scholarly journals Litter Flammability of 50 Southeastern North American Tree Species: Evidence for Mesophication Gradients Across Multiple Ecosystems

2021 ◽  
Vol 4 ◽  
Author(s):  
J. Morgan Varner ◽  
Jeffrey M. Kane ◽  
Jesse K. Kreye ◽  
Timothy M. Shearman

Widespread fire exclusion and land-use activities across many southeastern United States forested ecosystems have resulted in altered species composition and structure. These changes in composition and structure have been implicated in positive fire-vegetation feedbacks termed “mesophication” where fire spread and intensity are diminished. In forests and woodlands, inherent flammability of different species is the mechanistic driver of mesophication. To date, there has been limited work on documenting the high diversity of flammability among species in the region, limiting the ability to differentiate among species to restore fuels that sustain fire regimes. Here, we coalesce disparate flammability data and add missing species across the spectrum from species that facilitate fire (so called “pyrophytes”) to those that dampen fire (so called “mesophytes”). We present data on 50 important tree species from across the southeast, all burned using identical laboratory methods. We divide our results for four dominant ecosystems: Coastal Plain uplands, oak-hickory woodlands, Appalachian forests, and bottomland forests. Across ecosystems, the most flammable species were American chestnut (Castanea dentata), a suite of pines (Pinus palustris, P. elliottii, P. serotina, and P. rigida), several oaks (Q. laevis, Q. falcata, Q. margaretta, and Q. alba), and sourwood (Oxydendrum arboreum). At the mesophytic end, the least flammable species were Tsuga canadensis, Acer rubrum, and several other hardwoods previously implicated in mesophication. Each of the four ecosystems we studied contained species that spanned the pyrophytic to mesophytic gradient. These data fill in some key holes in our understanding of southeastern fire adaptations, but also provide context for restoration decisions and fire management prioritization efforts to restore and sustain fire-prone ecosystems of the region.

Fire ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 17 ◽  
Author(s):  
Rebecca A Dewhirst ◽  
Nicholas Smirnoff ◽  
Claire M Belcher

Fire is increasingly being recognised as an important evolutionary driver in fire-prone environments. Biochemical traits such as terpene (volatile isoprenoid) concentration are assumed to influence plant flammability but have often been overlooked as fire adaptations. We have measured the leaf-level flammability and terpene content of a selection of Pinus species native to environments with differing fire regimes (crown fire, surface fire and no fire). We demonstrate that this biochemical trait is associated with leaf-level flammability which likely links to fire-proneness and we suggest that this contributes to post-fire seedling survival. We find that surface-fire species have the highest terpene abundance and are intrinsically the most flammable, compared to crown-fire species. We suggest that the biochemical traits of surface fire species may have been under selective pressure to modify the fire environment at the leaf and litter scale to moderate fire spread and intensity. We indicate that litter flammability is driven not only by packing ratios and bulk density, but also by terpene content.


2017 ◽  
Vol 6 (2) ◽  
pp. 94 ◽  
Author(s):  
Xiongwen Chen ◽  
Dale G. Brockway

The scaling relationship between height and diameter is important for understanding the dynamic patterns of tree growth and estimating the accrual of tree biomass. Metabolic ecology predicts that tree growth follows a universal scaling invariant relative to the height-diameter relationship (i.e., no variation based on taxonomy or resource availability). Comparing field data for different tree species across a range of site conditions should be an informative test of that prediction. Our results indicate that the scaling exponents of height and diameter for longleaf pine (Pinus palustris Mill.) vary at the four locations across its natural range. As for swamp trees, the scaling exponents for red maple (Acer rubrum L.) and river birch (Betula nigra L.) were consistent with that predicted by metabolic ecology; however, those for water tupelo (Nyssa aquatica L.) and bald cypress (Taxodium distichum (L.) Rich) were not. Our study confirms that high plasticity and variation in allometric scaling of the tree height and diameter relationship may very well be the rule, rather than the exception.


2006 ◽  
Vol 36 (5) ◽  
pp. 1108-1120 ◽  
Author(s):  
Karen B Arabas ◽  
Keith S Hadley ◽  
Evan R Larson

We examined the fire history of 11 forest isolates surrounded by lava flows (kipukas) in central Oregon to determine historical differences in fire regimes between kipukas and the surrounding forest, and the role of spatial and environmental variables in fire occurrence. Tree-ring analysis and statistical comparisons show that historical agency records underestimate the number of fires based on the incidence of fire scars. Fires occurred more frequently on kipukas, were typically smaller, and were predominantly lightning-initiated. Except for three widespread fires, fires on kipukas and in the surrounding forest were largely asynchronous. The mean fire-return interval (MFRI) in the surrounding forest decreased following Euro-American settlement and increased on the kipukas with spot-fire removal. This suggests either that forest management and fire exclusion in the surrounding forest decreased fire spread to the kipukas, or that most fires originated on the kipukas. MFRI correlates strongly with distance to the nearest kipuka and a distance-weighted isolation index. The number of fires correlates with elevation change and distance to the nearest kipuka. Fire in naturally fragmented landscapes is influenced by the spatial arrangement of patches, environmental conditions, and human activities. Reconstructing fire histories from forest isolates in the context of their mainland counterparts may have methodological advantages and theoretical implications for forested landscapes characterized by human-imposed insularity.


2016 ◽  
Vol 25 (11) ◽  
pp. 1117 ◽  
Author(s):  
Marie-Pierre Rogeau ◽  
Mike D. Flannigan ◽  
Brad C. Hawkes ◽  
Marc-André Parisien ◽  
Rick Arthur

Like many fire-adapted ecosystems, decades of fire exclusion policy in the Rocky Mountains and Foothills natural regions of southern Alberta, Canada are raising concern over the loss of ecological integrity. Departure from historical conditions is evaluated using median fire return intervals (MdFRI) based on fire history data from the Subalpine (SUB), Montane (MT) and Upper Foothills (UF) natural subregions. Fire severity, seasonality and cause are also documented. Pre-1948 MdFRI ranged between 65 and 85 years in SUB, between 26 and 35 years in MT and was 39 years in UF. The fire exclusion era resulted in a critical departure of 197–223% in MT (MdFRI = 84–104 years). The departure in UF was 170% (MdFRI = 104 years), while regions of continuous fuels in SUB were departed by 129% (MdFRI = 149 years). The most rugged region of SUB is within its historical range of variation with a departure of 42% (MdFRI = 121 years). More mixed-severity burning took place in MT and UF. SUB and MT are in a lightning shadow pointing to a predominance of anthropogenic burning. A summer fire season prevails in SUB, but occurs from spring to fall elsewhere. These findings will assist in developing fire and forest management policies and adaptive strategies in the future.


2010 ◽  
Vol 3 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Jacob Godfrey Agea ◽  
Clement Akais Okia ◽  
Refaat Atalla Ahmed Abohassan ◽  
James Munga Kimondo ◽  
Susan B. Tumwebaze ◽  
...  

2007 ◽  
Vol 363 (1501) ◽  
pp. 2351-2356 ◽  
Author(s):  
Anders Granström ◽  
Mats Niklasson

Fire, being both a natural and cultural phenomenon, presents problems in disentangling the historical effect of humans from that of climate change. Here, we investigate the potential impact of humans on boreal fire regimes from a perspective of fuels, ignitions and culture. Two ways for a low technology culture to impact the fire regime are as follows: (i) by altering the number of ignitions and their spatial distribution and timing and (ii) by hindering fire spread. Different cultures should be expected to have quite different impacts on the fire regimes. In northern Fennoscandia, there is evidence for fire regime changes associated with the following: a reindeer herding culture associated with few ignitions above the natural; an era of cattle husbandry with dramatically increased ignitions and somewhat higher fire frequency; and a timber exploitation era with decreasing fire sizes and diminishing fire frequency. In other regions of the boreal zone, such schemes can look quite different, but we suggest that a close look at the resource extraction and land use of different cultures should be part of any analysis of past fire regimes.


Fire ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 48
Author(s):  
Kira M. Hoffman ◽  
Sara B. Wickham ◽  
William S. McInnes ◽  
Brian M. Starzomski

Fire exclusion and suppression has altered the composition and structure of Garry oak and associated ecosystems in British Columbia. The absence of frequent low severity ground fires has been one of the main contributors to dense patches of non-native grasses, shrubs, and encroaching Douglas-fir trees in historical Garry oak dominated meadows. This case study uses remote sensing and dendrochronology to reconstruct the stand dynamics and long-term fire history of a Garry oak meadow situated within Helliwell Provincial Park located on Hornby Island, British Columbia. The Garry oak habitat in Helliwell Park has decreased by 50% since 1950 due to conifer encroachment. Lower densities and mortalities of Garry oak trees were associated with the presence of overstory Douglas-fir trees. To slow conifer encroachment into the remaining Garry oak meadows, we recommend that mechanical thinning of Douglas-fir be followed by a prescribed burning program. Reintroducing fire to Garry oak ecosystems can restore and maintain populations of plants, mammals, and insects that rely on these fire resilient habitats.


2020 ◽  
Author(s):  
Cerena J. Brewen ◽  
John-Pascal Berrill ◽  
Martin W. Ritchie ◽  
Kevin Boston ◽  
Christa M. Dagley ◽  
...  

AbstractQuaking aspen (Populus tremuloides) is a valued, minor component on western landscapes. It provides a wide range of ecosystem services and has been in decline throughout the arid west for the last century. This decline may be explained partially by the lack of fire on the landscape as aspen benefit from fire that eliminates conifer competition and stimulates reproduction through root suckering. Managers are interested in aspen restoration but there is a lack of knowledge about their spatial dynamics in response to fire. Our study area in northeastern California on the Lassen, Modoc and Plumas National Forests has experienced recent large mixed-severity wildfires where aspen was present, providing an opportunity to study the re-introduction of fire. We observed two time periods; a 54-year absence of fire from 1941 to 1993 preceding a 24-year period of wildfire activity from 1993 to 2017. We utilized aerial photos to delineate aspen stand size, location and succession to conifers. We chose aspen stands in areas where wildfires overlapped (twice-burned), where only a single wildfire burned, and areas that did not burn within the recent 24-year period. We looked at these same stands within the first period of fire exclusion for comparison (i.e., 1941-1993). In the absence of fire, all aspen stand areas declined and all stands experienced increases in conifer composition. After wildfire, stands that burned experienced a release from conifer competition and increased in stand area. Stands that burned twice or at high severity experienced a larger removal of conifer competition than stands that burned once at low severity, promoting aspen recovery and expansion. Stands with less edge:area ratio also expanded more with fire present. Across both time periods, stand movement, where aspen stand footprints were mostly in new areas compared to footprints of previous years, was highest in smaller stands. In the fire exclusion period, smaller stands exhibited greater changes in area and location (movement), highlighting their vulnerability to loss in the absence of disturbances that provide adequate growing space for aspen over time.


2002 ◽  
Vol 32 (6) ◽  
pp. 928-941 ◽  
Author(s):  
Joseph J Hendricks ◽  
Carlos A Wilson ◽  
Lindsay R Boring

Foliar litter position and decomposition were assessed in longleaf pine (Pinus palustris Mill.) - wiregrass (Aristida beyrichiana Trin. & Rupr.) woodlands during a 3-year burn interval. Position assessments revealed 57.7 and 67.4% of foliar litter was elevated in wiregrass crowns 1 and 2 years, respectively, following burning. Decomposition assessments revealed soil-surface mass loss decay constants (range 0.097–0.282) similar to those measured in comparable pine forests. However, elevated longleaf pine and wiregrass litter exhibited decay constants (0.052 and 0.074, respectively) 50% lower than corresponding soil-surface rates and among the lowest values in the literature. With the exception of wiregrass, which did not exhibit an immobilization of the nutrients (N, P, Ca, K, and Mg) assessed, foliar litter exhibited either extensive P immobilization with minimal N immobilization or minimal, short-lived immobilization of N, P, or both N and P. The percentage of original N and P remaining after 3 years varied widely among the soil surface (N range 6.3–56.3%; P range 3.4–204.7%) and elevated (N range 76.8–94.9%; P range 52.0–99.2%) litter. These results suggest that fire regimes typically employed in longleaf pine – wiregrass woodlands may balance N losses via volatilization with P limitations via litter immobilization.


2013 ◽  
Vol 22 (12) ◽  
pp. 2919-2936 ◽  
Author(s):  
Sammy Carsan ◽  
Aldo Stroebel ◽  
Ian Dawson ◽  
Roeland Kindt ◽  
Frans Swanepoel ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document