"Andy wrote in message

That's no real issue and can easily be removed. I quite like to see
a certain amount of lichens on roof tiles. It makes them look more
interesting.....


Apparently lichens only grow in places of low atmospheric pollution,
so it's a good indicator of air quality, as well as any aesthetic
benefit.

but is the same true about moss? In fact, are moss and lichen
synonymous?
I know that lichens are rarer than they once were.

Actually, since the Clean Air Act came into force (yes I remember that!) the
pollution has reduced drastically. Most came from coal fires and those of us
of a certain age will remember those horrid yellow filthy smogs every winter
in the good old days. Whilst most pollution still comes from the home,
central heating etc, vehicle pollution has made drastic reductions too in
recent years, in fact the pollution from cars is a reversing trend despite
more and more on the roads. Because of this Litchens can now be seen on many
rooftops, walls and trees, even in towns, which is something one never saw
when I was a kid. Take a look as you drive along, you will spot some roofs
covered with grey litchens.

I seem to remember Kew saying recently that they were on the acendancy in
their garden and you aren't too far from there.


There are a whole spectrum of lichens and some will grow in moderately
polluted conditions. Others are more sensitive to conditions, so for
example you will see a richer set of lichens in a forest in Wales than
you will in town.

Mosses are rather different, in that theyare plants and produce
chlorophyll themselves and are generally attracted to places where
there is moisture - hence finding them in gutters...

Clearly it makes sense to remove moss from gutters to avoid them
cloggin and water running down the walls, but there is no reason to
remove them or lichens from roofs. Arguably there is more risk of
damage from blasting with a pressure washer or from use of chemicals.

True, it's a bit like Ivy, you do the damage getting it off.

Whilst there are some "green" roofs in the UK (Notcutts GC in Staines for
one) it is a strongly growing trend on the continent the idea being that
building a house and then having a green roof does not reduce the green
habitat for parts of the animal kingdom one bit. It's a bit like building
underground especially for the flying insects/birds.
So whilst moss in your gutters is not good, on the roof it isn't a problem.

Incidentally in certain parts of the country people used to plant Houseleeks
( Semperivivum tectorum ?) on their roofs to ward against Witches and
lightening. Plant them on the sunny side of the house. :-)

--
Regards
Bob

Use a useful Screen Saver...
http://setiathome.ssl.berkeley.edu/
and find intelligent life amongst the stars
359 data units completed.

"Bob Hobden" wrote in message
...

"Andy wrote in message

That's no real issue and can easily be removed. I quite like to
see
a certain amount of lichens on roof tiles. It makes them look more
interesting.....


Apparently lichens only grow in places of low atmospheric pollution,
so it's a good indicator of air quality, as well as any aesthetic
benefit.

but is the same true about moss? In fact, are moss and lichen
synonymous?
I know that lichens are rarer than they once were.

Actually, since the Clean Air Act came into
force (yes I remember that!) the
pollution has reduced drastically. Most came
from coal fires and those of us
of a certain age will remember those horrid
yellow filthy smogs every winter
in the good old days. Whilst most pollution
still comes from the home, central heating etc,
vehicle pollution has made drastic reductions too in
recent years, in fact the pollution from cars is a
reversing trend despite
more and more on the roads.

Pollution from homes: oil, gas and electricity generation, is approx 42%, so
clamping down on this is very productive. The MicroGen Stirling elec/gas
boiler will make a big impact here. The coming minimum 86% boiler
efficiency is welcome too and will make an impact. EU regulation on gas
burners, which are very clean anyhow, are tightening too.

Vehicles "are" a very large polluters, especially when they are concentrated
in cities, where masses of people live. Great progress is being made on
pollution from homes, in insulation standards, boiler efficiency , etc, yet
there appears no immediate solution to the filthy car. Technology is there
to make boilers very efficient and very clean burning, at no great cost,
also by increasing insulation standards, a homes emissions can be
drastically reduced. This can be done right now and people wonder why it is
not being implemented. The car? Well apart from taxing larger engines, not
much at all can be done. There are some advanced concept engines around,
but the big corps have not yet taken up these ideas, tending not wanting any
change at all.

Cars are even dirtier until the engine and exhaust is hot. So, in many
cases, when the car is used to go to Safeway or the school run, the thing is
hardly up to temperature before being switched off. In this period they
pollute heavily. The current piston internal combustion engine needs
totally replacing.



---
--

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Version: 6.0.558 / Virus Database: 350 - Release Date: 02/01/2004

"Bob Hobden" wrote in message
...

"Andy wrote in message

That's no real issue and can easily be removed. I quite like to
see
a certain amount of lichens on roof tiles. It makes them look more
interesting.....


Apparently lichens only grow in places of low atmospheric pollution,
so it's a good indicator of air quality, as well as any aesthetic
benefit.

but is the same true about moss? In fact, are moss and lichen
synonymous?
I know that lichens are rarer than they once were.

Actually, since the Clean Air Act came into
force (yes I remember that!) the
pollution has reduced drastically. Most came
from coal fires and those of us
of a certain age will remember those horrid
yellow filthy smogs every winter
in the good old days. Whilst most pollution
still comes from the home, central heating etc,
vehicle pollution has made drastic reductions too in
recent years, in fact the pollution from cars is a
reversing trend despite
more and more on the roads.

Pollution from homes: oil, gas and electricity generation, is approx 42%, so
clamping down on this is very productive. The MicroGen Stirling elec/gas
boiler will make a big impact here. The coming minimum 86% boiler
efficiency is welcome too and will make an impact. EU regulation on gas
burners, which are very clean anyhow, are tightening too.

Vehicles "are" a very large polluters, especially when they are concentrated
in cities, where masses of people live. Great progress is being made on
pollution from homes, in insulation standards, boiler efficiency , etc, yet
there appears no immediate solution to the filthy car. Technology is there
to make boilers very efficient and very clean burning, at no great cost,
also by increasing insulation standards, a homes emissions can be
drastically reduced. This can be done right now and people wonder why it is
not being implemented. The car? Well apart from taxing larger engines, not
much at all can be done. There are some advanced concept engines around,
but the big corps have not yet taken up these ideas, tending not wanting any
change at all.

Cars are even dirtier until the engine and exhaust is hot. So, in many
cases, when the car is used to go to Safeway or the school run, the thing is
hardly up to temperature before being switched off. In this period they
pollute heavily. The current piston internal combustion engine needs
totally replacing.



---
--

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.558 / Virus Database: 350 - Release Date: 02/01/2004

Andy Hall wrote:
There are a whole spectrum of lichens and some will grow in moderately
polluted conditions. Others are more sensitive to conditions, so for
example you will see a richer set of lichens in a forest in Wales than
you will in town.

I heard recently on some environmental thing on R4 about the
effects of pollution on buildings. All this is subject to
the vagiaries of my memory, but I think I've remembered the
gist of it right: In Victorian times, they
burnt loads of sulphorous coal, and got gypsum (or something)
deposits on buildings. Now, with all the petroleum fuel
being used, there's hardly any sulphur, but loads of
nitrogen-containing stuff -- which means that these days it's
easier for plants/algae/etc to grow on buildings.

--
#Paul

Andy Hall wrote:
There are a whole spectrum of lichens and some will grow in moderately
polluted conditions. Others are more sensitive to conditions, so for
example you will see a richer set of lichens in a forest in Wales than
you will in town.

I heard recently on some environmental thing on R4 about the
effects of pollution on buildings. All this is subject to
the vagiaries of my memory, but I think I've remembered the
gist of it right: In Victorian times, they
burnt loads of sulphorous coal, and got gypsum (or something)
deposits on buildings. Now, with all the petroleum fuel
being used, there's hardly any sulphur, but loads of
nitrogen-containing stuff -- which means that these days it's
easier for plants/algae/etc to grow on buildings.

--
#Paul

On Fri, 9 Jan 2004 16:30:56 -0000, "Bob Hobden"
wrote:


"
y

True, it's a bit like Ivy, you do the damage getting it off.


So whilst moss in your gutters is not good, on the roof it isn't a problem.


Except when it becomes loose and blocks gutters + downpipes etc.
It also makes a bit of a mess on patios + car roofs parked underneath

On Fri, 9 Jan 2004 16:30:56 -0000, "Bob Hobden"
wrote:


"
y

True, it's a bit like Ivy, you do the damage getting it off.


So whilst moss in your gutters is not good, on the roof it isn't a problem.


Except when it becomes loose and blocks gutters + downpipes etc.
It also makes a bit of a mess on patios + car roofs parked underneath