scholarly journals Shocks to the system: community assembly of the oak savanna in a 40-year fire frequency experiment

Ecology ◽  
2012 ◽  
Vol 93 (sp8) ◽  
pp. S52-S69 ◽  
Author(s):  
Jeannine Cavender-Bares ◽  
Peter B. Reich
Keyword(s):  
Community Assembly ◽  
Fire Frequency ◽  
Oak Savanna

scholarly journals Century-scale wood nitrogen isotope trajectories from an oak savanna with variable fire frequencies

2020 ◽  
Vol 17 (18) ◽  
pp. 4509-4522
Author(s):  
Matthew L. Trumper ◽  
Daniel Griffin ◽  
Sarah E. Hobbie ◽  
Ian M. Howard ◽  
David M. Nelson ◽  
...  
Keyword(s):  
20Th Century ◽  
Prescribed Burning ◽  
Fire Frequency ◽  
Oak Savanna ◽  
N Availability ◽  
Net N Mineralization ◽  
Vegetation Composition ◽  
Prescribed Burn ◽  
Decadal Scale

Abstract. Fire frequency exerts a fundamental control on productivity and nutrient cycling in savanna ecosystems. Individual fires often increase short-term nitrogen (N) availability to plants, but repeated burning causes ecosystem N losses and can ultimately decrease soil organic matter and N availability. However, these effects remain poorly understood due to limited long-term biogeochemical data. Here, we evaluate how fire frequency and changing vegetation composition influenced wood stable N isotopes (δ15N) across space and time at one of the longest running prescribed burn experiments in the world (established in 1964). We developed multiple δ15N records across a burn frequency gradient from precisely dated Quercus macrocarpa tree rings in an oak savanna at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. Sixteen trees were sampled across four treatment stands that varied with respect to the temporal onset of burning and burn frequency but were consistent in overstory species representation, soil characteristics, and topography. Burn frequency ranged from an unburned control stand to a high-fire-frequency stand that had burned in 4 of every 5 years during the past 55 years. Because N stocks and net N mineralization rates are currently lowest in frequently burned stands, we hypothesized that wood δ15N trajectories would decline through time in all burned stands, but at a rate proportional to the fire frequency. We found that wood δ15N records within each stand were remarkably coherent in their mean state and trend through time. A gradual decline in wood δ15N occurred in the mid-20th century in the no-, low-, and medium-fire stands, whereas there was no trend in the high-fire stand. The decline in the three stands did not systematically coincide with the onset of prescribed burning. Thus, we found limited evidence for variation in wood δ15N that could be attributed directly to long-term fire frequency in this prescribed burn experiment in temperate oak savanna. Our wood δ15N results may instead reflect decadal-scale changes in vegetation composition and abundance due to early- to mid-20th-century fire suppression.

scholarly journals Spatial scale in prescribed fire regimes: an understudied aspect in conservation with examples from the southeastern United States

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
David S. Mason ◽  
Marcus A. Lashley
Keyword(s):  
United States ◽  
Spatial Scale ◽  
Plant Community ◽  
Prescribed Fire ◽  
Community Assembly ◽  
Southeastern United States ◽  
Fire Regimes ◽  
Fire Frequency ◽  
In Fire ◽  
Plant Community Assembly

AbstractThe idea that not all fire regimes are created equal is a central theme in fire research and conservation. Fire frequency (i.e., temporal scale) is likely the most studied fire regime attribute as it relates to conservation of fire-adapted ecosystems. Generally, research converges on fire frequency as the primary filter in plant community assembly and structure, which is often critical to conservation goals. Thus, conservation success is commonly linked to fire frequency in fire regimes.The spatial scale of fire may also be vital to conservation outcomes, but this attribute is underrepresented in the primary literature. In our global, contemporary literature search, we found 37 published syntheses concerning the effects of prescribed fire in conservation over the last decade. In those syntheses, only 16% included studies that reported data-based inferences related to the spatial scale of the fire, whereas 73% included discussion of empirical studies on the temporal scale. Only one of the syntheses discussed studies that explicitly tested the effects of spatial extent, and none of those studies were experiments manipulating spatial scale. Further, understanding spatial-scale-dependent patterns may be relevant because two databases of fire-occurrence data from the United States indicated that spatial scale among lightning-ignited and prescribed fires may have been mismatched over the past few decades.Based on a rich ecological literature base that demonstrates pervasive scale-dependent effects in ecology, spatial-scale-dependent relationships among prescribed fire regimes and conservation outcomes are likely. Using examples from the southeastern United States, we explored the potential for scale-dependent ecological effects of fire. In particular, we highlighted the potential for spatial scale to (a) influence wildlife populations by manipulating the dispersion of habitat components, and (b) modulate plant community assembly and structure by affecting seed dispersal mechanics and spatial patterns in herbivory. Because spatial-scale-dependent outcomes are understudied but likely occurring, we encourage researchers to address the ecological effects of spatial scale in prescribed-fire regimes using comparative and manipulative approaches.

scholarly journals Century-scale wood nitrogen isotope trajectories from an oak savanna with variable fire frequencies

2020 ◽  
Author(s):  
Matthew Trumper ◽  
Daniel Griffin ◽  
Sarah E. Hobbie ◽  
Ian Howard ◽  
David M. Nelson ◽  
...  
Keyword(s):  
20Th Century ◽  
Prescribed Burning ◽  
Fire Frequency ◽  
Oak Savanna ◽  
N Availability ◽  
Net N Mineralization ◽  
Vegetation Composition ◽  
Prescribed Burn ◽  
Decadal Scale

Abstract. Fire frequency exerts a fundamental control on productivity and nutrient cycling in savanna ecosystems. A single fire event often increases short-term nitrogen (N) availability to individual plants, but repeated burning causes ecosystem carbon and N losses and can ultimately decrease soil organic matter and N availability. However, these effects remain poorly understood due to limited long-term biogeochemical data. Here, we leveraged one of the longest running prescribed burn experiments (established in 1964) to evaluate how fire frequency and changing vegetation composition influenced wood stable N isotopes (δ15N) across space and time. We developed multiple δ15N records across a burn frequency gradient from precisely dated Quercus macrocarpa tree-rings in an oak savanna at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. Sixteen trees were sampled across four treatment stands that varied in temporal onset of burning and burn frequency, but were consistent in overstory species representation, soil characteristics, and topography. Burn frequency ranged from an unburned control stand to a high fire-frequency stand that burned in four of every five years during the past 55 years. Because N stocks and net N mineralization rates are currently lowest in frequently burned stands, we hypothesized that wood δ15N trajectories would have declined over time in all burned stands, but at a rate proportional to fire frequency. We found that wood δ15N records within each stand were remarkably coherent in their mean state and trend through time. A gradual, temporally synchronous decline in wood δ15N occurred in the mid 20th century in the no-, low-, and medium-fire stands, whereas there was no trend in the high-fire stand. The decline in the three stands did not systematically coincide with the onset of prescribed burning. Thus, we found limited evidence for variation in wood δ15N that could be attributed directly to long-term fire frequency in this prescribed burn experiment in temperate oak savanna. Our wood δ15N results may instead reflect decadal-scale changes in vegetation composition and abundance due to early to mid 20th century fire suppression.

Experimentally altered rainfall regimes and host root traits affect grassland arbuscular mycorrhizal fungal communities

2019 ◽  
Author(s):  
Coline Deveautour ◽  
Suzanne Donn ◽  
Sally Power ◽  
Kirk Barnett ◽  
Jeff Powell
Keyword(s):  
Fungal Community ◽  
Community Assembly ◽  
Root Length ◽  
Specific Root Length ◽  
Root Traits ◽  
Arbuscular Mycorrhizal ◽  
Fungal Communities ◽  
Rainfall Regime ◽  
Precipitation Regimes ◽  
Rainfall Regimes

Future climate scenarios predict changes in rainfall regimes. These changes are expected to affect plants via effects on the expression of root traits associated with water and nutrient uptake. Associated microorganisms may also respond to these new precipitation regimes, either directly in response to changes in the soil environment or indirectly in response to altered root trait expression. We characterised arbuscular mycorrhizal (AM) fungal communities in an Australian grassland exposed to experimentally altered rainfall regimes. We used Illumina sequencing to assess the responses of AM fungal communities associated with four plant species sampled in different watering treatments and evaluated the extent to which shifts were associated with changes in root traits. We observed that altered rainfall regimes affected the composition but not the richness of the AM fungal communities, and we found distinctive communities in the increased rainfall treatment. We found no evidence of altered rainfall regime effects via changes in host physiology because none of the studied traits were affected by changes in rainfall. However, specific root length was observed to correlate with AM fungal richness, while concentrations of phosphorus and calcium in root tissue and the proportion of root length allocated to fine roots were correlated to community composition. Our study provides evidence that climate change and its effects on rainfall may influence AM fungal community assembly, as do plant traits related to plant nutrition and water uptake. We did not find evidence that host responses to altered rainfall drive AM fungal community assembly in this grassland ecosystem.

Marine bacterioplankton consortia follow deterministic, non-neutral community assembly rules

2017 ◽  
Vol 79 (2) ◽  
pp. 165-175 ◽  
Author(s):  
KL Vergin ◽  
N Jhirad ◽  
J Dodge ◽  
CA Carlson ◽  
SJ Giovannoni
Keyword(s):  
Community Assembly ◽  
Assembly Rules ◽  
Marine Bacterioplankton

Inter-taxonomic differences in bacterioplankton community assembly in oligotrophic mountain lakes of east Japan

2015 ◽  
Vol 75 (3) ◽  
pp. 251-257 ◽  
Author(s):  
M Fujii ◽  
T Hirao ◽  
H Kojima ◽  
M Fukui
Keyword(s):  
Community Assembly ◽  
Mountain Lakes ◽  
Bacterioplankton Community
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