scholarly journals The existence of a fire‐mediated tree‐recruitment bottleneck in an Asian savanna

2019 ◽  
Vol 46 (4) ◽  
pp. 745-756 ◽  
Author(s):  
Thuy T. Nguyen ◽  
Brett P. Murphy ◽  
Patrick J. Baker
Keyword(s):  
Tree Recruitment ◽  
Recruitment Bottleneck

scholarly journals Experimental evidence that fire causes a tree recruitment bottleneck in an Australian tropical savanna

2010 ◽  
Vol 26 (6) ◽  
pp. 595-603 ◽  
Author(s):  
Lynda D. Prior ◽  
Richard J. Williams ◽  
David M. J. S. Bowman
Keyword(s):  
Adult Size ◽  
Canopy Layer ◽  
Tree Recruitment ◽  
Savanna Vegetation ◽  
Fire Experiment ◽  
Adult Trees ◽  
Tropical Australia ◽  
Original Size ◽  
Recruitment Bottleneck ◽  
Stem Mortality

Abstract:A fire-mediated recruitment bottleneck provides a possible explanation for the coexistence of trees and grasses in mesic savannas. The key element of this hypothesis is that saplings are particularly vulnerable to fire because they are small enough to be top-killed by grass fires, but unlike juveniles, they take several years to recover their original size. This limits the number of recruits into the adult size classes. Thus savanna vegetation may be maintained by a feedback whereby fire restricts the density of adult trees and allows a grass layer to develop, which provides fuel for subsequent fires. Here, we use results from a landscape-scale fire experiment in tropical Australia, to explore the possible existence of a recruitment bottleneck. This experiment compared tree recruitment and survival over 4 y under regimes of no fire, annual early and annual late dry-season fire. Stem mortality decreased with increasing stem height in the fire treatments but not in the unburnt treatment. Tree recruitment was 76–84% lower in the fire treatments than the unburnt treatment. Such fire-induced stem loss of saplings and reduced recruitment to the canopy layer in this eucalypt savanna are consistent with the predictions of the fire-mediated recruitment bottleneck hypothesis.

Fire and stand history in two limber pine (Pinus flexilis) and Rocky Mountain bristlecone pine (Pinus aristata) stands in Colorado

2008 ◽  
Vol 17 (3) ◽  
pp. 339 ◽  
Author(s):  
Peter M. Brown ◽  
Anna W. Schoettle
Keyword(s):  
Tree Mortality ◽  
Fire Severity ◽  
Rocky Mountain ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Ice Age ◽  
Tree Recruitment ◽  
Fire Scar ◽  
Limber Pine ◽  
Bristlecone Pine

We developed fire-scar and tree-recruitment chronologies from two stands dominated by limber pine and Rocky Mountain bristlecone pine in central and northern Colorado. Population structures in both sites exhibit reverse-J patterns common in uneven-aged forests. Bristlecone pine trees were older than any other at the site or in the limber pine stand, with the oldest tree dating to 780 AD and several dating to the 1000s and 1100s. The oldest trees in the limber pine stand date to the 1400s, with a majority of recruitment after an apparent bark beetle outbreak in the early 1800s. Spatial patterning in the limber pine suggests that the oldest trees established from seed caches left by corvid birds. Fire scars present in the early part of each chronology document that surface fire regimes dominated during certain periods. Decreased fire frequency, increased tree recruitment, and changes in species composition from the 1600s to1800s in the bristlecone pine may be reflective of cooler and wetter conditions during the Little Ice Age. Results suggest that a recent (1978) severe fire in the bristlecone pine stand that caused complete tree mortality was outside the historical range of variability in fire severity for at least the past ~1000 years.

The reduction of organic-layer depth by wildfire in the North American boreal forest and its effect on tree recruitment by seed

2007 ◽  
Vol 37 (6) ◽  
pp. 1012-1023 ◽  
Author(s):  
David F. Greene ◽  
S. Ellen Macdonald ◽  
Sybille Haeussler ◽  
Susy Domenicano ◽  
Josée Noël ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Inverse Function ◽  
Organic Layer ◽  
Layer Depth ◽  
Tree Recruitment ◽  
Organic Layers ◽  
Boreal Region ◽  
The North ◽  
Forest Species Composition

We compared prefire and postfire organic-layer depths in boreal forest types (14 fires) across Canada, and examined tree recruitment as a function of depth. There was extensive within-stand variation in depth, much of it due to clustering of thinner organic layers around boles. There were no significant differences in postfire organic-layer depth among sites with different prefire forest species composition, but sites in the eastern boreal region had thicker postfire organic layers than those in the western boreal region. Mean organic-layer depth was much greater in intact stands than after fires; overall, fire reduced organic-layer depth by 60%, largely because of increases in the area of thin (<3 cm) organic layers (1% in intact stands vs. 40% in postfire stands). There was more variation in organic-layer depth within postfire than within prefire stands; notably, some areas in postfire stands were deeply combusted, while adjacent parts were only lightly combusted. We speculate that the diminished role of energy loss to latent heat around tree boles increased organic-layer consumption around tree boles. Seedlings were clustered around burned tree bases, where organic layers were thinner, and the dependence of a species on thin organic layers was an inverse function of seed size.

Role of Avian Seed Dispersers in Tree Recruitment in Woodland Pastures

Ecosystems ◽  
2016 ◽  
Vol 20 (3) ◽  
pp. 616-629 ◽  
Author(s):  
Daniel Martínez ◽  
Daniel García
Keyword(s):  
Tree Recruitment ◽  
Seed Dispersers

Enhanced Tree Recruitment Following Logging in Two Forest Reserves in Ghana

Biotropica ◽  
2008 ◽  
Vol 40 (3) ◽  
pp. 370-374 ◽  
Author(s):  
Michael D. Swaine ◽  
Victor K. Agyeman
Keyword(s):  
Tree Recruitment ◽  
Forest Reserves

scholarly journals Climate change effects on early stages of Quercus ariifolia (Fagaceae), an endemic oak from seasonally dry forests of Mexico

2019 ◽  
Author(s):  
Ernesto I. Badano ◽  
Francisco A. Guerra-Coss ◽  
Erik J. Sánchez-Montes de Oca ◽  
Carlos I. Briones-Herrera ◽  
Sandra M. Gelviz-Gelvez
Keyword(s):  
Climate Change ◽  
Functional Traits ◽  
Rainy Season ◽  
Extinction Risk ◽  
Seedling Emergence ◽  
Dry Forest ◽  
Tree Seedlings ◽  
Dry Forests ◽  
Tree Recruitment ◽  
Seasonally Dry

Background and Aims: Tree recruitment in seasonally dry forests occurs during the rainy season. However, higher temperatures and reduced rainfalls are expected in these ecosystems because of climate change. These changes could induce drought conditions during the rainy season and affect tree recruitment. Plants subjected to thermal or water stress often display morphological and physiological shifts addressed to prioritize their survival. If recently emerged tree seedlings display these responses, this could improve their development during the rainy season and increase their survival chances. Our aim was to test whether recently emerged oak seedlings display these responses.Methods: We performed a field experiment with Quercus ariifolia, an oak species endemic to seasonally dry forests of central Mexico. At the beginning of the rainy season (September 2016), we sowed acorns of this species in control plots under the current climate and plots in which climate change was simulated by increasing temperature and reducing rainfall (CCS plots). Seedling emergence and survival were monitored every seven days during the rainy season (until January 2017). At the end of the experiment, we measured several functional traits on surviving seedlings and compared them between controls and CCS plots.Key results: Higher temperature and lower rainfall generated water shortage conditions in CCS plots. This did not affect emergence of seedlings but reduced their survival. Seedlings that survived in CCS plots displayed shifts in their functional traits, which matched with those of plants subjected to thermal and water stress.Conclusions: Our results suggest that climate change can increase the extinction risk of Q. ariifolia in seasonally dry forest of Mexico by reducing the survival of its offspring. Nevertheless, the results also suggest that seedlings developed under climate change conditions can display functional shifts that could confer them tolerance to increased drought.

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