Next Article in Journal
Computer Vision, Machine Learning, and Deep Learning for Wood and Timber Products: A Scopus-Based Bibliometric and Systematic Mapping Review (1983–2026, Early Access)
Previous Article in Journal
Impact of Introduced Spatholobus suberectus and Dalbergia balansae on Soil N Accumulation and P Depletion in Chinese Fir Plantations
Previous Article in Special Issue
Shrub–Herb Plant Configuration Patterns and Their Relationship with Environmental Factors in the Northern and Southern Mountain Regions of Lhasa
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Forests
Volume 17
Issue 1
10.3390/f17010111
forests-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Impervious Surfaces Do Not Impact Urban Tree Crown Growth

by
Peter Cybula
,
Patricia R. Torquato
,
Amy Hahs
and
Stefan K. Arndt
*
School of Agriculture, Food and Ecosystem Sciences, The University of Melbourne, 500 Yarra Boulevard, Burnley, VIC 3121, Australia
*
Author to whom correspondence should be addressed.
Forests 2026, 17(1), 111; https://doi.org/10.3390/f17010111
Submission received: 8 December 2025 / Revised: 8 January 2026 / Accepted: 11 January 2026 / Published: 14 January 2026
(This article belongs to the Special Issue Growing the Urban Forest: Building Our Understanding)
Browse Figures
Versions Notes

Abstract

Tree canopies in urban areas have many important ecosystem functions, and councils have targets to increase urban tree canopy area, which has proved challenging. Urban centres have large areas of impervious surfaces, and there is a perception that impervious surfaces are harmful for urban tree growth as water cannot penetrate the soil in which trees are growing. We investigated tree crown growth of young trees of eight common urban tree species in a suburb of Melbourne, Australia, that either grew in streets that were impacted by impervious surfaces or in parks. Four tree species had shown sensitivity to rainfall by lower crown growth in a low-rainfall suburb before, while the other four species had similar crown growth in high- and low-rainfall suburbs. We identified 40 trees per species and location (street vs. park) that were planted between 2009 and 2011 and measured their tree crown area in 2014 and again in 2018 using remote-sensed images. Trees that grew in streets that were impacted by impervious surfaces had larger crowns in 2014 than trees in parks, but both showed similar crown growth rates of 2.3 m2 yr−1 in the four-year period. Only one species (Eucalyptus sideroxylon A.Cunn ex Woolls) had a statistically significant greater relative crown growth rate in parks compared to streets. There was no statistically significant difference in the relative or absolute crown growth rates in tree species that have shown a previous sensitivity to rainfall compared to those that were insensitive to rainfall. Our data indicate that impervious surfaces had no detrimental impact on tree crown growth. It is possible that trees grown in streets have sufficient water resources and may benefit from the lack of competition for water, whereas trees in parks must compete for water resources with other plants.

1. Introduction

More than 50% of the global population now live in cities, and this trend is expected to continue to reach over 67% by 2050 [1,2,3]. Improving the liveability of cities is closely linked to urban trees and their foliage cover [4]. Many local governments have adopted ambitious urban tree canopy targets to reduce urban heat islands and urban thermal heat stress [5], with goals ranging from a doubling of tree planting to percentage urban tree canopy cover targets (e.g., 30%–40%) in the public realm [6,7,8]. As a nature-based solution, urban trees provide multiple ecosystem services, which are largely dependent on tree size, canopy cover, growth rate, and longevity [9,10,11]. Benefits include improved air quality, ambient air temperature via evapotranspiration, reduced surface temperature under shade, reduced heating/cooling energy consumption, increased biodiversity connectivity, and the encouragement of greater physical outdoor activity and social cohesion in public parks and along urban forested streetscapes [2,12,13].
Urban development leads to increasing impervious surfaces such as roads, parking lots, driveways, and footpaths as essential built environment infrastructure [11]. So expansive is this coverage that more than half of land surfaces in cities, some as high as 67%, consist of hard and impervious surfaces [9,14,15]. Impervious surfaces are a significant contributor to the urban heat island effect, restrict rainfall infiltration of urban soils, disrupt soil nutrient cycling [11], and increase top-soil temperature, impacting root growth [8,10,15]. Impervious surfaces have also been linked to urban tree stress impacting allometric tree growth [16,17,18]. As a result, cities are often deemed stressful environments where impervious surfaces suppress urban tree growth by imposing heat, drought, nutrient, and soil compaction stress, leading to poor physiological growth and reduced life span [16,19,20]. However, other studies suggest little or no detrimental impact of impervious surfaces on urban tree crown growth, even when below-ground root morphology changes are evident [21], and/or that they may even assist urban tree establishment [9,12,14]. To our knowledge there have been no studies that have investigated whether urban trees subject to impervious surfaces (e.g., street trees) are more stressed, leading to slower crown growth compared to trees that are not subjected to impervious surfaces (e.g., park trees) over an extended period of time.
Knowledge gaps remain in understanding whether impervious surfaces cause a tree stress response that results in slower growth [9,12,22]. There is evidence for a differential response of tree crown growth to urban climate, with some tree species appearing to be more sensitive to climatic factors than others. Tree crown growth significantly differed between species in a study between a low- and high-rainfall suburb in Melbourne [23]. Some species in this study displayed a lower crown growth in the lower-rainfall suburb, whereas other species had similar crown growth in the low- and high-rainfall suburbs. Thus, it is possible that some species could also show a greater susceptibility to impervious surfaces than others.
Tree canopy cover in cities can be monitored using high-resolution imagery, providing critical information for managing the urban forest effectively and tracking progress towards canopy cover targets [24,25]. However, high-resolution imagery can also be used to monitor changes in crown sizes of individual trees, thereby providing integrated information of tree growth and crown expansion [12,23,26].
We aimed to investigate the impact of impervious surfaces on urban tree crown growth in Melbourne, Australia, using high-resolution imagery. The objectives of this study were (1) to compare the crown growth of young trees in a street (with impervious surfaces) and park environment (without impervious surfaces) in the same suburb for eight tree species and (2) to investigate if tree species that had previously shown a greater sensitivity of crown growth to rainfall would also show a greater sensitivity to impervious surfaces than tree species that were not sensitive in crown growth to rainfall.

2. Materials and Methods

2.1. Study Area

This study was conducted in Wyndham, an outer west metropolitan Melbourne local government area (LGA) in the state of Victoria, Australia. It has a size of approximately 542 km2 and has been a designated Urban Growth Area since 2002 [27]. It has been one of the fastest growing areas, experiencing rapid population and subdivision housing growth during 2006–2016 with a 160% increase in population (from 112,695 to 292,011) and the addition of more than 34,000 dwellings constructed [28,29]. The housing in the study area is developed from greenfields, typically pastures or other agricultural land, and is a dense suburban housing development of single- or double-storey individual dwellings on a small block of land (Figure S1).
Wyndham is in a mild temperate climate zone [30,31] with a low mean annual rainfall of 478 mm yr−1 (1981–2020) compared to other metropolitan Melbourne LGAs [23]. The average rainfall from 2014 to 2018 was 432.8 mm per year, ranging from a high of 534.8 mm in 2016 to a low of 358.2 mm in 2015 (Bureau of Meteorology monthly climate statistics station 087031). It had one of the lowest rates of urban tree canopy coverage in 2018 at just 4.2% (5.5% Western region), compared to 12.1% (Northern region) and 25.9% (Eastern region) in other metropolitan Melbourne LGAs [32,33]. Continued growth is expected to see Wyndham grow to a population of more than 445,000 by 2045 [34]. As a consulted stakeholder council establishing the Engineering Design and Construction Manual for Subdivision in Growth Areas in Victoria in 2011 [35], Wyndham has implemented these standards of road and streetscape design, including tree planting, since 2009 [36], making it a good study location to investigate historical growth of selected urban trees planted in contrasting contexts (street trees and park trees) across a citywide landscape over an extended period of time.

2.2. Data Collection and Selection

Georeferenced data of urban trees (park, street) planted between 2009 and 2011 was sourced from the Wyndham City Council urban tree inventory database and focused on species that had previously shown different sensitivities of crown growth to rainfall [23]. Some tree species had demonstrated slower crown growth in a low-rainfall zone (such as Wyndham, 478 mm yr−1) compared to the same species planted in a higher-rainfall region of metropolitan Melbourne (Whittlesea, 665 mm yr−1) over a ten-year period, whereas other species had no differences in crown growth between rainfall areas [23,37].
We used high-resolution aerial imagery (0.075 m/pixel, Nearmap, 2024) [38] with a map browser function capable of exporting georeferenced map tiles to measure crown area (m2) using QGIS version 3.34.39, an open-source geographical information system. The workflow is displayed in Figure S2. Nearmap image capture started in 2009, so crown growth could only be measured after that time. We therefore focused on the investigation of tree crown growth in trees that were planted in the period from 2009 to 2011, where we could match an inventory record to an aerial image. An equal number of park trees (pervious) and street trees (impervious) were needed to compare crown growth, resulting in eight urban tree species included in this study. The four species that were previously identified as having an insensitive crown growth to rainfall and had the required number of replicate trees that could be measured included one acacia, two bloodwoods (closely related to eucalypts), and one eucalypt species (Table 1). The four species that had a lower crown growth in low-rainfall areas included three eucalypts and one elm tree (Table 1). A sample size of up to 40 trees of each species resulted in a total of 1218 tree crown measures; there were 28 trees for Acacia implexa Benth. Negative crown growth measures were removed from the dataset (12 park trees and 4 street trees). Because urban trees are subject to a 2-year establishment period of active irrigation (watering) post planting, the summer of 2014 was the first opportunity to measure tree crown area, and late summer 2018 was selected as a second time to measure crown area, representing 8–10 years of established crown growth from urban trees planted between 2009 and 2018 (Table 1).

2.3. Urban Tree Selection

We used the following definition to select park and street trees: A park tree was defined as an urban tree planted with no surrounding impervious surfaces (road, driveway, footpath) within a general proximity of the tree’s expected crown dripline, or a park tree with impervious surfaces on one side (maximum) was also included (e.g., trees planted on a park perimeter along a roadside). A street tree was defined as an urban tree planted in a new subdivision development with three surrounding sides of impervious surfaces (road, driveway, and footpath) within a general proximity of the tree’s expected crown dripline, or two impervious surfaces on at least two sides minimum were also included (e.g., road and driveway, as not all new subdivisions include footpaths along all subdivision streets). Urban trees selected for crown area measurement were spatially dispersed to avoid grouped or side-by-side plantings and reduce the chance of crown expansion/merging with other trees between 2014 and 2018. For example, if a 2014 urban tree crown was found to have expanded to merge with another tree crown by 2018, that selected sample was removed and another similar species was selected for analysis. This approach was applied to park trees where on occasion park landscaping and/or redesign might occur and to street trees where trees planted on private property might result in crown expansion across into the nature strip area.

2.4. Crown Growth Measurements

QGIS (version 3.34.9), Nearmap Map browser, Microsoft Excel (Windows 11), and R programming (4.4.1) were used to construct a QGIS project file to record, measure, and analyse crown growth (Figure S2). First, a QGIS project file was created with Google Satellite and Google Road features selected, and Wyndham Urban Tree Inventory shapefile data (2009–2011) was imported and layered into the project file (Step 1). Second, Nearmap Map Browser was used to export map tiles (high resolution) covering urban trees that were planted between 2009 and 2011 across Wyndham LGA (georeferenced, GDA94/MGA Zone 55, 0.075 m/pixel) (Step 2). Next, the tree crown area was measured for selected park and street trees by drawing a polygon around the tree crown on the aerial images and saved as separate GIS layers. We selected images recorded on 4 March 2014 and 4 February 2018. A separate attribute table was created for each (recording species, crown area (m2), location, year of planting), which were converted to .csv file format (comma-separated value) (Steps 3 and 4). Finally, box plot calculations of mean (average), median (50th percentile), lower quartile range (0%–25%), interquartile range IQR (25%–75%), upper quartile range (75%–100%), and outlier values were completed in Excel, and statistical significance testing (95% confidence) was completed using R (version. 4.4.1) (Step 5). As the relative growth of tree crowns is greatest during the early life cycle of a tree, a rate-of-change measure is appropriate, as any impact on long-term urban tree crown growth should be most observable during this growth phase. The crown growth rate (%) calculation for this study was expressed as follows:
Crown growth rate (%) = (Crown Area (m2) 2018 − Crown Area (m2) 2014)/Crown Area (m2) 2014 × 100

2.5. Statistics

R programming (version 4.4.1) was used to calculate p-adjusted values (α = 0.05, confidence 95%) for statistical significance testing given multiple samples of park tree crown areas and street tree crown areas were generated by this study. To control for the number of false positives (or false discovery rate, FDR), the Benjamini–Hochberg (BH) method is also used to reduce the number of significant results, as the normal distribution of different samples does not overlap.

3. Results

3.1. Tree Crown Growth: Individual Species Compared—Park vs. Street Trees

The crown growth rate (%) of each tree species sampled (park, street) between 2014 and 2018 appears in Figure 1. All species show a positive crown growth rate over the period ranging from 97% to 444%, with Eucalyptus melliodora A.Cunn ex Schauer (park tree) exhibiting the largest range of growth variability compared to other samples. Eucalyptus polyanthemos Schauer (180%) recorded the lowest average crown growth rate in park trees. For street trees, Corymbia maculata Hook (168%) had the lowest average crown growth rate and Corymbia citriodora Hook (287%) the highest. Overall, most street trees exhibited a more consistent growth and smaller growth range compared to park trees, while rainfall-insensitive species (both park and street) exhibited an overall larger range of growth compared to rainfall-sensitive species (both park and street). None of the differences in crown growth rate between park trees and street trees were statistically significant except for Eucalyptus sideroxylon A.Cunn ex Woolls, where the average relative growth rate of this street tree (124%) was outside the 50% mid-spread range (box) of similar species park tree crown growth rate values (150%–262%).

3.2. Urban Tree Crown Growth: All Park Trees vs. All Street Trees

Street trees had a much greater crown area than park trees in 2014, when the crown measurements started (Table 2). The crown area of park trees ranged from 1.6 m2 (E. melliodora) to 5.5 m2 (E. polyanthemos) in 2014, whereas the crown area of street trees ranged from 4.5 m2 (C. citriodora) to 16.5 m2 (E. polyanthemos). The same trend was observed in 2018, where park trees also had a much smaller crown area compared to street trees. There was no statistically significant difference in crown area between rainfall-sensitive and insensitive groups of trees. When we averaged the crown area of all street and park trees, we observed that street trees had a 2.3 times greater crown area than park trees in 2014 (Figure 2). The same ratio was also observed in 2018, indicating a near-identical relative growth rate (163% in park trees vs. 156% in street trees).

3.3. Crown Growth of Rainfall-Sensitive Trees vs. Rainfall-Insensitive Species

Rainfall-sensitive street trees had a larger crown area (m2) than rainfall-sensitive park trees in 2014 (2.43 times), and this ratio slightly decreased in 2018 (2.14 times) (Figure 3). Thus, in 2018 rainfall-sensitive street trees had a mean crown size that was twice as large (21.4 m2) compared to rainfall-sensitive park trees (10.02 m2). Overall, the rainfall-sensitive species had a greater crown area than the rainfall-insensitive species, both in 2014 and in 2018. But in rainfall-insensitive species, the same trends between park and street trees were observed, with park trees being substantially smaller than street trees in 2014 and in 2018. The relative growth rates between 2014 and 2018 were variable among rainfall-sensitive and insensitive species. This was also driven by the large variability of crown area and crown growth rate between the species (Table 2).

4. Discussion

We observed that impervious surfaces in streets did not negatively impact urban tree crown growth as compared to park trees and that species that had previously shown sensitivities to rainfall had similar crown growth rates compared to trees that were not sensitive to rainfall.
Possible explanations for why impervious surfaces do not negatively impact urban street tree crown growth include (i) impervious surfaces surrounding street trees do not completely restrict rainfall infiltration or runoff towards the tree base, (ii) impervious surfaces may trap and/or reduce soil moisture evaporation during warmer/dry periods, (iii) street trees with impervious surfaces are less subject to soil moisture and nutrient competition compared to park trees, and (iv) the quality of tree nursery stock used for park trees and/or lack of a comparable 2-year maintenance regime significantly impact the early establishment of urban park tree crown growth.
Streetscape construction (including tree-planting specifications) has been a part of statutory planning regulatory guidelines across Victorian local government areas (LGAs) since 2011 [35], which Wyndham had already established in policy since May 2009 [36,39]. For example, a minimum midpoint clearance for tree planting of 0.75 m between kerb (roadside) and footpath is mandated [40]. As a result, this minimum surface clearance around the street tree, plus cracks or gaps in impervious surfaces or stormwater infrastructure, together with private garden irrigation runoff and surrounding soil hydration, may sufficiently reduce water deficit or drought stress for street trees and continue to support tree crown growth [12,41].
Street trees are subject to a 2-year period of maintenance, including periodic watering to support new tree root growth and establishment [34,40]. Impervious surfaces create a restrictive layer for rainfall infiltration but can also reduce soil dehydration and evaporation rate. This means that soil moisture is maintained during dry periods and slows rehydration during wetter periods in upper-level subsoils, with studies finding no detectable difference in deeper soil moisture levels compared to unpaved soil [9,15]. As a result, the 2-year period of maintenance and watering by the council appears to be a sufficient provision of soil moisture to accumulate beneath impervious surfaces to support and sustain street tree crown growth post-establishment growth even in low-rainfall zone areas such as this study. Sporadic and/or regular private garden watering could also provide sufficient runoff and/or soil moisture rehydration and provide for opportunistic street tree root growth to sustain crown growth.
Street trees in new subdivision areas are often established in sites surrounded by impervious surfaces and therefore subject to no other vegetation in competition for soil moisture or nutrients [36]. In contrast, park trees are often deliberately landscaped with grass, bushes, shrubs, or other park trees to provide additional ecosystem benefits, including biodiversity and habitat provision [42]. This leads to greater competition for surface rainfall interception, soil moisture, and nutrients. Grasses and other shallow-root vegetation can compete for moisture in low- and erratic-rainfall environments where root space is shared [43], leading to reduced tree growth [44,45,46]. In developed urban environments grasses have proved so successful in removing surface runoff that they are sometimes included as an alternative or additional surface runoff mitigation option with stormwater infrastructure such as tree pits [47]. As a result, it is possible that park trees are subject to greater competition for soil moisture and nutrients and hence may develop smaller crown areas compared to street trees.
Another possible reason for the smaller initial crown sizes in park trees could be the difference in quality of tree nursery stock and/or the lack of a comparable 2-year maintenance period during their initial establishment. While the year of planting information was recorded in the GIS urban tree inventory database, the age of the tree or height at time of planting is not provided. There are publicly available documented standards and guidelines for streetscape design, street tree planning, and establishment phase maintenance, including irrigation [35,36]. However, we were unable to identify any comparable information on park landscape guidelines over 2009–2011, apart from a recent urban ecology consultant report for another metropolitan Melbourne council [42].
One limitation of our study is that we classified street trees and park trees based on the amount of impervious surfaces that surrounded the trees, but we did not quantify impervious surfaces as a continuous variable. We were also not able to examine other variables such as soil type or pavement permeability, noting that pavement in new suburbs is usually similar in all locations with 10 cm concrete in slabs. We also acknowledge that we studied young trees, and as such, we cannot comment on any long-term effects that may arise.

Significance for Practitioners and Urban Planning Decision-Making

The results of this study are significant for practitioners (developers and urban planners) for three reasons. First, our data provide evidence that the subdivision guidelines and establishment phase of 2 years, introduced in Wyndham in 2009 (and across Victoria from 2011), appear to support successful urban street tree establishment and crown growth compared to park trees, particularly for rainfall-sensitive species over 2009–2018. It is likely that impervious surfaces will have a similar supportive impact for additional species’ crown growth as reported for Platanus x. acerifolia [9,48].
Our data would indicate that current park and reserve landscape design might benefit from a similar guidelines approach to park tree planting and establishment, following an investigation of the cost and feasibility of such an approach. We recommend further research to better understand why park tree crowns were on average lower than street trees, except for E. sideroxylon. Second, the results are significant because an increase in the number of suitable street trees also could encourage more biodiversity options and/or improve pest/pathogen resistance that can potentially be achieved if additional varieties of species can be supported in an environment with impervious surfaces. Finally, our data indicate that street trees recently planted at Wyndham are as or more successful than park trees because their contribution to canopy targets is due to both initial planting size and growth rates.

5. Conclusions

Our study demonstrated that impervious surfaces in streets in new developments are less harmful to tree growth than observed or suggested elsewhere. Tree crowns in streets were larger and grew at a similar rate compared to park environments that had no impervious surfaces. This is encouraging, as the Wyndham LGA is an area with the lowest rainfall in Greater Melbourne, and would thus have expected negative consequences of low water supply to be prominent in this area. Our data also indicate a large variability in absolute and relative growth rates between species. This is not unexpected, as the micro-environments in streets and parks differ substantially, and there will be genetic variation among the individual trees of a species. However, tree species whose crown growth had previously been susceptible to rainfall in the same study area had similar crown growth rates compared to species that were insensitive to rainfall in crown growth.
This indicates that species may respond with greater crown growth to more rainfall, but that in the low-rainfall zone, these apparent differences are not important. Overall, our study provides evidence that impervious surfaces have no negative impact on tree crown growth, at least in the early stages of tree establishment. Unlike street tree planting, park tree planting and landscaping appear to have no standard guidelines informing design, installation, or maintenance to support crown growth, something that ought to be investigated further.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/f17010111/s1, Figure S1: (a) Graphical representation of the methodology of measuring tree crown area and (b) Nearmap image of a typical street in the study area with polygon measurements of tree crown area in 2014 (red area) and in 2018 (red outline). Figure S2: (a) A typical streetscape in a new development in Wyndham, Melbourne, with left detail and right overview. Street trees are planted approximately in front of every property with a small grassy nature strip surrounding each tree. The area of impervious surfaces is substantial given the large houses, which intercept rainfall and drain it to stormwater; the concreted areas of driveways and footpaths; and the asphalt streets. (b) Images of the measurements of crown area for street trees (left) and park trees (right). The bright green shape indicates the canopy outline in 2014; the dotted green line is the polygon in 2018.

Author Contributions

Conceptualization, P.C. and S.K.A.; methodology, P.C., P.R.T., A.H. and S.K.A.; formal analysis, P.C.; resources, P.R.T., A.H. and S.K.A.; writing—original draft preparation, P.C.; writing—review and editing, P.R.T., A.H. and S.K.A.; visualization, P.R.T., A.H. and S.K.A.; supervision, P.R.T., A.H. and S.K.A. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in this study are included in the article/Supplementary Materials. Further inquiries can be directed to the corresponding author.

Acknowledgments

We wish to thank the City of Wyndham for the availability and use of their urban tree inventory data, which facilitated this research.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Biłozor, A.; Cieślak, I. Review of Experience in Recent Studies on the Dynamics of Land Urbanisation. Land 2021, 10, 1117. [Google Scholar] [CrossRef]
  2. Gillner, S.; Vogt, J.; Tharang, A.; Dettmann, S.; Roloff, A. Role of street trees in mitigation effects of heat and drought at highly sealed urban sites. Landsc. Urban Plan. 2015, 143, 33–42. [Google Scholar] [CrossRef]
  3. Revi, A.; Satterthwaite, D.; Aragón-Durand, F.; Corfee-Morlot, J.; Kiunsi, R.B.R.; Pelling, M.; Roberts, D.; Solecki, W.; Gajjar, S.P.; Sverdlik, A. Towards transformative adaptation in cities: The IPCC’s Fifth Assessment. Environ. Urban. 2014, 26, 11–28. [Google Scholar] [CrossRef]
  4. Livesley, S.J.; McPherson, E.G.; Calfapietra, C. The urban forest and ecosystem services: Impacts on urban water, heat, and pollution cycles at the tree, street, and city scale. J. Environ. Qual. 2016, 45, 119–124. [Google Scholar] [CrossRef] [PubMed]
  5. Meade, R.D.; Akerman, A.P.; Notley, S.R.; McGinn, R.; Poirier, P.; Gosselini, P.; Kenny, G.P. Physiological factors characterizing heat-vulnerable older adults: A narrative review. Environ. Int. 2020, 144, 105909. [Google Scholar] [CrossRef]
  6. City of Melbourne. Central City Urban Forest Precinct Plan 2013–2023, City of Melbourne Council Report; City of Melbourne: Melbourne, Australia, 2013; 20p. Available online: https://www.melbourne.vic.gov.au/urban-forest-precinct-plans (accessed on 14 November 2024).
  7. City of Toronto. Every Tree Counts: A Portrait of Toronto’s Urban Forest. 2013. Available online: https://www.toronto.ca/wp-content/uploads/2017/12/92de-every-tree-counts-portrait-of-torontos-urban-forest.pdf (accessed on 14 November 2024).
  8. Day, S.D.; Amateis, R.L. Predicting canopy and trunk cross-sectional area of silver linden (Tilia tomentosa) in confined planting cutouts. Urban For. Urban Green. 2011, 10, 317–322. [Google Scholar] [CrossRef]
  9. Fini, A.; Frangi, P.; Comin, S.; Vigevani, I.; Rettori, A.A.; Brunetti, C.; Moura, B.B.; Ferrini, F. Effects of pavements on established urban trees: Growth, physiology, ecosystem services and disservices. Landsc. Urban Plan. 2022, 226, 104501. [Google Scholar] [CrossRef]
  10. Mullaney, J.; Lucke, T.; Trueman, S.J. A review of benefits and challenges in growing street trees in paved urban environments. Landsc. Urban Plan. 2015, 134, 157–166. [Google Scholar] [CrossRef]
  11. Viswanathan, B.; Volder, A.; Watson, W.T.; Aitkenhead-Peterson, J.A. Impervious and pervious pavements increase soil CO2 concentrations and reduce root production of American sweetgum (Liquidambar styraciflua). Urban For. Urban Green. 2011, 10, 133–139. [Google Scholar] [CrossRef]
  12. Ren, X.; Torquato, P.R.; Arndt, S.K. Urban density does not impact tree growth and canopy cover in native species in Melbourne, Australia. Urban For. Urban Green. 2023, 81, 127860. [Google Scholar] [CrossRef]
  13. Jang, J.; Leung, D.W.M. The Morpho-Physio-Biochemical Attributes of Urban Trees for Resilience in Regional Ecosystems in Cities: A Mini-Review. Urban Sci. 2022, 6, 37. [Google Scholar] [CrossRef]
  14. Fini, A.; Frangi, P.; Mori, J.; Donzelli, D.; Ferrini, F. Nature based solutions to mitigate soil sealing in urban areas: Results from a 4-year study comparing permeable, porous, and impermeable pavements. Environ. Res. 2017, 156, 443–454. [Google Scholar] [CrossRef] [PubMed]
  15. Grassi, A.; Pagliarani, I.; Cristani, C.; Palla, M.; Fini, A.; Comin, S.; Frangi, P.; Giovannetti, M.; Turrini, A. Effects of pavements on diversity and activity of mycorrhizal, symbionts associated with urban trees. Urban For. Urban Green. 2023, 83, 127916. [Google Scholar] [CrossRef]
  16. Chen, Y.; Wang, X.; Jian, B.; Wen, Z.; Yang, N.; Li, L. Tree survival and growth are impacted by increased surface temperature on paved land. Landsc. Urban Plan. 2017, 162, 68–79. [Google Scholar] [CrossRef]
  17. Jim, C.Y. Resolving intractable soil constraints in urban forestry through research-practice synergy. Socio-Ecol. Pract. Res. 2018, 1, 41–53. [Google Scholar] [CrossRef]
  18. Wang, X.; Wang, X.; Sun, X.; Berlyn, G.P.; Rehim, A. Effect of pavement and water deficit on biomass allocation and whole-tree transpiration in two contrasting urban tree species. Urban Ecosyst. 2020, 23, 893–904. [Google Scholar] [CrossRef]
  19. Mullaney, J.; Lucke, T.; Trueman, S.J. The effect of permeable pavements with an underlying base layer on the growth and nutrient status of urban trees. Urban For. Urban Green. 2015, 14, 19–29. [Google Scholar] [CrossRef]
  20. Jim, C.Y. Rootability confinement and soil-husbandry solutions for urban trees in sealed and insular sites. Plant Soil 2023, 483, 153–180. [Google Scholar] [CrossRef]
  21. Volder, A.; Viswanathan, B.; Watson, W.T. Pervious and impervious pavement reduce production and decrease lifespan of fine roots of mature Sweetgum trees. Urban Ecosyst. 2014, 17, 445–453. [Google Scholar]
  22. Konarska, J.; Tarvainen, L.; Bäcklin, O.; Räntfors, M.; Uddling, J. Surface paving more important than species in determine the physiology, growth and cooling effects of urban trees. Landsc. Urban Plan. 2023, 240, 104872. [Google Scholar] [CrossRef]
  23. Torquato, P.R.; Hahs, A.K.; Szota, C.; Arndt, S.K.; Sun, Q.; Hurley, J.; Livesley, S.J. Spatially analysed expansion of individual street tree crowns enables species-specific crown expansion predictions in different rainfall zones. Urban For. Urban Green. 2024, 94, 128268. [Google Scholar] [CrossRef]
  24. Erker, T.; Wang, L.; Lorentz, L.; Stoltman, A.; Townsend, P.A. A statewide urban tree canopy mapping method. Remote Sens. Environ. 2019, 229, 148–158. [Google Scholar] [CrossRef]
  25. Miller, D.L.; Alonzo, M.; Roberts, D.A.; Tague, C.L.; McFadden, J.P. Drought response of urban trees and turfgrass using airborne imaging spectroscopy. Remote Sens. Environ. 2020, 240, 111646. [Google Scholar] [CrossRef]
  26. Torquato, P.R.; Szota, C.; Hahs, A.K.; Arndt, S.K.; Livesley, S.J. Insufficient space: Prioritizing large tree species and planting designs still fail to meet urban forest canopy targets. Landsc. Urban Plan. 2025, 256, 105287. [Google Scholar] [CrossRef]
  27. Victorian Government. Melbourne 2030: Planning for Sustainable Growth. 2002. Available online: https://www.planning.vic.gov.au/__data/assets/pdf_file/0036/636687/Melbourne-2030-Planning-for-sustainable-growth-text-only-version.pdf (accessed on 14 November 2024).
  28. Australian Bureau of Statistics (ABS). Wyndham Census All Persons Quickstats. 2006. Available online: https://www.abs.gov.au/census/find-census-data/quickstats/2006/LGA27260 (accessed on 14 November 2024).
  29. Australian Bureau of Statistics (ABS). Wyndham Census All Persons Quickstats. 2021. Available online: https://www.abs.gov.au/census/find-census-data/quickstats/2021/LGA27260 (accessed on 14 November 2024).
  30. Australian Building Codes Board (ABCB). Victoria Climate Zone Map. 2022. Available online: https://www.abcb.gov.au/sites/default/files/resources/2022/Climate-zone-map-vic.pdf (accessed on 14 November 2024).
  31. Commonwealth Scientific and Industrial Research Organisation (CSIRO). NCC Climates. 2024. Available online: https://ahd.csiro.au/dashboards/energy-rating/ncc-climates/ (accessed on 14 November 2024).
  32. Kaspar, J. Wyndham Canopy & Landscape Analysis, 2007 to 2017. 2019. Available online: https://www.wyndham.vic.gov.au/sites/default/files/2019-08/Wyndham%20Canopy%20Cover%20and%20Landscape%20Report%20-%20Greenspace%20Consultant.pdf (accessed on 14 November 2024).
  33. Victorian Government. Victoria’s Vegetation, Heat and Land Use Data. 2023. Available online: https://www.planning.vic.gov.au/guides-and-resources/Data-spatial-and-insights/melbournes-vegetation-heat-and-land-use-data (accessed on 14 November 2024).
  34. Wyndham City Council. Landscape Development Levels of Service (Part A); Wyndham City Council: Werribee, Australia, 2019.
  35. Victorian Planning Authority. Engineering Design and Construction Manual for Subdivision in Growth Areas. Growth Areas Authority. 2011. Available online: https://vpa.vic.gov.au/wp-content/Assets/Files/Engineering_Design_and_Construction_Manual-FINAL-April2011.pdf (accessed on 14 November 2024).
  36. Wyndham City Council. Wyndham City Council Subdivision Guidelines. 2009. Available online: https://www.wyndham.vic.gov.au/sites/default/files/2016-09/Wyndham%20City%20Council%20Subdivision%20Guidelines%202009.pdf (accessed on 14 November 2024).
  37. Torquato, P.R. Remotely Measuring Tree Crown Growth in Cities: Modelling Progress Towards Canopy Targets and Sensitivity to Rainfall Gradients. Ph.D. Dissertation, The University of Melbourne, Melbourne, Australia, 2023. [Google Scholar]
  38. Nearmap. MapBrowser. 2024. Available online: https://apps.nearmap.com/maps/#/L0hfupQTQpyvoXZZ1npkKQ/@-37.8686360,144.6952971,12.00z,0d/V+R/20240723 (accessed on 14 November 2024).
  39. Landcom. Street Tree Design Guidelines. 2008. Available online: https://landcom.com.au/assets/Landcom-design-guidelines-and-fact-sheets-2008-2011/street-tree-design-guidelines2.pdf (accessed on 14 November 2024).
  40. Wyndham City Council. Tree and Urban Forest Policy 2019. 2019. Available online: https://www.wyndham.vic.gov.au/sites/default/files/2019-11/Tree%20and%20Urban%20Forest%20Policy%20ADOPTED%202019_06_11%20%281%29.pdf (accessed on 14 November 2024).
  41. Szota, C.; Coutts, A.M.; Thom, J.K.; Virahsawmya, H.K.; Fletcher, T.D.; Livesley, S.J. Street tree stormwater control measures can reduce runoff but may not benefit established trees. Landsc. Urban Plan. 2019, 182, 144–155. [Google Scholar] [CrossRef]
  42. Eco Logical Australia. Park Improvement and Habitat Linkage Plan. Prepared for Bayside City Council. 2022. Available online: https://www.bayside.vic.gov.au/our-community/sustainability-and-environment/habitat-linkage-plan (accessed on 14 November 2024).
  43. Kulmatiski, A. Water matching: An explanation for plant growth and coexistence in water-limited systems. Discov. Soil 2024, 1, 2. [Google Scholar] [CrossRef]
  44. Owen-Smith, N. How Trees and Grasses Grow and Compete. In Only in Africa: The Ecology of Human Evolution; Cambridge University Press: Cambridge, UK, 2021; pp. 97–117. Available online: https://www.cambridge.org/core/books/only-in-africa/how-trees-and-grasses-grow-and-compete/8716895B502FF75FEC0C6E9D96863619 (accessed on 14 November 2024).
  45. Biro, A.; Wong, M.Y.; Zhou, Y.; Batterman, S.A.; Carla-Staver, A. Nitrogen and phosphorous availability alter tree-grass competition intensity in savannas. J. Ecol. 2024, 112, 1016–1038. [Google Scholar] [CrossRef]
  46. Wigley, B.J.; Coetsee, C.; February, E.D.; Dobelmann, S.; Higgins, S.I. Will trees or grasses profit from changing rainfall regimes in savannas? New Phytol. 2024, 241, 2379–2394. [Google Scholar] [CrossRef]
  47. Chen, W.Y. Urban Nature and Urban Ecosystem Services. In Greening Cities; Advances in 21st Century Human Settlements; Tan, P., Jim, C., Eds.; Springer: Singapore, 2017. [Google Scholar] [CrossRef]
  48. Coombes, A.; Martin, J.; Slater, M. Defining allometry of stem and crown diameter of urban trees. Urban For. Urban Green. 2019, 44, 126421. [Google Scholar] [CrossRef]
Forests 17 00111 g001
Figure 1. Crown growth rate (%) of tree crowns of four rainfall-insensitive (left) and four rainfall-sensitive (right) urban trees in parks (light green) and streets (dark green) in Wyndham (Melbourne, Australia), (2014–2018). The mean crown growth rate of each species is shown under the x-axis. Statistical significance α = 0.05; the asterisk (*) indicates statistically significant differences between crown growth of street and park trees.
Figure 1. Crown growth rate (%) of tree crowns of four rainfall-insensitive (left) and four rainfall-sensitive (right) urban trees in parks (light green) and streets (dark green) in Wyndham (Melbourne, Australia), (2014–2018). The mean crown growth rate of each species is shown under the x-axis. Statistical significance α = 0.05; the asterisk (*) indicates statistically significant differences between crown growth of street and park trees.
Forests 17 00111 g001
Forests 17 00111 g002
Figure 2. Mean crown area (m2) in 2014 and 2018 of all park trees (light green) and all street trees (dark green) in Wyndham (Melbourne, Australia). The table below the figure shows the crown growth rate (%) for all park and street trees and the ratio of street/park trees for crown area and crown growth rate.
Figure 2. Mean crown area (m2) in 2014 and 2018 of all park trees (light green) and all street trees (dark green) in Wyndham (Melbourne, Australia). The table below the figure shows the crown growth rate (%) for all park and street trees and the ratio of street/park trees for crown area and crown growth rate.
Forests 17 00111 g002
Forests 17 00111 g003
Figure 3. Crown area growth (m2) of rainfall-insensitive (left) and rainfall-sensitive (right) park trees (light green) and street trees (dark green). Crown growth rate (2014–2018), relative growth rate (RGR), ratio of street to park (S/P) (2014, 2018), Wyndham, Victoria.
Figure 3. Crown area growth (m2) of rainfall-insensitive (left) and rainfall-sensitive (right) park trees (light green) and street trees (dark green). Crown growth rate (2014–2018), relative growth rate (RGR), ratio of street to park (S/P) (2014, 2018), Wyndham, Victoria.
Forests 17 00111 g003
Table 1. Tree species that were investigated for tree crown area in 2014 and 2018 in the City of Wyndham (Melbourne, Australia). The species were planted between 2009 and 2011 where (i) denotes a species that was previously insensitive in crown growth to rainfall and (s) denotes a species that was previously sensitive in crown growth to rainfall [23]. Up to forty trees were sampled for tree crown area in 2014 and 2018 in parks and streets, with a total number of available trees given in parenthesis; only Acacia implexa had a lower sample number given the low number of individuals that were available. Check marks indicate the year of planting for each respective species.
Table 1. Tree species that were investigated for tree crown area in 2014 and 2018 in the City of Wyndham (Melbourne, Australia). The species were planted between 2009 and 2011 where (i) denotes a species that was previously insensitive in crown growth to rainfall and (s) denotes a species that was previously sensitive in crown growth to rainfall [23]. Up to forty trees were sampled for tree crown area in 2014 and 2018 in parks and streets, with a total number of available trees given in parenthesis; only Acacia implexa had a lower sample number given the low number of individuals that were available. Check marks indicate the year of planting for each respective species.
Year of PlantingTrees Sampled
[Total Trees Available]
Species2009201020112014 Park2018 Park2014 Street2018 Street
Acacia implexa (i)√ 282832 [32]32
Corymbia citriodora (i) √37 [76]3740 [80]40
Corymbia maculata (i) √ 38 [66]3840 [136]40
Eucalyptus melliodora (i) √ 38 [92]3840 [78]40
Eucalyptus mannifera (s) √ 40 [88]4040 [99]40
Eucalyptus polyanthemos (s)√ 40 [141]4040 [340]38
Eucalyptus sideroxylon (s)√ 40 [81]4040 [101]39
Ulmus parvifolia (s) √ 39 [47]3940 [88]40
Table 2. Mean urban tree crown area (m2) of rainfall-insensitive (i) and rainfall-sensitive (s) urban tree species in Wyndham (Melbourne, Australia) in parks and streets in 2014 and 2018. Average crown area in bold.
Table 2. Mean urban tree crown area (m2) of rainfall-insensitive (i) and rainfall-sensitive (s) urban tree species in Wyndham (Melbourne, Australia) in parks and streets in 2014 and 2018. Average crown area in bold.
SpeciesCrown Area (m2)
Park 2014		Crown Area (m2)
Street 2014		Crown Area (m2)
Park 2018		Crown Area (m2)
Street 2014
Acacia implexa (i)4.256.5810.4514.93
Corymbia citriodora (i)1.824.746.6017.13
Corymbia maculata (i)2.765.436.6916.34
Eucalyptus melliodora (i)1.575.635.8518.70
Average crown area (m2)2.605.607.4016.78
Eucalyptus mannifera (s)2.145.906.7318.80
Eucalyptus polyanthemos (s)5.4916.1712.7630.34
Eucalyptus sideroxylon (s)4.899.2214.1819.80
Ulmus parvifolia (s)2.905.406.5417.54
Average crown area (m2)3.869.1710.0521.60
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Cybula, P.; Torquato, P.R.; Hahs, A.; Arndt, S.K. Impervious Surfaces Do Not Impact Urban Tree Crown Growth. Forests 2026, 17, 111. https://doi.org/10.3390/f17010111

AMA Style

Cybula P, Torquato PR, Hahs A, Arndt SK. Impervious Surfaces Do Not Impact Urban Tree Crown Growth. Forests. 2026; 17(1):111. https://doi.org/10.3390/f17010111

Chicago/Turabian Style

Cybula, Peter, Patricia R. Torquato, Amy Hahs, and Stefan K. Arndt. 2026. "Impervious Surfaces Do Not Impact Urban Tree Crown Growth" Forests 17, no. 1: 111. https://doi.org/10.3390/f17010111

APA Style

Cybula, P., Torquato, P. R., Hahs, A., & Arndt, S. K. (2026). Impervious Surfaces Do Not Impact Urban Tree Crown Growth. Forests, 17(1), 111. https://doi.org/10.3390/f17010111

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop