A surprising development, RainForests grow when it's dry.

It's been recently discovered that much of the Brazillian rainforest experiences growth spurts during dry spells.

Most plants do their growing during the rainy season and stall out when it's dry. But in much of the Amazon rainforest, dry spells bring on growth spurts.
The finding, announced today, surprised scientists.

"Most of the vegetation around the world follows a general pattern in which plants get green and lush during the rainy season, and then during the dry season, leaves fall because there's not enough water in the soil to support plant growth," said lead researcher Alfredo Huete of the University of Arizona.

"What we found for a large section of the Amazon is the opposite," Huete said. "As soon as the rains stop and you start to enter a dry period, the Amazon becomes alive. New leaves spring out, there's a flush of green growth and the greening continues as the dry season progresses."

The discovery holds true only for undisturbed parts of the rainforest.

What's going on? Deep roots of trees can reach water even in the dry season, the researchers figure, and so they take advantage of the added sunlight. Vegetation in areas that have been logged or converted to other uses can't reach the deep water, which might explain why it goes dormant or dies in the dry season.


LiveScience.com

Pretty interesting stuff.
Just go's to show the Earths flora is more diverse than we give it credit for being.


Comments, Opinions?

did you know deep in the rainforest b/c of the condisions you can see 3 trees all simalar but all 3 a unique species there are no more like it it has evolved there and grown under ideal situations. hows that for unique

iori_komei

Great find!

Hope you don't mind, but I wanted to attach an older thread of mine about another surprising find regarding rainforests...

Man-made rainforest baffles scientists


[edit on 23-3-2006 by loam]

No scientist here...

... but not seeing too much to be "baffled" over.
My speculative and uneducated hunch would go like this:
The RainForests have inherently rich soil with good water saturation in the lower depths of its underground soil. Most trees within the RainForests are deep rooted, thus having the ability to continue to thrive even in dry seasons.

I simply postulate such because we have the same situation around where I live in Virginia---close to the Dismal Swamp. Even in drought-like situations, the trees and the like continue to thrive due to the water-saturation levels in the lower aspects of the soil.

Sometimes, though there is not surface indications of water or saturation due to a dry spell, period, etc., there is sufficient water and saturation underground in the lower levels of the soil to allow for vegetation to thrive.

Just a hunch.





seekerof

Just ran across this mention after reading the article:

What's going on? Deep roots of trees can reach water even in the dry season, the researchers figure, and so they take advantage of the added sunlight. Vegetation in areas that have been logged or converted to other uses can't reach the deep water, which might explain why it goes dormant or dies in the dry season.

From original article





seekerof

You know, Seekerof, that might be the case, but I always thought that most of the trees had shallow roots... See, for example, this description:

TREE ROOT SYSTEMS

Tropical rainforest trees are well-adapted to their environment and have mastered the problem of poor soils. Since the first six to eight inches (15-20 cm) of soil is a compost of decaying leaves, wood, and other organic matter, it is the richest source of nutrients on the ground. To tap this resource, canopy trees are shallow rooted, whereas most temperate tree roots extend more than 5 feet (1.5 m) deep. Many tropical species have roots that actually grow out of the ground to form a mat on the forest floor in order to more efficiently collect nutrients. These tiny roots form a network that, along with the mycorrhizae fungi, rapidly absorb nutrients.

The configuration of shallow roots and great height causes a great deal of instability for rainforest trees, especially with wet soils and strong winds of the upper canopy that can accompany tropical storms. To counter this, many tree species have extensive root systems that in some cases may run for over 325 feet (100 m). Other trees, especially tall emergent species, have evolved buttress roots—large, thin extensions of the trunk that begin some 20 feet from the ground. These structures are thought to also aid in water uptake and storage, increase surface area for gas exchange, and collect leaf litter for additional nutrition. Some trees, especially palms, have stilt roots for support.

Source.

I'm going to see if I can learn more about these root systems...

[edit on 23-3-2006 by loam]

Great finds everyone! Can't wait to see where your research takes us Loam. It would be so very interesting when it turns out the earth has already a struck a balance so that it can always ( for some obscure reason) soak Carbon Dioxide and release Oxygen.

Stellar

Originally posted by Seekerof
No scientist here...

... but not seeing too much to be "baffled" over.
My speculative and uneducated hunch would go like this:
The RainForests have inherently rich soil with good water saturation in the lower depths of its underground soil.
seekerof

Close, everything except the part about rich soil. Usually in rain forests the constant rain leeches away the nutrients. What isn't used in the top two layers is leeched away and soon replaced with newly fallen vegetation. I would wager that the dry spell allows the nutrients to stay in the ground longer , thus making a more fertile soil, thus increasing growth rate.

Predominant soils of the humid tropics are Oxisols (525 million ha) and Ultisols (413 million ha), comprising 63% of the total land area. These soils are old, highly weathered, and low in inherent soil fertility. Soils of intermediate fertility include Entisols (212 million ha) and Alfisols (53 million ha), comprising about 18% of the land area. Soils with good fertility and high productivity include Inceptisols (226 million ha), Histosols (27 million ha), and Mollisols (7 million ha), and comprise only 17.5% of the total land area. Other soils also are found in the humid tropics, but in very small proportions.
www.unu.edu...

Loam,
I've read lots of your posts and wondered about your name. Are you in the soil science field?

Hmm, Arius makes a good question, so are you loam-sama?


Filler-Filler-Filler-Filler-Filler



I.K

Originally posted by phoenixhasrisin
I would wager that the dry spell allows the nutrients to stay in the ground longer , thus making a more fertile soil, thus increasing growth rate.

Ding, ding, ding, ding.... I think we have a winner. Phoenixhasrisin, that explanation makes the most sense and remains consistent with the predominately shallow root systems of the trees. Good job!

Originally posted by arius
Loam,
I've read lots of your posts and wondered about your name. Are you in the soil science field?

Nope. White-collar capitalist.

[edit on 23-3-2006 by loam]

Nope. White-collar capitalist.

I know this is off topic, but what the hay, I started the thread.

Anways, that (White-collar capitalist) is exactly what one of my teachers is against.


Anyhow loaml, you are definately a very knowledgable person.
So because of that, I, and my teacher prolly would to, forgive you for being capitalist.

Originally posted by iori_komei
So because of that, I, and my teacher prolly would to, forgive you for being capitalist.

It's nice to be forgiven....

Some habits are hard to break....and I do love my vices...