KTSmith

Ha, ha, of course Jules is completely correct with regards to success being the result of a zillion random mutations over long periods of time. A killjoy? Not for me. Millions of unplanned experiments? You bet. That is where the joy is, for me as an observer, anyway. That the order comes without a master plan. Our forest managers in the eastern US have a real problem with native red maple, which is thin-barked and fire-intolerant replacing native oak which is (after sapling-stage, anyway) thick-barked and fire-tolerant. The last decades of fire suppression has shifted the environment so that the maple out-compete the oak in the sapling and small-pole stage of stand development. Under what we think as the natural cycles of fire occurrence, the oak hold their own and then some. So sure, investment in one strategy sometimes pays off and sometimes doesn't as the environment changes!

The goal of a tree as an individual, community, or species is to survive and spread in a competitive and sometimes hostile environment. The great diversity of tree species and life history reflects different strategies to survive and spread. All of these strategies cost metabolic energy gained from photosynthesis. As Macca and Sloth rightly say, some trees invest more in compartmentalization, some invest more in sprouting from root systems, some from seed, etc. This diversity of strategy helps the overall environment. Fast-growing and poor-compartmentalizing birch, pin-cherry, and striped-maple compete well for light and water after major site disturbance (fire, landslide, etc.), decay, die, and the decay process provides soil humus and energy to microorganisms to move essential elements around. That helps support later colonization by slower-growing, longer-lived species that are better compartmentalizers. Sorry for the North American species references, but I expect you know what I mean. Now, don't go and put too fine a point on it. Nature doesn't exist to fit our little boxes of r-selection or K-selection, early- or late-seral colonizers, so exceptions can be found. Still, sloth is quite right, "all very clever". I have a few articles on compartmentalization linked to: Kevin T. Smith - Northern Research Station

I'm having trouble with the orientation of the fruiting body and the point of attachment to the tree. Are we looking at the underside? Or some tops and some underneaths?

Thanks Guy for the invitation. I lurk in Arbtalk more than I post, to be sure. I usually jump in to express gratitude as above or to correct matters of fact from my own work or my FS colleagues (including Dr. Shigo). And even then, sometimes it's worth the effort and sometimes not. I must admit that as with Treebuzz, you often beat me to the punch. And that is a good thing. As we pretty much agree on the bulk of the important stuff, I usually don't split the hairs any more finely. But sure, I'll be more present when I feel the need. As for paper vs. electronic copies, Of course I agree that print is superior in many ways, particularly in books that were actually printed with actual printing plates, where the characters of type are actually impressed onto the paper. Still, I have electronic copies (courtesy of archive.org) of English translations of Hartig, Busgen and Munch, etc. that I likely could not afford. I have access to good library services, so for new books, if I check them out more than twice, I do buy them. Otherwise, the library borrowing works well. Oops, off topic again.

Thank you very making the book freely available for downloading. Much to absorb and learn from!

The post by D Mc seemed to be a bit garbled, above, so I have attached my letter to the editor of the Arboricultural Journal below. Please excuse the redundancy! **** The recent article “Towards a new model of branch attachment) by D. Slater and C. Harbinson (Vol. 33: 95-105. 2010) strongly criticizes the model of branch attachment described by Dr. Alex Shigo in 1985. As I recall, my first glimpse of Shigo’s model was literally drawn on the back of an airline cocktail napkin. He rushed into the lab that morning, in full flush of his “eureka” moment. At the time, I was a postdoctoral researcher with Dr. Walter C. Shortle who was part of Shigo’s team at the US Forest Service. The ball-point sketch showed the key elements of overlapping branch and stem tissues, with the vasculature of branch and stem continuous only on the underside of the branch. For me, one crucial difference between the 1985 and 2010 publications rests on the distinction between codominant stems (referred to as “forks” in the recent article) and branches. Codominant stems arise from multiple buds at the shoot apex or the fusion of appressed shoots. Branches arise from lateral or epicormic buds. Slater and Harbinson maintain that for arboriculture, the distinction is arbitrary and solely determined by the relative size of the two joined members. For them, the shape of the surfaces or “topological equivalence” is critical. I agree that most of the mechanical load of a uniform column is borne by the outer circumference. But the relative strength of the branch attachment is due to the overlapping stem and branch tissues which are absent in codominant stems (E. Gilman. 2003. Journal of Arboriculture 29(5): 291-293). Shigo emphasized that unlike the codominant stem crotch, the branch base contains constitutive and inducible boundaries that facilitate branch shedding and resist the spread of infection. This distinction is a reason to avoid tree topping and the removal of large codominant stems (which have no collars) versus acceptable pruning cuts to the outside of the branch collar. Such “natural target pruning cuts” as promoted by Shigo minimize injury to stem tissue and the loss of the protection zone at the branch base. Distinguishing intact codominant stems from branches can be difficult (A. Shigo. 1986. A New Tree Biology. Fig. 12-12). The substantial difference in structure of the attachments of branches and codominant stems is readily seen in dissection. Of course, the practicing arborist or student can’t dissect every encountered union, but transverse and axial dissections of a few of each with proper interpretation would make clear that the differences are not merely of relative size of the joined members. A complete point-by-point response to Slater and Harbinson (2010) is not possible in this space, but that may not be necessary. Some of the difficulties come from simple language usage. The recent article points to the obvious attachment at the upper side of a branch and stem as refutation of Shigo’s description of the connection being exclusively beneath the branch. For Shigo, connection always meant communication or flow. Back in the old days of wired telephones, lack of a phone connection didn’t mean the absence of wires, just that no message was flowing through them! The lack of connection described for the upper part of the branch/stem union referred to the lack of flow in the plumbing of the wood, not the absence of contact. Other difficulties come from the artistic limitations of representing the 4-dimensional process of growth at the branch/stem union in 2 dimensions. The “tail” to which Slater and Harbinson refers to in Shigo’s illustration is simply the growth increment which is continuous and confluent through the lower portion of the branch and the stem. Conceivably, that connection could be drawn to the root collar, but would make the illustration unwieldy. Shigo had the illustration drawn to show the length of connection along the stem axis to be in the same proportion as for branch knots in decaying logs. The biomechanics of trees has a lot to teach us and we have a lot to learn! We don’t have to blindly accept old teaching just because of tradition. Nor do we need to jump on the latest bandwagon that passes by. The challenge for the practitioner and the student is to understand the biological context for the elegant mechanical engineering that enables trees to survive and thrive. ****