There are no published Yield Class tables for common walnut Juglans regia – at least that I am aware of. A search on the European Forest Yield Tables Database reveals that data are only available for black walnut Juglans nigra in Hungary.
I wrote previously about research that I undertook exploring the crown sizes of major hardwood species – Estimating tree crown size. This work provides the next best available data on managing a stand of common walnut, in the form of basal areas for common walnut ref.
The table below shows the stem diameter (dbh), crown diameter (cd), crown/stem ratio (cd/dbh), number of trees per hectare (Nha) and acre (Nac), and Basal Areas (G) in m2 per hectare. These data were collected from trees grown in open conditions, and calculated for stand densities with zero crown overlap.
|
dbh |
cd |
cd/dbh |
N trees per ha |
N trees per acre |
Basal Area m2 per ha |
|
0.10 |
4.47 |
44.70 |
500 |
202 |
3.9 |
|
0.15 |
5.35 |
35.67 |
349 |
141 |
6.2 |
|
0.20 |
6.23 |
31.15 |
258 |
104 |
8.1 |
|
0.25 |
7.11 |
28.44 |
198 |
80 |
9.7 |
|
0.30 |
7.99 |
26.63 |
157 |
64 |
11.1 |
|
0.35 |
8.87 |
25.34 |
127 |
51 |
12.2 |
|
0.40 |
9.75 |
24.38 |
105 |
42 |
13.2 |
|
0.45 |
10.63 |
23.62 |
88 |
36 |
14.1 |
|
0.50 |
11.51 |
23.02 |
75 |
30 |
14.8 |
|
0.55 |
12.39 |
22.53 |
65 |
26 |
15.5 |
|
0.60 |
13.27 |
22.12 |
57 |
23 |
16.1 |
|
0.65 |
14.15 |
21.77 |
50 |
20 |
16.6 |
|
0.70 |
15.03 |
21.47 |
44 |
18 |
17.0 |
A growth rate of 1cm per year in stem diameter can be presumed, permitting this graph and data to be used in estimating suitable basal areas at different stand ages. If real dbh data is available, then the accurate growth rates will provide accurate basal area increase projections for a given site.
Gabriel Hemery
Reference
Hemery, G.E., Savill, P. & Pryor, S.N. (2005). Applications of the crown diameter – stem diameter relationship for different species of broadleaved trees. Forest Ecology and Management 215, 285-294. View abstract
This work is licensed under a Creative Commons Attribution- NonCommercial- NoDerivs 3.0 United States License.
I am surprised you include this reference in your review of the year:
>>I became deeply involved in this debate myself, commenting publicly on the proposed sales (see BBC TV interview
http://gabrielhemery.com/2011/01/26/film-interview-bbc-newsnight/
)>>
This was the Newsnight programme the day before the government launched its sell-off consultation. In your interviewyou said you didn’t see any reason why some of the forests shouldn’t be sold off!
Thanks for the comment Imogen. I think that the Newsnight interview was a highlight personally and for forestry in England, as it is rare to receive a media spotlight of such scale on the subject. Yes I clearly stated that I thought some public forests could be disposed of if they delivered low public benefits. This view was derived from direct experience of some woodlands that in my view would be better in the hands of private woodland owners. For example those woodlands with no public access and little biodiversity or landscape value.
The recommendation coming from Our Forests vision published today, that naturally I totally agree with are that (Our Forests vision, Principle 1, page 8):
“But until the PFE is provided with stronger, lasting protection as a national resource of public woods and forests, there must be no sales.”
I hope that this clarifies.
Gabriel