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Posts Tagged ‘insects’

Fire benefits plants by disrupting antagonistic interactions

October 2nd, 2016 2 comments

There are many plants that benefit from fire. Typical examples are those that despite they may be killed by fire, the germination of their seeds is stimulated by the fire (either by the heat or by the smoke; [1,2]), and thus they recruit very well (high offspring abundance) and often increase there population size postfire. Species with fire-stimulated flowering [3,4] also benefit from fire. In a recent paper [5] we propose that there may be another mechanisms by which fire may benefit plants: fire may remove seed predators, and thus create a window of opportunity for reproduction under a lower predation pressure (predator release hypothesis). This is specially applicable to specialist plant-insect interactions. We documented two cases: in Ulex parviflorus, a plant species with fire-stimulated germination [1,2], fire eliminated there specialist seed predator weevil (Exapion fasciolatum, Apioninae, Brentidae) and thus increased the available seed number for germination. Similarly, in Asphodelus ramosus, a fire-stimulated flowering species [3], fire reduced the specialist herbivore and seed predator (Horistus orientalis, Miridae, Hemiptera) and increased their fruit production. Thus, fire, by disrupting the antagonistic interactions, benefit plants; the temporal window of this predator release is likely to depend on fire size. For more information see reference [5].

Ulex-Exapion

Figure: Proportion of predated fruits of Ulex parviflorus in unburned sites (grey boxes) and at the edge and center of a recently burned area (white boxes), 2 and 3 years postfire. Data from two large wildfires in Valencia (2012) [5]; Edge and Center of the burned area refer to <1 km and >1.5 km from the fire perimeter, respectively. Photo of the seed predator (Exapion) from BioLib.cz.

References

[1] Moreira B., Tormo J., Estrelles E., Pausas J.G. 2010. Disentangling the role of heat and smoke as germination cues in Mediterranean Basin flora. Annals of Botany 105: 627-635. [pdf | doi | blog]

[2] Moreira B and Pausas JG. 2012. Tanned or Burned: the role of fire in shaping physical seed dormancy. PLoS ONE 7:e51523. [doi | plos | pdf]

[3] Postfire blooming of Asphodelous, jgpausas.blogs.uv.es/2014/04/05

[4] Postfire flowering: Narcissus, jgpausas.blogs.uv.es/2015/05/02

[5] García Y., Castellanos M.C. & Pausas J.G. 2016. Fires can benefit plants by disrupting antagonistic interactions. Oecologia 182: 1165–1173. [doi | pdf] <- New!!

 

Odena fire: first visitors

August 10th, 2015 1 comment

The 27th of July a fire in Òdena (Anoia, central Catalonia, NE Spain) burned ca. 1200 ha, mainly of Pinus halepensis. It was a crown fire of relatively high intensity. Twelve days after the fire, everything was still black, there were not yet signs of any plant resprouting; however, there were already few visitors. Here a couple of examples.

 

bitxos
Charaxes jasius (left) and Parasteropleurus (Steropleurus) perezii (right) on recently burned trees (Photos by A. Mazcuñan and P. Mazcuñan, respectively).

 

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