Red Alder Coppice Spacing

[Feanor]

Hi All,

 

I will soon be planting hybrid willows for a short rotation forestry (on an 8 years rotation). This is to provide me with firewood. I will also plant red alders along in a kind of support role to provide nitrogen as well as firewood.

 

Here's the plan of one "coupe" with about 2/3 of the space dedicated to willows (light green) the rest going to red alder (1/3). Actual proportions will doubtless tend towards 3/4 and 1/4. Planned willow spacing is 5ft and alder is 9ft at the moment.

 

As for local conditions, I am on a Welsh hill with some high winds and shallow loamy soil (2-3 ft deep).

 

My question is on spacing the red alder. On an 8 yr. rotation, what spacing would you plant them on?

 

I would love to hear your thoughts on this.

 

Thanks!

[Stereo]

I would say something like 6'. Enough space but also encourage to go up and not out.

[woodyguy]

If you're looking for a fairly quick return on logs then I'd go for a 6 foot maximum spacing. Also you say Alder for nitrogen fixation but then the two species are totally separated. How will nitrogen fixation help the willow 100 yards away? Presumably you'd need to mingle the alders amongst the willows to get any useful benefit overall? Or have I got the wrong end of the stick.

[Feanor]

Hi there,

 

Thanks you both for your answers.

 

woodyguy, that's a good question. I had a quick look in one of my books. There is some info in Creating a Forest Garden by Martin Crawford. He says most of the nitrogen will come from litterfall as well as root turnover (fine roots dying every years). According to him, there is a mycorrhidal fungi present around the roots of most trees including willows. This fungi is able to move nitrogen around. Here's a quote from the book:

 

Mycorrhizal Fungi: These are symbiotic fungi that form an association with plant roots - nearly all plants form such associations. Where there is an established mycorrhizal mat (typically under trees with the soil not cultivated and not heavily fertilised), the fungi can move nutrients around, and will move nitrogen from areas of the soil where it is in high amount (e.g. under/around nitrogen-fixing plants) to areas where it is lacking (i.e. under/around demanding plants), sometimes miving it several tens of metres.

 

I am pleased with this answer. I felt putting alders close to the willows would have cause to much competition. Hybrid willows are so very agressive! There will be a maintenance track between the alders and the willows so hopefully this will work.

 

Because we're talking about an 8 year rotation plan, I think the nitrogen will have had enough time to be moved from the alders to the willows.

 

Thanks again!

[Parker]

Why the monoculture of hybrid Willow and Red Alder?

 

Surely it would be better to mix in other species such as Sycamore, Hazel, Sweet Chestnut to ensure viability in the future if the two species that you have planted become infected with a pathogen.....Ash and Chalara fraxinea come to mind.

 

Will also be better for the native wildlife

[Stereo]

Martin is just up the road from me. I don't know him but his stuff is fascinating. I have also read that the nitrogen fixing has a wide range. I think that's why you often get lots of ash near alder.

[Feanor]

Why the monoculture of hybrid Willow and Red Alder?

 

Surely it would be better to mix in other species such as Sycamore, Hazel, Sweet Chestnut to ensure viability in the future if the two species that you have planted become infected with a pathogen.....Ash and Chalara fraxinea come to mind.

 

Will also be better for the native wildlife

 

My first choice would have been to plant a mixed native coppice. Thing is, I only have 2 acres to spare and a very hungry wood-fired range. I'd say I need about 8-10 cu. m. (or around 75 Mbtus) per year.

 

From what I understand, using only native species, I would be hard pressed to ever become "firewood self-sufficient" from these two acres. I looked at the trees that grow fast and produce the most energy (btus/acre/year). Hybrid willows and poplars are on top of the list.

 

But then, maybe I'm wrong. I'd love to hear alternative ideas.

[woodyguy]

For sheer biomass it is impossible to beat hybrid willows. Alders are pretty good as are sycamore and poplars. Can't see how the nitrogen moves beyond the root zone of the tree but that can be pretty extensive with Alders.