Renowned journalist, publisher and geologist Robert Chambers spent the majority of his 19th Century life actively engaged in two - often antagonistic - worlds, the world of science and that of the high-society Scottish elite. It may have been his struggle to maintain balance between these two worlds, one that valued rationality and meticulous observation, the other preferring political correctness and adherence to theological dictates, which helped guide him to the decision to anonymously publish his 1844 work ‘Vestiges of the Natural History of Creation.’ The work was truly progressive by almost any measure and it would go on to influence such diverse individuals as the scientifically minded Charles Darwin and the poetically endowed Alfred, Lord Tennyson.
It was a combination of Vestiges’ theological implications and the loss of a dear friend that motivated Lord Tennyson to pen the following stanza:
It was a combination of Vestiges’ theological implications and the loss of a dear friend that motivated Lord Tennyson to pen the following stanza:
Who trusted God was love indeed
And love Creation's final law
Tho' Nature, red in tooth and claw
With ravine, shriek'd against his creed
(In Memoriam A.H.H., Canto 27)
‘Nature, red in tooth and claw’ is an often quoted metaphor for natural selection, and as such, it has been a recurrent theme here at Ecographica. During several previous posts, a harmonious – ‘all is in balance’ - view of nature was contrasted with the perspective of nature as a series of oppositional organisms struggling to gain a competitive edge over rivals. During these comparisons, the ‘red in tooth and claw’ view was the hands-down victor in all cases; being both more analytically accurate, and the more observationally sound perspective. As a case in point, two recently published articles, one appearing in the December edition of The American Naturalist, the other in the July New Phytologist have compelled the issuance of an update to a post made back in April; a post that emphasized the above described contrasting views of nature. Both of the published articles lend further credence to the conceptual “fire gene,” an idea coined in the April blog. One article supports the fire gene concept through development of ecological disturbance feedback models; the other tells the story of an invasive plant with a contrasting and adversarial phenotype to the one detailed in the original post, a phenotype that suppresses fire – it bears what can be called an “anti-fire gene.” As with the original blog post, the re-write begins in the Big Cypress Preserve, with a somewhat overly embellished lead-in…
Nature Red in Tooth and Flame
Gazing across the tranquil landscape of the Big Cypress Preserve, nature seems to be in balance, unchanging and at peace - picturesque beyond any poetic description. Within this serene setting, anthropogenic throngs of sharply angled concrete and glass edifices suspend their battle for roadside commercial dominance and yield themselves to a sea of sparsely treed savannas, rolling prairies of grass, and randomly scattered islands of thickly vegetated hammocks. It’s the perfect environment for a relaxing stroll, a picnic, or, an inquiry into the natural world...
Gazing across the tranquil landscape of the Big Cypress Preserve, nature seems to be in balance, unchanging and at peace - picturesque beyond any poetic description. Within this serene setting, anthropogenic throngs of sharply angled concrete and glass edifices suspend their battle for roadside commercial dominance and yield themselves to a sea of sparsely treed savannas, rolling prairies of grass, and randomly scattered islands of thickly vegetated hammocks. It’s the perfect environment for a relaxing stroll, a picnic, or, an inquiry into the natural world...
All may appear calm within this enchanting panorama with its diverse array of plants, animals and abiotic ornamentation; however, this perceived tranquility is but a chimera. It is a mere illusion of serenity resulting from shortfalls in the ability of the observer’s photoreceptors to see beyond that narrow range of the electromagnetic spectrum called visible light, an inability to hear sound outside of 22000 Hertz, and the failure of the human olfactory system to nose its way into the vast chemo-landscape of pheromones and other volatile chemicals in which it is continuously assailed. Indeed, if only the sensory apparatus of Homo sapiens was keener – if only it was more finely calibrated – the landscape of the Big Cypress would be seen for what it truly is… How very different it would seem.
Picture taken from Turner river Rd - Big Cypress Preserve
Before getting to the exploitation of fire, it is important to understand that natural plant communities exist in a continuum of environments and have adapted to inhabit almost every available niche on the planet; from “box thorns” in Death Valley to fully aquatic hyacinths floating around the lakes of Brazil, genetic plasticity in plants is clearly evidenced as a product of natural selection. And although the conquest of diverse habitats represent a surmountable challenge, a multitude of both biotic and abiotic factors conspire to determine the overall abundance (density), composition (diversity) and ultimate success of plant communities at any given location.
For example, looking across the landscape of the Big Cypress, densely concentrated hardwood trees form hammocks which, due to the broad area of their collective canopies, limit the amount of sunlight available to underlying herbaceous groundcover. This is a straight forward relationship, no sunlight reaching the ground means fewer plants on the ground. Following this rationale, if the tree canopy should be opened, say by a storm, hurricane or by the death of older trees, this would permit sunlight to temporarily penetrate to the floor and a rapid emergence (recruitment) of both herbaceous plants and new saplings would be predicted. This is precisely what happens; in this example sunlight is the limiting resource and once made available those plants best able to take advantage of the situation through rapid growth will be able to quite literally overshadow their competitors. Stated differently, plants with genetic compliments favoring a period of ‘initial rapid growth’ are at an advantage and will be positively selected if positioned to compete for sunlight with a species lacking such a genetic compliment.
Similar to the botanical quarrels described for wooded hammocks - those in which plants have undergone selection for rapid growth - plants also engage in conflict to secure access to the resources offered by prairies and savannas. And, just as with the battles for sunlight on the forest floor, contenders occupying hammock-savanna ecotones have evolved specific defensive and offensive phenotypes to aid in their advance; as alluded to earlier, a few have even acquired the ability to harness the power of fire. Like the genetic compliment that allows a plant to undergo a period of initial rapid growth when a break in the hammock’s canopy becomes manifest, some plants possess a genetic compliment that allow for direct modification of local ecology. In short, the genetic compliment allows the plant to apply heat and flame in a cutthroat effort to destroy competitors, and to assert themselves as ecosystem engineers.
[The second installment of this post is available HERE.]
Beckage, B., Platt, W., & Gross, L. (2009). Vegetation, Fire, and Feedbacks: A Disturbance‐Mediated Model of Savannas The American Naturalist, 174 (6), 805-818 DOI: 10.1086/648458
Stevens, J., & Beckage, B. (2009). Fire feedbacks facilitate invasion of pine savannas by Brazilian pepper New Phytologist, 184 (2), 365-375 DOI: 10.1111/j.1469-8137.2009.02965.x
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