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Arboriculture & Urban Forestry

Arboriculture & Urban Forestry quizzes are available free online to members for one year after the date of publication; a maximum of six quizzes are available at any time. Online quizzes over one-year old may be purchased by members for $10.95 and by non-members for $13.95. If you are certified and successfully pass the quiz with a score of 80% or higher, CEUs will be posted to your account within 48 hours.

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TitleCEUsPrice

Arboriculture & Urban Forestry quizzes are available free online to members for one year after the date of publication; a maximum of six quizzes are available at any time. CEU quizzes for older articles may be purchased by both members and non-members. 

Professional credentialing refers to the process of obtaining a certification or license that validates an individual’s knowledge, skills, and abilities according to industry-accepted ethics and standards. The International Society of Arboriculture (ISA) confers and manages professional arborist certification as well as other arborist credentials. However, many communities, such as in the southern United States, have few if any credentialed commercial tree care professionals. This study explores the motivations and barriers commercial tree care workers place on professional arborist certification. The research employed 60 qualitative interviews from 3 of the 8 southern states to elicit emergent themes and detailed understanding of participants’ attitudes and experiences. In addition, an online survey of 742 international respondents was conducted to validate and complement interview findings. 1 CEU (A, U, M, T, Bm)  

ISA's scientific journal Arboriculture & Urban Forestry (AUF) helps disseminate new research findings about the management of trees in urban environments. This quiz highlights an article from an issue of AUF with the objective of bridging the gap between scientific research and practical application. Learn about the latest arboricultural research happening around the world while also earning your CEUs. 

CEUs for this quiz may be earned only once during the life of your certification.


1 CEU
ISA Members: $0.00
Retail Price: $13.95
All prices in US Dollars

Arboriculture & Urban Forestry quizzes are available free online to members for one year after the date of publication; a maximum of six quizzes are available at any time. CEU quizzes for older articles may be purchased by both members and non-members. 

Stewarding newly planted urban trees to maturity involves consideration of above- and belowground factors. While landscape architects and urban planners often focus on aboveground tree aspects, understanding root structure and function is crucial, especially in urban areas with limited underground space and diverse soil conditions. To address the importance and challenges of belowground planning for urban tree roots, we propose a protocol for site assessment and demonstrate root growth forecasting as a complement to existing urban planning approaches. This paper describes adaptations to a plant root architecture simulator, RootBox, and its subsequent application in 4 scenarios created to assess its efficacy as a complement to the phase of urban planning that prescribes vegetation type and planting location in the context of a myriad of other site considerations. RootBox was parameterized based on observed conformity of root growth simulations to generalized tree root architecture reported in the literature. 

1 CEU (A, U, M, T, Bs)  

CEUs for this quiz may be earned only once during the life of your certification.

ISA's scientific journal Arboriculture & Urban Forestry (AUF) helps disseminate new research findings about the management of trees in urban environments. This quiz highlights an article from an issue of AUF with the objective of bridging the gap between scientific research and practical application. Learn about the latest arboricultural research happening around the world while also earning your CEUs.


1 CEU
ISA Members: $0.00
Retail Price: $13.95
All prices in US Dollars

Arboriculture & Urban Forestry quizzes are available free online to members for one year after the date of publication; a maximum of six quizzes are available at any time. CEU quizzes for older articles may be purchased by both members and non-members.

Extreme summer heat events in which temperatures exceed 40 °C are expected to increase in duration and intensity worldwide. Consequently, selecting heat-tolerant trees for future predicted climatic conditions will be one of the significant challenges for urban landscape managers. The effect of heat stress (44 °C for 4 hours) on chlorophyll variable:maximum fluorescence (Fv/Fm) ratios and Soil Plant Analysis Development (SPAD) values as measures of damage to the leaf photosynthetic system and leaf chlorophyll content was quantified in 8 Acer genotypes (Acer pseudoplatanus ‘Negenia’, A. pseudoplatanus ‘Spaethii’, A. platanoides ‘Royal Red’, A. platanoides ‘Princeton Gold’, A. platanoides ‘Emerald Queen’, A. platanoides ‘Drummondii’, A. campestre, A. campestre ‘Louisa Red Shine’). 

1 CEU (A, U, M, T, Bs)

CEUs for this quiz may be earned only once during the life of your certification.

ISA's scientific journal Arboriculture & Urban Forestry (AUF) helps disseminate new research findings about the management of trees in urban environments. This quiz highlights an article from an issue of AUF with the objective of bridging the gap between scientific research and practical application. Learn about the latest arboricultural research happening around the world while also earning your CEUs.


1 CEU
ISA Members: $0.00
Retail Price: $13.95
All prices in US Dollars

Arboriculture & Urban Forestry quizzes are available free online to members for one year after the date of publication; a maximum of six quizzes are available at any time. CEU quizzes for older articles may be purchased by both members and non-members.


Urban forests are increasingly recognized as important tools in climate change mitigation and adaptation, prompting many cities to set tree canopy cover targets. However, current gaps in knowledge include understanding relationships and the feasibility of maximizing benefits between urban greening and other climate actions, such as densification. This study offers a data-driven and manageable framework for assessing current and anticipated future urban forestry conditions using spatial tree and built-form model. 1 CEU (A, U, M, T, Bm)

ISA's scientific journal Arboriculture & Urban Forestry (AUF) helps disseminate new research findings about the management of trees in urban environments. This quiz highlights an article from an issue of AUF with the objective of bridging the gap between scientific research and practical application. Learn about the latest arboricultural research happening around the world while also earning your CEUs.


1 CEU
ISA Members: $0.00
Retail Price: $13.95
All prices in US Dollars

Achieving the urban tree trifecta will require collaboration among municipal departments and the development of a range of public and private initiatives, but it has the potential to maximize nature-based solutions in cities facing rapid shifts due to densification and climate change. In order to ensure that urban forests are both resilient to threats and confer the maximum possible benefits, we must be able to project decades into the future in order to understand the implications of current urban forestry decisions. This study outlines a framework for creating urban-forest scenario models and reports the results of a case study conducted to highlight the ways in which decisions made at each stage of the scenario-development process impact its outcomes and application. Our case study focused on a neighbourhood in Vancouver, Canada, that is simultaneously undergoing urban densification and aiming to significantly increase canopy cover by 2050. Our study demonstrates that a salubrious, resilient, and diverse urban forest can be created via a strategic program that complements extant trees in the public domain with planting programs along blue-green streets and on private property. 1 CEU (A, U, M, T, Bs, Bm)


1 CEU
ISA Members: $0.00
Retail Price: $13.95
All prices in US Dollars

Arboriculture & Urban Forestry quizzes are available free online to members for one year after the date of publication; a maximum of six quizzes are available at any time. CEU quizzes for older articles may be purchased by both members and non-members.


Potential impacts from climate change and other disturbances expedite the need to address vulnerabilities of urban forests. Low species diversity is a contributor to high urban forest vulnerability, and this study examined 40 public and private tree inventories in the metropolitan area of Milwaukee, Wisconsin, USA. Applying an established vulnerability framework, this study helps to identify the current and future
resilience of the urban forest in the face of climate change and other urban forest threats. A Milwaukee metropolitan area tree inventory was compiled and includes 439,974 trees. This inventory then was assessed under 2 climate change models through the end of the century (2070 to 2099). It also was assessed for species diversity under multiple diameter classes, and the Shannon Diversity Index was used to determine correlations between tree size and diversity. This data can help inform urban forestry practitioners during species selection for planting trees in their communities. 

1 CEU (A, U, M, T, Bs, Bm)

CEUs for this quiz may be earned only once during the life of your certification.


1 CEU
ISA Members: $0.00
Retail Price: $13.95
All prices in US Dollars

Urban soil is often compacted during anthropogenic activities, which presents a challenging substrate for tree growth. Two techniques for decompacting soils were evaluated alone and in combination with the soil amendment biochar and/or a woodchip mulch, and effects on soil quality were monitored over 5 years. This article and accompanying CEU quiz review the results of this study and different treatment options.

1 CEU (A, U, M, T, Bs, Bp)


1 CEU
ISA Members: $10.95
Retail Price: $13.95
All prices in US Dollars

Standardized tree risk assessment protocols are beneficial to utility vegetation management (UVM) in that they provide the most consistent qualitative assessment of a tree’s likelihood of failure, likelihood of impact, and overall risk. Yet, utility foresters do not often inspect off-right-of-way (ROW) vegetation due to constraints such as accessibility and time, which leaves many off-ROW trees unmonitored or with limited monitoring. This review focuses on the key studies addressing the application of unmanned aerial systems (UAS)-based LIDAR systems, especially in terms of UVM along electrical distribution systems. 

1 CEU (A, U, M, T, L, Bm)


1 CEU
ISA Members: $10.95
Retail Price: $13.95
All prices in US Dollars

Planning to prepare for storms should involve the estimation of tree debris. This paper tested an improvement of a rapid estimation model of tree debris following ice storms. An initial model found using 30-m resolution National Land Cover Database (NLCD) tree canopy cover (TCC) data did not significantly (P ≈ 0.20) improve estimation of tree debris within a community right-of-way (ROW) following an ice storm. We tested if finer resolution National Agriculture Imagery Program (NAIP) TCC imagery (2-m resolution or better) could more accurately predict tree debris after an ice storm. Tree canopy cover was estimated with NAIP across the entire community (TCCCITY) and also the area that only covered the ROW plus a 15.24-m (50-foot) buffer on each side (TCCROW). The TCCCITY (P = 0.08) estimate marginally improved tree debris prediction in the overall multiple regression model (R2 adj = 0.917; F = 133.8; df = 3,33), but this was not the case with the TCCROW (P = 0.66) estimate. The TCCCITY estimate was 34.7% (SEM = 2.0) and significantly (P < 0.001) 2 times greater than in the 16.2% (SEM = 2.2) TCC estimate from NLCD imagery. We found the TCCROW was 32.6% (SEM = 1.6) and significantly lower (P = 0.003) than in TCCCITY. Results from this study may improve the overall ability to predict tree debris following ice storms from the regional models currently used to a more local estimate for a city. Future investigations are needed to determine if this is the case. 1 CEU (A, U, M, Bm)

ISA's scientific journal Arboriculture & Urban Forestry (AUF) helps disseminate new research findings about the management of trees in urban environments. This quiz highlights an article from an issue of AUF with the objective of bridging the gap between scientific research and practical application. Learn about the latest arboricultural research happening around the world while also earning your CEUs.

CEUs for this quiz may be earned only once during the life of your certification.


1 CEU
ISA Members: $10.95
Retail Price: $13.95
All prices in US Dollars

Laurel wilt is a lethal disease of American Lauraceae caused by Harringtonia lauricola. Propiconazole is a systemic fungicide which arrests fungal growth among a variety of plant hosts. Propiconazole as a preventive treatment against laurel wilt in sassafras (Sassafras albidum) has not been evaluated. We treated sassafras trees with propiconazole using the Arborjet QUIK-jet® Micro-Injection™ and TREE I.V. Micro-Infusion™ systems (Arborjet, Inc., Woburn, MA, USA) and challenged trees by inoculating them with H. lauricola. Out of 7 trees treated using the QUIK-jet Micro-Injection system, 6 (86%) survived 52 or more weeks following inoculation with H. lauricola, while only 11% of inoculated control trees (1 of 9) survived over this period. All trees not damaged by hurricanes (n = 13) treated with propiconazole using the TREE I.V. Micro-Infusion system survived significantly longer than untreated control trees after inoculation with H. lauricola; 10 of 13 trees (77%) survived with < 50% crown loss, and 8 of 13 trees (62%) appeared entirely healthy 54 weeks post-inoculation. In the TREE I.V. Micro-Infusion system trial, 15 of 19 control trees (79%) had either died or lost ≥ 50% of living crown 54 weeks post-inoculation with H. lauricola. Results indicate sassafras trees treated with propiconazole using the Arborjet QUIK-jet Micro-Injection and TREE I.V. Micro-Infusion systems are significantly less likely to die within one year of infection with H. lauricola; however some trees may exhibit significant crown decline (≥ 50%) over this period. 1 CEU (A, U, M, Bp)


1 CEU
ISA Members: $10.95
Retail Price: $13.95
All prices in US Dollars

Background: Arboricultural tree climbing is inherently dangerous, in part because of the possibility of failure of the tie-in point (TIP). To help climbing arborists choose TIPs wisely, we have conducted several studies to quantify the magnitude and frequency of loading associated with arboricultural tree climbing. One parameter that has not been previously studied is whether the choice of climbing line influences loads experienced by a TIP as a climbing arborist ascends. Methods: The lead author conducted trials in which he ascended to 3 TIPs (in different trees) using 2 ascent techniques and 3 different climbing lines. During each trial, we measured loads at the TIP, and from the resulting time histories analyzed the magnitude and frequency of loading. We compared the effect of ascent technique, climbing line, and their interaction on the magnitude and frequency of loading. Results: During trials, the magnitude of loading varied between 1.1 and 1.5 times the lead author’s weight and did not differ between ascent techniques, climbing lines, or their interaction. Loading frequency varied among ascent techniques, but not climbing lines. Footlocking induced loads at a wide range of frequencies, but 2 distinct frequencies were associated with ropewalking. Conclusion: Climbing arborists can use the results of this and our previous studies to help select a suitable TIP. It is important for climbing arborists to understand the magnitude of forces associated with ascending into and working in a tree. Future studies should investigate the load-bearing capacity of a TIP from the ground. 1 CEU (A, U, M, T, L, Bp)


1 CEU
ISA Members: $10.95
Retail Price: $13.95
All prices in US Dollars

Background: Urban tree canopy (UTC) is often proposed as a mitigation strategy for simultaneously decreasing carbon emissions and urban heating in cities. Not only can trees reduce outdoor temperatures through shading and transpiration, but research also suggests that microclimate regulation by trees surrounding buildings can lead to cooler indoor temperatures and a subsequent decrease in summertime energy use. Methods: We analyzed summertime cooling electricity consumption for 21,048 single-family homes in a semi-arid city in northern Colorado, USA. Using Pearson’s correlation coefficients and multiple linear regression models, we evaluated the potential impact of UTC on cooling electricity use in 16 different zones around each house. We hypothesized that trees closer to the home, and trees located on the west and south sides of homes, would have the greatest impact on cooling electricity use. Results: UTC in all 16 zones around residential buildings was associated with negative correlation coefficients, indicating that UTC may be having an impact on energy use. Our regression results showed that UTC on the east side of single-family homes had the greatest effect. Conclusions: Although our results indicated that trees in landscapes around residential buildings can lead to some decreases in household-level energy consumption, the reductions in electricity usage were not as substantial as previous studies have predicted. Past research has shown that tree location matters, and our results indeed show that where UTC is located in reference to a building can change how much impact trees have on energy use. However, our results also show that trees on the east side of buildings have the most impact on household energy consumption in a semi-arid city in Colorado during the summer months. These results directly contradict predictions offered by popular ecosystem service models that show trees on the west and south sides of buildings as having the most impact on energy use in the Northern Hemisphere. Furthermore, many studies have suggested that the energy benefits provided by urban trees outweigh their carbon sequestration potential, and our results indicated this assumption may not hold true in all cities. 1 CEU (A, U, M, Bs, Bm)


1 CEU
ISA Members: $10.95
Retail Price: $13.95
All prices in US Dollars
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