Blackhall, M., Raffaele, E., Paritsis, J., Tiribelli, F., Morales, J. M. , Kitzberger, T., Gowda, J. H. and Veblen, T. T. (2017) Effects of biological legacies and herbivory on fuels and flammability traits: a long-term experimental study of alternative stable states. Journal of Ecology, 105(5), pp. 1309-1322. (doi: 10.1111/1365-2745.12796)
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Abstract
1. Ecological memory, often determined by the extent and type of retained biological legacies present following disturbance, may produce persistent landscape patterns. However, after fire, the persistence or switch to an alternative state may depend on the complex interplay of ecological memory (biological legacies) and potential effects of new external factors influencing the post-fire environment. The current study assesses both the strength of ecological memory resulting from biological legacies of pre-burn vegetation types as well as post-fire effects of livestock. 2. Following a severe fire in 1999, we set up a network of long-term exclosures to examine the effects of legacies and cumulative herbivory by cattle on fuel types, amounts, distribution, flammability and microenvironmental conditions in two post-fire communities representing alternative fire-driven states: pyrophobic Nothofagus pumilio subalpine forests and pyrophytic Nothofagus antarctica tall shrublands in northwestern Patagonia, Argentina. 3. Our results show that the retained post-disturbance legacies of tall shrublands and subalpine forests largely determine fuel and flammability traits of the post-fire plant communities 16 years after fire. The importance of biological legacies retained from the unburned plant communities was reflected by the substantially higher amounts of total fine fuel, greater vertical and horizontal fuel continuity and the higher temperatures reached during experimental tissue combustion at post-fire shrubland compared to post-fire forest sites. 4. We show that herbivores may produce antagonistic effects on flammability by decreasing tissue ignitability, total fine fuel and litter depth, and disrupting the vertical and horizontal fine fuel continuity, therefore reducing the probability of fire propagation. However, cattle can increase ratios of dead to live fine fuels, reduce soil moisture, and inhibit tree height growth to canopy size, consequently impeding the development of a closed pyrophobic forest canopy. 5. Synthesis. Our results support the hypothesis that biological legacies, most importantly the dominance by pyrophytic woody plants that resprout vigorously vs. the dominance by pyrophobic obligate seeders, favour fuel and flammability characteristics at the community level which reinforce the mechanisms maintaining pyrophytic shrublands vs. pyrophobic forests. Herbivory by introduced cattle can partially blur sharp pyrophobic/pyrophytic state boundaries by promoting the development of novel post-fire transitional states.
| Item Type: | Articles |
|---|---|
| Additional Information: | Research was supported by PIP grant no. 112 201101 00058, PICT grants2012-2371 and 2012-0949, awards 0956552 and 0966472 from the United States National Science Foundation, and Universidad Nacional del Comahue (UNC B172). |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Morales, Professor Juan |
| Authors: | Blackhall, M., Raffaele, E., Paritsis, J., Tiribelli, F., Morales, J. M., Kitzberger, T., Gowda, J. H., and Veblen, T. T. |
| College/School: | College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine |
| Journal Name: | Journal of Ecology |
| Publisher: | Wiley |
| ISSN: | 0022-0477 |
| ISSN (Online): | 1365-2745 |
| Published Online: | 19 April 2017 |
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