Productivity of Two Prairie Grasses in Relation to Fire Frequency

Ecology ◽  
1963 ◽  
Vol 44 (2) ◽  
pp. 389-395 ◽  
Author(s):  
Elmer B. Hadley ◽  
Barbara J. Kieckhefer
The Holocene ◽  
2020 ◽  
Vol 30 (7) ◽  
pp. 1091-1096 ◽  
Author(s):  
Eleanor MB Pereboom ◽  
Richard S Vachula ◽  
Yongsong Huang ◽  
James Russell

Wildfires in the Arctic tundra have become increasingly frequent in recent years and have important implications for tundra ecosystems and for the global carbon cycle. Lake sediment–based records are the primary means of understanding the climatic influences on tundra fires. Sedimentary charcoal has been used to infer climate-driven changes in tundra fire frequency but thus far cannot differentiate characteristics of the vegetation burnt during fire events. In forested ecosystems, charcoal morphologies have been used to distinguish changes in fuel type consumed by wildfires of the past; however, no such approach has been developed for tundra ecosystems. We show experimentally that charcoal morphologies can be used to differentiate graminoid (mean = 6.77; standard deviation (SD) = 0.23) and shrub (mean = 2.42; SD = 1.86) biomass burnt in tundra fire records. This study is a first step needed to construct more nuanced tundra wildfire histories and to understand how wildfire will impact the region as vegetation and fire change in the future.


Fire ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 32
Author(s):  
Judy A. Foulkes ◽  
Lynda D. Prior ◽  
Steven W. J. Leonard ◽  
David M. J. S. Bowman

Australian montane sclerophyll shrubland vegetation is widely considered to be resilient to infrequent severe fire, but this may not be the case in Tasmania. Here, we report on the vegetative and seedling regeneration response of a Tasmanian non-coniferous woody montane shrubland following a severe fire, which burned much of the Great Pine Tier in the Central Plateau Conservation Area during the 2018–2019 fire season when a historically anomalously large area was burned in central Tasmania. Our field survey of a representative area burned by severe crown fire revealed that more than 99% of the shrubland plants were top-killed, with only 5% of the burnt plants resprouting one year following the fire. Such a low resprouting rate means the resilience of the shrubland depends on seedling regeneration from aerial and soil seedbanks or colonization from plants outside the burned area. Woody species’ seedling densities were variable but generally low (25 m−2). The low number of resprouters, and reliance on seedlings for recovery, suggest the shrubland may not be as resilient to fire as mainland Australian montane shrubland, particularly given a warming climate and likely increase in fire frequency.


2021 ◽  
Author(s):  
Scott L. Collins ◽  
Jesse B. Nippert ◽  
John M. Blair ◽  
John M. Briggs ◽  
Pamela Blackmore ◽  
...  

1992 ◽  
Vol 70 (8) ◽  
pp. 1596-1602 ◽  
Author(s):  
S. P. Bentivenga ◽  
B. A. D. Hetrick

Previous research on North American tallgrass prairie grasses has shown that warm-season grasses rely heavily on vesicular–arbuscular mycorrhizal symbiosis, while cool-season grasses are less dependent on the symbiosis (i.e., receive less benefit). This led to the hypothesis that cool-season grasses are less dependent on the symbiosis, because the growth of these plants occurs when mycorrhizal fungi are inactive. Field studies were performed to assess the effect of phenology of cool- and warm-season grasses on mycorrhizal fungal activity and fungal species composition. Mycorrhizal fungal activity in field samples was assessed using the vital stain nitro blue tetrazolium in addition to traditional staining techniques. Mycorrhizal activity was greater in cool-season grasses than in warm-season grasses early (April and May) and late (December) in the growing season, while mycorrhizal activity in roots of the warm-season grasses was greater (compared with cool-season grasses) in midseason (July and August). Active mycorrhizal colonization was relatively high in both groups of grasses late in the growing season, suggesting that mycorrhizal fungi may proliferate internally or may be parasitic at this time. Total Glomales sporulation was generally greater in the rhizosphere of cool-season grasses in June and in the rhizosphere of the warm-season grasses in October. A growth chamber experiment was conducted to examine the effect of temperature on mycorrhizal dependence of cool- and warm-season grasses. For both groups of grasses, mycorrhizal dependence was greatest at the temperature that favored growth of the host. The results suggest that mycorrhizal fungi are active in roots when cool-season grasses are growing and that cool-season grasses may receive benefit from the symbiosis under relatively cool temperature regimes. Key words: cool-season grasses, tallgrass prairie, vesicular–arbuscular mycorrhizae, warm-season grasses.


1993 ◽  
Vol 23 (6) ◽  
pp. 1213-1222 ◽  
Author(s):  
E.A. Johnson ◽  
D.R. Wowchuk

In this paper we present evidence for a large-scale (synoptic-scale) meteorological mechanism controlling the fire frequency in the southern Canadian Rocky Mountains. This large-scale control may explain the similarity in average fire frequencies and timing of change in average fire frequencies for the southern Canadian Rocky Mountains. Over the last 86 years the size distribution of fires (annual area burned) in the southern Canadian Rockies was distinctly bimodal, with a separation between small- and large-fire years at approximately 10–25 ha annual area burned. During the last 35 years, large-fire years had significantly lower fuel moisture conditions and many mid-tropospheric surface-blocking events (high-pressure upper level ridges) during July and August (the period of greatest fire activity). Small-fire years in this period exhibited significantly higher fuel moisture conditions and fewer persistent mid-tropospheric surface-blocking events during July and August. Mid-tropospheric surface-blocking events during large-fire years were teleconnected (spatially and temporally correlated in 50 kPa heights) to upper level troughs in the North Pacific and eastern North America. This relationship takes the form of the positive mode of the Pacific North America pattern.


Forests ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 210 ◽  
Author(s):  
Rebecca Harris ◽  
Tomas Remenyi ◽  
Paul Fox-Hughes ◽  
Peter Love ◽  
Nathaniel Bindoff

2014 ◽  
Vol 23 (2) ◽  
pp. 234 ◽  
Author(s):  
Ellis Q. Margolis

Piñon–juniper (PJ) fire regimes are generally characterised as infrequent high-severity. However, PJ ecosystems vary across a large geographic and bio-climatic range and little is known about one of the principal PJ functional types, PJ savannas. It is logical that (1) grass in PJ savannas could support frequent, low-severity fire and (2) exclusion of frequent fire could explain increased tree density in PJ savannas. To assess these hypotheses I used dendroecological methods to reconstruct fire history and forest structure in a PJ-dominated savanna. Evidence of high-severity fire was not observed. From 112 fire-scarred trees I reconstructed 87 fire years (1547–1899). Mean fire interval was 7.8 years for fires recorded at ≥2 sites. Tree establishment was negatively correlated with fire frequency (r=–0.74) and peak PJ establishment was synchronous with dry (unfavourable) conditions and a regime shift (decline) in fire frequency in the late 1800s. The collapse of the grass-fuelled, frequent, surface fire regime in this PJ savanna was likely the primary driver of current high tree density (mean=881treesha–1) that is >600% of the historical estimate. Variability in bio-climatic conditions likely drive variability in fire regimes across the wide range of PJ ecosystems.


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