scholarly journals Fire Season, Overstory Density and Groundcover Composition Affect Understory Hardwood Sprout Demography in Longleaf Pine Woodlands

Forests ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 423 ◽  
Author(s):  
Andrew Whelan ◽  
Seth Bigelow ◽  
Mary Nieminen ◽  
Steven Jack
Keyword(s):  
Ecosystem Management ◽  
Prescribed Fire ◽  
Longleaf Pine ◽  
Growing Season ◽  
Fire Season ◽  
Fire Intensity ◽  
Seasonal Timing ◽  
Closed Canopy ◽  
Dormant Season ◽  
Global Increase

Seasonal timing of prescribed fire and alterations to the structure and composition of fuels in savannas and woodlands can release understory hardwoods, potentially resulting in a global increase of closed-canopy forest and a loss of biodiversity. We hypothesized that growing-season fire, high overstory density, and wiregrass presence in longleaf pine woodlands would reduce the number and stature of understory hardwoods, and that because evergreen hardwoods retain live leaves, dormant-season fire would reduce performance and survival of evergreen more than deciduous hardwoods. Understory hardwood survival and height were monitored over seven years in longleaf pine woodlands in southwest Georgia with a range of overstory density, groundcover composition, and season of application of prescribed fire. Hardwood stem survival decreased with increasing overstory density, and deciduous hardwoods were more abundant in the absence of wiregrass. Contrary to expectations, evergreen hardwood growth increased following dormant-season fire. Differences in hardwood stem survival and height suggest that low fire intensity in areas with low overstory density increase the risk that hardwoods will grow out of the understory. These results indicate a need for focused research into the effects of groundcover composition on hardwood stem dynamics and emphasize that adequate overstory density is important in longleaf ecosystem management.

Effects of fire season and intensity on Prosopis glandulosa Torr. var. glandulosa

2003 ◽  
Vol 12 (2) ◽  
pp. 147 ◽  
Author(s):  
Paul B. Drewa
Keyword(s):  
Chihuahuan Desert ◽  
Growing Season ◽  
Stem Growth ◽  
Western United States ◽  
Prosopis Glandulosa ◽  
Fire Season ◽  
Fire Intensity ◽  
Canopy Area ◽  
Heat Penetration ◽  
Dormant Season

In pyrogenic ecosystems, responses of resprouting woody vegetation may depend more on fire season than on intensity. I explored this hypothesis by examining fire season and intensity effects on response of Prosopis glandulosa, a resprouting shrub in Chihuahuan desert grasslands of the south-western United States. Clipping as well as low and high intensity fires (natural and added fuels, respectively) were applied during the 1999 growing season and the 2000 dormant season. Both fire season and intensity affected shrub responses. Numbers of resprouts increased 16%, and heights increased 8% after dormant season versus growing season treatments of fire and clipping combined. Height and resprout number decreased with increased fire intensity. Fire season and intensity effects on canopy area and stem growth were generally not detected. My results do not support the above hypothesis. Instead, fire season and intensity influence shrub responses in different ways via different mechanisms. Prosopis glandulosa has the potential to respond more after dormant season than growing season fires, perhaps as determined by carbohydrate availability in underground organs at the time of fire. However, realization of this potential is contingent on fire intensity as influenced primarily by fuel amount. In turn, fire intensity will determine the amount and duration of heat penetration into soils and thus the amount of damage to growing points of under-ground organs.

scholarly journals Characterizing Growing Season Length of Subtropical Coniferous Forests with a Phenological Model

Forests ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 95
Author(s):  
Yuan Gong ◽  
Christina L. Staudhammer ◽  
Susanne Wiesner ◽  
Gregory Starr ◽  
Yinlong Zhang
Keyword(s):  
Climate Change ◽  
Soil Water ◽  
Prescribed Fire ◽  
Water Availability ◽  
Longleaf Pine ◽  
Growing Season ◽  
Soil Water Availability ◽  
Future Climate Change ◽  
Short Term ◽  
Phenological Model

Understanding plant phenological change is of great concern in the context of global climate change. Phenological models can aid in understanding and predicting growing season changes and can be parameterized with gross primary production (GPP) estimated using the eddy covariance (EC) technique. This study used nine years of EC-derived GPP data from three mature subtropical longleaf pine forests in the southeastern United States with differing soil water holding capacity in combination with site-specific micrometeorological data to parameterize a photosynthesis-based phenological model. We evaluated how weather conditions and prescribed fire led to variation in the ecosystem phenological processes. The results suggest that soil water availability had an effect on phenology, and greater soil water availability was associated with a longer growing season (LOS). We also observed that prescribed fire, a common forest management activity in the region, had a limited impact on phenological processes. Dormant season fire had no significant effect on phenological processes by site, but we observed differences in the start of the growing season (SOS) between fire and non-fire years. Fire delayed SOS by 10 d ± 5 d (SE), and this effect was greater with higher soil water availability, extending SOS by 18 d on average. Fire was also associated with increased sensitivity of spring phenology to radiation and air temperature. We found that interannual climate change and periodic weather anomalies (flood, short-term drought, and long-term drought), controlled annual ecosystem phenological processes more than prescribed fire. When water availability increased following short-term summer drought, the growing season was extended. With future climate change, subtropical areas of the Southeastern US are expected to experience more frequent short-term droughts, which could shorten the region’s growing season and lead to a reduction in the longleaf pine ecosystem’s carbon sequestration capacity.

Within-stand variation in understorey vegetation affects fire behaviour in longleaf pine xeric sandhills

2011 ◽  
Vol 20 (7) ◽  
pp. 866 ◽  
Author(s):  
Evelyn S. Wenk ◽  
G. Geoff Wang ◽  
Joan L. Walker
Keyword(s):  
Prescribed Fire ◽  
Longleaf Pine ◽  
Fire Intensity ◽  
National Wildlife Refuge ◽  
Understorey Vegetation ◽  
Eastern Usa ◽  
Turkey Oak ◽  
Pine Stands ◽  
Sandhills Region ◽  
Vegetation Layer

The frequent fires typical of the longleaf pine ecosystem in the south-eastern USA are carried by live understorey vegetation and pine litter. Mature longleaf pine stands in the xeric sandhills region have a variable understorey vegetation layer, creating several fuel complexes at the within-stand scale (20 m2). We identified three fuel complexes found in frequently burned stands on the Carolina Sandhills National Wildlife Refuge, and used prescribed fire to test whether distinct sets of fire conditions were associated with each fuel complex. Study plots were dominated by either turkey oak or wiregrass in the understorey, or lacked understorey vegetation and contained only longleaf pine litter. Turkey oak-dominated plots had the highest fuel loads, and during burns they had higher total net heat flux than wiregrass- or longleaf pine litter-dominated plots, and longer burn durations than wiregrass-dominated plots. Across all plots, the quantity of litter fragments had the greatest effect on fire temperature and duration of burn. These results show that the patchy understorey vegetation within longleaf pine stands will create heterogeneous fires, and areas dominated by turkey oak may have increased fire intensity and soil heating compared with the other two fuel complexes.

Effects of late growing-season and late dormant-season prescribed fire on herbaceous vegetation in restored pine-grassland communities

1998 ◽  
Vol 9 (1) ◽  
pp. 133-142 ◽  
Author(s):  
Jeffrey C. Sparks ◽  
Ronald E. Masters ◽  
David M. Engle ◽  
Michael W. Palmer ◽  
George A. Bukenhofer
Keyword(s):  
Prescribed Fire ◽  
Growing Season ◽  
Herbaceous Vegetation ◽  
Dormant Season ◽  
Grassland Communities

scholarly journals Physiological Mechanisms of Foliage Recovery after Spring or Fall Crown Scorch in Young Longleaf Pine (Pinus palustris Mill.)

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 208
Author(s):  
Mary Anne S. Sayer ◽  
Michael C. Tyree ◽  
Eric A. Kuehler ◽  
John K. Jackson ◽  
Dylan N. Dillaway
Keyword(s):  
Gas Exchange ◽  
Prescribed Fire ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Growing Season ◽  
Stem Growth ◽  
Starch Accumulation ◽  
Crown Scorch ◽  
Growth Loss ◽  
Developmental Responses

We hypothesized that physiological and morphological responses to prescribed fire support the post-scorch foliage recovery and growth of young longleaf pine. Two studies conducted in central Louisiana identified three means of foliage regrowth after fire that included an increase in the gas exchange rate of surviving foliage for 3 to 4 months after fire. Saplings also exhibited crown developmental responses to repeated fire that reduced the risk of future crown scorch. Starch reserves were a source of carbon for post-scorch foliage regrowth when fire was applied in the early growing season. However, the annual dynamics of starch accumulation and mobilization restricted its effectiveness for foliage regrowth when fire was applied late in the growing season. As such, post-scorch foliage regrowth became increasingly dependent on photosynthesis as the growing season progressed. Additionally, the loss of foliage by fire late in the growing season interrupted annual starch dynamics and created a starch void between the time of late growing season fire and mid-summer of the next year. The occurrence of drought during both studies revealed barriers to foliage reestablishment and normal stem growth among large saplings. In study 1, spring water deficit at the time of May fire was associated with high crown scorch and poor foliage and stem growth among large saplings. We attribute this lag in stem growth to three factors: little surviving foliage mass, low fascicle gas exchange rates, and poor post-scorch foliage recovery. In study 2, May fire during a short window of favorable burning conditions in the tenth month of a 20-month drought also reduced stem growth among large saplings but this growth loss was not due to poor post-scorch foliage recovery. Application of this information to prescribed fire guidelines will benefit young longleaf pine responses to fire and advance efforts to restore longleaf pine ecosystems.

Season of burn and nutrient losses in a longleaf pine ecosystem

2004 ◽  
Vol 13 (4) ◽  
pp. 443 ◽  
Author(s):  
L. R. Boring ◽  
J. J. Hendricks ◽  
C. A. Wilson ◽  
R. J. Mitchell
Keyword(s):  
Longleaf Pine ◽  
Mineral Soil ◽  
Soil Surface ◽  
Growing Season ◽  
Plant Litter ◽  
N Fixation ◽  
Nutrient Pools ◽  
Fire Cycle ◽  
Dormant Season

Fire regulates the structure and function of longleaf pine ecosystems, including potential nutrient controls on productivity, forest floor and groundcover nutrient pools, and nutrient availability. Little is known about comparative influences of seasonality of fire, litter types, and mass on N and P balance and soil processes in longleaf pine ecosystems. This study primarily addresses the hypothesis that nutrient volatilization during growing season burning, due to combustion of live biomass, exceeds losses from winter burning of standing dead plant litter. Summer and winter burns were conducted experimentally in different groundcover types with ambient, double-ambient and no litter loadings to contrast 2–3 years of litter accumulation with very low and high fuels. As a comparison, the seasonal burns were repeated with fuel and temperature measurements on sites that had actual fuel accumulations ranging from 1 to 3 years following the last fire. Peak fire temperatures and duration of burning were similar, but with high variation across groundcover types and seasons due to variation in fuel moisture content. The highest pine litter loadings produced maximum mineral soil/litter interface temperatures that never exceeded 700°C. Groundcovers without pine litter burned incompletely and with low temperatures. Biomass and N content were greater in summer groundcover than winter groundcover, and were greater in wiregrass than old-field groundcover. More N was lost from growing season burning as biomass had higher N in green foliage at that time. With ambient litter loadings, mass losses were 88–94% of total litter and groundcover. Percentages of N lost were comparable (80–90% across all groundcovers and seasons), but amounts of N lost were below that estimated to be replenished by legume N fixation and regional atmospheric deposition over a dormant season prescribed fire cycle. Net N balances with growing season fire were generally negative only if growing season burning was projected exclusively over the long-term. P content was not significantly different among groundcovers, but summer standing stocks were higher than winter. No P losses were detected with any experimental treatments and, following burning, all P was returned to soil pools, attributable to soil surface temperatures remaining largely below 700°C. We conclude that frequent, dormant season, or even variable season burning should not seriously deplete long-term nitrogen balance of longleaf pine ecosystems.

scholarly journals How do fire behavior and fuel consumption vary between dormant and early growing season prescribed burns in the southern Appalachian Mountains?

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Matthew C. Vaughan ◽  
Donald L. Hagan ◽  
William C. Bridges ◽  
Matthew B. Dickinson ◽  
T. Adam Coates
Keyword(s):  
Fuel Consumption ◽  
Prescribed Fire ◽  
Fire Behavior ◽  
Growing Season ◽  
Fire Spread ◽  
Prescribed Burns ◽  
Management Objectives ◽  
Southern Appalachian ◽  
Dormant Season ◽  
Season Of Burn

Abstract Background Despite the widespread use of prescribed fire throughout much of the southeastern USA, temporal considerations of fire behavior and its effects often remain unclear. Opportunities to burn within prescriptive meteorological windows vary seasonally and along biogeographical gradients, particularly in mountainous terrain where topography can alter fire behavior. Managers often seek to expand the number of burn days available to accomplish their management objectives, such as hazardous fuel reduction, control of less desired vegetation, and wildlife habitat establishment and maintenance. For this study, we compared prescribed burns conducted in the dormant and early growing seasons in the southern Appalachian Mountains to evaluate how burn outcomes may be affected by environmental factors related to season of burn. The early growing season was defined as the narrow phenological window between bud break and full leaf-out. Proportion of plot area burned, surface fuel consumption, and time-integrated thermocouple heating were quantified and evaluated to determine potential relationships with fuel moisture and topographic and meteorological variables. Results Our results suggested that both time-integrated thermocouple heating and its variability were greater in early growing season burns than in dormant season burns. These differences were noted even though fuel consumption did not vary by season of burn. The variability of litter consumption and woody fuelbed height reduction were greater in dormant season burns than in early growing season burns. Warmer air temperatures and lower fuel moisture, interacting with topography, likely contributed to these seasonal differences and resulted in more burn coverage in early growing season burns than in dormant season burns. Conclusions Dormant season and early growing season burns in southern Appalachian forests consumed similar amounts of fuel where fire spread. Notwithstanding, warmer conditions in early growing season burns are likely to result in fire spread to parts of the landscape left unburnt in dormant season burns. We conclude that early growing season burns may offer a viable option for furthering the pace and scale of prescribed fire to achieve management objectives.

scholarly journals Fire, land cover, and temperature drivers of bat activity in winter

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Marcelo H. Jorge ◽  
Sara E. Sweeten ◽  
Michael C. True ◽  
Samuel R. Freeze ◽  
Michael J. Cherry ◽  
...  
Keyword(s):  
Land Cover ◽  
Habitat Management ◽  
Deciduous Forest ◽  
Pinus Palustris ◽  
Growing Season ◽  
Early Spring ◽  
Bat Activity ◽  
White Nose Syndrome ◽  
Dormant Season ◽  
Wind Energy Development

Abstract Background Understanding the effects of disturbance events, land cover, and weather on wildlife activity is fundamental to wildlife management. Currently, in North America, bats are of high conservation concern due to white-nose syndrome and wind-energy development impact, but the role of fire as a potential additional stressor has received less focus. Although limited, the vast majority of research on bats and fire in the southeastern United States has been conducted during the growing season, thereby creating data gaps for bats in the region relative to overwintering conditions, particularly for non-hibernating species. The longleaf pine (Pinus palustris Mill.) ecosystem is an archetypal fire-mediated ecosystem that has been the focus of landscape-level restoration in the Southeast. Although historically fires predominately occurred during the growing season in these systems, dormant-season fire is more widely utilized for easier application and control as a means of habitat management in the region. To assess the impacts of fire and environmental factors on bat activity on Camp Blanding Joint Training Center (CB) in northern Florida, USA, we deployed 34 acoustic detectors across CB and recorded data from 26 February to 3 April 2019, and from 10 December 2019 to 14 January 2020. Results We identified eight bat species native to the region as present at CB. Bat activity was related to the proximity of mesic habitats as well as the presence of pine or deciduous forest types, depending on species morphology (i.e., body size, wing-loading, and echolocation call frequency). Activity for all bat species was influenced positively by either time since fire or mean fire return interval. Conclusion Overall, our results suggested that fire use provides a diverse landscape pattern at CB that maintains mesic, deciduous habitat within the larger pine forest matrix, thereby supporting the diverse bat community at CB during the dormant season and early spring.

scholarly journals Twenty-first century droughts have not increasingly exacerbated fire season severity in the Brazilian Amazon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Libonati ◽  
J. M. C. Pereira ◽  
C. C. Da Camara ◽  
L. F. Peres ◽  
D. Oom ◽  
...  
Keyword(s):  
Forest Fires ◽  
Brazilian Amazon ◽  
First Century ◽  
Fire Season ◽  
Fire Intensity ◽  
Amazon Forest ◽  
Active Fire ◽  
Fire Activity ◽  
Twenty First Century ◽  
In Fire

AbstractBiomass burning in the Brazilian Amazon is modulated by climate factors, such as droughts, and by human factors, such as deforestation, and land management activities. The increase in forest fires during drought years has led to the hypothesis that fire activity decoupled from deforestation during the twenty-first century. However, assessment of the hypothesis relied on an incorrect active fire dataset, which led to an underestimation of the decreasing trend in fire activity and to an inflated rank for year 2015 in terms of active fire counts. The recent correction of that database warrants a reassessment of the relationships between deforestation and fire. Contrasting with earlier findings, we show that the exacerbating effect of drought on fire season severity did not increase from 2003 to 2015 and that the record-breaking dry conditions of 2015 had the least impact on fire season of all twenty-first century severe droughts. Overall, our results for the same period used in the study that originated the fire-deforestation decoupling hypothesis (2003–2015) show that decoupling was clearly weaker than initially proposed. Extension of the study period up to 2019, and novel analysis of trends in fire types and fire intensity strengthened this conclusion. Therefore, the role of deforestation as a driver of fire activity in the region should not be underestimated and must be taken into account when implementing measures to protect the Amazon forest.

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