Background and aims: Organic matter is often used as an amendment to attempt restoration of degraded soils to improve tree establishment and growth. One key aim is to increase plant available water in the soil profile. The texture of the soil, the type of organic amendment (e.g. compost or biochar), and the native environment of the tree (mesic or xeric) will impact how successful restoration efforts are. We aimed to determine whether compost and biochar amendments, either individually or in combination, would improve plant available water (PAW) in both clay and sand soils. We then aimed to measure whether changes in PAW would translate into increased water use and plant growth of both mesic (Corymbia maculata) or xeric (Eucalyptus torquata) tree species under well-watered (WW) or water deficit (WD) conditions. Methods: Clay and sand soils were amended with compost, biochar or a compost and biochar mix, whilst unamended soils acted as controls. Soil moisture characteristics of the soil mixes were determined with samples in the laboratory. Fifteen replicate pots (61) of each soil treatment were then planted with either mesic and xeric tree species. All pots and trees were subjected to either a WW or WD irrigation regime for 7 weeks. WD irrigation was a set percentage of the daily WW evapotranspiration (ET). ET was calculated as total pot mass one hour after irrigation (to allow for drainage) minus the total pre-dawn pot mass of the subsequent day. The tree biomass, biomass partitioning, ET, and tree water status were measured throughout the experiment to understand growth and stress responses. Key results: The xeric tree species (E. torquata) grown in sand soil had a significant increase in growth with all three OM amendments but did not when grown in clay soil. In contrast, we found no significant growth response for the mesic tree species (C. maculata) when grown in either clay or sand amended with any OM treatment. The ET of the xeric tree species was greater for all the OM amended soils for both WW and WD plants in the sand soil. Conclusions: This study shows that OM amendments may improve the soil water properties of sand-based soils which in turn can increase the growth of xeric tree species. However, more expensive organic amendments may not be necessary, nor mixing of OM types, as we found no tree growth differences amongst the three different OM treatments.

Soil compaction can be a major impediment to tree growth as it damages soil physical and biological properties and reduces plant available water. This may result in trees that are more vulnerable to seasonal water stress. Improving soil physical and biological properties by increasing soil organic matter content may lead to improved tree establishment. Organic matter (OM), in the form of municipal green waste compost (MGWC) or biochar was incorporated into compacted urban soils at two sites. We established six soil treatments: 1) unamended, 2) tillage only, 3) tillage with MGWC (20% v/v), 4) tillage with biochar (10% v/v), 5) tillage with MGWC + biochar (10% & 5% v/v - low), and 6) tillage with MGWC + biochar (20% & 10% v/v - high) (one site only). The treatments were established to a depth of 0.5 m in 2 × 2 m plots. One Corymbia maculata sapling was planted into each plot. Bulk density, hydraulic conductivity, stem diameter growth and tree water status were measured during tree establishment. At the end of the 30-month experiment, development of water stable aggregates, the rate of microbiological decomposition of OM, and tree size (diameter at breast height; DBH, and canopy growth index) were measured. All OM amended treatments improved soil physical and biological properties. There were no significant differences among the OM treatments. At the end of the experiment, tree DBH and canopy growth index were greater in the OM treatments than tillage only and unamended. As such, we recommend using local and sustainable forms of OM to improve soils and assist tree establishment in challenging sites where soil water is limited, or evapotranspiration demand is high.

The recent prolonged drought in Melbourne, Australia has had a deleterious effect on the urban forest, resulting in the premature decline of many mature trees and a consequent decline in the environmental services that trees are able to provide to urban residents. Measuring the severity of tree stress and defoliation due to various climatic factors is essential to the ongoing delivery of environmental services such as shade and carbon sequestration. This study evaluates two methods to assess the vitality of drought stressed Elm trees within an inner-city environment—bark chlorophyll fluorescence measured on large branches and an urban visual vitality index. Study species were Ulmus procera Salisb. (English Elm) and Ulmus × hollandica (Dutch Elm), which are important character and shade tree species for Melbourne. Relationships were identified between leaf water potential and the urban visual vitality index and between leaf water potential and bark chlorophyll fluorescence measured on large branches, indicating that these methods could be used to assess the effect of long-term drought and other stressors on urban trees.

Large trees are often seen as a means of offsetting negative consequences of growing urban densification. To increase the tree canopy cover of dense urban landscapes, developers, planners and urban tree managers are often forced to plant into damaged and compacted sites. Compacted urban soils can hinder the establishment and growth of deep rooted, woody plants by: 1) impeding root exploration and development which is critical for water and nutrient acquisition; 2) reducing infiltration of water into the soil and the availability of water to plants; and 3) reducing gas exchange and the balance between anaerobic and aerobic conditions. At three sites in Melbourne, Australia with compacted and damaged soils, we established four soil re mediation treatments: 1 & 2) tillage to 0.25 m with and without 50% (v/v) municipal green waste compost (MGWC) additions, and 3 & 4) tillage to 0.5 m with and without 50% MGWC addition, plus a non-remediated control. Each treatment was replicated (n = 3), and one Corymbia maculata (spotted gum) tree was planted into the centre of each 2 x 2 m treatment plot (n = 15), at all three sites (n = 45). Bulk density and field-saturated hydraulic conductivity were improved by tillage, at least in the short-term. The use of MGWC may maintain these changes for longer. Depending on site soil conditions tree growth may be improved by tillage alone. At one site, we found that additions of MGWC lead to nitrogen immobilisation due to site soil conditions. At another site, deep tillage (with or without MGWC) led to significantly improved tree growth. Compacted and degraded urban soils may be improved through simple tillage and/or organic amendment strategies for the successful establishment of deep rooted woody plants. However, site soil conditions will dictate whether the addition of MGWC is beneficial or not, as one site showed no positive response to any tillage or MGWC. This research has examined a technique that can be used by landscape managers to improve soil physical characteristics and, in certain circumstances, can improve deep-rooted woody plant establishment and growth in challenging compacted urban soil conditions.

The direct effects of atmospheric and re-radiated heat from surfaces surrounding a street tree can affect its establishment, growth and development through high-temperature-induced injury. Sunscald is a symptom of direct heat injury to plant tissue that occurs on the trunk and branches as a result of high solar radiation causing the dehydration and death of plant tissues. This research was designed to investigate the impact of different paving surfaces, tree orientation at the time of planting and high ambient temperatures on the establishment of roadside trees in Melbourne, Australia. Thirty young Platanus × acerifolia trees were planted along the centre median of a major road and on the west side, directly adjacent to each tree, a 0.5 m2 paved surface was installed in a timber plinth box, with a 50 mm gap between the tree trunk and plinth. Four different materials were used to surface the boxes – concrete and organic mulch (recycled wood) for which there were seven replicates and asphalt and granitic sand for which there were eight replicates. Fourteen of the trees had their north facing orientation from the nursery maintained and 16 trees were rotated 180° so that their orientation was reversed and they faced south. In the morning, mulch and asphalt were up to 2 °C hotter than concrete and granitic sand, but by late afternoon, concrete and asphalt were on average 5 °C hotter than mulch and granitic sand. The data on afternoon temperatures showed mulch and asphalt being significantly hotter than concrete and granitic sand by 10 °C or more, but by late afternoon mulch had cooled by as much as 30 °C. The asphalt remained the hottest surface throughout the day and into the evening. While not significant (p = 0.077) reversing orientation at planting appeared to interact with pavement surface to reduce shoot tip extension. This research established a relationship between the occurrence of sunscald on the trunks and poor tree growth which warrants further investigation as the Australian climate warms.

The way a street tree is able to modify the local microclimate on pedestrian walkways may vary according to tree species according to key canopy and leaf characteristics, such as leaf angle, leaf size, canopy architecture or simply canopy density. Three similar north-south orientated streets, with three different tree species possessing different canopy and leaf characteristics were studied in summer 2014. Microclimatic parameters were measured on pedestrian walkways below and away from tree canopies between 06:00 and 20:00 on three cloudless days. Physiological Equivalent Temperature (PET) was estimated to indicate pedestrian thermal comfort. Microclimate conditions were measured below and away from trees at solar noon for a wide range of trees with different Plant Area Index (PAI) as determined using full-frame photography. In streets with Ulmus procera and Platanus x acerifolia trees, the microclimatic benefits were significantly greater than the street with Eucalyptus scoparia trees, however no significant differences in the estimated PET. Microclimate benefit increased with increasing PAI for all three tree species, however no significant difference in under-canopy micro climate amongst tree species when the PAI was similar. It appears that differences in PAI are paramount in determining the microclimatic and PET benefits. Obviously, certain tree species have a limit of the PAI they can achieve, and that should be considered when selecting or comparing tree species for shading and cooling benefits. This study assists urban planners and landscape professionals in selecting street tree species for cooling benefits based on the expected or managed tree canopy area. (C) 2016 Elsevier B.V. All rights reserved.

Maintaining human thermal comfort (HTC) is essential for pedestrians because people outside can be more susceptible to heat stress and heat stroke. Modification of street microclimates using tree canopy cover can provide important benefits to pedestrians, but how beneficial and under what circumstances is not clear. On sunny summer days, microclimatic measures were made in residential streets with low and high percentages of tree canopy cover in Melbourne, Australia. Streets with east-west (E-W) and streets with north-south (N-S) orientation were repeatedly measured for air temperature, relative humidity, wind speed, solar radiation, and mean radiant temperature on both sides of the street between early morning and midafternoon. Physiological equivalent temperature was estimated to indicate HTC throughout the day. In streets with high-percentage canopy cover, air temperature, relative humidity, solar radiation, and mean radiant temperature were significantly lower than in streets with low-percentage canopy cover. The reductions in air temperature under high-percentage canopy cover were greater for E-W streets (2.1°C) than for N-S streets (0.9°C). For N-S streets, air temperature, mean radiant temperature, and solar radiation were greater on the east pavement in the early morning and greatest on the west pavement in the midafternoon. The midday thermal benefits are restricted to E-W streets, which are oriented in the same direction as the summer sun's zenith. High-percentage canopy cover reduced wind speeds but not enough to offset the other microclimate benefits. These findings can assist urban planners in designing street tree landscapes for optimal HTC in summer, especially in areas of high pedestrian density.

Drought can lead to mortality in urban tree populations. The City of Melbourne, Victoria, Australia, manages a large population of trees that provide important ecosystem services and cultural heritage values. Between 1997 and 2009 Melbourne was affected by a serious drought resulting in significant tree health decline. Elms and planes in particular, were badly affected. This paper presents data from a survey of tree health status, and of studies of retrofitted buried drip line irrigation. A study of soil wetting in autumn of 2009 found that the use of drip irrigation had, in most cases, little or no effect on soil moisture levels and a modeled study of tree water use showed that water delivered by drip irrigation provided only a fraction of the water required by a mature tree. By contrast, drip irrigation in late winter was able to recharge soil moisture levels. Mechanisms responsible for the decline in tree health seen during the drought are discussed. While the drought has temporarily been alleviated, climate change scenarios for southern Australia suggest that increased rainfall variability and drought events will be more common. The experiences gained during the recent drought event provide useful information for urban tree managers planning for the future.

Sporadic and costly failure of newly planted vines is an ongoing problem in the Australian wine industry. Failed vines are frequently infected with wood pathogens, including the fungi associated with Young Vine Decline. Hot water treatment (HWT) and other nursery practices have also been implicated in vine failure. We undertook a survey of Australian grapevine nurseries to develop an understanding of current propagation practices and to facilitate the development of reliable propagation procedures that consistently produce high quality vines. A survey covering all aspects of grapevine propagation including sources of cuttings, HWT, sanitation and cold storage was mailed to all 60 trading Australian vine nurseries. In all, 25 nurseries responded, a response rate of 41.7%. Practices were found to vary widely both within and between nurseries. The vast majority of respondents (20) reported that they currently used, or had used, HWT, but the reliability of HWT was questioned by most nursery operators. A majority (18) felt that some Vitis vinifera varieties were more sensitive to HWT than others. Hydration also emerged as an important factor that had the potential to affect vine quality. All respondents used hydration and although the majority used treated water, cuttings were not generally seen as a source of cross contamination. Our study identified a clear need for further research into the effects of HWT on cutting physiology and the role of hydration in the epidemiology of grapevine pathogens, and the importance of incorporating the results of such research into practical and comprehensive propagation guidelines for vine nurseries.

Journal of Arboriculture. Volume 27 Number 1 January 2001. In The influence of compaction and soil strength on the establishment of four Australian landscape trees by Karen D. Smith, Peter B. May, and Gregory M. Moore, two experiments tested the hypothesis that trees able to establish in urban soils will have a higher-thanaverage tolerance to the greater mechanical impedance and soil strength of compacted soils. Experiment I tested the ability of the roots of Corymbia maculata (spotted gum, syn. Eucalyptus maculata), Lophostemon confertus (brush box), Corymbia ficifolia (red flowering gum, syn. Eucalyptus ficifolia), and Agonis flexuosa (willow myrtle) seedlings to penetrate a sandy loam soil compacted to bulk densities of I.4 and 1.8 mg m3 at 13 per cent gravimetric moisture content. Total root penetration depth was reduced by 60 per cent in all four species, at the greater bulk density. Experiment 2 tested the ability of Corymbia maculata and C. ficifolia to penetrate soil at bulk densities of 1.4, 1.6, and 1.8 mg m3 at 7 and I 0 per cent gravimetric moisture. At 7 per cent, both species penetrated soil compacted to 1.4 and 1.6 mg m3, but neither species was able to penetrate the 1.8 mg m3 soil. At 10 per cent, both species were able to penetrate soil compacted to 1.4, 1.6 mg m3 and 1.8 mg m3• In Tree moisture stress and insect damage in urban areas in relation to heat island effects by Bert M. Cregg and Mary Ellen Dix, crown air temperature, volumetric soil moisture, leaf water potential, rates of gas exchange, and insect pests of green ash (Fraxinus pennsylvanica 'Marshall's Seedless'), Austrian pine (Pinus nigra Arnold), and northern red oak (Quercus rubra L.) trees were monitored during a relatively hot summer in Lincoln, Nebraska, U.S.A. Air temperatures and vapor pressure deficits (VPD) were much higher in trees growing downtown than in nearby trees growing on the University of Nebraska campus. Increased VPDs and reduced soil moisture decreased pre-dawn water potential and gas exchange of ash and oak trees on the downtown site compared to trees on campus. Green ash trees downtown had more damage from lilac borers (Podosesia syringae (Harris) (Sesiidae)) than did trees on campus. Aphids (Aphidiae) and lace bugs (Tingidae Corythucha arcuata (Say)) appeared to be more numerous on oak trees growing downtown than on those growing on campus. In Differential Feeding by Adult Japanese Beetles on Foliage of Birch (Betula) Species and Hybrids by FrankS. Santamour, Jr., assessment of the relative resistance of various birches to foliar feeding by adult Japanese beetles was complicated by the insects' marked preference for leaves on spur shoots, as opposed to long-shoot leaves, on many trees. Based on the limited numbers of trees tested, the susceptible (most preferred) taxa were Betula alleghaniensis, B. davurica, B. nigra, B. nigra 'Heritage', B. papyrifera, B. populifolia, B. pubescens, B. uber, and B. utilis var. jacquemontii, although some resistant individuals of B. papyrifera and B. populifolia were found. Resistant taxa included B. lenta, B. maximowicziana,