In addition, there is a book called Tropical Trees and Forests : An Architectural Analysis by F. Halle, R.A.A. Oldeman and P.B. Tomlinson that provides a fairly exhaustive description of inherited and opportunistic tree architecture, including info about reiterations.
Bill Hascher Asheville NC From: [email protected] [mailto:[email protected]] On Behalf Of Will Blozan Sent: Thursday, March 12, 2009 4:36 PM To: [email protected] Subject: [ENTS] Re: Another Big White Pine Ed, Here is an excerpt from the Tsuga Search Project that should help: Wood distribution In total, this project sampled 3,340.1 m (10,955 ft) of eastern hemlock trunks (N=53) with a cumulative wood volume of 1,672.3 m3 (59,053 ft3)[1]. The modeled trees did not always conform to a simplistic, single trunk form however, and required measuring some challenging structures (See Reiterations and bifurcations below). In all trees sampled, "conventional" main trunk wood composed anywhere from 63.7% to 100% of total tree volume. Bifurcations (forks of vertical leaders) accounted for a maximum of 36.3% of total wood volume, considerably more than a maximum of 10.05% for reiterations (limbs upturned into secondary trunks). Bifurcations were much larger; even though a total of 633.1 m (2,076.6 ft) of reiterations were measured, total bifurcation volume (42.9 m3; 1514.2 ft3) was 240% more with only two-thirds of the cumulative path length. Path lengths (length of all measured wood structures) of individual trees ranged from simply the length of the trunk to a maximum of 200.7 m (658.4 ft). See Appendix 4: Wood distribution of subject trees for more detail. Reiterations and bifurcations Reiterations are replicated trunks formed by the tree to exploit a light gap. Structure and growth of reiterations are markedly different from normal descendent or ascendant branches. Reiterations are included in trunk volume calculations as they are part of permanent, branch bearing structures of the tree. Their origin arises from the sprouting of normal branches and can be initiated by a light gap from the side or from crown damage above. The apically dominant portion of these structures are often much younger and model-conforming as in a young tree. The cross-section changes to a more oval shape as reaction wood is built up to support the added weight from increased growth and sap demands as the reiteration gains vigor. The buttressing allows a more permanent attachment than a conventional branch due to support on the lower portion being less likely to fail from injury to the upper surface. This also allows wounds with associated decay to persist and form a suitable substrate for vascular epiphytes (Sillett, Van Pelt 2007) Studies in redwood forests indicate that structural diversity in the canopy is strongly linked with aerial biological diversity. Reiterations generate niches not found anywhere else in the forest (Sillett, Van Pelt 2007). Our observations indicated moss mats, epiphytic plants and lichen gardens to be associated with these large structures. Large reiterations and breaks in the trunks were hosts to shade intolerant shrubs and wind disseminated trees such as Rubus and Betula. Complex, reiterated crowns could be refugia for those species lying in wait for a light gap or breach in the rhododendron. Of the thirty trees discussed in this project, eleven trees had large reiterations. Four of these were tall trees and seven were large trees (two trees are replicated). A total of thirty-seven reiterations were measured, ten of which grew on the Usis Hemlock, the most on a single tree in the project. Total reiterated trunk length measured on the Usis Hemlock totaled over 147.8 m (485 ft) for a tree total of 200.7 m (658.5 ft) of trunk. Likewise, the Cheoah Hemlock had a total of 185.6 m (608.7 ft) of measured trunk length in reiterations and bifurcations. These structures are likely to greatly increase the crown area of the tree, and bolster wood production. Reiterations on the subject trees (no repeated trees) totaled 14.7 m3 (518.8 ft3) in volume, 527.0 m (1,728.6 ft) in cumulative length, and were found to compose anywhere from 0.5% to 10% of total tree volume, averaging 4.2% for all trees. Volume of individual reiterations reached a maximum of 1.78 m3 (62.9 ft3) and a maximum structure length of 18.96 m (62.2 ft). On average, the reiterations were 31% larger and 12% longer on the large subject trees than on the tall subjects. Fusions between reiterations were documented in two trees, forming a strong interlocked crown with braced bifurcations that likely reduce mechanical failure of non-conventional crowns. "Transplanted" branches were noted in the Cheoah Hemlock. This occurs when a grafted branch severs its connection from its origin. This phenomenon is well documented in the coast redwoods of California, and is encountered in dense hemlock hedges as well. The Cheoah Hemlock and the Usis Hemlock both exhibited reiteration fusions; one of which started at 14.3 m (47 ft) and fused to another reiteration 9.7 m (31.9 ft) higher in the tree. The Cheoah Hemlock had a branch that crossed the inner canopy while grafting to three separate structures. Height of origin was noted for every measured reiteration. The lowest occurred at 12.59 m (41.3 ft) and the highest at 38.35 m (125.8 ft) above mid-slope. The highest recorded reiteration was over 25 cm (12 in) in diameter and was encountered in the Usis Hemlock. This tree also contained the highest cumulative and relative volume of reiterations; 4.36 m3 (154.3 ft3) and 10.05% respectively. The most massive reiteration was found in the Cheoah Hemlock and scaled 1.78 m3 (62.9 ft3). This individual structure alone contained a path length of 34.33 m (112.6 ft) of measured trunks. A graphing of the origin heights below likely reveals a random height of origin as the events initiating the formation of a reiteration would likewise be random. Data gathered from a control population of non-superlative trees are needed for comparison. [cid:[email protected]] Of the thirty subject trees, three had large bifurcations that warranted frame mapping along the section(s) of trunk fusion. These massive, fused areas were up to 1.6 m (5.25 ft) across. Two other subject trees were bifurcated but did not exhibit reiterations. Of the subject trees, only the Cheoah Hemlock was both reiterated and bifurcated. This tree, supporting a bifurcation more than 83 feet long, was also nearly entirely cloaked in live crown from base to top. The longest and largest bifurcation occurred on the Yonaguska Hemlock; 28.75 m (94.3 ft) long and 5.37m3 (189.6 ft3) respectively. See example of a frame-mapped bifurcation fusion below: [cid:[email protected]] Frame mapping example from the Yonaguska Hemlock bifurcation fusion All the remaining trees in the project had a single trunk; one of which was broken at 31.74 m (104.1 ft). This tree (the Headless Giant) - as well as several others - had the vast majority of the crown originating on reiterations with very few non-reiterated branches. Several reiterations reiterated again (second order) with one fourth order reiteration noted in the Usis Hemlock. This immense tree had a fusion of two giant reiterations that supported a complex limb system supporting multiple reiterated sprouts - some originating from the same limb like a row of small trees extending upwards of ~12 m (~40 ft) from the trunk origin. Will F. Blozan President, Eastern Native Tree Society President, Appalachian Arborists, Inc. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Edward Frank Sent: Wednesday, March 11, 2009 11:04 PM To: [email protected] Subject: [ENTS] Re: Another Big White Pine ENTS, I am wondering about these reiterations. We have talked about it before, but everything is not clear in my mind. A reitteration is what exactly? It appears to be a secondary trunk formed ntially from an upturned limb... How do they form and why? What species of trees are know to have these reiterations? I know this white pine, some of the hemlocks in the Tsuga Search project, Many of the giant conifers from Bob Van Pelts book. Are there examples of reiterations in trees that are not conifers? Please enliughten me on the subject. Ed Frank ________________________________ ________________________________ [1] The cumulative volume total of all subjects in this study is just slightly more than the entire trunk volume of the largest known giant sequoia (Van Pelt 2001). --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
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