form factor norway spruce and corsican pine

[Dean O]

just trying to get my head around some mensuration without the blue book to hand

Does any one have the form factors for norway and corsican to hand please

 

thanks

[slack ma girdle]

just trying to get my head around some mensuration without the blue book to hand

Does any one have the form factors for norway and corsican to hand please

 

thanks

 

They generally grow up from the ground.

[Dean O]

ehhh?

[slack ma girdle]

ehhh?

 

You wanted to know what form.

[openspaceman]

just trying to get my head around some mensuration without the blue book to hand

Does any one have the form factors for norway and corsican to hand please

 

thanks

 

Yes, what heights do you want to compare, at 10m its 3.9 and 4.31, 18m its 8.35 and 7.64

 

I can probably scan the lot tomorrow.

[Dean O]

not sure catweazel - I've taken three sample plots of 0.01 hect each.

 

measured my dbh's and worked out a basal area for each tree and therefore for each of the plots.

Ive measured the height of the largest diameter tree in each plot to get a top height.

 

area x height will give me the volume of the cylinder but I thought I have to correct this to allow for the taper by the form factor for each tree????

 

Arghh

[openspaceman]

not sure catweazel - I've taken three sample plots of 0.01 hect each.

 

measured my dbh's and worked out a basal area for each tree and therefore for each of the plots.

Ive measured the height of the largest diameter tree in each plot to get a top height.

 

area x height will give me the volume of the cylinder but I thought I have to correct this to allow for the taper by the form factor for each tree????

 

Arghh

 

You are right, that is what the form height does, so at 18 metres the volume per ha of true cylinders would be basal area times true height but because trees have different form factors either side of a cone the actual volume for norway spruce would be basal area times 8.35 not 18.

 

There are a couple of ways to do this, easiest is to get a tariff number for each tree by running its height off against its dbh on one of the charts.

 

The arithmetic method requires you to convert the basal area at breast height from your plots into a basal area per hectare. Then using your top height read what the form height is. As volume is area times height you then multiply these two numbers to give a volume per hectare.

 

Please don't ask me about relascopes as I've had a 40 year mental block understanding them.

[Dean O]

I see

Should I work in averages - ie the average top height over my three (0.01ha) norway plots is 19.5m

the average Basal Area is 8607cm2 (86.07m2).

 

Ive managed to find tariff numbers from notes for the three top heights I have for Norway - but without any further charts they arent much help.

[openspaceman]

I see

Should I work in averages - ie the average top height over my three (0.01ha) norway plots is 19.5m

Past my bedtime but

 

I suppose this depends on what the variation in top height is

 

 

the average Basal Area is 8607cm2 (86.07m2).

 

Per hectare?

 

That gives a form height for NS of 8.34 and CP 9.11

 

8.34 times 86.07 equals 723.08m^3 norway spruce

9.11 times 86.07 equals 784.10m^3 corsican pine

[Dean O]

Thank you for your help -

 

sorry I should have noted that the av basal area given is the av basal area of trees over the three plots sampled (0.01Ha)

 

so an av basal area of 86.07m2 per 0.01Ha = 8607m2/ha

 

8607x8.34 = 71782.38m3/ha

 

sounds a lot for a ha?