Thinning licence how do I estimate Volume

[Cassie]

Hi All, I'm waiting for a reply from forestry woodlands officer as I'm applying for a thinning license for my small coniferous woodland, but in the meantime I'm hoping you guys can help me?

The first paragraph is from the woodlands officer and the second paragraph is my reply.

Woodlands officer:-

have a best guess at this and we can put it right when we assess the application. conifers usually planted at 2250 tree/ha (spaced 2.1m apart (ish)) check roughly tree spacing and estimate trees/ha. plan on removing 40 or so percent to get the number of trees. Volume estimate 30-40cubic metres/ha to be removed... There are 2.5acres/ha ish...

My reply:-

We will do a rough physical count over the weekend, but I'm confused with the volume estimate you are saying at 30-40 cubic meters/ha to be removed.

Lets say there are 800 trees on my 0.5 ha of land, 40% = 320 trees and that the average tree is 15m length by 25cm mid diameter, each tree would be 0.74 cubic metres based on the volume chart on your website giving a total estimated volume of 236.8?

Am I missing something and working this out incorrectly?

[MartinD]

Cassie - link to Forestry Commission calculator for timber volumes - http://www.forestry.gov.uk/pdf/timbervolume.pdf/$FILE/timbervolume.pdf

[Cassie]

Thanks Martin this was the volume chart I used to make my calculation which is why I can't understand why my figure varies so much from the woodland officer hopefully he will come back to me soon with an answer

[alexw]

Hi,

My guess would be that he meant 30-40% not 30- 40 m3, as that is the proportion of of our Ash that we are thinning as recomended by the forestry commission.

hope that helps

Alex

[Cassie]

Thanks Alex that does seem to make more sense, do they come on site to assess the woodland before issuing the licence?

[carlight]

don't know if this helps ,but i can't really see a 15m tree making .74 m3 .

[Cassie]

I understand what you are saying carlight but if you click on the link MartinD has provided and check the forestry website volume chart it calculates that a 15m tree x 25cm mid diameter = 0.74 cu metres?

[carlight]

hi .

Perhaps there is some confusion . To me , the second table refers to sawlogs , ie ,what one sees stacked in loading bays.

( although .at 15m , a jolly long sawlog)

A sawlog is pretty much the tasty first bit of a much longer tree. Hence it will have only minimal taper ,once buttresses are removed . So a mid diameter measurement is a usefull indicator of volume .

( I may be behind the times , but standing volume is got from measuring diameter at chest height .)

How old are your conifers ? What make ?

40% seems a large percentage - is this first or second thinning in an overstood plantation ?

If your trees are 25cm diameter at chest height that gives about .45 m3 .

Hope that helps .

(seem to remember that the link above is to a fc site - 'nuff said )

[alexw]

Hi Cassie,

Yes they come out on site and will discuss what you want to do and what they think you should do. They can guide you on volumes so just put what you think and they will correct it. I underestimated the volume of sweet chestnut coppice on our application and they upped it from 150m3 to 280m3. The form is more of a guide as they will come and check anyway