How one tree can change the future of a neighbourhood: The process behind the creation of the Boerenhof Park as an example for tactical urban planning

In this paper, the process behind the making of the Boerenhof Park on an urban Waiting Space in Ghent (Belgium) is discussed. We are highlighting how in this case ‘tactical urbanism’ actions, such as planting a tree, turned out to have a long-term impact and as such can inform a ‘tactical urban planning’ approach. Through a learning by reflection method, the Boerenhof Park case has been re-analysed using a conceptual framework built up around the concepts of ‘scratch’, ‘scar’ and ‘score’. The focus was on discerning the transgressional elements for moving from short-term interventions to long-term change. Three key aspects are brought to light: the incremental approach, a desire-driven program, and a transversal collaboration. We argue that these are key aspects for the operationalisation of a tactical urban planning approach.     

Effects of agriculture,climate, and policy on NDVI change in a semi-arid river basin of the Chinese Loess Plateau

In 1999, the Grain for Green Project was implemented by the Chinese government. Since then, the vegetation of Zuli River Basin, a semi-arid river basin of the Chinese Loess Plateau, has been greatly changed. Clearly understanding the impact of natural and artificial factors on vegetation change is important for policy making and ecosystem management. In this study, spatio-temporal variations in vegetation cover in Chinese Zuli River Basin during 1999–2016 were investigated using Landsat normalized difference vegetation index (NDVI) data. Analyses of several indicators, including changes in NDVI in different slopes and land use changes and the relationships between climatic factors and NDVI change, were presented to quantitatively evaluate the effects of agriculture, climate, and policy on NDVI change. The NDVI in the Zuli River Basin increased during the study period, and the main contributors to this change were forest in 1999–2011, cropland, abandoned farmland, and grassland in 2009–2016, and land with slopes ≤ 15°. Land with slope > 15°, where the “Project” was implemented, slightly contributed to the increase in regional NDVI. In 1999–2011, the project (?98.16%) combined with climate change (?68.18%) showed negative effects on the increase in NDVI in the Zuli River Basin, but agriculture (22.28%) played a positive role in increasing this index. In 2009–2016 and 1999–2016, the project (38.45% and 35.25%, respectively), the project combined with climate change (49.83% and 46.30%, respectively), agriculture (18.61% and 23.30%, respectively), promoted increases in NDVI in the basin.     

Biodiversity in sacred urban spaces of Bengaluru,India

Urban green spaces provide critical social and ecological support for cities, but we know little about their diversity and composition in cities of the Global South. This is especially true of lesser known urban spaces such as sacred sites, which are of important cultural and biodiversity significance. We examine tree diversity and composition in sacred sites in Bengaluru, one of India’s fastest growing cities. We recorded 5504 trees from 93 species across 62 temples, churches, and Hindu, Christian and Muslim cemeteries in central areas of Bengaluru. Over half (52%) of the tree species were of native origin, a much higher proportion when compared to other green spaces in the city such as parks. Tree density in sacred sites was much higher than that in parks and informal settlements in Bengaluru. Temples and Hindu cemeteries contained the highest proportion of native species, with large numbers of Ficus benghalensis, a keystone sacred species. Trees in sacred spaces provide an important buffer against urban environmental stress in Indian cities, and serve as refuges for urban wildlife and biodiversity. We need greater information on these lesser known, but culturally significant alternate spaces. They play an important, though ignored role in the environmental sustainability of rapidly growing cities in the Global South.     

The impact of seasonal colour change in planting on patients with psychotic disorders using biosensors

The beneficial effect of nature on patients with mental disorders is of particular importance. There has been an increase in mental illnesses in recent years, but research on the design of healing gardens for mental and behavioural disorders remains limited. This paper is part of a wider study that aims to investigate the effect of selected design elements of healing gardens on patients with mental disorders. This study examines the effect of seasonal colour change in plantings in the design of healing gardens on patients suffering from psychotic disorders by using a questionnaire survey and by recording and analysing human behaviour. Images depicting seasonal colour change in different plantings were viewed on a computer monitor by patients. Patients’ behaviour was studied using biosensors for eye-tracking, facial expression analysis and galvanic skin response. The results showed that differences in gender and age between participants did not affect their preferences. However, it appeared to be more difficult to positively affect the emotions of male participants compared to female participants. Seasonal colour change in a tree canopy created positive and intense emotions in the patients. Based on the results, the use of deciduous trees is proposed in the design of healing gardens for patients with psychotic disorders to create seasonal colour change. Further research is necessary to obtain more detailed design recommendations for landscape architects.     

Identifying factors that determine kernel number in wheat

Understanding variation in kernel number per unit area (KNO) is of major importance in understanding yield and in identifying opportunities to increase yield potential. Factors that determine KNO should therefore be identified considering wide ranges in both crop and environmental conditions. Several field experiments with various spring wheat cultivars were conducted over three years in Mexico. Wide ranges in crop and environmental conditions were obtained by varying N application rates and timing and by different planting dates and locations. Crop development from emergence (DC10) to physiological maturity (DC90) was divided in three phases, with the intermediate phase II ranging approximately from early booting (DC40) to final anthesis (DC70). A photothermal quotient (PTQ) during phase II failed to explain the variation in KNO. Biomass at anthesis explained 72% of the variance, but could not explain some deviant situations and the relation was strongly cultivar specific. Biomass accumulation during phase II more accurately (80%) explained the deviant situations, except one particular location, and cultivar differences became even more pronounced. At this location KNO was also well explained by non-grain spike weight at a week from anthesis, with a constant number of kernels per unit spike dry matter, while differences among cultivars tended to disappear. Factors that are identified to determine KNO are discussed.     

How do urban forests with different land use histories influence soil organic carbon?

Urban forests play a vital role in building soil organic carbon pools in urban areas. In many cases, urban forests are constructed on land previously used for agriculture, parks, or buildings. However, it is still being determined whether historical land use affects soil organic carbon (SOC) stocks in these forests. In this study, we asked: 1) How are SOC and its labile fractions (LOC) in urban forests affected by historical land use? and 2) How do SOC and LOC vary with time and vegetation type in urban forests built on land with different histories? We collected soil samples at three soil depths, 0–10, 10–20, and 20–30 cm, in 48 evergreen and 77 deciduous forest plots in 77 parks in Beijing, all built within the last 30 years. Plots represent two historical land use types, vegetated or non-vegetated, and three planting time classes, young (5–10 years), intermediate (11–20 years), and old (21–30 years). Our findings showed that there were significant differences between historical land use types in SOC and microbial organic carbon (MBC), this may be due to backfill soil before greening on non-vegetated land. Urban forests that were built on vegetated land accumulated SOC over time, while those on historically non-vegetated land did not. Evergreen forests had greater SOC and LOC than deciduous forests only on historically non-vegetated land. In addition, SOC and LOC were found to be negatively affected by increased soil bulk density. However, soil bulk density was not significantly different between both historical land use types and urban forest types. Overall, our study indicates that if SOC sequestration is a high priority in urban forests, cities could concentrate on more efficient management to increase SOC, such as soil rehabilitation and the use of evergreen tree species.     

微塑料对双酚A在鲤鱼肠道中累积及生长生理的影响

探明微塑料（MPs）对双酚A （BPA）在鱼类肠道中累积特征及鱼类生长生理的影响,本研究以黄河鲤鱼为模型生物,分析了0.5 μm聚苯乙烯微塑料（PS-MPs）与BPA联合作用下鲤鱼肠道中微塑料及BPA的累积特征、鲤鱼生长及其抗氧化酶活性,以及它们之间的响应关系。结果表明：联合处理下鲤鱼肠道中的PS-MPs含量随时间呈线性增加,且随投加的微塑料浓度增加而增加,而PS-MPs累积速率随时间呈先增加后减小趋势,其中在BPA+PS（L）处理（1 mg·L^-1 BPA+20 μg·L^-1 PS-MPs）下,0.25 d时鲤鱼肠道中PS-MPs累积速率达到峰值（373.81 μg·g^-1·d^-1）,BPA+PS（H）处理（1 mg·L^-1 BPA+100 μg·L^-1 PS-MPs）下,则是在0.125 d达到最高（644.00 μg·g^-1·d^-1）。与单一BPA暴露相比,联合暴露下鲤鱼肠道中BPA累积量增加,与BPA （1 mg·L^-1 BPA）处理相比,BPA+PS （L）和BPA+PS （H）处理下鲤鱼肠道中BPA含量分别提高了6.13%和9.74%,BPA累积速率分别增加了190.01%、373.80%。相较于对照处理,BPA处理和MPs与BPA联合处理均引起鲤鱼肠组织中超氧化物歧化酶（SOD）活性、过氧化氢酶（CAT）活性、还原型谷胱甘肽（GSH）含量、丙二醛（MDA）含量增加,使体质量下降幅度减缓,其中BPA、BPA+PS （L）和BPA+PS （H）处理下鲤鱼体质量（21 d）较对照处理分别下降1.22%、3.90%、4.33%。当微塑料投加量达到100 μg·mL^-1时,联合处理会增加鲤鱼肠道中SOD活性、CAT活性和GSH含量,抑制MDA产生,从而缓解MPs和BPA联合作用对鲤鱼造成的氧化损伤,并且减缓鲤鱼体质量下降。研究表明,微塑料的存在会增加双酚A在鲤鱼肠道中的累积,且两者联合作用对鲤鱼产生了协同毒理效应,导致鲤鱼生长速率减缓,体质量下降。     

Valuing urban trees: A hedonic investigation into tree canopy influence on property values across environmental and social contexts in Baltimore,Maryland

Urban tree canopy yields numerous environmental and social benefits. This study investigates whether the marginal contribution of tree canopy cover to home values depends on certain characteristics of a property and its location. We address this using a hedonic property analysis with data from Baltimore, Maryland. Both Ordinary Least Square and Spatial Lag models were conducted, all including interaction terms between tree canopy cover and various site factors. Our results indicated that, on average, the amount of tree canopy in the 100–400 zone around a single-family property is positively associated with home price. We also find that the marginal impact of canopy on property price increases for properties that are larger in lot size and closer to downtown Baltimore. Model results were mixed in terms of the interactive effects of crime and proximity to major roadway with tree canopy. We suggest that the benefits that tree canopy provides in the form of added privacy, reduced urban heat, noise and pollution may influence these price increases. These findings may signal concerns about the potential for urban greening to contribute to gentrification. In a competitive housing market, those with the capacity to afford to pay more for urban tree canopy and the benefits it provides such as a cooler downtown environment, privacy on larger lots, or reduced noise and pollution from a major roadway may price out those who are unable to pay this urban tree canopy premium. There is, therefore, the potential for unequal increases in home equity across neighborhoods following tree planting and urban greening in Baltimore.     

Demographic and spatial variables associated with spending time in nature during COVID-19 lockdowns

To stop the spread of SARS-CoV-2 coronavirus (COVID-19) governments around the world implemented lockdowns restricting public travel. In the Australian state of Victoria, this included limiting permitted reasons for leaving home and restricting movements to within a 5 km radius of one’s home. In 2020, we conducted a state-wide survey (N = 1024) of Victorians that coincided with a lockdown. We asked respondents where they had spent time in nature and how they perceived lockdowns affected the amount of time they spent in nature. We then considered demographic and spatial predictors of spending more or less time in nature. Women, younger people, and those living in areas with higher socio-economic status were likely to report spending more time in nature. Closer proximity of residents to parks and waterways and higher proportional area of native vegetation within a 1-km radius were also associated with more time in nature. Understanding how different groups were affected by restrictions on access to nature can help improve government management of crises like pandemics, including through urban planning for green space, supporting improved individual and societal resilience. We discuss the implications of our findings for improving access to nature during lockdowns as well as opportunities for a post-pandemic relationship with nature, particularly in urban settings.