Estimation of broad-leaved canopy growth in the urban forested area using multi-temporal airborne LiDAR datasets

Inter-annual canopy growth is one of the key indicators for assessing forest conditions, but the measurements require laborious field surveys. Up-to-date LiDAR remote sensing provides sufficient three-dimensional morphological information of the ground to monitor canopy heights on a broad scale. Thus, we attempted to use multi-temporal airborne LiDAR datasets in the estimation of vertical canopy growth, across various types of broad-leaved trees in a large urban park.The growth of broad-leaved canopies in the EXPO '70 urban forest in Osaka, Japan was assessed with 19 plots at the stand level and 39 selected trees at the individual-tree level. Airborne LiDAR campaigns repeatedly observed the park in the summers of 2004, 2008, and 2010. We acquired canopy height models (CHMs) for each year from the height values of the uppermost laser returns at every 0.5 m grid. The annual canopy growth was calculated by the differences in CHMs and validated with the annual changes in field-measured basal areas and tree heights.LiDAR estimations revealed that the average annual canopy growth from 2004 to 2010 was 0.26 ± 0.11 m m⁻² yr⁻¹ at the plot level and 0.26 ± 0.10 m m⁻² yr⁻¹ at the individual-tree level. This result showed that growing trends were consistent at different scales through 2004 to 2010 despite uncertainty in estimating short-term growth for small crown areas at the individual-tree level. This LiDAR-estimated canopy growth shows a moderate relation to field-measured increase of basal areas and average heights. The estimation uncertainties seem to result from the complex canopy structure and irregular crown shape of broad-leaved trees. Challenges still remain on how to incorporate the growth of understory trees, growth in the lateral direction, and gap dynamics inside the canopy, particularly in applying multi-temporal LiDAR datasets to the large-scale growth assessment.     

Mapping of urban roadside trees – A case study in the tree register update process in Helsinki City

This case study describes a method for utilizing leaf-off airborne laser scanning (ALS) data for mapping characteristics of urban trees. ALS data were utilized to detect and update all street trees in the tree inventory of the City of Helsinki, Finland. The inventory consists of roughly 20,000 street trees with mean diameter at breast height (DBH) of 24 cm and mean height of 10.6 m. The large number of trees makes the manual updating process very laborious. The automatic mapping procedure presented in this paper detected 88.8% of all trees in the inventory. Tree height was predicted with root mean square error (RMSE) of 1.27 meters and tree DBH with RMSE of 6.9 cm. The presented method provides a practical and cost–effective tool for the mapping of urban tree characteristics. The cost–efficiency was further enhanced because the used ALS data were originally collected for other urban planning purposes.     

Relationships between bole and crown size for young urban trees in the northeastern USA

Knowledge of allometric equations can enable urban forest managers to meet desired economic, social, and ecological goals. However, there remains limited regional data on young tree growth within the urban landscape. The objective of this study is to address this research gap and examine interactions between age, bole size and crown dimensions of young urban trees in New Haven, CT, USA to identify allometric relationships and generate predictive growth equations useful for the region. This study examines the 10 most common species from a census of 1474 community planted trees (ages 4–16). Regressions were applied to relate diameter at breast height (dbh), age (years since transplanting), tree height, crown diameter and crown volume. Across all ten species each allometric relationship was statistically (p < 0.001) significant at an α-level of 0.05. Consistently, shade trees demonstrated stronger relationships than ornamental trees. Crown diameter and dbh displayed the strongest fit with eight of the ten species having an R² > 0.70. Crown volume exhibited a good fit for each of the shade tree species (R² > 0.85), while the coefficients of determination for the ornamentals varied (0.38 < R² < 0.73). In the model predicting height from dbh, ornamentals displayed the lowest R² (0.33 < R² < 0.55) while shade trees represented a much better fit (R² > 0.66). Allometric relationships can be used to develop spacing guidelines for commonly planted urban trees. These correlations will better equip forest managers to predict the growth of urban trees, thereby improving the management and maintenance of New England's urban forests.     

Data quality in citizen science urban tree inventories

Citizen science has been gaining popularity in ecological research and resource management in general and in urban forestry specifically. As municipalities and nonprofits engage volunteers in tree data collection, it is critical to understand data quality. We investigated observation error by comparing street tree data collected by experts to data collected by less experienced field crews in Lombard, IL; Grand Rapids, MI; Philadelphia, PA; and Malmö, Sweden. Participants occasionally missed trees (1.2%) or counted extra trees (1.0%). Participants were approximately 90% consistent with experts for site type, land use, dieback, and genus identification. Within correct genera, participants recorded species consistent with experts for 84.8% of trees. Mortality status was highly consistent (99.8% of live trees correctly reported as such), however, there were few standing dead trees overall to evaluate this issue. Crown transparency and wood condition had the poorest performance and participants expressed concerns with these variables; we conclude that these variables should be dropped from future citizen science projects. In measuring diameter at breast height (DBH), participants had challenges with multi-stemmed trees. For single-stem trees, DBH measured by participants matched expert values exactly for 20.2% of trees, within 0.254 cm for 54.4%, and within 2.54 cm for 93.3%. Participants’ DBH values were slightly larger than expert DBH on average (+0.33 cm), indicating systematic bias. Volunteer data collection may be a viable option for some urban forest management and research needs, particularly if genus-level identification and DBH at coarse precision are acceptable. To promote greater consistency among field crews, we suggest techniques to encourage consistent population counts, using simpler methods for multi-stemmed trees, providing more resources for species identification, and more photo examples for other variables. Citizen science urban forest inventory and monitoring projects should use data validation and quality assurance procedures to enhance and document data quality.     

The overlooked carbon loss due to decayed wood in urban trees

Decayed wood is a common issue in urban trees that deteriorates tree vitality over time, yet its effect on biomass yield therefore stored carbon has been overlooked. We mapped the occurrence and calculated the extent of decayed wood in standing Ulmus procera, Platanus × acerifolia and Corymbia maculata trees. The main stem of 43 trees was measured every metre from the ground to the top by two skilled arborists. All trees were micro-drilled in two to four axes at three points along the stem (0.3 m, 1.3 m, 2.3 m), and at the tree’s live crown. A total of 300 drilling profiles were assessed for decay. Simple linear regression analysis tested the correlation of decayed wood (cm²) against a vitality index and stem DBH. Decay was more frequent and extensive in U. procera, than P. acerifolia and least in C. maculata. Decay was found to be distributed in three different ways in the three different genera. For U. procera, decay did appear to be distributed as a column from the base to the live crown; whereas, decay was distributed as a cone-shape in P. acerifolia and was less likely to be located beyond 2.3 m. In C. maculata decay was distributed as pockets of variable shape and size. The vitality index showed a weak but not significant correlation with the proportion of decayed wood for P. acerifolia and C. maculata but not for U. procera. However, in U. procera, a strong and significant relationship was found between DBH and stem volume loss (R² = 0.8006, P = 0.0046, n = 15). The actual volume loss ranged from 0.17 to 0.75 m³, equivalent to 5%–25% of the stem volume. The carbon loss due to decayed wood for all species ranged between 69–110 kg per tree. Based on model’s calculation, the stem volume of U. procera trees with DBH ≥ 40 cm needs to be discounted by a factor of 13% due to decayed wood regardless of the vitality index. Decayed wood reduces significantly the tree’s standing volume and needs to be considered to better assess the carbon storage potential of urban forests.     

Defect-disorder and risk assessment of heritage trees in urban Hong Kong

Heritage trees in a city, echoing factors conducive to outstanding performance, deserve special care and conservation. To understand their structural and health conditions in urban Hong Kong, 30 defect-disorder (DD) symptoms (physical and physiological) subsumed under four tree-position groups (soil-root, trunk, branching, and crown-foliage) and tree hazard rating were evaluated. The surveyed 352 trees included 70 species; 14 species with 233 trees were native. More trees had medium height (10–15 m), medium DBH (1–1.5 m) and large crown (>15 m). In ten habitats, public park and garden (PPG) accommodated the most trees, and roadside traffic island (RTI) and public housing estate (PH) had the least. Tree dimensions and tree habitats were significantly associated. The associations between the 2831 DD and tree-position groups, tree habitats and tree hazard rating were analyzed. Fourteen trees from Ficus microcarpa, Ficus virens and Gleditsia fera had high hazard rating, 179 trees from 22 species moderate rating, and 159 trees from 55 species low rating. RTI, roadside tree strip (RTS), roadside tree pit (RTP), roadside planter (RP) and stone wall (SW) had more moderate hazard rating, and PPG, roadside slope (RS) and government, institutional and community land (GIC) more low rating. Redundancy analysis showed that DD were positively correlated with RTS, RTP, RP and SW, but negatively correlated with PPG, RS and GIC (p < 0.05). The DD significantly increased tree hazard rating and failure potential. Future management implications for heritage-tree conservation and enhancement focusing squarely on critical tree defect-disorder in urban Hong Kong were explored, with application to other compact cities.     

Stemflow chemistry in relation to tree size: A preliminary investigation of eleven urban park trees in British Columbia,Canada

Given increased atmospheric loads in cities, quantification of stemflow chemistry is necessary for a holistic understanding of elemental cycling in urban ecosystems. Accordingly, the stemflow volume and associated solute fluxes (K⁺, Ca²⁺, Na⁺, Mg²⁺) were measured for eleven deciduous trees in a manicured park setting in Kamloops, British Columbia, Canada. Over nine rainfall events from late June to early September 2013, larger trees [diameter at breast height (DBH) > 30 cm] were found to generally produce higher event stemflow volumes but lower funneling ratios than the smaller trees (DBH < 30 cm). The median flux-based enrichment ratio, which compares the solute input of stemflow to that of rainfall on a per unit trunk basal area, also tended to be greater for smaller trees than larger ones. Under all-tree and single-leader tree conditions, significant negative non-linear relationships between tree DBH and mean flux-based enrichment ratios were found for Ca²⁺, Na⁺, and Mg²⁺, but not for K⁺. These preliminary results indicate that urban trees can considerably enrich rainfall that is partitioned into stemflow, and that ion concentrations and enrichment ratios exhibit notably high interspecific variability. In this study, tree size and presence of single versus multiple leaders explained some of this heterogeneity; however, further study into those physical tree characteristics that affect stemflow volume and stemflow chemistry must be carried out if the impact and challenges of urban greening, nutrient cycling, and stormwater management initiatives are to be more fully understood.     

Assessing the performance of urban forest carbon sequestration models using direct measurements of tree growth

Across cities worldwide, people are recognizing the value of greenspace in ameliorating the health and well-being of those living there, and are investing significant resources to improve their greenspace. Although models have been developed to allow the quantification of ecosystem services provided by urban trees, refinement and calibration of these models with more accurate site- and species-specific data can increase confidence in their outcomes. We used data from two street tree surveys in Cambridge, MA, to estimate annual tree mortality for 592 trees and diameter growth rates for 498 trees. Overall tree turnover between 2012 and 2015 was relatively low (annualized 3.6% y⁻¹), and mortality rate varied by species. Tree growth rates also varied by species and size. We used stem diameter (DBH) and species identity to estimate CO₂ sequestration rates for each of 463 trees using three different model variations: (1) i-Tree Streets, (2) Urban Tree Database (UTD) species-specific biomass allometries and growth rates, and (3) empirically measured growth rates combined with UTD biomass allometries (Empirical + UTD). For most species, the rate of CO₂ sequestration varied significantly with the model used. CO₂ sequestration estimates calculated using i-Tree Streets were often higher than estimates calculated with the UTD equations. CO₂ sequestration estimates were often the lowest when calculated using empirical tree growth estimates and the UTD equations (Empirical + UTD). The differences among CO₂ sequestration estimates were highest for large trees. When scaled up to the entire city, CO₂ sequestration estimates for the Empirical + UTD model were 49.2% and 56.5% of the i-Tree Streets and UTD estimates, respectively. We suggest future derivations of ecosystem service provision models allow localities to input their own species-specific growth values. By adding capacity to easy-to-use tools, such as i-Tree Streets, we can increase confidence in the model output.     

Non-destructive method for above-ground biomass estimation of Fraxinus uhdei (Wenz.) Lingelsh in an urban forest

One of the limiting factors to estimate accurately the biomass stocks of urban forests is the availability of allometric models developed from urban trees measurements. In addition, the traditional methods (destructive) to develop biomass equations are rarely applied in cities. The aim of this study was to develop a non-destructive method based on fractal analysis for trees of Fraxinus uhdei present in the green areas of Chapultepec Park in Mexico City. Diameter at breast height (DBH), total height and the height of the whorls of 46 randomly-selected trees were measured. In each tree, three different-order branches were collected to measure their total length and that of their links, the diameter before and after each branching point, the insertion angle, the number of branches, twigs and leaves, and fresh and dry weight. The felling of seven individuals at the site was taken advantage of to fit a taper function for the trunk and determine its biomass. Acceptable estimates with good accuracy were obtained for F. uhdei trees with a DBH of less than 23 cm. It is feasible to develop biomass models from measuring the branches and the trunk of young F. uhdei trees through the implementation of structural indices based on fractal geometry and without the need to fell healthy trees.     

Mapping leaf area of urban greenery using aerial LiDAR and ground-based measurements in Gothenburg,Sweden

Leaf area of urban vegetation is an important ecological characteristic, influencing urban climate through shading and transpiration cooling and air quality through air pollutant deposition. Accurate estimates of leaf area over large areas are fundamental to model such processes. The aim of this study was to explore if an aerial LiDAR dataset acquired to create a high resolution digital terrain model could be used to map effective leaf area index (L_e) and to assess the L_e variation in a high latitude urban area, here represented by the city of Gothenburg, Sweden. L_e was estimated from LiDAR data using a Beer-Lambert law based approach and compared to ground-based measurements with hemispherical photography and the Plant Canopy Analyser LAI-2200. Even though the LiDAR dataset was not optimized for L_e mapping, the comparison with hemispherical photography showed good agreement (r² = 0.72, RMSE = 0.97) for urban parks and woodlands. Leaf area density of single trees, estimated from LiDAR and LAI-2200, did not show as good agreement (r² = 0.53, RMSE = 0.49). L_e in 10 m resolution covering most of Gothenburg municipality ranged from 0 to 14 (0.3% of the values >7) with an average L_e of 3.5 in deciduous forests and 1.2 in urban built-up areas. When L_e was averaged over larger scales there was a high correlation with canopy cover (r² = 0.97 in 1 × 1 km² scale) implying that at this scale L_e is rather homogenous. However, when L_e was averaged only over the vegetated parts, differences in L_e became clear. Detailed study of L_e in seven urban green areas with different amount and type of greenery showed a large variation in L_e, ranging from average L_e of 0.9 in a residential area to 4.1 in an urban woodland. The use of LiDAR data has the potential to considerably increase information of forest structure in the urban environment.     

Allometric equations for estimating the aboveground volume of five common urban street tree species in Daegu,Korea

Quantifying urban tree biomass and carbon (C) storage by using allometric equations is required for various studies such as assessing the inventory, modelling, and measuring ecosystem services of urban trees. However, the lack of urban-specific allometric equations leads to uncertainty when estimating urban tree biomass and C storage. Therefore, we followed a nondestructive approach and developed allometric equations specifically for Acer buergerianum Miq., Ginkgo biloba L., Platanus orientalis L., Prunus yedoensis Matsum., and Zelkova serrata (Thunb.) Makino in Daegu, Korea. Diameter at breast height (DBH)-based and DBH-and-height-based allometric equations were highly accurate at estimating the aboveground volume (R² > 0.92), while the allometric equations for P. orientalis and Z. serrata developed for traditional forests overestimated volume by 68% and 427%, respectively. The addition of a height variable into the DBH-based allometric equations did not increase the reliability of the allometric equations at a local level. The mean aboveground C storage of urban street trees was 24.9 Mg C/ha except for P. orientalis with a mean of 69.7 Mg C/ha, and the total aboveground C storage of urban street trees in Daegu was 10.6 Gg C. Alternatively, a generalized allometric equation which compiled species-specific equations can be applied for large-scale estimation. The generalized equations developed in this study and those found in the literature may suggest a constant value (～2.3–2.4) for the scaling exponent in the generalized equations. Allometric equations developed from natural or artificial stands may overestimate the volume of urban street trees; therefore, estimating urban tree biomass and C storage requires urban-specific allometric equations.     

Restorative potential,fascination, and extent for designed digital landscape models

Few studies have investigated whether manipulating objective measures related to fascination and extent affect respondents’ ratings of restorative potential (RP) and estimations of fascination and extent. The following study addresses this need. We manipulated or measured variables in 27 color digital landscape model views. Tree height represented a measure of fascination. Three measures related to extent: The number of organized plant groups represented coherence. Shannon’s Information Entropy bit values represented plant species complexity. The visible view polygon area in each model represented scope. We included 65 respondents’ RP ratings for the digital model views in analyses, along with estimations of fascination (n = 48), extent (n = 43), coherence (n = 38), complexity (n = 44), and scope (n = 35). Collinearity diagnostics indicated dependency between respondents’ estimations of fascination, extent, and complexity, and between estimations of coherence and scope. A strong, inverse correlation occurred between respondents’ RP ratings and the view polygon area. Repeated measures ANOVA test results suggest that respondents’ RP ratings increased as mean designed tree height increased. RP ratings for model views depicting scattered and formally arranged plants were significantly higher than views of clustered plants. Moreover, the decrease in RP ratings between scattered and clustered scenes was greater when plants represented three bits of entropy instead of two. Chief among the implications stemming from this study is that increasingly taller trees and groundcover plants may have increasingly greater restorative potential.     

Private residential urban forest structure and carbon storage in a moderate-sized urban area in the Midwest,United States

In conjunction with urbanization and its importance as a major driver of land-use change, increased efforts have been placed on understanding urban forests and the provisioning of ecosystem services. However, very little research has been conducted on private property and little is known about the structure and function of privately owned urban forests. This research examines the structure of and carbon storage services provided by private residential urban forests in a moderate-sized Midwestern city. The primary research questions are as follows: What is the structure of private urban forests, and how does it vary across parcels? How much carbon is stored in tree and soil pools of private urban forests, and how does carbon vary across parcels? Ecological inventories were conducted on 100 residential parcels within 14 Neighborhood and Homeowners Associations of varying size and development age. Tree species richness, diversity, density, and diameter distribution were determined on a per parcel basis and for the entire tree population sampled. Further, tree and soil carbon storage were determined for each parcel. Results of this research demonstrated large variability in per-parcel tree metrics. Twelve of the parcels sampled had two or fewer trees, while eleven had greater than 50 trees. Further, tree carbon storage ranged from no carbon to 11.22 kg C m^?2. Alternatively, soil carbon storage was less variable and averaged 4.7 kg C m^?2, approximately 1.9 times higher than the average carbon stored in trees (2.5 kg C m^?2). Management efforts aimed at maintaining or enhancing carbon storage and other ecosystem services should focus on both soil protection and maximizing services in living biomass. Our results demonstrate that sustaining tree-produced ecosystem services requires maintenance of large old trees and species diversity, not only in terms of relative abundance, but also relative dominance, and in combination, species–specific size distributions.     

Influence of changing trees locations on thermal comfort on street parking lot and footways

Locations of trees in street parking lots (SPL) impact outdoor thermal comfort and should be considered during the urban planning process. In this paper we developed a procedure for changing trees locations in order to improve outdoor thermal comfort on SPL and associated footways. Furthermore, a sensitivity test on the effect of different tree crown shapes on outdoor thermal comfort was carried out. We applied theprocedure on real-world SPL design in the City of Novi Sad (Serbia). A temporal analysis is performed for the heat wave period using Universal Thermal Climate Index (UTCI) calculations in the Ladybug software.The results showed improvement of outdoor thermal comfort on 77 % of all body locations in proposed SPL design with predetermined number of trees. The largest outdoor thermal comfort improvement was noticed in the afternoon hours with up to 3.3 °C UTCI decrease on single body location. By adding trees to the SPL, heat stress was reduced on 84 % of all body locations with maximal UTCI decrease of 3.7 °C on single body location. Furthermore, heat stress reduction by cylinder-shaped tree crowns showed to be more pronounced compared to the sphere-shaped and the cone-shaped tree crowns. Proposed procedure showed that the locations of trees as well as tree crown shapes are very important for the improvement of outdoor thermal comfort and creation of environmentally conscious SPL design.     

Current and potential carbon stocks of trees in urban parking lots in towns of the Eastern Cape,South Africa

Greening of shopping centre parking lots is a potentially important strategy that can contribute to urban carbon mitigation efforts, improve aesthetics and the shopping experience of consumers, whilst adding to urban biodiversity. Twenty-eight shopping centre parking lots in six Eastern Cape urban centres, South Africa, were sampled to determine tree species composition, density and annual carbon sequestration potential. The best case parking lot found during the study was used as a benchmark to display the difference between current tree density and above-ground carbon stocks relative to the potential optimum. The highest tree density was 66 trees ha^?1, whereas the average density across all sampled parking lots was less than half that (27.2 ± 22.6 trees ha^?1). The average annual carbon sequestration potential per parking lot was 1390 ± 2503 kg ha^?1. Planting density was positively related to annual sequestration rates, whilst parking lot age and the mean annual rainfall of the town had no influence. Mean tree species richness per parking lot was 2.3 ± 1.8 species, with a positive relationship to parking lot size, but not to mean annual rainfall of the site. The majority of trees (62.5%) in parking lots were alien species, although newer parking lots had significantly greater proportions of indigenous species. There was no difference in mean annual carbon sequestration rate per tree between indigenous and alien trees species. Low tree densities and small parking lot areas constrained the potential for earning carbon credits from trees in parking lots. Nonetheless, planners and designers need to be more aware of the potential contribution of trees towards urban sustainability.     

Influence of temperature and bark injuries on the development of Phytophthora cactorum and P. Citrophthora on peach trees

The effect of temperature and bark injuries on the occurrence of crown rot of peach trees caused by P. cactorum and P. citrophthora were examined in field and laboratory. Lesions developed at 35 °C (the complete range of temperatures tested) but maximum development occurred at 20–25 °C. Greatest growth of these fungi on cornmeal agar (CMA) also occurred between 15 and 30 °C. Both pathogens could infect injured trees up to 20 days after wounding, but could not infect uninjured plants or plants wounded 40 and 30 days before inoculation, respectively. This study showed that temperature is a critical factor for the development of Phytophthora crown rot of peach trees. In addition, crown rot developed from recent wounds inoculated with agar plugs of Phytophthora.     

Testing the accuracy of imaging software for measuring tree root volumes

Manually measuring tree root characteristics can be inefficient and limiting. To test the application of a new digital technology in tree root architecture research, root systems from 29 green ash (Fraxinus pennsylvanica 'Patmore') trees were unearthed, cleaned, and photographed to create 3D models using structure from motion (SfM) photogrammetry. Three root segments from each root system were selected, marked, and removed after being photographed. The volumes of these segments (derived from the 3D models) were compared against volumes measured using water displacement. In addition to the root segments, model and water displacement volumes were compared for three complete root systems. Regression analysis showed a strong linear relation between the two volumes measurements (adjusted R² = 0.97 for the root segment data). The RMSE for the root segment volume estimates was 40.37 cm³ (12.3%), with a bias of 17.2 cm³ (5.3%). This error rate was similar to previous published work and suggests the technology used may allow researchers to improve efficiency in data capture, add new measurements (i.e., surface area) to their modeling efforts, and digitally preserve tree root systems for future study.     

Estimating the stormwater attenuation benefits derived from planting four monoculture species of deciduous trees on vacant and underutilized urban land parcels

This paper presents research that was undertaken to determine whether planting deciduous trees, using intensive tree planting schemes, on vacant and underutilized urban land provides significant hydrologic benefits. This work contributes to an ongoing discussion on how to use vacant and underutilized land productively, and may be important to land use decision-makers, whose policies support the use of green infrastructure for stormwater management. Tree growth parameters for four monoculture planting schemes were modeled (all trees had a 50.8 mm caliper at planting) and included (i) 450 Ginkgo biloba, (ii) 92 Platanus × acerifolia, (iii) 120 Acer saccharinum, and (iv) 434 Liquidambar styraciflua, on a 1.6-acre parcel. i-Tree Hydro (formerly UFORE-Hydro) was used to derive a simplified Microsoft Excel-based water balance model to quantify the canopy interception potential and evaporation, based on 7 years (2002–2008) of historical hourly rainfall and mean temperature data in Hamilton, Ontario, Canada. This study revealed that three of the species responded similarly, while one species (L. styraciflua) performed significantly better with respect to total canopy storage potential and evaporation, capturing and evaporating 2.9 m³/tree over the 7 years analyzed, or 1280 m³ for the total tree stand of 434 trees. The analyses presented herein demonstrate that the tree canopy layer was able to intercept and evaporate approximately 6.5%–11% of the total rainfall that falls onto the crown across the 7 years studied, for the G. biloba, P. × acerifolia and A. saccharinum tree stands and 17%–27% for the L. styraciflua tree stand. This study revealed that the rate at which a species grows, the leaf area index of the species as it matures, and the total number of trees to be planted need to be determined to truly understand the behavior and potential benefits of different planting schemes; had the mature leaf area been used as the sole indicator of the stormwater attenuating potential for each species, the A. saccharinum would have been the selected species. Also, had attenuation and evaporation per unit of tree been the only measurement reported, the P. × acerifolia stand would have been deemed the best performing tree, attenuating and evaporating 8.1 m³/tree. While the actual values presented herein may be uncertain because of a lack of locally-derived tree growth models, the approach described warrants further investigation.     

Effect of protected cultivation on the precocity,yield and fruit quality in loquat

The advantages of the high density and protected cultivation over open field were investigated in three loquat cultivars. Both of these methods are new and have not been previously studied in Turkey. The study was conducted with Gold Nugget, Hafif Çukurgöbek, and Sayda cultivars planted at high-density with planting spaces of 3 m × 3 m in May 1997. The experiments for cultivation were done in greenhouses where the side height was 2.5 m and the highest point was 4.0 m. Phenological variables such as first blossoming, full bloom, end of bloom and harvest time and pomological variables such as fruit and seed weight, fruit dimension, seed number/fruit, and acidity were determined. The trunk diameter, 10 cm above the bud union, was also recorded each year during the study. The total above ground tree canopy volume was calculated from height and width measurements. The productivity parameters including yield/plant, yield/hectare, cumulative production/plant, cumulative production/hectare and yield/unit trunk cross-sectional area and yield/unit of canopy volume were calculated. The results indicated that protected cultivation caused earliness of 13–20 days when compared to open field. The mean yield was higher in protected cultivation than the open field for both yield/tree and yield/ha. Conversely, the mean yield was higher in open field than protected cultivation for yield/unit trunk cross-sectional area and yield/unit of canopy volume of trees. Pomological quality of the fruits was higher in the open field than protected cultivation.     

Adapting and applying evidence gathering techniques for planning and investment in street trees: A case study from Brisbane,Australia

Trees along footpath zones (or verges) grow on the “front-line” of urban forest ecosystems, increasingly recognised as essential to the quality of human life in cities. Growing so close to where residents live, work and travel, these street trees require careful planning and active management in order to balance their benefits against risks, liabilities, impacts and costs. Securing support and investment for urban trees is tough and robust business cases begin with accurate information about the resource. Few studies have accounted for spatial heterogeneity within a single land-use type in analyses of structure and composition of street tree populations. Remotely sensed footpath tree canopy cover data was used as a basis for stratification of random sampling across residential suburbs in the study area of Brisbane, Australia. Analysis of field survey data collected in 2010 from 80 representative sample sites in 52 suburbs revealed street tree population (432,445 ± 26,293) and stocking level (78%) estimates with low (6.08%) sampling error. Results also suggest that this population was transitioning to low risk, small-medium sized species with unproven longevity that could limit the capacity of the Brisbane’s Neighbourhood Shadeways planting program to expand from 35% footpath tree canopy cover in 2010, to a target of a 50% by 2031. This study advances the use of contemporary techniques for sampling extensive, unevenly distributed urban tree populations and the value of accurate resource knowledge to inform evidence-based planning and investment for urban forests.