scholarly journals Wiregrass (Aristida beyrichiana) survival and reproduction after fire in a long-unburned pine savanna

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0247159
Author(s):  
Jennifer M. Fill ◽  
Cesar Zamora ◽  
Carolina Baruzzi ◽  
Javier Salazar-Castro ◽  
Raelene M. Crandall
Keyword(s):  
Fire Regimes ◽  
Plant Size ◽  
Fire Effects ◽  
High Survival ◽  
Pine Savanna ◽  
Survival And Reproduction ◽  
Fire Exclusion ◽  
Fuel Accumulation ◽  
Filled Seeds ◽  
Fire Feedbacks

Restoring fire regimes is a major goal of biodiversity conservation efforts in fire-prone ecosystems from which fire has been excluded. In the southeastern U.S.A., nearly a century of fire exclusion in pine savannas has led to significant biodiversity declines in one of the most species-rich ecosystems of North America. In these savannas, frequent fires that support biodiversity are driven by vegetation-fire feedbacks. Understory grasses are key components of these feedbacks, fueling the spread of fires that keep tree density low and maintain a high-light environment. When fire is reintroduced to long-unburned sites, however, remnant populations of bunchgrasses might experience high mortality from fuel accumulation during periods of fire exclusion. Our objective was to quantify fire effects on wiregrass (Aristida beyrichiana), a key component of vegetation-fire feedbacks, following 16 years without fire in a dry pine savanna typically considered to burn every 1–3 years. We examined how wiregrass size and fuel (duff depth and presence of pinecones) affected post-fire survival, inflorescence and seed production, and seed germination. Wiregrass exhibited high survival regardless of size or fuels. Probability of flowering and inflorescence number per plant were unaffected by fuel treatments but increased significantly with plant size (p = 0.016). Germination of filled seeds was consistent (29–43%) regardless of fuels, although plants in low duff produced the greatest proportion of filled seeds. The ability of bunchgrasses to persist and reproduce following fire exclusion could jumpstart efforts to reinstate frequent-fire regimes and facilitate biodiversity restoration where remnant bunchgrass populations remain.

Spatial and temporal variations of fire regimes in the Canadian Rocky Mountains and Foothills of southern Alberta

2016 ◽  
Vol 25 (11) ◽  
pp. 1117 ◽  
Author(s):  
Marie-Pierre Rogeau ◽  
Mike D. Flannigan ◽  
Brad C. Hawkes ◽  
Marc-André Parisien ◽  
Rick Arthur
Keyword(s):  
Rocky Mountains ◽  
Fire History ◽  
Fire Severity ◽  
Ecological Integrity ◽  
Fire Regimes ◽  
Temporal Variations ◽  
Fire Season ◽  
Canadian Rocky Mountains ◽  
Southern Alberta ◽  
Fire Exclusion

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.

Fire and open ecosystems

2019 ◽  
pp. 97-120
Author(s):  
William J. Bond
Keyword(s):  
Vegetation Structure ◽  
Open Systems ◽  
Fire Regime ◽  
Alternative Stable States ◽  
Fire Regimes ◽  
Fire Effects ◽  
Emergent Property ◽  
Stable States ◽  
Mosaic Landscapes ◽  
Patterns And Processes

Can fire account for the widespread occurrence of open ecosystems? This chapter explores fire as a major consumer shaping vegetation in diverse regions worldwide. The concept of fire regime helps explain the diverse influences of fire on vegetation structure. Fire regimes select compatible growth forms from the species pool. These, in turn, create the fuel which in large part determines the fire regime. Experimental evidence can show whether fire is a major determinant of vegetation structure or merely an emergent property of ecosystems determined by climate and soils. Whether fires consume closed forests or stop at their margins will determine the dominant vegetation in mosaic landscapes. A mechanistic framework for analysing processes influencing fire effects on the boundary is introduced with examples. Pyrophilic open systems in mosaics with pyrophobic closed forests have been considered as examples of Alternative Stable States. Recent evidence for the patterns and processes expected by ASS theory are discussed.

Multidecadal decline and recovery of aspen experiencing contrasting fire regimes: long-unburned, infrequent and frequent mixed-severity wildfire

2020 ◽  
Author(s):  
Cerena J. Brewen ◽  
John-Pascal Berrill ◽  
Martin W. Ritchie ◽  
Kevin Boston ◽  
Christa M. Dagley ◽  
...  
Keyword(s):  
Populus Tremuloides ◽  
Spatial Dynamics ◽  
Minor Component ◽  
Fire Regimes ◽  
Quaking Aspen ◽  
Aerial Photos ◽  
Wide Range ◽  
Fire Exclusion ◽  
Time Periods ◽  
Root Suckering

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.

Fire Ecology

Ecology ◽  
2012 ◽  
Author(s):  
John Parminter
Keyword(s):  
Fire Ecology ◽  
Fire History ◽  
Spatial Scales ◽  
Natural Disturbance ◽  
Terrestrial Ecosystems ◽  
Fire Regimes ◽  
Fire Effects ◽  
Forest Harvesting ◽  
Natural Disturbances ◽  
Wilderness Areas

Abiotic natural disturbance agents include wildfire, wind, landslides, snow avalanches, volcanoes, flooding, and other weather-related phenomena. Fire is of particular interest because of its antiquity, its natural role in many terrestrial ecosystems, its long-term use by humans to modify vegetation, and its potentially serious threat to life and property. Fire ecology is the art and science of understanding natural and human fire history and fire effects on the environment, species, ecosystems, and landscapes. This knowledge aids the development of fire and ecosystem management plans and activities. Fire history is determined by a number of techniques that use available physical or cultural evidence to examine particular temporal and spatial scales. Fire effects on the environment and organisms are determined by observation and experimentation, but the findings are variable and often contradictory. Fire regimes are used to characterize the role of fire in specific ecosystems and can help guide ecosystem restoration activities. Attitudes toward fire have evolved over time, as good and bad experiences combined with improved scientific understanding to influence our perspectives. Natural disturbances came to be viewed as integral parts of ecosystems rather than external perturbations. We now strive to allow fire to maintain its natural role in wilderness areas and parks and also to emulate natural disturbances, such as fire, when designing forest harvesting operations. This article focuses on how and what we know about fire’s history, its effects on different components of the environment, its role in specific vegetation types, and its relationship with human culture.

The contradictory role of fire from the nature conservation perspective

2020 ◽  
Author(s):  
Orsolya Valkó
Keyword(s):  
Nature Conservation ◽  
Land Surface ◽  
Fire History ◽  
Prescribed Burning ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Effects ◽  
Negative Effects ◽  
Fire Policy

<p>Fire is a globally relevant natural or anthropogenic phenomenon with a rapidly increasing importance in the era of the climate change. In each year, approximately 4% of the global land surface burns. For effective ecosystem conservation, we need to understand fire regimes, identify potential threats, and also the possibilities in the application of prescribed burning for maintaining ecosystems.</p><p>Here I provide an overview on the contradictory role of fire in nature conservation from two continents with contrasting fire histories, focusing on European and North-American grasslands. I show that the ecological effects of fire depend on the fire regime, fire history, ecosystem properties and the socio-economic environment. Catastrophic wildfires, arson, too frequent or improperly planned human-induced fire often lead to the degradation of the ecosystems, the disappearance of rare plant and animal species, and to the encroachment of weed and invasive species. I illustrate with examples that these negative fire effects act synergistically with the human-induced changes in land use systems.</p><p>I also underline with case studies that in both regions, properly designed and controlled prescribed burning regimes can aid the understanding and managing disturbance-dependent ecosystems. Conservation in these dynamic and complex ecosystems is far more than fencing and hoping to exclude disturbance; but the contrary: disturbance is needed for ecosystem functioning. Therefore, the conservation of dynamic, diverse and functioning ecosystems often require drastic interventions and an unconventional conservation attitude. However, the expanding urban-wildlife interface makes the application of prescribed burning challenging worldwide. A major message for the future is about fire policy: it is crucial to moderate the negative effects of fire, however, properly designed prescribed burning should be used as a tool for managing and conserving disturbance-dependent ecosystems.</p>

Effect of seed weight on height growth of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) seedlings in a nursery

1985 ◽  
Vol 15 (6) ◽  
pp. 1109-1115 ◽  
Author(s):  
Frank C. Sorensen ◽  
Robert K. Campbell
Keyword(s):  
Seed Size ◽  
Seed Weight ◽  
Germination Rate ◽  
Plant Size ◽  
Height Growth ◽  
Douglas Fir ◽  
Genetic Makeup ◽  
Practical Implications ◽  
Filled Seeds

Different mean seed weights were produced within each of 10 young Douglas-fir trees by leaving some developing cones unbagged and enclosing others in Kraft paper bags for two different durations. On the average, 10 days in the bag increased filled-seed weight by about 1%. Unbagged cones and cones from the 117-day bagging duration were wind pollinated. Seeds from these cones were, therefore, of comparable genetic makeup and were used in further nursery growth tests. To eliminate the effect of germination rate or time, samples of filled seeds from each treatment on each parent tree were sown as germinant seedlings on one date. Cotyledon number was counted and 1st-year epicotyl lengths and 2nd-year total heights were measured on all seedlings. Seedling volumes were estimated by assuming diameters were proportional to heights. On the average, bagging cones for 117 days increased seed weight by 10.7%, 1st-year epicotyl length by 9.1%, and 2-year total height by 4.0%. All differences were statistically significant. Results were compared with other reports of the relations between seed weight and growth and reasons for inconsistencies were discussed. Size differences were projected to later ages with a growth model and practical implications of long-term seed effects on plant size, of increasing seed size through cultural techniques, and of grading seed lots by size were considered.

Demographic variation between populations of Caladenia orientalis - a fire-managed threatened orchid

2009 ◽  
Vol 57 (4) ◽  
pp. 326 ◽  
Author(s):  
Fiona Coates ◽  
Michael Duncan
Keyword(s):  
Reproductive Effort ◽  
Fire Regimes ◽  
Plant Size ◽  
Biological Information ◽  
Time Since Fire ◽  
Pollen Transport ◽  
Study Sites ◽  
Site Population ◽  
Future Management

Caladenia orientalis (G.W.Carr) Hopper & A.P.Br. is a critically endangered orchid. The largest known populations are confined to fire-managed coastal heathland in southern Victoria. Trends in population dynamics at two closely occurring sites were evaluated against time since fire and rainfall, between 2000 and 2008, to provide ecological and biological information relevant to population management. At both sites, decreased plant size was inversely correlated with time since fire and the number of non-reproductive plants was positively correlated with time since fire. Rates of flowering were inversely correlated with time since fire at only one site (Population 2). The vegetation at this site rapidly accumulated after fire, whereas recovery was relatively slow at the other site. Rainfall was not correlated with rates of flowering or leaf width at either of the study sites, although there was a weak inverse relationship between rainfall and the number of non-reproductive plants at one site (Population 1). Rates of pollen transport and fruit set were within reported ranges for deceptive species. Fruiting plants were significantly smaller in the following year, whereas non-reproductive plants remained the same size. The results suggest that there may be costs associated with reproductive effort, and that hand-pollinating plants to boost seed production may lead to decreased plant size in the following year. Annual variation in rates of flowering may be influenced by previous reproductive effort. However, long-term population trends are better explained by competition from dominant shrubs, which become increasingly abundant with a lack of fire. Future management prescriptions should include site-specific fire regimes to maintain an open heathland.

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
Keyword(s):  
Tree Species ◽  
Acer Rubrum ◽  
Pinus Palustris ◽  
Fire Regimes ◽  
Fire Spread ◽  
Fire Adaptations ◽  
Composition And Structure ◽  
Litter Flammability ◽  
Bottomland Forests ◽  
Fire Exclusion

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.

scholarly journals Balancing uncertainty and complexity to incorporate fire spread in an eco-hydrological model

2017 ◽  
Vol 26 (8) ◽  
pp. 706 ◽  
Author(s):  
Maureen C. Kennedy ◽  
Donald McKenzie ◽  
Christina Tague ◽  
Aubrey L. Dugger
Keyword(s):  
Hydrological Model ◽  
Fire Regimes ◽  
Fire Spread ◽  
Fire Effects ◽  
Hydrologic Model ◽  
Simulation System ◽  
Model Assessment ◽  
Topographic Slope ◽  
Spread Model ◽  
Fire Spread Model

Wildfire affects the ecosystem services of watersheds, and climate change will modify fire regimes and watershed dynamics. In many eco-hydrological simulations, fire is included as an exogenous force. Rarely are the bidirectional feedbacks between watersheds and fire regimes integrated in a simulation system because the eco-hydrological model predicts variables that are incompatible with the requirements of fire models. WMFire is a fire-spread model of intermediate complexity designed to be integrated with the Regional Hydro-ecological Simulation System (RHESSys). Spread in WMFire is based on four variables that (i) represent known influences on fire spread: litter load, relative moisture deficit, wind direction and topographic slope, and (ii) are derived directly from RHESSys outputs. The probability that a fire spreads from pixel to pixel depends on these variables as predicted by RHESSys. We tested a partial integration between WMFire and RHESSys on the Santa Fe (New Mexico) and the HJ Andrews (Oregon State) watersheds. Model assessment showed correspondence between expected spatial patterns of spread and seasonality in both watersheds. These results demonstrate the efficacy of an approach to link eco-hydrologic model outputs with a fire spread model. Future work will develop a fire effects module in RHESSys for a fully coupled, bidirectional model.

Fire effects on geomorphology: what can we expect with climate change?

2020 ◽  
Author(s):  
Cathelijne Stoof
Keyword(s):  
Climate Change ◽  
Debris Flow ◽  
Soil Properties ◽  
Overland Flow ◽  
Complex Function ◽  
Fire Behavior ◽  
Fire Regimes ◽  
Fire Effects ◽  
Natural Process ◽  
Streamflow Generation

<p>Climate change is expected to alter fire regimes but also rainfall patterns. Fire is a natural process that removes vegetation and may affect soil properties, resulting in changes in overland flow and streamflow generation. Some fires cause erosion and may even cause destructive debris flow and other events, which can not only threaten lives and property but also leave lasting imprints in landscapes. The geomorphological response after fire events is a complex function of pre-fire landscape and vegetation properties, fire behavior and effects, and post-fire rainfall timing, duration and intensity. In this talk, I highlight these processes using examples of past events, and explore geomorphological response to fires in a future where both fire and rainfall may be be rather different.</p><p> </p>

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