Shop - 1

Design and development of product lines goes on apace, so for those of you wondering whether we will ever get round to announcing opening of the farm shop, here is some insight into what we are working on. There is a gradual confluence of development, and all of the nuts we have harvested to date are stored on the farm for machinery testing purposes. We will update this post regularly as more detail becomes available, so you may want to bookmark it. Until the on-line shop is open, please email for more detail. We will not ship NTTPs into the US.

Non-Timber Tree Products (NTTPs)

Seed

Kernel
Shell
Husk - We have a limited amount of air-dried husk currently available for dyers and other craft purposes.

Timber Tree Products (TTPs)

Wood blanks for joinery/turning
Carbon

Non-Tree Products (NTPs)

Datafiles
Designs
Machines
Biomass Nut Book
Carbon club memberships

As I walk the walnuts - 1

As I walk the walnuts, which I do twice a day when I’m on the farm, Kahlua with her nose in the grass somewhere, I remember comments from some visitors who seem offended by my approach to tree management: you really should get rid of those lower branches. Not everyone tells me why – some assume that I’ll get the message that they know better than I do. Others clearly come from a forestry background, where any branch on the first 30’ of bole is not only an eyesore but probably also an offence punishable by excommunication from the College of Foresters. None actually asks me why I’ve left so many branches.

My purpose is actually to let the trees fill their space. Removal of a branch cannot be undone. Branches subtend the tree’s functional interface with its habitat. Remove a branch and you have reduced that interface. So what?

The conical growth rule discussed earlier ‘builds’ on one simple principal, relative growth, i.e. that growth is a consequence of growth accumulated before. Remove some of that growth and you immediately reduce the tree’s future potential growth. It affects the leaf area the tree can subtend, and the surface area upon which it can lay down the present year’s captured carbon. An open- grown tree explores every opportunity to push its tendrils out into unoccupied territory, and if I leave those lower branches where they are that territory is at my height, where I can see and feel the tree’s features, its health, and thus , in purely practical terms, its productivity.

Of tree equivalents and methane

I am not the only one using tree equivalents to account for carbon offsetting. However, the term clearly means different things to different people. If you enter it as a Google search term, you’ll raise all sorts of esoteric stuff, mainly to do with analytical methods in economics, but here’s an interesting analysis from TransCanada Pipelines (http://www.methanetomarkets.org/events/2005/all/docs/cormack.pdf)

TransCanada Pipelines
Emissions saved in no of tree equivalents
Year	2002	2003
tonnes methane	191,000	223,000
tree equivalents	232,000	270,630
tonnes per tree (CO2E)	1.2	1.2

TransCanada is trying to show what impacts the prevention of emissions (basically leaks) from its pipelines will have. It assigns a factor of 1.2 t of carbon dioxide equivalent (CO₂E, different from the straight carbon, C_2, that I have been using – the factor would be 0.32 t C₂) to a tree, and claims that it has prevented emissions equivalent to hundreds of thousands of trees. I am assuming that the analysis attempts to quantify the offset tree planting program it would have to launch if it were to address emissions by this means.

If I have tried to do anything so far, it is to indicate that emissions offsetting must be viewed from the point of view of annual increments in sequestration per tree. A tree does not go from zero to 1 t of sequestration of CO₂E in a single year. Perhaps TransCanada wouldn’t actually plant, and has identified a stand of actively growing larger trees somewhere in the tropics of Costa Rica which have been assessed as capable of sequestering this much annually, and it is these which it has selected for its sequestration factor. This analysis is no better than that of my fuel-dump story yesterday. What is essential is to understand that the process of carbon sequestration in trees builds upon that which has already occurred (there is something called a relative growth rate), and that conditions remain such that the trees can grow actively for the period during which sequestration is being sought. In the early years, sequestration is in the order of kg, not t, per tree.

Methane has a much higher (21 times) global warming potential (GWP) than CO_2, so it is not entirely clear to me that the factor of 1.2 t is actually in CO₂E. This is actually 1.2 t of methane, equivalent to 25.2 t of CO₂ in global warming terms, so if I’ve done my calculations correctly, TransCanada’s tree equivalents should more honestly be numbered in the millions. These data were shown in a Powerpoint presentation, so I’m assuming that if no-one questioned the concepts espoused, they all went home feeling warm and fuzzy.

Of tree planting and offset programmes

These posts should tell you one thing - that planting trees is not the immediate solution to offsetting carbon emissions. I remember seeing an article datelined Australia, which indicated that planners of a recent major celebration in Sydney were going to offset the consequences of a spectacular fuel dump by a military jet (and the fuel's ensuing conflagration) by planting 300 trees somewhere. Given the droughts and fires in Australia, my suspicion is that if the trees were ever planted they are probably already dead. But I'd also be intrigued to know who is auditing or will audit this offset, otherwise it is just as much hot air as was left by the jet in its wake. In the case of our example, it would take close to 15 years to reach the point where the number of trees required to offset that fuel dump did not have a lot of zeros attached. In short, it takes an already-planted well-developed tree growing rapidly to offer a short-term outcome. This is why avoiding emissions has to be the first step, and tree planting an associated initiative to get as much of the free atmospheric carbon dioxide as possible fixed back into some longer-term natural form that enhances biological capital, and, hopefully, our appreciation for the aesthetic values of landscapes rather than subdivisions. I think those Aussie planners were more concerned for simple and immediate pleasures ('aaah'), and felt no personal or professional responsibility for the display's effects. I do not actually know whether the display went ahead. I do know that they should be planning to plant trees now for the probability of any such display (or any other flyby, even in Iraq) 15 years from now. Otherwise, don't do it.

So, how many trees to a tank of gas?

Black Walnut Carbon Sequestration, Field 3 Lostwithiel Farm
	2003	2004	2005	2006
Average C per tree (kg)	2.37	3.54	5.56	6.98
Annual C increment per tree (kg)		1.16	2.02	1.42
Annual C increment per tree (%)		49.0%	57.1%	25.6%
Litres of gasoline equivalent in increment (l)		1.88	3.26	2.29
Tree equivalents per 50 litre tank of gas		26.64	15.35	21.82

What I really mean by this is, how many trees of the average age and size of the trees we have in Field 3 will it take to sequester the carbon emitted by combustion of 50 litres of gas? The answer is, currently, about 20. You can see that the trees are growing quite rapidly, increasing in sequestering capacity by about 50% per year (except 2006, which was very wet and cool, and apparently not favourable for growth; a substantially thinner cone was laid down in 2006 than 2005. We won't know about 2007 until we take measurements while the trees are still dormant in April 2008). Annual estimates are made on the increment in sequestration capacity, and not on the basis of total carbon fixed.

Of cones and hemispheres

Here is a visualization of the annual superimposition of cones which represents tree growth (lowest/earliest cones are not shown). We can extend this a little further. At the apex of each cone are laid down the buds which will grow into our new twigs next year. These grow in the same manner, expanding into the branches which subtend our expanding canopy (shown here as successive approximately-hemispherical helmets). The relationships which govern our tree’s physical development (which make a black walnut look like a black walnut, or a Norfolk Island Pine like a Norfolk Island Pine) are under close genetic control, and it is basically the annual variability in the environment which results in our tree in any given year growing a little bit more or a little bit less.

Of straight lines and carbon

At the heart of our understanding of the tree’s storage of carbon (beyond the physiological processes) is the discovery that the black walnut trunk from ground to tip grows as a very slender cone. How did we discover this? We take measurements annually of tree height (H) and diameter at breast height (DBH, a forester’s standard; for us 1.35m from the ground) of the 575 trees in Field 3. All trees grow at different rates, so what we were measuring was diameter (D) at 575 different distances from the tree’s tip (DFT) on our ‘average’ tree. When we plotted D against DFT on graph paper, we saw a straight line. Successive annual measurements of H and DBH, converted to D and DFT, of the same 575 trees gave us the same straight line. ‘Same’ in this regard means parallel to the lines for previous years, but with very small differences in lateral distance between lines. Using trigonometry, we can calculate the tip angle of our cone, which turns out to be very close to 1.5^o. In other words, the tree, every year, lays a new cone down on top of the previous one, of uniform thickness at all points along the length (actually height) of that cone.