ARBORICULTURE CONTENTS & URBAN FORESTRY Volume 45, No. 6, November 2019 Formerly the Journal of Arboriculture, 1975 – 2005 (Volumes 1 – 31) Gary Watson Landscape Below Ground IV: Introduction to a Special Issue ........................................................ 237 Abstract. This special issue is dedicated to research presented at the 2018 Landscape Below Ground IV conference. We describe highlights from the ten original research articles included in this issue. With these articles, we aim to support the advancement of tree care practices and inform managers and policymakers to choose, site, plant, and care for healthier, longer-lived trees by focusing on their critical and vulnerable root systems and the soil that surrounds them. Keywords. Anchorage; Infrastructure; Root Development; Site Design; Stability; Tree Planting and Establishment. Gregory M. Moore, Alicia Fitzgerald, and Peter B. May Soil Compaction Affects the Growth and Establishment of Street Trees in Urban Australia....... 239 Abstract. Growing conditions for street tree roots are generally harsh with restricted space and soils compacted from streetscape infrastructure. Alloca- suarina littoralis, Corymbia maculata, Cupressus sempervirens var. stricta, Eucalyptus polyanthemos, Lophostemon confertus, Olea europaea, Quer- cus palustris, and Waterhousea floribunda were grown in compacted and uncompacted soils for 20 months in experimental blocks. The bulk density and penetrative resistance of the soils and height, canopy spread, trunk diameter, leaf area, and chlorophyll fluorescence were measured regularly. Root and shoot biomass were determined after harvesting. Since the bulk density of compacted compared to uncompacted soil was root growth limiting, it was hypothesised that species would have reduced growth in compacted soils. However, C. maculata and E. polyanthemos grew better, C. sempervirens, Q. palustris, and W. floribunda grew well, and A. littoralis, L. confertus, and O. europaea were the worst performing in compacted soil. E. polyanthemos, L. confertus, and Q. palustris had higher canopy:root ratios in compacted soil. Q. palustris had greater mass below ground than above, which has impli- cations for its use in confined sites. In a field study, C. maculata, E. polyanthemos, L. confertus, O. europaea, and Q. palustris growing as street trees were surveyed to determine their rates of establishment and growth under urban conditions. In addition to the soil and tree parameters mentioned above, a Visual Tree Assessment (VTA) was undertaken. E. polyanthemos had the largest trunk diameter, height and canopy spread, indicating its potential for rapid establishment in streets. It was the only species with a larger mean leaf area in compacted soil. E. polyanthemos and O. europaea were the only species classed as healthy from chlorophyll fluorescence but there was no significant difference in fluorescence between compacted and uncompacted soils. VTA showed that C. maculata and O. europaea performed best and that E. polyanthemos, L. confertus, and Q. palustris had reduced but accept- able growth in compacted soil. Soils ranged from non-saline to moderately saline and were slightly to strongly acidic. All soils were compacted to some degree and penetrative resistance was at root limiting levels. The results suggest that careful species selection and soil amelioration for species prone to the effects of compaction would facilitate street tree establishment. Keywords. Australian Street Trees; Soil Compaction; Street Tree Establishment; Street Tree Growth. Angela Hewitt, Frank Balestri, Marvin Lo, and Gary Watson Species Variation in Root Tolerance of Soil Compaction and Poor Drainage ................................ 254 Abstract. Loam-over-compacted-clay and loam soil profiles were created in 10 cm × 10 cm × 25 cm containers. Containers were placed in trays of water to simulate poor subsoil drainage in the landscape. Four urban tolerant species, Acer negundo, Catalpa speciosa, Gleditsia triacanthos, Ulmus americana, and two less tolerant species, Quercus rubra and Acer saccharum, were direct seeded in the containers. Soil volumetric water content and oxygen diffusion rate were monitored. At the conclusion of the study, length of fine roots (< 2 mm diameter) was measured throughout the soil profile. Oxygen decreased and moisture increased with soil depth. Fine root density of all species decreased with depth except Ulmus Americana. Catalpa spe- ciosa was the only species showing a difference in root growth between soil types throughout the profile and had up to seven times the root density of other species at the surface and up to four times at the bottom. Root growth of most species seemed to be reduced more by high soil moisture and reduced aeration than soil texture and compaction. Keywords. Root Growth; Oxygen; Waterlogging. ©2019 International Society of Arboriculture
November 2019
| Title Name |
Pages |
Delete |
Url |
| Empty |
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. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
