???Moss Blocks Oxygen???

[AlainK]

Bonsai Nut is quite right.

There are hundreds of different types of moss, growing in different environments and having different properties, a fascinating world that some once took to a passion: "A passing fad for moss-collecting in the late 19th century led to the establishment of mosseries in many British and American gardens. The mossery is typically constructed out of slatted wood, with a flat roof, open to the north side (maintaining shade). Samples of moss were installed in the cracks between wood slats. The whole mossery would then be regularly moistened to maintain growth."

The whole article on Wikipedia is worth reading:

https://en.wikipedia.org/wiki/Moss

Actually I'm writing this reply because that brought back memories of a time when there was no internet, a black and white TV at home, when I was 7 or 8 years old. I remember playing outside, and making landscape for my plastic cow-boys and indians with moss, sedums and other plants that are probably used now as shitakusa or kusamono. First time I've remembered that for ages!

Wow! An early vocation that stayed dormant for decades?...

Pleasingly Freudian...

 

[johng]

Near view?

c'mon Vin...I thought I made it clear...that is moss view!

 

[Vin]

c'mon Vin...I thought I made it clear...that is moss view!

I'll get it right someday

 

[MichaelS]

I agree, it's the oxygenated water in the pot that is accessible to the roots. Each time you water (IF you water thoroughly until water runs out of the bottom) you replace water depleted of oxygen by the roots, with oxygenated water. As long as moss doesn't significantly reduce water flow it's not a problem from an oxygen standpoint. It way cause other problems or solve certain problems, depending on your specific situation.

Forget the water. It has very little to do with the watering. The air drawn in to the medium after watering would be depleted in a matter of hours. After that the tree still needs to find oxygen. It works like this: As the tree roots breathe, (draw in oxygen), so more is replaced from the outside. It is ''sucked'' in due to lower concentration around the root to maintain equilibrium with the atmosphere. That is by far the main way air is obtained by the plant. Example: In winter, because we get a lot of light drizzle along with very high humidity here, I may go 2 months without watering. If air was replaced mainly by displacement during watering, all my trees would have suffocated long ago.
Back to the moss. The above diffusion of air into the medium is much faster through large pore spaces than small. The very tight nature of some mosses have very small pore space so if you combine that with the fact that the only places air can reach the roots of a potted plant is from the surface and the drainage holes, you are slowing down the diffusion. Normally it would not be a problem but if you have a tree in old broken down soil with fine particles and full of roots topped with a thick layer of felt moss, the exchange of gases (including water vapour as evaporation - so more water is held in the mix further reducing pore space) will be slowed down. Sometimes to the point of root death.
Basically, felt moss on the surface of bonsai does nothing for the health of the tree. It may look good and it may hold the soil together on a slab planting but that's about it.

 

[Vin]

Forget the water. It has very little to do with the watering. The air drawn in to the medium after watering would be depleted in a matter of hours. After that the tree still needs to find oxygen. It works like this: As the tree roots breathe, (draw in oxygen), so more is replaced from the outside. It is ''sucked'' in due to lower concentration around the root to maintain equilibrium with the atmosphere. That is by far the main way air is obtained by the plant. Example: In winter, because we get a lot of light drizzle along with very high humidity here, I may go 2 months without watering. If air was replaced mainly by displacement during watering, all my trees would have suffocated long ago.
Back to the moss. The above diffusion of air into the medium is much faster through large pore spaces than small. The very tight nature of some mosses have very small pore space so if you combine that with the fact that the only places air can reach the roots of a potted plant is from the surface and the drainage holes, you are slowing down the diffusion. Normally it would not be a problem but if you have a tree in old broken down soil with fine particles and full of roots topped with a thick layer of felt moss, the exchange of gases (including water vapour as evaporation - so more water is held in the mix further reducing pore space) will be slowed down. Sometimes to the point of root death.
Basically, felt moss on the surface of bonsai does nothing for the health of the tree. It may look good and it may hold the soil together on a slab planting but that's about it.

You had me at "sucked" but the explanation is a good one

 

[BrianBay9]

Sorry, I disagree. Does a landscape tree pull gaseous oxygen through the soil? No, it comes in as dissolved oxygen in the water.

 

[M. Frary]

I put moss gathered from a sunny location in my yard on everything I can. Colanders,pots or buckets.
1. Helps retain moisture.
2. Gives the roots access to more substrate. This means they can utilize every square inch of the pot.
I haven't seen any difference in the health of trees with moss versus those with none.
I do have to replace the moss about every month or so. Large doses of fertilizer seem to kill it.
Plus the moss looks pretty.

 

[MichaelS]

Sorry, I disagree. Does a landscape tree pull gaseous oxygen through the soil? No, it comes in as dissolved oxygen in the water.

So what happens to a tree in the desert when it doesn't rain for 20 years? What about a cactus in a pot which is not watered for 6 months?

Air diffuses into soil due to roots and microbes creating a differential in the concentration of gas (oxygen) between the rhizosphere and the atmosphere.
http://www.rsc.org/Education/Teachers/Resources/cfb/gas.htm

Think of it like this. When your partner gets up before you in the morning and burns a piece of toast. You don't smell it for quite a while because the bedroom door is closed and the gas (smell) needs to find it's way under the door (small pore) When your partner opens the door to wake you up, you yell ''Did you burn the toast again!!'' because the smell (gas) has come through the open door (large pore). The gas (smell) has diffused from high concentration (in the kitchen) to low concentration (bedroom) After a while, the gas has equalized by diffusing throughout the house and you can't smell it anymore. If you turn on a vacuum cleaner (root) in the bedroom, some of the smell will get sucked up changing the concentration and more will come in to replace it.
The same thing happens with oxygen in the atmosphere (kitchen) and soil (bedroom)

 

[Woodland Spirit]

People, read up on photosynthesis for starters.

 

[jomawa]

read up on photosynthesis for starters.

Please do, but in short it's the use of energy from the sun or light into things like sugars, and oxygen happens to be released into the air as a by product. The question we are dealing with is the uptake of oxygen through the roots. After reading through all these helpful posters my question now tends to be "do the roots take the oxygen out of the water or the air spaces in the soil, or both?"

 

[M. Frary]

So what happens to a tree in the desert when it doesn't rain for 20 years?

It dies.

 

[jomawa]

read up on photosynthesis for starters.

Please do, but in short it's the conversion of energy from the sun or light into things like sugars, and oxygen happens to be released into the air as a by product. The question we are dealing with is the uptake of oxygen through the roots. After reading through all these helpful posters my question now tends to be "do the roots take the oxygen out of the water or the air spaces in the soil, or both?"

 

[jomawa]

"do the roots take the oxygen out of the water or the air spaces in the soil, or both?"

Research seems to say oxygen is used to develope roots to be able to uptake water. Thus the need for aerated "bonsai dirt".

 

[Anthony]

Moss has to be thinned when it forms a carpet. You have to make holes about a dime to a quarter sized all over or the moss
will die.
The holes will aid in the Air getting there.

Additionally, you also have to lift and flatten [ thin the moss ] as time goes by or it will die and lots water will be held in the
brown mass under the green layer.

You have to Bonsai the moss as well, there is no something for nothing.
Good Day
Anthony

* We can only have moss during the rainy season, the dry weather winds, will kill it.
Or you have to protect the moss - mosquito mesh and toothpicks.

 

[MichaelS]

"jomawa, post: 328862, member: 19410"After reading through all these helpful posters my question now tends to be "do the roots take the oxygen out of the water or the air spaces in the soil, or both?"

A oxygen molecule is an oxygen molecule wherever it is. The aerial root of an epiphytic plant or a fig can take up oxygen from mid air or from underwater if it is there.

 

[0soyoung]

A oxygen molecule is an oxygen molecule wherever it is. The aerial root of an epiphytic plant or a fig can take up oxygen from mid air or from underwater if it is there.

If I might rephrase (and maybe it is a different question than @jomawa was asking). If roots must be damp, does this mean the oxygen must first to dissolve into the water on the root surface before it can be loaded into the root? Or, does the root have hairs, say, the protrude thru this water film and directly load oxygen from the airspace(s) instead?

 

[MichaelS]

If I might rephrase (and maybe it is a different question than @jomawa was asking). If roots must be damp, does this mean the oxygen must first to dissolve into the water on the root surface before it can be loaded into the root? Or, does the root have hairs, say, the protrude thru this water film and directly load oxygen from the airspace(s) instead?

Pretty sure roots take up free oxygen through specialized pores. (similar to leaves)

 

[0soyoung]

Pretty sure roots take up free oxygen through specialized pores. (similar to leaves)

Similar to lenticels, I suppose. At any rate, I guess that means oxygen is adsorbed by the roots directly from the airspace. When there is so much water that these specialized pores are clogged with water, roots drown (apoxia). Further, it makes clear why it doesn't matter whether one uses highly oxygenated water or 'still' water (now that is an ambiguous term for the opposite of oxygenated ).

I'm completely in the dark about the respiration rate of tree roots; i.e., the rate of oxygen consumption. I could go searching but do you have that in hand? On another thread we've been discussing that 10% to 15% air filled porosity (AFP) is a good growing substrate. I'm trying to relate that to gas volumes and diffusion rates which underlie your thesis here.

There's nothing better than simply finding things out.

Thanks.

 

[Anthony]

Roots under moss tend to come to the surface.
If you are growing moss on your soil [ normally only for exhibition / show - the lawn ] it has to remain thinned.
So you are looking a couple mm's, not sure how much air that is going to block or hold back moisture.

Growing moss is normally done in trays for transferring to the tree's soil for exhibition.

Bad form to be trying to grow moss all of the time on the soil, the moss requires extra moist care.

So the above discussion would be mostly irrelevant.

During the rainy season on our side, moss appears by itself simply because our moss thrives on asphalt and
there is an abundance of asphalt in this yard.

Be careful trying techniques without understanding why used.
Good Day
Anthony

* Not talking about the spaghnum moss technique used after re-potting in dry air zones.

 

[BrianBay9]

Pretty sure roots take up free oxygen through specialized pores. (similar to leaves)

To my knowledge there are no structures on roots or root hairs comparable to the stomata (pores) on leaves.

Root hairs are constantly coated in a film of water. Porous soil in the first couple of inches at the surface, or in bonsai pots, may have space for gas exchange from the atmosphere to some degree, but oxygen will have to dissolve in water to make it into the roots. Roots growing deeper than a couple of inches in the ground will not receive any significant gas exchange from the atmosphere, barring burrowing animals to create channels. Water carries dissolved oxygen to those roots. Water carries dissolved oxygen to bonsai roots too. If you don't water enough to fully flush the deoxygenated water from your pot, eventually the root zone will become anoxic and roots will die. This is one of the primary reasons beginners are advised to water from the top until water runs freely out of the bottom of the pot.