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 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.

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.

Concurrent and antecedent soil moisture relate positively or negatively to probability of large wildfires depending on season

2016 ◽  
Vol 25 (6) ◽  
pp. 657 ◽  
Author(s):  
Erik S. Krueger ◽  
Tyson E. Ochsner ◽  
J. D. Carlson ◽  
David M. Engle ◽  
Dirac Twidwell ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Growing Season ◽  
Fuel Moisture ◽  
Fuel Production ◽  
Antecedent Soil Moisture ◽  
Plant Water Stress ◽  
Wildfire Occurrence ◽  
Water Capacity ◽  
Available Water Capacity ◽  
Dormant Season

Measured soil moisture data may improve wildfire probability assessments because soil moisture is physically linked to fuel production and live fuel moisture, yet models characterising soil moisture–wildfire relationships have not been developed. We therefore described the relationships between measured soil moisture (concurrent and antecedent), as fraction of available water capacity (FAW), and large (≥405 ha) wildfire occurrence during the growing (May–October) and dormant (November–April) seasons from 2000 to 2012 in Oklahoma, USA. Wildfires were predominantly grass and brush fires but occurred across multiple fuel types including forests. Below-average FAW coincided with high wildfire occurrence each season. Wildfire probability during the growing season was 0.18 when concurrent FAW was 0.5 (a threshold for plant water stress) but was 0.60 when concurrent FAW was 0.2 (extreme drought). Dormant season wildfire probability was influenced not only by concurrent but also by antecedent FAW. Dormant season wildfire probability was 0.29 and 0.09 when FAW during the previous growing season was 0.9 (near ideal for plant growth) and 0.2, respectively. Therefore, although a wet growing season coincided with reduced wildfire probability that season, it also coincided with increased wildfire probability the following dormant season, suggesting that the mechanisms by which soil moisture influences wildfire probability are seasonally dependent.

Phenology of seed maturation in babysbreath (Gypsophila paniculata) in northwest Michigan, USA, and its relation to glyphosate efficacy

2019 ◽  
Vol 12 (03) ◽  
pp. 194-201 ◽  
Author(s):  
Emma K. Rice ◽  
Pamela Martínez-Oquendo ◽  
James N. McNair
Keyword(s):  
United States ◽  
Quantitative Assessment ◽  
Invasive Plant ◽  
Growing Season ◽  
Field Population ◽  
Seed Maturation ◽  
Western United States ◽  
Successive Treatment ◽  
Gypsophila Paniculata ◽  
Percent Germination

AbstractBabysbreath or perennial babysbreath (Gypsophila paniculata L.) is an aggressive invasive plant in large parts of southern Canada and the northern and western United States. It reproduces and disperses by seed, so the phenology of seed maturation is important in designing management programs. The present study provides the first quantitative assessment of G. paniculata seed-maturation phenology in a field population, as well as the first quantitative assessment of how the efficacy of herbicide treatment in preventing production of germinable seeds depends on the timing of treatment in relation to this phenology. Seeds were collected from untreated plants on five dates during July and August in both 2016 and 2017 and tested for germinability. Percent germination increased from 20% to 81% between July 22 and 28 and exceeded 90% by August 4, 2016. The seed-maturation phenology in 2017 was similar but delayed by about 4 d. On a growing degree-day scale, seed-maturation phenologies for the 2 yr were nearly identical. We also tested germinability of seeds from plants sprayed with glyphosate (23.4 ml ae L−1) on July 11, 18, and 25, 2016 (one date per plant). Percent germination increased from 0% to 13% to 20% over successive treatment dates, highlighting the importance of completing treatment early in the growing season.

Diversity of woody species 10 years after four harvesting treatments in the oak–pine type

1992 ◽  
Vol 22 (8) ◽  
pp. 1179-1183 ◽  
Author(s):  
James W. McMinn
Keyword(s):  
Species Richness ◽  
Woody Species ◽  
Growing Season ◽  
Dormant Season ◽  
Pine Stands ◽  
Whole Tree

Oak–pine stands in the Upper Piedmont of Georgia were whole-tree harvested to 10- and 2.5-cm DBH limits in both the dormant and early growing season, then allowed to regenerate spontaneously with no further perturbations. After 10 years, stands harvested in the early growing season exhibited higher diversity than those harvested in the dormant season. After the dormant-season harvests, 10-cm-limit stands tended to be more diverse than 2.5-cm-limit stands. The harvest disturbance primarily affected evenness, rather than species richness.

Cambial electrical resistance related to the number of vascular cambial cells in balsam fir

1984 ◽  
Vol 14 (6) ◽  
pp. 950-952 ◽  
Author(s):  
K. T. Smith ◽  
R. O. Blanchard ◽  
W. C. Shortle
Keyword(s):  
Electrical Resistance ◽  
Growing Season ◽  
Balsam Fir ◽  
Periodic Growth ◽  
Cambial Zone ◽  
Dormant Season ◽  
Cambial Cells ◽  
The Relationship ◽  
Number Of Cells ◽  
Scanning Electron

Cambial electrical resistance (CER) was related to the number of cells per radial file of vascular cambium in dominant and codominant balsam fir (Abiesbalsamea (L.) Mill.) trees sampled during the growing season. Scanning electron microscopy (SEM) was used to examine the vascular cambial zone (VCZ) of balsam fir during the growing and dormant seasons. Trees selected for SEM were categorized as having growing season CER < 10 kΩ or CER > 12 kΩ. The two growing trees with CER < 10 kΩ had a mean of seven cells per radial file of VCZ in contrast with four cells per radial file in the two trees of CER > 12 kΩ. Trees of either growing season category had dormant season CER > 12 kΩ and four cells per radial file of VCZ. The relationship between CER and the number of cells per radial file of VCZ supports the hypothesis relating CER to periodic growth rate in balsam fir.

scholarly journals Nitrogen dynamics in runoff from two small heathland catchments representing opposite extremes with respect to climate and N deposition in Norway

2002 ◽  
Vol 6 (3) ◽  
pp. 351-362 ◽  
Author(s):  
Ø. Kaste ◽  
B. L. Skjelkvåle
Keyword(s):  
Growing Season ◽  
N Deposition ◽  
Climatic Conditions ◽  
Steady Increase ◽  
Humid Climate ◽  
N Dynamics ◽  
Snowmelt Flood ◽  
Catchment Size ◽  
Dormant Season ◽  
Dilution Effects

Abstract. Effects of contrasting climatic conditions and nitrogen (N) deposition levels on streamwater N dynamics are assessed at two small heathland catchments; Dalelva in northern Norway (69°N) and Øygard in southwestern Norway (58°N). The study comprises 11 years of data on climate, hydrology and N inputs/outputs from Dalelva and 8 years of corresponding data from Øygard. Both sites are comparable in catchment size, geology and land cover characteristics, but have large differences in climate and N deposition. Dalelva is characterised by a cold, arctic climate and low N deposition (2-3 kg N ha–1y–1), whereas the Øygard site has a more mild, humid climate with much larger N deposition (13–19 kg N ha–1yr–1). Streamwater nitrate (NO3‾) concentrations at Dalelva generally were negligible during the growing season, but showed a steady increase during the dormant season until a maximum of 40-100 μg N L–1 was reached just before snowmelt. At onset of the snowmelt flood, NO3‾ concentrations decreased momentarily to very low levels, suggesting that N eluted from the seasonal snowpack to a great extent was infiltrated and immobilised in the soils. At Øygard, flood peaks occurred frequently during all seasons, and usually there was no distinct spring flood. A lack of clear dilution effects from floods on streamwater N3‾ concentrations may indicate a relatively high NO3‾ leaching potential in this catchment. On average, the annual NO3– export was negligible at Dalelva (<0.1 kg N ha–1yr–1), while at Øygard it amounted to 3.0±0.3 (±1 s.d.) kg ha–1yr–1, or nearly 20% of the annual N deposition. In addition to this relatively high annual N loss, elevated NO3‾ concentrations during the growing season further indicate that the N supply at Øygard is in excess of the combined plant and microbial demand. Keywords: catchments, surface water, nitrogen deposition, nitrate leaching, climate, hydrology, snowmelt, Dalelva brook, Øygard brook

scholarly journals Fire regimes in eastern coastal fynbos: Imperatives and thresholds in managing for diversity

Koedoe ◽  
2013 ◽  
Vol 55 (1) ◽  
Author(s):  
Tineke Kraaij ◽  
Richard M. Cowling ◽  
Brian W. Van Wilgen
Keyword(s):  
Fire Ecology ◽  
Large Scale ◽  
Prescribed Burning ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Season ◽  
Fire Intensity ◽  
Plant Management ◽  
Alien Plant ◽  
Invasive Alien Plant

Until recently, fire ecology was poorly understood in the eastern coastal region of the Cape Floral Kingdom (CFK), South Africa. Rainfall in the area is aseasonal and temperatures are milder than in the winter-rainfall and drier inland parts of the CFK, with implications for the management of fire regimes. We synthesised the findings of a research programme focused on informing ecologically sound management of fire in eastern coastal fynbos shrublands and explored potential east–west trends at the scales of study area and CFK in terms of fire return interval (FRI) and fire season. FRIs (8–26 years; 1980–2010) were comparable to those elsewhere in the CFK and appeared to be shorter in the eastern Tsitsikamma than in the western Outeniqua halves of the study area. Proteaceae juvenile periods (4–9 years) and post-fire recruitment success suggested that for biodiversity conservation purposes, FRIs should be ≥ 9 years in eastern coastal fynbos. Collectively, findings on the seasonality of actual fires and the seasonality of fire danger weather, lightning and post-fire proteoid recruitment suggested that fires in eastern coastal fynbos are not limited to any particular season. We articulated these findings into ecological thresholds pertaining to the different elements of the fire regime in eastern coastal fynbos, to guide adaptive management of fire in the Garden Route National Park and elsewhere in the region.Conservation implications: Wildfires are likely to remain dominant in eastern coastal fynbos, whilst large-scale implementation of prescribed burning is unattainable. Fires occurring in any season are not a reason for concern, although other constraints remain: the need for sufficient fire intensity, safety requirements, and integration of fire and invasive alien plant management.

Woody tissue photosynthesis increases radial stem growth of young poplar trees under ambient atmospheric CO2 but its contribution ceases under elevated CO2

2020 ◽  
Vol 40 (11) ◽  
pp. 1572-1582
Author(s):  
Linus De Roo ◽  
Fran Lauriks ◽  
Roberto Luis Salomón ◽  
Jacek Oleksyn ◽  
Kathy Steppe
Keyword(s):  
Co2 Concentration ◽  
Growing Season ◽  
Stem Growth ◽  
Atmospheric Co2 ◽  
Canopy Conductance ◽  
Leaf Photosynthesis ◽  
Woody Tissue ◽  
Atmospheric Co2 Concentration ◽  
Tree Survival ◽  
Woody Tissue Photosynthesis

Abstract Woody tissue photosynthesis (Pwt) contributes to the tree carbon (C) budget and generally stimulates radial stem growth under ambient atmospheric CO2 concentration (aCO2). Moreover, Pwt has potential to enhance tree survival under changing climates by delaying negative effects of drought stress on tree hydraulic functioning. However, the relevance of Pwt on tree performance under elevated atmospheric CO2 concentration (eCO2) remains unexplored. To fill this knowledge gap, 1-year-old Populus tremula L. seedlings were grown in two treatment chambers at aCO2 and eCO2 (400 and 660 ppm, respectively), and woody tissues of half of the seedlings in each treatment chamber were light-excluded to prevent Pwt. Radial stem growth, sap flow, leaf photosynthesis and stomatal and canopy conductance were measured throughout the growing season, and the concentration of non-structural carbohydrates (NSC) in stem tissues was determined at the end of the experiment. Fuelled by eCO2, an increase in stem growth of 18 and 50% was observed in control and light-excluded trees, respectively. Woody tissue photosynthesis increased radial stem growth by 39% under aCO2, while, surprisingly, no impact of Pwt on stem growth was observed under eCO2. By the end of the growing season, eCO2 and Pwt had little effect on stem growth, leaf photosynthesis acclimated to eCO2, but stomatal conductance did not, and homeostatic stem NSC pools were observed among combined treatments. Our results highlight that eCO2 potentially fulfils plant C requirements, limiting the contribution of Pwt to stem growth as atmospheric [CO2] rises, and that radial stem growth in young developing trees was C (source) limited during early phenological stages but transitioned towards sink-driven control at the end of the growing season.

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