Detection of morphological and eco-physiological traits of ornamental woody species to assess their potential Net O3 uptake.

Urban greening can improve cities' air quality by filtering the main gaseous pollutants such as tropospheric ozone (O3). However, the pollutant removal capacity offered by woody species strongly depends on eco-physiological and morphological traits. Woody species with higher stomatal conductance (gs) can remove more gases from the atmosphere, but other species can worsen air quality due to high O3 forming potential (OFP), based on their emitting rates of biogenic volatile organic compounds (bVOCs) and Leaf Mass per Area (LMA). Presently, there is a lack of data on eco-physiological (gs, bVOCs emissions) and foliar traits (LMA) for several ornamental species used in urban greening programs, which does not allow assessment of their O3 removal capacity and OFP. This study aimed to (i) parameterize gs, assess bVOCs emissions and LMA of 14 ornamental woody species commonly used in Mediterranean urban greening, and (ii) model their Net O3 uptake. The gs Jarvis model was parameterized considering various environmental conditions alongside isoprene and monoterpene foliar bVOCs emission rates trapped in the field and quantified by gas chromatography-mass spectrometry. The results are helpful for urban planning and landscaping; suggesting that Catalpa bignonioides and Gleditsia triacanthos have excellent O3 removal capacity due to their high maximum gs (gmax) equal to 0.657 and 0.597 mol H2O m-2 s-1. Regarding bVOCs, high isoprene (16.75 µg gdw-1 h-1) and monoterpene (13.12 µg gdw-1 h-1) emission rates were found for Rhamnus alaternus and Cornus mas. In contrast, no bVOCs emissions were detected for Camellia sasanqua and Paulownia tomentosa. In conclusion, 11 species showed a positive Net O3 uptake, while the use of large numbers of R. alaternus, C. mas, and Chamaerops humilis for urban afforestation planning are not recommended due to their potential to induce a deterioration of outdoor air quality.

Characterizing Non-governmental Organizations And Local Government Collaborations In Urban Forest Management Across Canada.

Urban forests are being threatened by rapid urbanization, biodiversity crises, and climate variability. In response, governments are increasingly collaborating with the public for solutions to these mounting challenges. Non-governmental organizations (NGOs) are dominant players in these collaborations because of their ability to supplement governments' expertize and resources and bring social and ecological issues to the forefront of civic agendas. Despite their growing visibility in urban forest management, there is a lack of attention directed to the forms and range of NGO relationships. This study focuses on addressing this gap and examining collaborations between local governments and NGOs in urban forest programming by characterizing their components including mandates, relationship ties, accountability, resource exchange, and power dynamics. We collected data using semi-structured interviews with three groups: leaders of NGOs, municipal government officials in an urban forest or public works departments, and urban-forest experts who have observed their interactions. The participants represent 32 individuals in nine Canadian cities. Our results indicate that NGO-government collaborations have relational ties and accountability processes that are both formal and informal in nature. Formality in collaborations is often associated with the amount of funding, proximity to government, or size of the NGO. In addition, our findings suggest that NGOs present an opportunity for local governments to supplement their resources and capacity. While the strength and formality of collaborations may be a product of NGO size and budgets, public servants should not hesitate to engage smaller, grassroots NGOs to realize their public service mandates. Characterizing the components of these governance processes provides a benchmark for practitioners participating in similar public-civic interactions and arms them with the knowledge to navigate collaborative decision-making.

Impacts of rising COVID-19 incidence and changed working conditions on forest visits in early 2020 of the pandemic: Evidence from Switzerland.

The COVID-19 pandemic forced many nations to implement a certain degree of lockdown measures to contain the spread of the virus. It has been reported that recreational visits to forests and green spaces increased in response to the lockdown. In this study, we investigated the effect of the policy-induced changes in working conditions during the lockdown period, as well as the effect of COVID-19 infection rates, on forest visits throughout Switzerland early in the COVID-19 pandemic. We analyzed data from an online panel survey first conducted one week before the government imposed the lockdown in Switzerland and repeated two weeks after the lockdown began. We use a modeling approach to assess the impact of the home-office and short-time working situation on forest visitation frequency, as well as their effects on the length of visits to the forest. For those who visited the forest both before and during the lockdown, the frequency of forest visits increased during the early lockdown phase considered here, while the duration of visits decreased. According to our model, the opportunity to work from home was a significant driver of the increased frequency of forest visits by this visitor group, while COVID-19 infection rates had no effect on their forest visits.

Designing "Tiny Forests" as a lesson for transdisciplinary urban ecology learning.

The sustainability and livability of urban areas call for the next generation of scientists, practitioners and policy makers to understand the benefits, implementation and management of urban greenspaces. We harnessed the concept of "Tiny Forests©" - a restoration strategy for small wooded areas (~100-400 m2) - to create a transdisciplinary and experiential project for university forestry students that follows an ecology-with-cities framework. We worked with 16 students and a local municipality in the Munich, Germany metropolitan region to survey a community about its needs and desires and then used this information alongside urban environmental features and data collected by students (e.g., about soil conditions) to design a Tiny Forest. In this article, we describe the teaching concept, learning outcomes and activities, methodological approach, and instructor preparation and materials needed to adapt this project. Designing Tiny Forests provides benefits to students by having them approach authentic tasks in urban greening while experiencing the challenges and benefits of transdisciplinary communication and engagement with community members. Supplementary Information: The online version contains supplementary material available at 10.1007/s11252-023-01371-7.

Nature-based cooling potential: a multi-type green infrastructure evaluation in Toronto, Ontario, Canada.

The application of green infrastructure presents an opportunity to mitigate rising temperatures using a multi-faceted ecosystems-based approach. A controlled field study in Toronto, Ontario, Canada, evaluates the impact of nature-based solutions on near surface air temperature regulation focusing on different applications of green infrastructure. A field campaign was undertaken over the course of two summers to measure the impact of green roofs, green walls, urban vegetation and forestry systems, and urban agriculture systems on near surface air temperature. This study demonstrates that multiple types of green infrastructure applications are beneficial in regulating near surface air temperature and are not limited to specific treatments. Widespread usage of green infrastructure could be a viable strategy to cool cities and improve urban climate.

Effect of air quality improvement by urban parks on mitigating PM2.5 and its associated heavy metals: A mobile-monitoring field study.

Field mobile monitoring of PM2.5, equipped with a highly accurate device, was performed for two types of urban parks in Taiwan. Measurements were taken in the morning and evening rush hours, on certain weekdays and weekends, every month over a year. We designed six calculation schemes of the rate of PM2.5 mitigation by urban parks to comprehensively compare the average and maximum mitigation effects in relation to the vegetation barriers. The mitigation rate, from the lowest (2.51%) to the highest (35.57%) depended on the calculation schemes. The Taipei Botanical Garden (TBG) with a dense, multilevel forest has a stable PM2.5 mitigation effect and strong ability to improve air quality inside the park under severe PM2.5 pollution. In contrast, Zhonghe No.4 Park (ZHP), an open park with mostly a single-storied stand, has variable PM2.5 mitigation effect, leading to either quick dissipation or accumulation of PM2.5 inside the park. Furthermore, the dry deposition of PM and the associated heavy metals were investigated using camphor trees as bioaccumulators. Dry deposition flux of the leaf-deposited PM2.5 exhibited similar results in ZHP; whereas, noticeable higher results were observed inside TBG. In addition, most of the PM2.5 deposition flux from field estimations were similar to those in i-Tree Eco when considering the loss of mass due to the dissolution through water filtration, indicating that i-Tree Eco may be reliable to model the removal of PM2.5 in the parks in Taiwan. Moreover, we examined nine heavy metals' content in the deposited PM, and most of the detectable elements were significantly higher outside both parks, demonstrating the mitigation effects of urban parks in reducing not only the PM2.5 concentration but also the toxicity of the pollutant. This study provides direct evidence of the important ecosystem services, namely air quality improvement and biomonitoring effect, derived from urban parks.

Positive long-term impacts of restoration on soils in an experimental urban forest.

As urbanization increases worldwide, investments in nature-based solutions that aim to mitigate urban stressors and counter the impacts of global climate change are also on the rise. Tree planting on degraded urban lands-or afforestation-is one form of nature-based solution that has been increasingly implemented in cities around the world. The benefits of afforestation are, however, contingent on the capacity of soils to support the growth of planted trees, which poses a challenge in some urban settings where unfavorable soil conditions limit tree performance. Soil-focused site treatments could help urban areas overcome impediments to afforestation, yet few studies have examined the long-term (>5 yr) effects of site treatments on soils and other management objectives. We analyzed the impacts of compost amendments, interplanting with shrubs, and tree species composition (six species vs. two species) on soil conditions and associated tree growth in 54 experimental afforestation plots in New York City, USA. We compared baseline soil conditions to conditions after 6 yr and examined changes in the treatment effects from 1 to 6 yr. Site treatments and tree planting increased soil microbial biomass, water holding capacity, and total carbon and nitrogen, and reduced soil pH and bulk density relative to baseline conditions. These changes were most pronounced in compost-amended plots, and the effects of the shrub and species composition treatments were minimal. In fact, compost was key to sustaining long-term changes in soil carbon stocks, which increased by 17% in compost-amended plots but declined in unamended plots. Plots amended with compost also had 59% more nitrogen than unamended plots, which was associated with a 20% increase in the basal area of planted trees. Improvements in soil conditions after 6 yr departed from the initial trends observed after 1 yr, highlighting the importance of longer-term studies to quantify restoration success. Altogether, our results show that site treatments and tree planting can have long-lasting impacts on soil conditions and that these changes can support multiple urban land management objectives.

Natural regeneration in urban forests is limited by early-establishment dynamics: implications for management.

Urban forested natural areas are valuable ecological and social resources, but long-term sustainability of these habitats is challenged by environmental and social factors associated with urban ecosystems. Advances in city-scale assessments of urban forests have increased the resolution of forest community types and conditions, allowing for improved understanding of ecological function, such as natural regeneration, in these urban habitats. By applying metrics of tree regeneration that are commonly used for the management of rural forests, urban ecologists can test the potential for traditional forest management strategies within our cities. In this study, we compare urban and rural oak-hickory forest composition and structure and the capacity for natural regeneration in the New York metropolitan area. Specifically, we use two metrics of advance regeneration that describe the abundance of seedlings and saplings at different size classes to test whether this management for natural regeneration is a viable option. We found differences in recruitment dynamics between urban and rural forests that have implications for the sustainability of these forests and new management strategies. First, after controlling for forest community type, species composition in urban and rural sites was significantly different across multiple strata and within the seed bank. Species-specific capacity for natural regeneration was different in urban and rural sites, signaling the possibility of divergent successional trajectories. Second, while differences in species composition exist, both urban and rural sites were dominated by native species across all forest strata except for urban seed banks. Third, despite finding significantly lower average annual seedling abundance in urban (1.9 seedlings/m2 ) compared to rural (7.1 seedlings/m2 ) sites, we observed greater density of saplings in urban forests, and no significant difference in stocking index between sites. These findings suggest that early-establishment barriers to recruitment are greater in urban forest sites. However, once established, seedling transition into advance regeneration stages may not be different between site types, and advance regeneration may, in some cases, be more viable in urban forested natural areas. These results highlight functional differences between urban and rural forest recruitment dynamics that may impact on the future community composition of oak-hickory forests in the two landscape settings.

Testing an invasion mechanism for Eucalyptus globulus: Is there evidence of allelopathy?

PREMISE: Sparse understory communities, in association with non-native tree species, are often attributed to allelopathy, the chemical inhibition of a plant by another. However, allelopathy is a difficult ecological phenomenon to demonstrate as many studies show conflicting results. Eucalyptus globulus, a tree native to Australia, is one of the most widely planted trees around the world. Sparse understories are common beneath E. globulus plantations and are often attributed to allelopathy, but the ecological impacts of E. globulus on native plant communities outside Austrialia are poorly understood. METHODS: To assess allelopathy as a mechanism of understory inhibition, we tested volatile- and water-soluble leaf extracts from E. globulus, Salvia apiana, and Quercus agrifolia on seed germination of California native plants. We also quantified germination rates and early seedling growth of California native plants grown in soil from E. globulus plantations versus soil from an adjacent native plant community. RESULTS: Volatile compounds from E. globulus did not significantly reduce germination for any species. Inhibition from water-soluble E. globulus compounds was comparable to that of a native tree, Quercus agrifolia (10%). Eucalyptus globulus soil supported germination and early seedling growth of native species equal to or better than coastal scrub soil, although species responses were variable. CONCLUSIONS: In contrast to previous studies, our results fail to support the hypothesis that E. globulus chemically inhibits germination of native species. California native plants germinate and grow well in soils from E. globulus plantations, which may have significant implications for management and restoration of land historically occupied by E. globulus plantations.

Heat waves and adaptation strategies in a mediterranean urban context.

BACKGROUND: Heat waves can be considered as an emerging challenge among the potential health risks generated by urbanization and climate changes. Heat waves are becoming more frequent, long and intense, and can be defined as meteorological extreme events consisting in prolonged time of extremely high temperatures in a particular region. The following paper addresses health threats due to heat waves presenting the case study of Lecce, a city located in Southern Italy; the Mediterranean area is already recognized in international literature as a hot-spot for climate changes. This work assesses the potential impact of two different adaptation strategies. METHODS: We have tested the effectiveness of cool surfaces and urban forestry as adaptation approaches to cope with heat waves. The microclimate computer-based model "ENVI-met" was adopted to predict thermal scenarios arising from the two proposed interventions. The parameters analysed consisted in temperature and relative humidity. RESULTS: Urban forestry approach seem to lower temperature (that represents the major cause of urban overheating) better than cool surfaces strategy, but relative humidity produced by the evapotranspiration processes of urban forestry has also negative influences on temperature perceived by pedestrians (thermal discomfort). CONCLUSION: Vegetation represents both an adaptation and a mitigation strategy to climate changes that guarantees an improvement of air quality, with consequent psychological and physical benefits. Wide campaigns aimed at planting trees and increasing the urban green coverage should be systematically planned and fostered by national, regional and local institutions preferably with the involvement of research departments, schools and citizens' associations.

Evaluating and comparing the green wall retrofit suitability across major Australian cities.

Urban densification continues to present a unique set of economic and environmental challenges. A growing shortage of green space and infrastructure is intrinsically linked with urban growth and development. With this comes the loss of ecosystem services such as urban heat island effects, reduction of air quality and biodiversity loss. Vertical greenery systems (VGS) offer an adaptive solution to space-constrained areas that are characteristic of dense urban areas, and can potentially improve the sustainability of cities. However, in order to promote VGS uptake, methods are required to enable systematic appraisal of whether existing walls can be retrofitted with VGS. Further, feasibility studies that quantify the potential for retrofit suitability of VGS across entire urban areas are lacking. This study established an evaluation tool for green wall constructability in urban areas and validated the assessment tool by determining the quantity of walls in five major Australian cities that could potentially have VGS incorporated into the existing infrastructure. Each wall was analysed using an exclusionary set of criteria that evaluated and ranked a wall based on its suitability to VGS implementation. Sydney and Brisbane recorded the greatest proportional length of walls suitable for VGS, with 33.74% and 34.12% respectively. Conversely, Perth's urban centre was the least feasible site in which to incorporate VGS, with over 97% of surveyed walls excluded, mainly due to the prevalence of <1 m high fence lines and glazed shopfronts. This study aimed to evaluate feasibility assessments of green wall retrofitability in highly urbanised areas with the intention of creating an analytical method that is accessible to all. This method, coupled with the promising number of feasible walls found in this study, emphasises the need for more government policy and incentives encouraging green wall uptake and could play a pivotal role in the expansion of green infrastructure and urban forestry.

Are street tree inequalities growing or diminishing over time? The inequity remediation potential of the MillionTreesNYC initiative.

Most street tree inequality studies focus on examining tree abundance at single time point, while overlooking inequality dynamics measured based on a complete set of tree measures. Whether the severities of street tree inequalities vary with different tree structure measures, whether street tree inequalities are diminishing or growing over time, and how the inequality dynamics are affected by tree-planting programs remain largely unexplored. To fill these gaps, this study applied binned regression and cluster analyses to street tree census data of 1995-2015 in New York City. We investigated different structural measures of street tree inequalities pertaining to various aggregations of people, compared street tree inequalities over time, and revealed the inequity remediation role of the MillionTreesNYC initiative. We found that the underprivileged populations, characterized by higher percentages of the poor, racial minorities, young people, and less-educated people, are more likely to have lower tree abundance, less desired tree structure, poorer tree health condition, and more sidewalk damages. When disaggregating inequalities across various aggregations of people, income-based and education-based inequalities were the most severe, but the inequalities diminished over time. The race-based and age-based inequalities show mixed results that disfavor Hispanics, Blacks, and young people. The equity outcome of the MillionTreesNYC initiative is not ideal as the inequalities decrease when measured using tree count and species diversity, whereas they increase when measured using tree health and average diameter at breast height. The findings have important implications for more effective decision-making to balance resources between planting trees and protecting existing trees, and between increasing tree abundance and improving tree structure.

The politics of urban trees: Tree planting is associated with gentrification in Portland, Oregon.

This study evaluated the hypothesis that urban-tree planting increases neighborhood gentrification in Portland, Oregon. We defined gentrification as an increase in the median sales price of single-family homes in a Census tract compared to other tracts in the city after accounting for differences in the housing stock such as house size and number of bathrooms. We used tree-planting data from the non-profit Friends of Trees, who have planted 57,985 yard and street trees in Portland (1990-2019). We estimated a mixed model of gentrification (30 years and 141 tracts) including random intercepts at the tract level and a first-order auto-regressive residual structure. Tract-level house prices and tree planting may be codetermined. Therefore, to address potential endogeneity of tree planting in statistical modeling, we lagged the number of trees planted by at least one year. We found that the number of trees planted in a tract was significantly associated with a higher tract-level median sales price, although it took at least six years for this relationship to emerge. Specifically, each tree was associated with a $131 (95% CI: $53-$210; p-value=0.001) increase in tract-level median sales price six years after planting. The magnitude of the association between the number of trees planted and median sales price generally increased as the time lag lengthened. After twelve years, each tree was associated with a $265 (95% CI: $151-$379; p-value<0.001) increase in tract-level median sales price. Tree planting was not merely a proxy for existing tree cover, as the percent of tract covered in tree canopy was independently associated with an increase in median sales price. Specifically, each 1-percentage point increase in tree-canopy cover was associated with a $882 (95% CI: $226-$1,538; p-value=0.008) increase in median sales price. In conclusion, tree planting is associated with neighborhood-level gentrification, although the magnitude of the association is modest.

The impact of the Covid-19 pandemic on green space use in Turkey: Is closing green spaces for use a solution?

With the advent of effects of the Covid-19 pandemic spreading far and wide throughout many countries in the world, both similar and differing measures are being taken in an effort to manage and curtail them. In addition to weekend lockdowns and closures of café's and public meeting places throughout Turkey in the early stages of the pandemic, public coasts and urban green spaces (UGS's) were also closed in order to maintain social distancing. The aim of the current study is to reveal the opinions of UGS users regarding the measures taken in general against the pandemic, and the measure of closing the coasts and UGS's for use. For this purpose, the distribution of a questionnaire to 239 UGS users was coordinated. The results indicate that people do not support both pandemic measures in general, and the measure of closing the coasts and UGS's for use. According to the findings based on the opinions of the survey participants, the Covid-19 pandemic has caused more psychological problems than physical problems. UGS's are very important in aiding the elimination of some of the negative effects the pandemic has helped create, as well as the effects of the measures taken in general against it. Covid-19 restrictions have given rise to the need to redesign UGS's, and the lessons learned from the pandemic and usage habits must be taken into account in new designs.

Knowledge Co-production at the Research-Practice Interface: Embedded Case Studies from Urban Forestry.

Cities are increasingly engaging in sustainability efforts and investment in green infrastructure, including large-scale urban tree planting campaigns. In this context, researchers and practitioners are working jointly to develop applicable knowledge for planning and managing the urban forest. This paper presents three case studies of knowledge co-production in the field of urban forestry in the United States. These cases were selected to span a range of geographic scales and topical scopes; all three are examples of urban researcher-practitioner networks in which the authors are situated to comment on reflexively. The three cases resemble institutional structures described in the knowledge co-production literature, including participatory research, a hybrid organization of scientists and managers, and a community of practice. We find that trust, embeddedness, new approaches by both practitioners and researchers, and blending of roles all serve to recognize multiple forms of capability, expertise, and ways of knowing. We discuss the impacts of knowledge co-production and the ways in which hybrid institutional forms can enable its occurrence.

Integrating ecosystem services analysis into scenario planning practice: accounting for street tree benefits with i-Tree valuation in Central Texas.

Scenario planning continues to gain momentum in the United States as an effective process for building consensus on long-range community plans and creating regional visions for the future. However, efforts to integrate more sophisticated information into the analytical framework to help identify important ecosystem services have lagged in practice. This is problematic because understanding the tradeoffs of land consumption patterns on ecological integrity is central to mitigating the environmental degradation caused by land use change and new development. In this paper we describe how an ecosystem services valuation model, i-Tree, was integrated into a mainstream scenario planning software tool, Envision Tomorrow, to assess the benefits of public street trees for alternative future development scenarios. The tool is then applied to development scenarios from the City of Hutto, TX, a Central Texas Sustainable Places Project demonstration community. The integrated tool represents a methodological improvement for scenario planning practice, offers a way to incorporate ecosystem services analysis into mainstream planning processes, and serves as an example of how open source software tools can expand the range of issues available for community and regional planning consideration, even in cases where community resources are limited. The tool also offers room for future improvements; feasible options include canopy analysis of various future land use typologies, as well as a generalized street tree model for broader U.S. application.

Different explanations for surface and canopy urban heat island effects in relation to background climate.

The background climatic conditions and urban morphology greatly influence urban heat island effects (UHIs), but one-size-fits-all solutions are frequently employed to mitigate UHIs. Here, attribution models for surface UHIs (SUHIs) and canopy UHIs (CUHIs) were developed to describe UHI formation. The contribution of factors to SUHIs and CUHIs shows similar dependencies on background climate and urban morphology. Furthermore, the factors that mainly contributed to CUHIs were more complex, and anthropogenic heat was the more critical factor. Influence from urban morphology also highlights that there is no one-size-fit-all solution for heat mitigation at the neighborhood. In particular, maintaining a low building density should be prioritized, especially mitigating CUHIs. Moreover, it is more effective to prioritize urban irrigation maintenance over increasing green cover in arid regions but the opposite in humid regions. The work can provide scientific evidence to support developing general and regional guidelines for urban heat mitigation.

Polycyclic aromatic hydrocarbon (PAH) phytoaccumulation in urban areas by Platanus × acerifolia, Celtis australis, and Tilia grandifolia leaves and branches.

Polycyclic aromatic hydrocarbon (PAH) concentrations in the leaves and 1-year-old branches of three common tree species growing in a middle-sized city located in a moderate climate zone were estimated. For this purpose, PAH phytoaccumulation in Platanus × acerifolia, Celtis australis, and Tilia grandifolia species from highly urbanized, traffic congested, and highly PAH-contaminated streets was compared with trees from non-contaminated parks in the same urban core. The gathered data was used to define 17 PAH profiles, identify the main PAH pollution emission sources, and determine the organ and species specificity of PAHs accumulation. Due to the direct absorption of polluted air via stomata, the leaves accumulated up to 30% more PAHs compared to the 1-year-old branches. As expected, PAH concentrations were much higher in street trees, while heavy weight PAHs (with five and six rings) were accumulated in the highest concentrations. The highest foliar Σ17 PAH concentrations were detected in street-grown C. australis, followed by P. acerifolia and T. grandifolia (502.68, 488.45, and 339.47 ng g-1 dry weight (DW), respectively). The same pattern was noted for Σ17 PAHs in branches (414.89, 327.58, and 342.99 ng g-1 DW, respectively). Thus, T. grandifolia emerged as the least effective PAH sink as it accumulated up to ~ 40% less PAHs than P. acerifolia and C. australis leaves/branches. Among the 17 tracked PAHs, benzo[a]anthracene, benzo[a]pyrene, dibenzo[a,h]anthracene, and pyrene were found to have accumulated in the highest concentrations in all analyzed species irrespective of the site, and accounted for more than 50% of the total detected PAHs. Finally, a "black box" about species and organ specificity, as well as specific drivers that limit PAHs uptake capacity by trees, was opened, while this work provides insights into further PAH phytoremediation strategies.

Are the ladybugs Cryptolaemus montrouzieri and Exochomus quadripustulatus (Coleoptera: Coccinellidae) candidate predators of Toumeyella parvicornis (Hemiptera: Coccidae)?

BACKGROUND: Toumeyella parvicornis is an alien pest of recent introduction in Italy that infests stone pines (Pinus pinea L.), its main host plant in Europe. Infestations are currently controlled through endotherapic treatments, but the high costs and the long-term inefficacy highlight the need for alternative control strategies applicable in natural systems as well. An analysis of the effectiveness of autochthonous and naturalized predators is the first step to achieve this goal. This work focused on two candidate predators, Exochomus quadripustulatus and Cryptolaemus montrouzieri (Coleoptera: Coccinellidae), that may potentially control T. parvicornis. The analysis was carried out under laboratory-controlled and semi-field conditions. RESULTS: Laboratory tests were carried out to assess: (i) the predation rate of the ladybugs over different densities of pest preimaginal stages, and (ii) the effect of the presence of heterospecific and conspecific predators on the attractiveness of prey colonies. Semi-field experimentations were carried out by wrapping infested stone pine twigs with net sleeves and applying one of three treatments: (i) Exochomus quadripustulatus, (ii) Cryptolaemus montrouzieri, and (iii) control containing only the pest population. Both the ladybugs were attracted by T. parvicornis, offered as prey. Exochomus quadripustulatus was more attracted to conspecific and heterospecific ladybugs than Cryptolaemus montrouzieri and responded to prey more quickly. CONCLUSIONS: The results obtained could be useful for planning further experimentations to explore the potential use of these predators in biological control programs that may be applied in infested areas. Besides the use in an urban context, where pesticide use is strongly limited, the release of natural enemies may help safeguard stone pine forests. © 2024 Society of Chemical Industry.

Public safety considerations constraint the conservation of large old trees and their crucial ecological heritage in urban green spaces.

Large old trees in urban public green spaces deliver a diversity of values essential for human well-being, including biodiversity conservation. Yet, the conservation of large old trees bearing key wildlife microhabitats interferes with safety considerations. This intuitive notion, however, is backed by an insufficient and scattered body of evidence. Here, we empirically examined this process using data on 5974 trees across 510 sample plots, organized as quintuplets within 102 sample sites, including urban parks, cemeteries, recreational forests, and historic reserves in the urban agglomeration of Kraków, Poland. Our analyses demonstrate that trees situated in areas frequently visited by people, or those near walking paths, benches, or playgrounds, have elevated accident hazards and, therefore, necessitate intensive tree surgeries (pruning and logging) to remain harmless. Large old trees, which bear the most diverse microhabitats and pose greater risks when they collapse, are especially affected by these measures. Accordingly, we found that the co-occurrence of large trees with elevated accident hazards results in significant losses of dead and sloped trees, and trees with cavities, injuries, crown deadwood, fungal fruiting bodies, or epiphytes, particularly in parks and, to a lesser extent, in recreational forests. Apparently, some tree-related microhabitats, such as injuries, cavities, and microsoils, also emerge in risky spots after pruning. Our findings underscore that the conservation of large old trees and their ecological functions faces significant challenges due to safety considerations. To address conservation challenges and harmonize human coexistence with biodiversity, we recommend enhancing environmental awareness and reevaluating arboricultural and planning policies. This would involve establishing strategic and pocket reserves on city peripheries and interiors, allowing larger older trees to thrive and develop important microhabitats without compromising public safety. Otherwise, we risk losing many large old trees and/or their superior value for wildlife, which will regenerate over decades, if not centuries.