Sinan Kordon

Türkiye holds the world’s largest natural stands of Lebanon cedar (Cedrus libani A. Rich.) and extensive Crimean juniper forest (Juniperus excelsa M. Bieb.), together comprising 884,361 ha of closed, drought-exposed forest. Both assimilate at needle water potentials near −3.0 MPa, yet lose part of their potential assimilation to photorespiration and to stomatal closure under water deficit. A literature-parameterized scenario model relaxes both constraints against a radiation-limited ceiling. The zonal photorespiratory and stomatal input fractions are structured expert estimates, not measurements, which are: 8–16% and 14–28% of potential gross primary production (GPP), or 13–23% and 11–23% after coupling. Together they reduce weighted-mean net primary productivity from 3.29 to 2.17 Mg C ha⁻¹ yr⁻¹, a 34.1% reduction in potential GPP (Monte Carlo interval 31.0–36.4%, conditional on the elicitation). Of that loss, 39–46% is obligate photorespiration beyond management reach, depending on how the jointly caused interaction is assigned; the obligate share falls along the aridity gradient. Radial growth in these species occupies a narrow climatic window that does not coincide with peak assimilation, so forgone wood is reported as a function of the source-control coefficient φ, with φ = 1 as an upper bound. At φ = 1, the estate forgoes up to 1.5 million m³ yr⁻¹ of stemwood, and the 3.6 million Mg yr⁻¹ of unfixed carbon (as CO₂-equivalent, not net sequestration) is worth, together with that wood, about US$ 0.20 billion; at φ = 0.5 the wood and the value halve, and at φ = 0 no wood is forgone.

Urban conditions may increase woody-vegetation drought stress, although management and canopy composition can modify urban–peri-urban differences. We compared spectral anomalies of persistent woody canopy in Berlin, Madrid, and Vienna using Harmonized Landsat–Sentinel-2 observations from 2013 to 2024. Seventy urban–peri-urban pairs were matched on elevation, long-term temperature, precipitation, and retained woody area. Of 26 predefined candidate recurrent-drought events, 12 met the 80% observation-support criterion. Outcomes were event medians of within-pair urban-minus-peri-urban anomalies in the two-band enhanced vegetation index (EVI2) and normalized difference moisture index (NDMI). Each index produced seven positive and five negative contrasts; medians were 0.00047 for EVI2 and 0.00065 for NDMI. Event-level models adjusted for city and current drought severity examined antecedent severity and inter-event interval. The standardized predictor coefficients ranged from −0.00225 to 0.00252 in terms of index units. All four heteroskedasticity-consistent 95% confidence intervals included zero. The same pattern emerged in pair-within-event resampling, spatial buffering, and models based on growing-season severity, with every interval crossing zero. As the primary regressions contained 12 events and five fitted terms, there were only seven residual degrees of freedom, resulting in imprecise estimates and low statistical power. Climate antecedents were identifiable for all 26 candidates, and analytical inclusion was determined by vegetation observation support. Across the retained cases, we found neither a consistent urban spectral disadvantage nor a clear relationship between the contrast and drought history. The matched design is reproducible, but the evidence it provides comes from a small sample selected based on observation availability and from dense canopies that persisted throughout the study period. Accordingly, these estimates should not be generalized to whole urban forests or interpreted as measures of physiological response, mortality, or canopy loss.

Türkiye holds the world's largest natural stands of Lebanon cedar (Cedrus libani A. Rich.) and extensive Crimean juniper forest (Juniperus excelsa M. Bieb.), together 884,361 ha of closed, drought-exposed forest. Both assimilate at needle water potentials near −3.0 MPa, yet lose some of their potential assimilation to photorespiration and stomatal closure under water deficit. A literature-parameterized scenario model relaxes both constraints against a radiation-limited ceiling. Zonal photorespiratory and stomatal input fractions of potential gross primary production (GPP) are 8%–16% and 14%–28%; after coupling, the model removes 13%–23% and 12%–23%. Together, these reduce weighted-mean net primary productivity from 3.29 to 2.14 Mg C ha⁻¹ yr⁻¹, a 34.9% reduction in potential GPP (Monte Carlo interval 31.7%–37.3%, conditional on the elicitation). Of that loss, 37%–45% is obligate photorespiration beyond management reach, depending on how the jointly caused interaction is assigned; the obligate share falls along the aridity gradient. Whether the loss becomes forgone wood is a separate question: radial growth in these species is confined to a narrow climatic window that does not coincide with peak assimilation. Under complete source control, the estate forgoes 1.5 million m³ and 3.7 million Mg CO₂ annually, worth US$ 0.21 billion; under complete sink control, none.

Urban parks are key components of green infrastructure, yet their long-term functionality increasingly depends on the ecological tolerance of plant species under multiple environmental stressors. Evaluating plant tolerance traits can therefore support more resilient species selection and park management in cities affected by climate change. This study assessed the ecological tolerance characteristics of woody plant taxa in five urban parks in Samsun, located in the Central Black Sea Region of Türkiye. A total of 104 woody taxa were identified through repeated field surveys in Kurupelit Campus Park, Batı Park, Tekkeköy Park, Doğu Park, and Adnan Kahveci Park. Plant taxa were photographed, recorded in a park-based inventory, and evaluated for air pollution, drought, wind, salinity, heat, and cold tolerance using published literature and plant databases. Air pollution, drought, wind, and salinity were scored on a four-level ordinal scale, while heat and cold were evaluated as binary variables. Descriptive statistics, Kruskal-Wallis H tests, Pearson’s chi-square tests, effect size calculations, and Principal Component Analysis were applied. The highest proportions of tolerant taxa were found for cold (77.9%), air pollution (77.2%), and heat (71.6%). In comparison, high tolerance was lower for drought (59.9%), wind (52.1%), and salinity (51.4%). No statistically significant inter-park differences were detected, and effect sizes were negligible, indicating broadly similar tolerance compositions. PCA identified two main gradients: abiotic stress tolerance and urban climatic stress tolerance. The findings provide practical criteria for integrating ecological tolerance into plant selection and climate-resilient urban park planning.

This study aims to evaluate the surface temperatures of different materials under sun-exposed and shaded conditions, as well as variations in local ambient air temperature, in urban open spaces with moderate to high levels of pedestrian use in central Lisbon. Field measurements were conducted between 20 and 25 May 2025. A total of 852 surface temperature measurements collected over six days from 142 distinct surface points and 138 ambient air temperature measurements from 23 locations were analyzed using mixed-effects models. Under sun-exposed conditions, surface temperatures differed significantly among material types; artificial turf, composite materials, and asphalt showed higher temperature values, whereas natural grass showed lower values. No significant differences among material types were found under shaded conditions. The effect of sun/shade conditions varied by material type, with the largest temperature difference observed for asphalt. In the complementary color analysis, dark-colored surfaces were 8.6°C warmer than light-colored surfaces under sun-exposed conditions, while no significant difference between the color groups was observed under shaded conditions. Ambient air temperatures were highest in hardscape settings surrounded by other hard surfaces. Points within tree-covered, park-like surroundings showed lower temperature values, while water-edge settings were also cooler than hardscape settings. Within water-edge settings, however, no significant difference was found according to whether the surrounding environment consisted of hard surfaces or tree-covered, park-like surroundings. The findings indicate the importance of considering material selection, shading, surface characteristics, vegetation, and proximity to water together in the design of urban open spaces.

Permakültür; sürdürülebilirlik, ekolojik tasarım, kentsel tarım ve topluluk temelli planlama gibi çok disiplinli kavramlarla etkileşim hâlinde olan bir yaklaşım olarak, çevresel sorunların derinleştiği günümüz kentlerinde hem araştırma hem de uygulama boyutunda artan bir öneme sahiptir. Bu çalışma, Türkiye'de permakültür konusunda hazırlanmış olan lisansüstü tezlerin sistematik biçimde bibliyometrik analizini sunmayı, bu alandaki akademik üretimin niceliksel ve niteliksel eğilimlerini ortaya koymayı amaçlamaktadır. Bu bağlamda, YÖK Ulusal Tez Merkezi verilerinden alınan permakültür konulu 37 lisansüstü tez, tez yılı, tez türü, danışman sayısı ve unvanı, üniversite ve enstitü türü, ana bilim ve bilim dalı, yazım dili, sayfa ve kaynak sayısı, anahtar kelime yoğunluğu olmak üzere toplamda 17 farklı tematik içerik bu kriterler doğrultusunda analiz edilmiştir. Bulgular, permakültür konulu lisansüstü tezlerin sayıca son yıllarda, özellikle 2022 ve 2024 yıllarında belirgin bir artış gösterdiğini, çalışmaların büyük oranda yüksek lisans düzeyinde ve devlet üniversitelerinde üretildiğini ortaya koymuştur. Tezlerde en sık karşılaşılan temalar; permakültür yaklaşımının teorik temelleri, sürdürülebilir mimarlık, ekolojik konut ve kent bostanları gibi uygulama modelleri, kültürel ve sosyolojik perspektifler ile eğitim ve yönetim politikaları olmuştur. Disiplinler arası dağılım, mimarlık, peyzaj mimarlığı, şehir ve bölge planlama, çevre bilimleri ve sosyal bilimler arasında geniş bir yelpazeye yayılmıştır. Sayfa ve kaynak sayısı analizleri, çalışmaların bilimsel yeterlilik düzeyine dair önemli göstergeler sunarken, anahtar kelime analizleri içerik yoğunluğu hakkında bilgi vermektedir. Bu bibliyometrik analiz, permakültürün Türkçe literatürde bir ivmelenme yakalayarak, araştırmacıların gündemine girmeyi başardığını ve özellikle sürdürülebilir yaşam pratikleriyle bağlantılı özgün tez çalışmalarına zemin oluşturduğunu göstermektedir. Çalışmanın sonunda, bu alanda literatürdeki boşlukların giderilmesi ve disiplinlerarası iş birliklerinin artırılmasına yönelik çeşitli öneriler sunulmuştur.

In addition to aggressive urbanization, climate change and ecological challenges also have serious negative effects on urban green areas. Moreover, the selection of inappropriate plants in urban green space landscape projects increases the severity of these negatives. Therefore, inappropriate plant selection is considered a significant threat to the sustainability of urban green spaces. This situation highlights the importance of selecting plants with high ecological tolerance in urban park landscape projects. In this study, all tree, shrub, and ground cover plants identified in 11 urban parks and open green areas in Rize province were evaluated in terms of ecological tolerance criteria (air pollution, drought, wind, temperature, cold, and salinity). A total of 223 plant taxa were examined (77 native, 3 semi-native, 143 exotic), and it was determined that 149 taxa (49 native, 100 exotic) were sensitive to at least one of these criteria, while the remaining 74 taxa (27 native, 47 exotic) had sufficient tolerance to all ecological variables examined. Prunus serrulata Lindl. ‘Kanzan’ was identified as the taxon with the weakest ecological tolerance, and the resilience statuses of the other taxa were presented in the assessment table created. As a result, it was found that there are taxa used in Rize urban open green areas that pose risks against ecological factors, and recommendations were made for future landscape planting projects.

Although community gardening provides numerous environmental, economic, health, and social benefits, public involvement and support are still not at the desired level for their permanency in cities. While there are numerous studies regarding people’s motivations to participate in community gardening, empirical research is very limited for people’s reasons not to participate in community gardening. For increased involvement and public support, knowledge about people’s reasons not to participate in community gardening is important. Using a survey instrument, this research identified people’s primary reasons that negatively influence their participation in community gardening in five disadvantaged neighborhoods of Roanoke, Virginia. Descriptive statistics, T-test, and factor analysis procedures were used at a 95% significance level. Results showed that the statements associated with “theft and damage”, “difficult access”, “too much effort”, and “no personal interest” were the main reasons not to participate in community gardening. Based on these, this research brings design and maintenance recommendations for the increase of more successful community garden projects. In the long term, this can contribute to the long-term survival of these landscapes in cities by providing higher public involvement and support for community garden projects.

Although community gardens provide numerous economic, environmental, and social benefits, some have been lost to other land uses due to the lack of organized and effective public support. Knowledge about people’s attitudes and perceptions towards these landscapes is important to achieve greater public support. This study used a scene rating survey to investigate attitudes and perceptions of four different groups (community gardeners, community and home gardeners, home gardeners, and non-gardeners) in Roanoke, Virginia. Content analysis, factor analysis, descriptive statistics, customized Kruskal- Wallis test (ANOVA) and content identifying method (CIM) procedures were used. All statistical analyses were completed at a 95% significance level using SPSS version 21. Results showed that there are seven dimensions important to participants’ preferences in community gardens including “Gathering and Seating”, “Plots with Boundaries”, “Focal Points”, “Plots without Boundaries”, Garden Entrance”, Untidy Space”, and “Composting Structures”. Excluding the “Gathering and Seating” dimension, a significant difference was detected between participant groups. Based on these dimensions, this study provides design recommendations for community garden projects to minimize possible opposition between gardeners and non-gardeners and to develop more successful community garden programs for the long-term survival of these landscapes in cities.