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Author Topic: How do plants grow in and on rocks?  (Read 11414 times)

Offline Mononoke

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How do plants grow in and on rocks?
« on: 26/03/2014 18:50:13 »
As there is no soil for them to get their vital nutrients from, how do they grow and survive? As much information on these type of plants would be much appreciated including some examples please.


 

Offline CliffordK

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Re: How do plants grow in and on rocks?
« Reply #1 on: 28/03/2014 05:43:25 »
I was actually thinking a little about this today. 

Here in Oregon, we have multiple lava flows from the 3 sisters mountains, easily visible at the McKenzie Pass (in the summer).  The top of the pass crosses a lava flow that is about 2,600 years old, which I believe is overlapping a 6000 year old flow (or so). 

Anyway the 2600 year old flow is quite desolate looking, at least from a distance.  There is, however, a nice tour loop pathway to take which will explain some of the features not immediately visible from the distance.  I believe that one of the primary colonizers are lichens, and they are capable of breaking down solid rock.  In places where some dirt or debris has deposited, small scraggly trees have also taken hold.  As these die, they become the soil for the next generation of trees.  The older lava flow at the pass, 6000 or so years, I think, still has a lot of lava rock visible, but many more trees.

Keep in mind that "rock" may actually contain nutrients for plants if it can be broken down.  I believe that pumice is actually quite nutritious for plants...  except in the pumice desert near Crater Lake where the depth of pumice and porosity makes it difficult for it to hold enough water for the plants.
 

Offline evan_au

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Re: How do plants grow in and on rocks?
« Reply #2 on: 28/03/2014 09:13:06 »
Many of today's fertile farmlands in Europe and North America are thought to be due to glaciers in the last ice age, which ground down the rocks, releasing nutrients and leaving behind a soil. This soil can be more easily colonised than solid rock.
 

Offline Don_1

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Re: How do plants grow in and on rocks?
« Reply #3 on: 28/03/2014 12:47:48 »
Before plants existed, bare rock was the norm. Lichens and mosses came along and managed to tease out nutrients from these rocks. Such a precarious life may well have been short lived. The dead matter left behind would have been ideal for a new growth. Over millions of years, so much death among these plants would have left a nutrient rich decomposed mass, which is just what soil is. With the coming of larger plants, they would only need to find small crevices in the rock to enable them to put down a root. As the plant grew, so the root grew and would split the rock enabling more plants to gain a foothold. More and more bigger and bigger plants went through this life until the rocks they grew on could no longer sustain plant growth. So more and more bigger and bigger plants died, creating more and more soil.
 

Offline CliffordK

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Re: How do plants grow in and on rocks?
« Reply #4 on: 28/03/2014 17:59:26 »
There may also be inorganic weathering of rocks.  As Evan mentioned, glaciers, snow, and ice may be a significant component of inorganic weathering.  However, there is also rain, wind, and the sea.  I've also encountered a type of rock that tends to be fairly solid when hydrated, but crumbles once it is exposed to air and dries out.  Volcanic Ash is also a type of fines that could support life.

The moon may be different from Earth, but it is covered in a layer of fine dust created by inorganic processes.
 

Offline Mononoke

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Re: How do plants grow in and on rocks?
« Reply #5 on: 01/04/2014 13:32:15 »
There may also be inorganic weathering of rocks.  As Evan mentioned, glaciers, snow, and ice may be a significant component of inorganic weathering.  However, there is also rain, wind, and the sea.  I've also encountered a type of rock that tends to be fairly solid when hydrated, but crumbles once it is exposed to air and dries out.  Volcanic Ash is also a type of fines that could support life.

The moon may be different from Earth, but it is covered in a layer of fine dust created by inorganic processes.

How does volcanic ash support life? I can't find any information on that.

 

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Re: How do plants grow in and on rocks?
« Reply #5 on: 01/04/2014 13:32:15 »

 

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