. Ferguson ◽  
Julia E. Ruthford ◽  
Steven J. McKay ◽  
David Wright ◽  
Clint Wright ◽  
...  
Keyword(s):  
Forest Floor ◽  
Meteorological Data ◽  
Fire Severity ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Pine Forests ◽  
Fuel Load ◽  
Fuel Moisture ◽  
Weather Stations ◽  
Moisture Conditions

To understand the combustion limit of biomass fuels in a longleaf pine (Pinus palustris) forest, an experiment was conducted to monitor the moisture content of potentially flammable forest floor materials (litter and duff) at Eglin Air Force Base in the Florida Panhandle. While longleaf pine forests are fire dependent ecosystems, a long history of fire exclusion has allowed large amounts of pine litter and duff to accumulate. Reintroducing fire to remove excess fuel without killing the longleaf pine trees requires care to burn under litter and duff moisture conditions that alternately allow fire to carry while preventing root exposure or stem girdle. The study site was divided into four blocks that were burned under litter and duff moisture conditions of wet, moist, dry, and very dry. Throughout the 4-month experiment, portable weather stations continuously collected meteorological data, which included continuous measurements of water content in the forest floor material from in situ, time-domain reflectometers. In addition, volumetric moisture samples were collected almost weekly, and pre-burn fuel load and subsequent consumption were measured for each burn. Meteorological variables from the weather stations compared with trends in fuel moisture showed the influence of relative humidity and precipitation on the drying and wetting rates of the litter and duff. Fuel moisture conditions showed significant influence on patterns of fuel consumption and could lead to an understanding of processes that govern longleaf pine mortality.

Canopy tree density and species influence tree regeneration patterns and woody species diversity in a longleaf pine forest

2021 ◽  
Vol 490 ◽  
pp. 119082
Author(s):  
Daniel J. Johnson ◽  
Lukas Magee ◽  
Karun Pandit ◽  
Jacqueline Bourdon ◽  
Eben N. Broadbent ◽  
...  
Keyword(s):  
Species Diversity ◽  
Longleaf Pine ◽  
Woody Species ◽  
Pine Forest ◽  
Tree Regeneration ◽  
Tree Density ◽  
Canopy Tree ◽  
Woody Species Diversity

Overstory and understory relationships in longleaf pine plantations 14 years after thinning and woody control

2011 ◽  
Vol 41 (12) ◽  
pp. 2301-2314 ◽  
Author(s):  
Timothy B. Harrington
Keyword(s):  
Species Richness ◽  
Longleaf Pine ◽  
Basal Area ◽  
Pinus Palustris ◽  
Pine Plantations ◽  
Control Treatment ◽  
Prescribed Fires ◽  
Cumulative Mortality ◽  
Accelerated Growth ◽  
Herb Species

To develop silvicultural strategies for restoring longleaf pine ( Pinus palustris Mill.) savannas, mortality and growth of overstory pines and midstory hardwoods and abundance and species richness of herbs were studied for 14 years after pine thinning and nonpine woody control. Pine cover in thinned stands was about half of that in nonthinned stands through year 5, but it lagged by only 8% and 3% in years 9 and 14, respectively, because of vigorous crown responses. Despite a cumulative mortality of 64% of hardwood stems from prescribed fires in years 0, 4, and 9, hardwood basal area in thinned stands (2.1 m2·ha–1) was three times that in nonthinned stands (0.7 m2·ha–1) in year 14. Thinning was associated with 13%–22% more cover and six to eight more species of herbs in years 3–8 but only 6% more cover and two more species in year 14 because of accelerated growth of pine cover and hardwood basal area. However, similar increases in cover and richness of herb species in the woody control treatment were retained through year 14 because it had sustained reductions in hardwood and shrub abundance. Silvicultural strategies that substantially delay encroachment by pines, hardwoods, and shrubs will be those most effective at retaining herb species in longleaf pine savannas, including planting pines at wide spacing, periodic thinning and woody control, and frequent burning.

scholarly journals Estimation of wildfire size and risk changes due to fuels treatments

2012 ◽  
Vol 21 (4) ◽  
pp. 357 ◽  
Author(s):  
M. A. Cochrane ◽  
C. J. Moran ◽  
M. C. Wimberly ◽  
A. D. Baer ◽  
M. A. Finney ◽  
...  
Keyword(s):  
Wildland Fire ◽  
Fire Severity ◽  
Fire Risk ◽  
Fire Spread ◽  
Prescribed Fires ◽  
Fuel Treatments ◽  
Human Land Use ◽  
Trade Offs ◽  
Management Policies ◽  
Fuels Treatments

Human land use practices, altered climates, and shifting forest and fire management policies have increased the frequency of large wildfires several-fold. Mitigation of potential fire behaviour and fire severity have increasingly been attempted through pre-fire alteration of wildland fuels using mechanical treatments and prescribed fires. Despite annual treatment of more than a million hectares of land, quantitative assessments of the effectiveness of existing fuel treatments at reducing the size of actual wildfires or how they might alter the risk of burning across landscapes are currently lacking. Here, we present a method for estimating spatial probabilities of burning as a function of extant fuels treatments for any wildland fire-affected landscape. We examined the landscape effects of more than 72 000 ha of wildland fuel treatments involved in 14 large wildfires that burned 314 000 ha of forests in nine US states between 2002 and 2010. Fuels treatments altered the probability of fire occurrence both positively and negatively across landscapes, effectively redistributing fire risk by changing surface fire spread rates and reducing the likelihood of crowning behaviour. Trade offs are created between formation of large areas with low probabilities of increased burning and smaller, well-defined regions with reduced fire risk.

Does frequent burning affect longleaf pine (Pinus palustris) bark thickness?

2011 ◽  
Vol 41 (7) ◽  
pp. 1562-1565 ◽  
Author(s):  
G. Geoff Wang ◽  
Steve R. Wangen
Keyword(s):  
Longleaf Pine ◽  
Critical Role ◽  
Pinus Palustris ◽  
Stand Age ◽  
Prescribed Fires ◽  
Bark Thickness ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
And Control

Bark thickness plays a critical role in protecting a tree’s cambium from damage by fires. Does frequent surface fire stimulate bark production compared with a fire-suppressed control? Based on data from an ongoing, long-term prescribed fire study, we explored differences in bark thickness from 0 to 200 cm above the ground for longleaf pine ( Pinus palustris P. Mill.) trees on burned and control sites. Biennial prescribed fires, applied between 1973 (stand age = 14 years) and 2006 (stand age = 47 years), significantly reduced diameter at breast height. After adjusting for differences in diameter at breast height, we found no difference in bark thickness of trees from the burn and control sites, except for bark thickness measured at 0 cm aboveground where control sites had significantly thicker bark than burned sites. Results suggest that frequent burning did not stimulate bark production in longleaf pine.

scholarly journals Effects of Soil Abiotic and Biotic Factors on Tree Seedling Regeneration Following a Boreal Forest Wildfire

Ecosystems ◽  
2021 ◽  
Author(s):  
Theresa S. Ibáñez ◽  
David A. Wardle ◽  
Michael J. Gundale ◽  
Marie-Charlotte Nilsson
Keyword(s):  
Boreal Forest ◽  
Betula Pendula ◽  
Fire Severity ◽  
Tree Regeneration ◽  
Soil Biota ◽  
Fire Disturbance ◽  
Burn Severity ◽  
Soil Conditions ◽  
Tree Seedling ◽  
Seedling Regeneration

AbstractWildfire disturbance is important for tree regeneration in boreal ecosystems. A considerable amount of literature has been published on how wildfires affect boreal forest regeneration. However, we lack understanding about how soil-mediated effects of fire disturbance on seedlings occur via soil abiotic properties versus soil biota. We collected soil from stands with three different severities of burning (high, low and unburned) and conducted two greenhouse experiments to explore how seedlings of tree species (Betula pendula, Pinus sylvestris and Picea abies) performed in live soils and in sterilized soil inoculated by live soil from each of the three burning severities. Seedlings grown in live soil grew best in unburned soil. When sterilized soils were reinoculated with live soil, seedlings of P. abies and P. sylvestris grew better in soil from low burn severity stands than soil from either high severity or unburned stands, demonstrating that fire disturbance may favor post-fire regeneration of conifers in part due to the presence of soil biota that persists when fire severity is low or recovers quickly post-fire. Betula pendula did not respond to soil biota and was instead driven by changes in abiotic soil properties following fire. Our study provides strong evidence that high fire severity creates soil conditions that are adverse for seedling regeneration, but that low burn severity promotes soil biota that stimulates growth and potential regeneration of conifers. It also shows that species-specific responses to abiotic and biotic soil characteristics are altered by variation in fire severity. This has important implications for tree regeneration because it points to the role of plant–soil–microbial feedbacks in promoting successful establishment, and potentially successional trajectories and species dominance in boreal forests in the future as fire regimes become increasingly severe through climate change.

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