Is leylandii ok for a pond ramp?

[Red Robin]

Originally Posted by wanlock dod

Whilst I am sure that their presence indicates that the pond is not significantly affected by sewage, I am not too sure that they really indicate much more than that!

....I have both read and heard from two totally independent sources that the presence of Caddisfly larvae in a pond DOES indicate very good water quality inasmuch that they only inhabit such. Hence why I posted what I did

[Dogghound]

Originally Posted by Red Robin

....I have both read and heard from two totally independent sources that the presence of Caddisfly larvae in a pond DOES indicate very good water quality inasmuch that they only inhabit such. Hence why I posted what I did

Its right and wrong in the fact that we have a large number of species which occupy different habitat types and have different preferences in water quality. Unless you know the species you cant really say.

[Red Robin]

Originally Posted by Dogghound

Its right and wrong in the fact that we have a large number of species which occupy different habitat types and have different preferences in water quality. Unless you know the species you cant really say.

....It's well known that Caddisfly larvae have a particular preference for good water quality is it not.

[Dogghound]

Originally Posted by Red Robin

....It's well known that Caddisfly larvae have a particular preference for good water quality is it not.

As I said in my previous post, its dependent on species, some like fast oxygen rich streams, others like stagnant oxygen poor ponds, and can tolerate pollutants. Each species obviously exists within what is good water quality for itself. However if a species is in a pond it does not automatically make it good water quality. Additionally good water quality is subjective anyway. What is good water quality for a rat tailed maggot is not usually good quality for a mayfly nymph.

[JohanJ]

If there's another type of wood you can use I'd say use that instead, just for the benefit of the doubt. Amongst other things, evergreen needles in a pond will raise its pH. Raising pH is not really a great thing because it makes ammonia even more toxic.

Sorry I'm not enough of a Leylandi nut to know if the needles are more alkali than the main tree, but my profoundly uneducated guess would be no, that tree and needle are probably similar. And a mass of tree branch is the equivalent to a hell of a lot of needles =).

[Red Robin]

Originally Posted by Dogghound

As I said in my previous post, its dependent on species, some like fast oxygen rich streams, others like stagnant oxygen poor ponds, and can tolerate pollutants. Each species obviously exists within what is good water quality for itself. However if a species is in a pond it does not automatically make it good water quality. Additionally good water quality is subjective anyway. What is good water quality for a rat tailed maggot is not usually good quality for a mayfly nymph.

....Okay, thanks for clarifying that - I hadn't understood your earlier post correctly

[Red Robin]

Originally Posted by JohanJ

If there's another type of wood you can use I'd say use that instead, just for the benefit of the doubt. Amongst other things, evergreen needles in a pond will raise its pH. Raising pH is not really a great thing because it makes ammonia even more toxic.

Sorry I'm not enough of a Leylandi nut to know if the needles are more alkali than the main tree, but my profoundly uneducated guess would be no, that tree and needle are probably similar. And a mass of tree branch is the equivalent to a hell of a lot of needles =).

....I remove at least 95% of the Leylandii needle drops from my pond on a regular daily basis. I use a stainless steel kitchen strainer which I keep in my garden. In other words, they have little chance of seriously effecting pH levels.

[wanlock dod]

I have both read and heard from two totally independent sources that the presence of Caddisfly larvae in a pond DOES indicate very good water quality inasmuch that they only inhabit such.

There are many different ways of judging "water quality", for example based on individual parameters such as pH, dissolved oxygen, nutrient levels, heavy metals, pesticides, or based on the communities that can be found there. These days it is not so uncommon to take account of a number of parameters to assess overall quality.

Benthic inverts, including caddisflies, are included in ecological monitoring systems in Britain, but it is important to understand the purpose of the monitoring to understand what it means. A scoring system was devised which approximately indicated the sensitvity of different invertebrate species to "sanitary pollution", that is releases from sewage works. Sewage pollution is generally typified by ammonia and low dissolved oxygen, and groups which are sensitive to these stressors will score highly. You may find that the indications of the sensitivity of caddisflies to "water quality" relate back to thsi BMWP scoring system.

Many of the caddisfly families are sensitive to these stressors, but this does not necessarily mean that they wil be sensitive to other forms of pollution or contamination. If your pond does not contain significant quantities of decaying organic matter (dead fish, excess food etc.) which consumes oxygen and releases ammonia, then you pond should be fine in this regard. That does not, however, mean that other aspects of water quality, whether they be nutirent status, heavy metals, pesticides, or anything else, are also good.

Dod

[Red Robin]

^
Thanks, Dod

No fish in my pond and it's only exposed to direct sun for about 4-5 hours a day in summer. All the blanket weed and duckweed has disappeared (or been gobbled up by snails) and the water is very clear.