The unique challenges of conserving forest giants

April 22, 2016, Cell Press
A coastal redwood in northern California. Credit: Rhett Butler

The redwood and sequoia trees in California, the baobab trees in Madagascar, and the rose gum Eucalyptus trees in northeastern Australia are only a few of the spectacular large, old trees still growing today. Protecting these trees, some hundreds or thousands of years old, requires thinking long-term about concerns such as their unique habitat needs and the impacts of climate change, researchers write in a Forum published April 22, Earth Day, in Trends in Ecology & Evolution.

"How many of us as children have stared up at a cathedral-like crown in wonder, or climbed a giant tree and just had that be a really special part of our lives?" asks Bill Laurance, a tropical ecologist at James Cook University. "These big trees are just taking it in the neck from every direction.We're dealing with organisms that have evolved for long periods of ecological stability, and that's becoming a really scarce commodity in the world in which we live."

"There's a lot to discuss on the issue," says David Lindenmayer, a conservation ecologist at the Australian National University. "Climate change will mean that, in some places, big trees will not reach the same sizes they used to." The effects of , including prolonged droughts, more invasive species, new pathogens, and habitat fragmentation, compound the simple physical challenges that large trees already face in pulling water from their roots to their leaves and withstanding windstorms.

Lindenmayer and Laurance define "large, old trees" as the largest five percent of sexually mature trees within a species. The flexible definition means that in some forests, the large, old trees might be only 20 meters tall and 100 years old, but the big trees might be taller than a football field is long in other areas, and over 2,000 years old.

This figure shows the height, girth, and locations of some of the world's largest tree species. Credit: Lindenmayer and Laurance/Trends in Ecology & Evolution 2016

These large, old trees dominate the surrounding plant communities, affect water and nutrient distribution, and provide food and shelter for wildlife. "They're really the breadbaskets, the supermarkets, of the forest," says Laurance. "This is a very environmentally and ecologically important group of organisms, and they need special care and handling."

Identifying the distribution and habitat requirements for large, in the landscape is a first step towards ensuring their survival, say Lindenmayer and Laurance. Conservation efforts may take shape as preserving large swaths of forest or as maintaining single trees in urban environments, with further innovations for trees that exist as small clusters or individuals in savanna or desert regions.

"We have to ensure that we're thinking long-term, to match the way these trees have existed for hundreds or even thousands of years," says Laurance. "It's going to be a real challenge to maintain some places in the world that still have something like a wild nature—that still have natural wildlife, seed dispersers, pollinators, large predators, and the magnificent cathedral-like that we all really care about."

A rainforest tree in tropical Australia festooned with lianas, epiphytic orchids and ferns, and mosses. Many big trees provide habitats for a zoo of other plants and animals. Credit: William Laurance

Explore further: Future grim for 'biggest and most magnificent' trees

More information: Trends in Ecology & Evolution, Lindenmayer and Laurance: "The unique challenges of conserving large old trees" DOI: 10.1016/j.tree.2016.03.003

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5 / 5 (6) Apr 22, 2016
Many of the conifer species will grow to rather large sizes, however they tend to get logged off very fast since they do not have the same protections. WWII, with it's need for masses of Spruce for the brand new aircraft industry led to the destruction of some truly monstrous Spruce trees, long before 'tourists' could add them to their Must See list.

I have seen Douglas Fir with over 6 foot boles, which, whine not as impressive as Sequoia is certainly right up there. The main point is that there are still some monster tree Species out there if they would ever be allowed to just grow to full ripe old age.

And, yes, it is true that most will not make it that long, survival is rough, any way ye go, same is true with ALL species, but the few that DO live long will have that extra genetic chance to live a LONG time and to, more importantly, SEED many times!

But there are Several Monster type tree species, and may they all live long and prosper!

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