Natures wonders: plant fire defenses (Introduction)

by David Turell , Sunday, October 22, 2023, 16:55 (396 days ago) @ David Turell
edited by David Turell, Sunday, October 22, 2023, 17:09

A Brazilian study:

https://phys.org/news/2023-10-cerrado-combine-strategies-survive.html

"'Fire plays an important role in the history of the Cerrado's savanna-type vegetation. To survive fires, these plants have developed various strategies, which the different lineages have refined during a long evolutionary process," Chiminazzo said.

"'We've known since we began studying the biome that the Cerrado's plants have thick bark to protect their internal tissues. They also have a wide array of below-ground organs that enable them to resprout because they're protected by being under the surface. However, these two strategies require plants to deploy a lot of resources. Our key question was whether they could do both at the same time—whether typical species of the Cerrado with below-ground organs were also able to produce significant amounts of above-ground bark."

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"By comparing below-ground organs and bark production rates, the authors of the study were able to show that plant species in the Cerrado can produce large amounts of bark (up to 0.9 millimeters per unit of growth) and at the same time develop below-ground organs that specialize in resprouting. In other words, they can protect themselves from fire by hiding a large proportion of their biomass below ground.

"'We also found a clear division between clonal species and species that occupy the same space throughout their life cycle [in a phenomenon termed on-spot persistence]. Specifically, clonal species with woody rhizomes tend to produce more bark, protect themselves better and grow taller than species with xylopodia and root crowns," he said.

"These differences suggest that the plants have evolved two distinct strategies for resprouting from underground buds: clonal growth associated with a considerable effort to protect aerial branches; and on-spot persistence, possibly linked to a stronger focus on protecting buds in organs below ground.

"'The findings show that plants in the Cerrado are capable of investing in different strategies to protect themselves against fire," Bombo said. "The usual view is that that they invest either in above- or below-ground strategies. The ability to invest in both reflects the extent to which woody plants have adapted to fire in the Cerrado. Having both aerial and underground fire-related strategies for regeneration and persistence enables these species to survive fire events of varying intensities.'"

Comment: wildfire plays a definite role in plant evolution. Our Western pines have a different mechanism for fire survival.

https://www.nationalforests.org/our-forests/your-national-forests-magazine/how-trees-su...

"Trees in fire-prone areas develop thicker bark, in part, because thick bark does not catch fire or burn easily. It also protects the inside of the trunk, the living tissues that transport water and nutrients, from heat damage during high-frequency, low-intensity fires. Ponderosa pine (Pinus ponderosa, also commonly known as the bull pine, blackjack pine or western yellow pine) is a great example.

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"This fire-survival strategy allows for the complete destruction of above-ground growth. Typically, species that regenerate by re-sprouting after they’ve burned have an extensive root system. Dormant buds are protected underground, and nutrients stored in the root system allow quick sprouting after the fire.

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"In environments where hot, fast moving fires are frequent, some pine species have developed very thick, hard cones that are literally glued shut with a strong resin. These “serotinous” cones can hang on a pine tree for years, long after the enclosed seeds mature. Only when a fire sweeps through, melting the resin, do these heat-dependent cones open up, releasing seeds that are then distributed by wind and gravity.

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"As opposed to serotinous cones, which protect enclosed seeds during a fire, the actual seeds of many plants in fire-prone environments need fire, directly or indirectly, to germinate. These plants produce seeds with a tough coating that can lay dormant, awaiting a fire, for several years. Whether it is the intense heat of the fire, exposure to chemicals from smoke or exposure to nutrients in the ground after fire, these seeds depend on fire to break their dormancy."

Comment: how did these plants survive before developing these mechanisms? Wildfires are a constant natural event. Not by Darwinian theory. Design is required.