scholarly journals Re-introducing fire in sagebrush steppe experiencing decreased fire frequency: does burning promote spatial and temporal heterogeneity?

2020 ◽  
Vol 29 (8) ◽  
pp. 686
Author(s):  
Kirk W. Davies ◽  
Jon D. Bates
Keyword(s):  
Fire Frequency ◽  
Community Response ◽  
Sagebrush Steppe ◽  
Spatial And Temporal Variability ◽  
Long Term Effects ◽  
Vegetation Shifts ◽  
Burned Areas ◽  
Shrub Steppe ◽  
Steppe Communities ◽  
Fire Exclusion

Fire frequency has decreased in many shrub-steppe communities. Re-introducing fire may be needed to increase spatial and temporal variability in vegetation, but is often hindered by concerns of undesired vegetation shifts. These concerns arise, in part, because long-term effects of fire re-introduction in these communities after prolonged fire exclusion and other departures from historical conditions are unknown. To better understand the effects of re-introducing fire, we evaluated plant community response to re-introducing fire for 12 years post fire in six mountain big sagebrush communities. Herbaceous biomass production was 1.7-fold greater in burned compared with unburned areas at the conclusion of the study. Exotic annual grasses appeared to be problematic in the first 8 years post fire, but became inconsequential (~1% cover) by the end of the study. Re-introducing fire promoted other shrubs (excluding sagebrush) that were probably inhibited by competition from sagebrush. Sagebrush cover and density remained low in burned areas for the duration of the study, because of limited recruitment in the years immediately post fire and competition from herbaceous vegetation. Re-introducing fire appears to increase temporal and spatial heterogeneity in shrub-steppe communities experiencing prolonged fire exclusion and, therefore, may be needed to maintain a diversity of plant communities.

Community Structure Affects Annual Grass Weed Invasion During Restoration of a Shrub–Steppe Ecosystem

2014 ◽  
Vol 7 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Phil S. Allen ◽  
Susan E. Meyer
Keyword(s):  
Community Structure ◽  
Native Species ◽  
Propagule Pressure ◽  
Alternative Hypothesis ◽  
Perennial Grasses ◽  
Invasion Success ◽  
Sagebrush Steppe ◽  
Annual Grass ◽  
Shrub Steppe ◽  
Steppe Communities

AbstractEcological restoration of shrub–steppe communities in the western United States is often hampered by invasion of exotic annual grasses during the process. An important question is how to create restored communities that can better resist reinvasion by these weeds. One hypothesis is that communities comprised of species that are functionally similar to the invader will best resist invasion, while an alternative hypothesis is that structurally more complex and diverse communities will result in more effective competitive exclusion. In this field experiment, we examined the effects of restored community structure on the invasion success of three annual grass weeds (downy brome, jointed goatgrass, and cereal rye). We created replicated community plots that varied in species composition, structural complexity and density, then seeded in annual grass weeds and measured their biomass and seed production the following year, and their cover after 1 and 3 yr. Annual grass weeds were not strongly suppressed by any of the restored communities, indicating that it was difficult for native species to completely capture available resources and exclude annual grass weeds in the first years after planting. Perennial grass monocultures, particularly of the early seral grass bottlebrush squirreltail, were the most highly invaded communities, while structurally complex and diverse mixtures of shrubs (big sagebrush, rubber rabbitbrush), perennial grasses (bluebunch wheatgrass and bottlebrush squirreltail) and forbs (Lewis flax, Utah sweetvetch, hairy golden aster, gooseberryleaf globemallow) were more resistant to invasion. These results suggest that restoration of sagebrush steppe communities resistant to annual grass invasion benefits from higher species diversity; significant reduction of weed propagule pressure prior to restoration may be required.

scholarly journals Habitat Use by Nuttall’s Cottontails (Sylvilagus nuttallii nuttallii) at their Northern Range Edge (British Columbia, Canada)

2017 ◽  
Vol 131 (2) ◽  
pp. 133-140
Author(s):  
Emily J. Herdman ◽  
Karen E. Hodges
Keyword(s):  
British Columbia ◽  
Habitat Use ◽  
Natural Habitat ◽  
Movement Patterns ◽  
Sagebrush Steppe ◽  
Fragmented Habitats ◽  
Native Habitat ◽  
Range Edge ◽  
Shrub Steppe ◽  
Northern Edge

in Canada, Nuttall’s Cottontails (Sylvilagus nuttallii nuttallii) occur in southcentral British Columbia (BC), where they are federally listed as a species of special Concern due to their presumed small populations and limited distribution in fragmented habitats. Their habitat use and movement patterns are poorly known at this northern edge of their distribution. We used livetrapping, radio-collaring, and fecal pellet surveys to examine Nuttall’s Cottontails’ use of remaining patches of native habitat as well as use of human-impacted areas. Cottontails were present in low densities and only about half of presumably suitable patches of native sagebrush-steppe were occupied. Cottontails were more likely to occur in shrubby habitat, but at a fine scale cottontails used areas that had a lower density of shrubs and finer substrates. movement patterns differed significantly between areas of varying habitat quality, with longer movements in natural habitat. one radio-collared male cottontail used anthropogenic habitats adjacent to native habitat; this use corresponds with landowner reports. However, it is not clear whether Nuttall’s Cottontails are able to use anthropogenically-impacted areas to maintain populations or in areas where such habitats are not near native habitats. our results suggest that these animals are rare and occur primarily in remnant patches of shrub-steppe within BC.

Effects of fire on carbon fluxes of a calcareous grassland

2014 ◽  
Vol 23 (3) ◽  
pp. 425 ◽  
Author(s):  
Andrej Vončina ◽  
Mitja Ferlan ◽  
Klemen Eler ◽  
Franc Batič ◽  
Dominik Vodnik
Keyword(s):  
Plant Cover ◽  
Carbon Fluxes ◽  
Co2 Exchange ◽  
Fire Disturbance ◽  
Calcareous Grassland ◽  
Sink Strength ◽  
Long Term Effects ◽  
Natural Fire ◽  
Burned Areas ◽  
C Cycle

Frequent fires on drought-prone grasslands, such as pastures in the sub-Mediterranean region, can induce large post-fire variations of CO2 fluxes between the ecosystem and the atmosphere. Consequently, substantial changes in the C-cycle can be expected. In our research, we studied post-fire carbon fluxes (net canopy CO2 exchange (NE) and canopy respiration) on calcareous karst grassland after two spring fire events, a natural one in 2010 and a man-induced (anthropogenic) one in 2011. Canopy chamber measurements performed at short regular time intervals throughout the season revealed the rapid recovery of NE after the initial loss of C-sink strength. The long-term effects of the natural fire were largely masked by an early-season drought. In contrast, the burned areas did not reach the productivity of non-disturbed sites until the end of the season after the anthropogenic fire in 2011, when the post-burning period was characterised by favourable growing conditions. The similar NE values could be explained by a significant reduction of respiration at burned areas. Our research showed that C-sink strength of grassland after a fire disturbance can be re-established quite rapidly, after a month, although a full recovery (regeneration of plant cover, C fluxes) can take more time. The re-establishment is largely dependent on environmental conditions (soil water availability).

Modelling plant growth dynamics in sagebrush steppe communities affected by fire

2007 ◽  
Vol 69 (1) ◽  
pp. 144-157 ◽  
Author(s):  
R. Mata-González ◽  
R.G. Hunter ◽  
C.L. Coldren ◽  
T. McLendon ◽  
M.W. Paschke
Keyword(s):  
Plant Growth ◽  
Growth Dynamics ◽  
Sagebrush Steppe ◽  
Steppe Communities

Fall and spring grazing influence fire ignitability and initial spread in shrub steppe communities

2017 ◽  
Vol 26 (6) ◽  
pp. 485 ◽  
Author(s):  
Kirk W. Davies ◽  
Amanda Gearhart ◽  
Chad S. Boyd ◽  
Jon D. Bates
Keyword(s):  
Grazing Management ◽  
Management Tool ◽  
Fuel Moisture ◽  
Fire Propagation ◽  
Shrub Steppe ◽  
The World ◽  
Steppe Communities ◽  
Fuel Characteristics ◽  
Wildfire Season ◽  
Fire Ignition

The interaction between grazing and fire influences ecosystems around the world. However, little is known about the influence of grazing on fire, in particular ignition and initial spread and how it varies by grazing management differences. We investigated effects of fall (autumn) grazing, spring grazing and not grazing on fuel characteristics, fire ignition and initial spread during the wildfire season (July and August) at five shrub steppe sites in Oregon, USA. Both grazing treatments decreased fine fuel biomass, cover and height, and increased fuel moisture, and thereby decreased ignition and initial spread compared with the ungrazed treatment. However, effects differed between fall and spring grazing. The probability of initial spread was 6-fold greater in the fall-grazed compared with the spring-grazed treatment in August. This suggests that spring grazing may have a greater effect on fires than fall grazing, likely because fall grazing does not influence the current year’s plant growth. Results of this study also highlight that the grazing–fire interaction will vary by grazing management. Grazing either the fall or spring before the wildfire season reduces the probability of fire propagation and, thus, grazing is a potential fuel management tool.

scholarly journals A Disrupted Historical Fire Regime in Central British Columbia

2021 ◽  
Vol 9 ◽  
Author(s):  
Wesley Brookes ◽  
Lori D. Daniels ◽  
Kelsey Copes-Gerbitz ◽  
Jennifer N. Baron ◽  
Allan L. Carroll
Keyword(s):  
British Columbia ◽  
Prescribed Burning ◽  
Fire Regime ◽  
Spatial Scales ◽  
Fire Frequency ◽  
Dry Forest ◽  
Moderate Severity ◽  
High Severity ◽  
Wide Range ◽  
Fire Exclusion

In the 2017 and 2018, 2.55 million hectares burned across British Columbia, Canada, including unanticipated large and high-severity fires in many dry forests. To transform forest and fire management to achieve resilience to future megafires requires improved understanding historical fire frequency, severity, and spatial patterns. Our dendroecological reconstructions of 35 plots in a 161-hectare study area in a dry Douglas-fir forest revealed historical fires that burned at a wide range of frequencies and severities at both the plot- and study-area scales. The 23 fires between 1619 and 1943 burned at intervals of 10–30 years, primarily at low- to moderate-severity that scarred trees but generated few cohorts. In contrast, current fire-free intervals of 70–180 years exceed historical maximum intervals. Of the six widespread fires from 1790 to 1905, the 1863 fire affected 86% of plots and was moderate in severity with patches of higher severity that generated cohorts at fine scales only. These results indicate the severity of fires varied at fine spatial scales, and offer little support for the common assertion that periodic, high-severity, stand-initiating events were a component of the mixed-severity fire regime in these forest types. Many studies consider fires in the late 1800s relatively severe because they generated new cohorts of trees, and thus, emphasize the importance of high-severity fires in a mixed-severity fire regime. In our study area, the most widespread and severe fire was not a stand-initiating fire. Rather, the post-1863 cohorts persisted due disruption of the fire regime in the twentieth century when land-use shifted from Indigenous fire stewardship and early European settler fires to fire exclusion and suppression. In absence of low- to moderate-severity fires, contemporary forests are dense with closed canopies that are vulnerable to high-severity fire. Future management should reduce forest densities and to restore stand- and landscape-level heterogeneity and increase forest resilience. The timing and size of repeat treatments such as thinning of subcanopy trees and prescribed burning, including Indigenous fire stewardship, can be guided by our refined understanding of the mixed-severity fire regime that was historically dominated by low- to moderate-severity fires in this dry forest ecosystem.

scholarly journals Long-Term Effects of Periodical Fires on Archaeal Communities from Brazilian Cerrado Soils

Archaea ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Aline Belmok ◽  
Thiago Rodrigues-Oliveira ◽  
Fabyano A. C. Lopes ◽  
Heloisa S. Miranda ◽  
Ricardo H. Krüger ◽  
...  
Keyword(s):  
16S Rrna ◽  
Vegetation Structure ◽  
Archaeal Community ◽  
Fire Frequency ◽  
Sensu Stricto ◽  
Burned Area ◽  
Long Term Effects ◽  
Terrestrial Environments ◽  
Archaeal Communities

The Cerrado biome corresponds to an extensive area of Brazil and is considered a biodiversity hotspot. Frequent fires are a natural feature in this biome and have influences on vegetation structure and composition. However, continuous anthropogenic actions are promoting changes in fire frequency and seasonality. Despite the high biodiversity of the Cerrado, little is known about its microbiome, with few publications describing some aspects of the bacterial and fungal communities found on this biome and almost no references about archaea. In this study, we describe the archaeal diversity in Cerradosensu strictosoils, comparing the archaeal communities from soils of an area long protected from fires to one exposed to biennial fires, using both 16S rRNA andamoAgenes as molecular markers. Almost all 16S rRNA sequences from both studied areas were affiliated with I.1b and 1.1cThaumarchaeota, groups commonly detected in terrestrial environments. A higher relative abundance of I.1b thaumarchaeal subgroup was detected in the frequently burned area even though no statistically significant differences were observed in archaeal 16S rRNA richness and diversity between the investigated areas. Many ammonia-oxidizing archaea (AOA) are affiliated with this group, which is consistent with the higheramoAdiversity and OTU numbers detected in the area periodically burned. Taken together, our results suggest that, although total archaeal community richness and diversity do not seem to greatly differ between the investigated conditions, alterations in wood cover and vegetation structure caused by frequent fires likely cause long-term effects in AOA diversity in Cerrado soils.

scholarly journals Impact of Watershed Geomorphic Characteristics on the Energy and Water Budgets

2006 ◽  
Vol 7 (3) ◽  
pp. 389-403 ◽  
Author(s):  
Giacomo Bertoldi ◽  
Riccardo Rigon ◽  
Thomas M. Over
Keyword(s):  
Heat Flux ◽  
Land Surface ◽  
Large Scale ◽  
Sensible Heat Flux ◽  
Subsurface Water ◽  
Spatial And Temporal Variability ◽  
Long Term Effects ◽  
Channel Network ◽  
Soil Thickness ◽  
Adequate Treatment

Abstract The GEOtop model makes it possible to analyze the short- and long-term effects of geomorphic variation on the partitioning of the lateral surface and subsurface water and surface energy fluxes. The topography of the Little Washita basin (Oklahoma) and of the Serraia basin (Trentino, Italy) have been used as base topographies from which virtual topographies with altered slopes and elevations have been created with corresponding modifications of the soil thickness and the extension of the channel network, according to applicable geomorphological theories, in order to quantify the contribution of these topographic features to the spatial and temporal variability of energy and water fluxes. Simulation results show that both a more extended channel network and more accentuated slopes cause an increase in the discharge balanced by a diminution of the evapotranspiration. The diminution of the latent heat flux is balanced by the increase in the sensible heat flux. Net radiation shows a minor sensitivity to topography. Evaporative fraction, on the contrary, is shown to be strongly dependent on geomorphic characteristics. The results confirm the importance of including an adequate treatment of topography in large-scale land surface models.

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