146 Moore: Root Tip Growth and the Presence of Leaves Affect Epicormic and Lignotuberous Shoot Development had been killed. Such plant deaths may be due to a failure of roots to resume growth or the effective heat girdling of the stem below the lignotuber, depriving roots of resources for growth. These results suggest that before deciding on whether a tree is likely to survive after a severe stress, the condition of the root crown and roots should be ascertained if possible. If the tissue below the lignotu- ber is killed in young trees, there may be no buds available for recovery, and if the tissue of the root crown has been killed, then again, there may be no capacity for recovery. Such situations may occur after a bushfire or in an urban context when a young tree suffers trunk tissue necrosis under the lignotuber due to mower or line trimmer/brush cutter damage. In the aftermath of stresses such as fires or floods, particularly in urban and peri-urban sites, soils are often overlooked. In the clean-up after such events, heavy vehicles are often used to clear debris and silt to make the sites safe and usable. The vehicles can compact soil, but so too can vibrations from smaller items of equipment (Trowbridge and Bassuk 2004; Watson 2006; Hascher and Wells 2007). This may lead to a second dose of stress being placed upon already seriously stressed specimens. Tree managers should ensure that soil conditions are optimised after stressful events and do their utmost to minimise inad- vertent damage to root systems to enhance tree recov- ery through successful shoot growth. CONCLUSION While shoots may be initiated at more than one nodal position, the highest available healthy epicormic bud usually develops into a dominant shoot that reestab- lishes a single leader habit for seedlings. Lignotuber- ous buds at nodal positions 1 to 3 only develop when there are few, if any, epicormic buds available. Healthy root systems are crucial to overall tree health and vigour. After experiencing high levels of stress, the production of lignotuberous and epicormic shoots by trees depends on the resumption of root tip growth. Urban forest managers need to ensure that there are good soil conditions for the resumption of growth and avoid further stressing the tree by compacting soils in post-stress clean-up operations. For trees of high his- toric, botanical, landscape, or cultural value, the removal of dead tissue may allow earlier and more successful shoot production, and the added cost could be justified for such significant trees. Trees that retain ©2021 International Society of Arboriculture some healthy foliage after being stressed are more likely to recover through successful shoot production, and so premature removal of trees or parts of trees bearing healthy foliage should be avoided during post- stress clean-up activities. LITERATURE CITED Aloni R. 2015. Ecophysiological implications of vascular differ- entiation and plant evolution. Trees. 29:1-16. https://doi.org/ 10.1007/s00468-014-1070-6 Ashton DH. 1981. Tall open forests. In: Groves RH, editor. Austra- lian vegetation. Melbourne (Australia): Cambridge University Press. 449 p. Aubry S, Fankhauser N, Ovinnikov S, Pružinská A, Stirnemann M, Zienkiewicz K, Herrfurth C, Feussner I, Hörtensteiner S. 2020. Pheophorbide a may regulate jasmonate signaling during dark-induced senescence. Plant Physiology. 182(2): 776-791. https://doi.org/10.1104/pp.19.01115 Baluska F, Mancuso S, Volkmann D, Barlow P. 2004. Root apices as plant command centres: The unique “brain-like” status of the root apex transition zone. Biologia. 59:9-17. Bamber RK, Mullette KJ. 1978. Studies of the lignotubers of Eucalyptus gummifera (Gaertn. & Hochr.). II. Anatomy. Austra- lian Journal of Botany. 26(1):15-22. https://doi.org/10.1071/ BT9780015 Bär A, Michaletz ST, Mayr S. 2019. Fire effects on tree physiology. New Phytologist. 223(4):1728-1741. https://doi.org/10.1111/ nph.15871 Beadle NCW. 1981. The vegetation of Australia. Sydney (Australia): Cambridge University Press. 717 p. Boland DJ, Brooker MIH, Chippendale GM, Hall N, Hyland BPM, Johnston RD, Kleinig DA, Turner JD. 1984. Forest trees of Australia. Melbourne (Australia): Nelson-CSIRO. 687 p. Bruce D. 1956. Effect of defoliation on growth of longleaf pine seedlings. Forest Science. 2(1):31-35. https://doi.org/10.1093/ forestscience/2.1.31 Burrows GE. 2002. Epicormic strand structure in Angophora, Eucalyptus and Lophostemon (Myrtaceae)—Implications for fire resistance and recovery. New Phytologist. 153(1):111-131. https://doi.org/10.1046/j.0028-646X.2001.00299.x Busse MD, Hubbert KR, Fiddler GO, Shestack CJ, Powers RF. 2005. Lethal soil temperatures during burning of masticated forest residues. International Journal of Wild Fire. 14(3):267-276. https://doi.org/10.1071/WF04062 Carr DJ, Janhke R, Carr SGM. 1984. Initiation, development and anatomy of lignotubers in some species of Eucalyptus. Austra- lian Journal of Botany. 32(4):415-437. https://doi.org/10.1071/ BT9840415 Carrodus BB, Blake TJ. 1970. Studies on the lignotubers of Euca- lyptus obliqua L’Herit. I. The nature of the lignotuber. New Phytologist. 69(4):1069-1072. https://doi.org/10.1111/j.1469-8137 .1970.tb02488.x Chattaway MM. 1958. Bud development and lignotuber forma- tion in eucalypts. Australian Journal of Botany. 6(2):103-115. https://doi.org/10.1071/BT9580103 Clarke PJ, Lawes MJ, Midgley JJ, Lamont BB, Ojeda F, Bur- rows GE, Enright NJ, Knox KJE. 2013. Resprouting as a key
July 2021
| Title Name |
Pages |
Delete |
Url |
| Empty |
Ai generated response may be inaccurate.
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success.
Downloading PDF
Generating your PDF, please wait...
This process might take longer please wait
