Abundance and aesthetics

Soga, M., Fukano, Y., Koyanagi, T.F. & Gaston, K.J. 2021. Species abundance as a determinant of aesthetic values of flowering plant communities. Urban Forestry & Urban Greening 63, 127194.

Both the conservation of biodiversity and the maintenance of ecosystem services are important and fundamental goals in response to the current biodiversity crisis. Cultural ecosystem services – the non-material benefits people derive from their interactions with nature – are an important component of ecosystem services. However, determining the contributions of different components of biodiversity to these benefits has proven more challenging than for other ecosystem services. Here, we determine the relative contributions of diversity (measured as cultivar richness) and abundance (number of individuals) to the aesthetic value of flowering plant communities, using sunflowers as a model organism. We created grassland vegetation plots consisting of different numbers of sunflower cultivars and individuals, presented these treatments to people, and measured their aesthetic preferences (both self-reported and objective behavioural measures) towards them. We found that people’s aesthetic preferences were unrelated to differences in the cultivar richness of the plots but increased substantially with the number of individuals. More importantly, these preference patterns did not differ with a participants’ nature orientation, ecological knowledge, or gender, suggesting the generality of the results. Our findings indicate that the abundance of wildlife can play a crucial role in shaping the cultural services provided by ecosystems. Researchers and policy-makers should therefore pay more attention to the role of abundance in maintaining ecosystem services. 


On the verge

Phillips, B.B., Navaratnam, A., Hooper, J., Bullock, J.M., Osborne, J.L. & Gaston, K.J. 2021. Road verge extent and habitat composition across Great Britain. Landscape and Urban Planning 214, 104159.

 There is growing societal and scientific interest in enhancing road verges for nature and the environment. This is partly because they are estimated to cover large areas in some regions. Yet, to our knowledge, there has been no quantitative assessment of national road verge extent, or of the habitats they encompass. We present a novel method for characterising and classifying road verges remotely. We use this to evaluate the extent and habitat composition of road verges across Great Britain, and to identify opportunities for improving verges for nature and the environment.

We use stratified random sampling of freely-available road maps combined with satellite (Google Earth) and ground-level imagery (Google Street View). Overall, we estimate that there are 2,579 km2 (2,149-3,010 km2) of road verges across Great Britain, equivalent to 1.2% of land area, of which 707 km2 (27.47%) is short, frequently-mown grassland, 1,062 km2 (40.87%) is regular grassland, 480 km2 (18.73%) is woodland, and 272 km2 (10.66%) is scrub. By comparison, we estimate that there are 3,694 km2 of hard road surfaces across Great Britain, equivalent to 1.8% of land. Only 27% of frequently-mown grassland verges contained trees, indicating potential for planting trees and shrubs to provide environmental benefits.

Our findings suggest that there are significant opportunities to enhance (i) verges along major roads, because these constitute a disproportionately large area of road verge and have the widest verges, and (ii) frequently-mown grassland verges for example by, where appropriate, reducing mowing frequencies and/or planting trees. Our method can be used, adapted and further developed by others, for 


People, nature and COVID-19

Soga, M., Evans, M.J., Cox, D.T.C. & Gaston, K.J. 2021. Impacts of the COVID-19 pandemic on human-nature interactions: pathways, evidence and implications. People and Nature [online early].

1. The coronavirus (COVID-19) pandemic and the global response have dramatically changed people’s lifestyles in much of the world. These major changes, as well as the associated changes in impacts on the environment, can alter the dynamics of the direct interactions between humans and nature (hereafter human–nature interactions) far beyond those concerned with animals as sources of novel human coronavirus infections. There may be a variety of consequences for both people and nature.

2. Here, we suggest a conceptual framework for understanding how the COVID-19 pandemic might affect the dynamics of human–nature interactions. This highlights three different, but not mutually exclusive, pathways: changes in (a) opportunity, (b) capability and (c) motivation.

3. Through this framework, we also suggest that there are several feedback loops by which changes in human–nature interactions induced by the COVID-19 pandemic can lead to further changes in these interactions such that the impacts of the pandemic could persist over the long term, including after it has ended.

4. The COVID-19 pandemic, which has had the most tragic consequences, can also be viewed as a ‘global natural experiment’ in human–nature interactions that can provide unprecedented mechanistic insights into the complex processes and dynamics of these interactions and into possible strategies to manage them to best effect.


Lighting Madrid’s night sky

Robles, J., Zamorano, J., Pascual, S., Sánchez de Miguel, A., Gallego, J. & Gaston, K.J. 2021. Evolution of brightness and color of the night sky in Madrid. Remote Sensing 13, 1511.

Major schemes to replace other streetlight technologies with Light-Emitting Diode (LED) lamps are being undertaken across much of the world. This is predicted to have important consequences for nighttime sky brightness and color. Here, we report the results of a long-term study of these characteristics focused on the skies above Madrid. The sky brightness and color monitoring station at Universidad Complutense de Madrid (inside the city) collected Johnson B, V, and R sky brightness data, Sky Quality Meter (SQM), and Telescope Encoder Sky Sensor-WiFi (TESS-W) broadband photometry throughout the night, every night between 2010-2020. Our analysis includes a data filtering process that can be used with other similar sky brightness monitoring data. Major changes in sky brightness and color took place during 2015-2016, when a sizable fraction of the streetlamps in Madrid changed from High-Pressure Sodium (HPS) to LEDs. The sky brightness detected in the Johnson B band darkened by 14% from 2011 to 2015 and brightened by 32% from 2015 to 2019.


Road pollution – no getting away

Phillips, B.B., Bullock, J.M., Osborne, J.L. & Gaston, K.J. 2021. Spatial extent of road pollution: a national analysis. Science of the Total Environment 773, 145589.

Roads form vast, pervasive and growing networks across the Earth, causing negative environmental impacts that spill out into a ‘road-effect zone’. Previous research has estimated the regional and global extent of these zones using arbitrary distances, ignoring the spatial distribution and distance-dependent attenuation of different forms of road environmental impact. With Great Britain as a study area, we used mapping of roads and realistic estimates of how pollution levels decay with distance to project the spatial distribution of road pollution. We found that 25% of land was less than 79 m from a road, 50% of land was less than 216 m and 75% of land was less than 527 m. Roadless areas were scarce, and confined almost exclusively to the uplands (mean elevation 391 m), with only ca 12% of land in Great Britain more than 1 km from roads and <4% of land more than 2.5 km from roads. Using light, noise, heavy metals, NO2, and particulate matter PM2.5 and PM10 as examples, we estimate that roads have a zone of influence that extends across >70% of the land area. Potentially less than 6% of land escapes any impact, resulting in nearly ubiquitously elevated pollution levels. Generalising from this, we find that, whilst the greatest levels of road pollution are relatively localised around the busiest roads, low levels of road pollution (which may be ecologically significant) are pervasive. Our findings demonstrate the importance of incorporating greater realisminto road-effect zones and considering the ubiquity of road pollution in global environmental issues. We used Great Britain as a study area, but the findings likely apply to other densely populated regions at present, and to many additional regions in the future due to the predicted rapid expansion of the global road network.


Artificial light and lockdown

Bustamante-Calabria, M., Sánchez de Miguel, A., Martín-Ruiz, S., Ortiz, J-L., Vílchez, J.M., Pelegrina, A., García, A., Zamorano, J., Bennie, J. & Gaston, K.J. 2021. Effects of the COVID-19 lockdown on urban light emissions: ground and satellite comparison. Remote Sensing, 13, 258.

‘Lockdown’ periods in response to COVID-19 have provided a unique opportunity to study the impacts of economic activity on environmental pollution (e.g., NO2, aerosols, noise, light). The effects on NO2 and aerosols have been very noticeable and readily demonstrated, but that on light pollution has proven challenging to determine. The main reason for this difficulty is that the primary source of nighttime satellite imagery of the earth is the SNPP-VIIRS/DNB instrument, which acquires data late at night after most human nocturnal activity has already occurred and much associated lighting has been turned off. Here, to analyze the effect of lockdown on urban light emissions, we use ground and satellite data for Granada, Spain, during the COVID-19 induced confinement of the city’s population from 14 March until 31 May 2020. We find a clear decrease in light pollution due both to a decrease in light emissions from the city and to a decrease in anthropogenic aerosol content in the atmosphere which resulted in less light being scattered. A clear correlation between the abundance of PM10 particles and sky brightness is observed, such that the more polluted the atmosphere the brighter the urban night sky. An empirical expression is determined that relates PM10 particle abundance and sky brightness at three different wavelength bands.


Variability and suitability

Gardner, A.S., Gaston, K.J. & Maclean, I.M.D. 2021. Accounting for inter-annual variability alters long-term estimates of climate suitability. Journal of Biogeography [online early].

Aim: Species respond to environmental conditions and so reliable assessments of climate suitability are important for predicting how climate change could alter their distributions. Long-term average climate data are often used to evaluate the climate suitability of an area, but in these aggregated climate datasets, inter-annual variability is lost. Due to non-linearity in species’ biological responses to climate, estimates of long-term climate suitability from average climate data may be biased and so differ from estimates derived from the average annual suitability over the same period (average response). We investigate the extent to which such differences manifest in a regional assessment of climate suitability for 255 plant species across two 17-year time periods.

Location: Cornwall in South-West England provides a case study.

Taxon: Plantae.

Methods: We run a simple mechanistic climate suitability model and derive quantitative estimates of climate suitability for 1984–2000 and 2001–2017. For each period, we run the model using climate data representing average monthly values for that period. We then run the model for each year using monthly climate data for that year and average the annual suitability scores across each period (average response). We compare estimates of climate suitability from these two approaches.

Results: Average climate data gave higher estimates of suitability than the average response, suggesting bias against years of poor suitability in temporally aggregated climate datasets. Differences between suitability estimates were larger in areas of high climate variability and correlated with species’ environmental requirements, being larger for species with small thermal niches and narrow ranges of precipitation tolerance.

Main Conclusions: Incorporating inter-annual variability into climate suitability assessments or understanding the extent to which average climate data might obscure this variance will be important to predict reliably the impacts of climate change on species distributions and should be considered when using mechanistic species distribution models.


Nature interactions vary between cities

Oh, R.R.Y., Fielding, K.S., Nghiem, L.T.P., Chang, C.C., Shanahan, D.F., Gaston, K.J., Carrasco, L.R. & Fuller, R.A. 2021. Factors influencing nature interactions vary between cities and types of nature interactions. People and Nature 3, 405-417.

1. There is mounting concern that people living more urbanised, modern lifestyles have fewer and lower quality interactions with nature, and therefore have limited access to the associated health and well-being benefits. Yet, variation in the different types of nature interactions and the factors that influence these interactions across populations are poorly understood.

2. We compared four types of nature interactions by administering surveys across two cities that differ markedly in urbanisation pattern and population density – Singapore and Brisbane – : (a) indirect (viewing nature through a window at work or at home); (b) incidental (spending time in nature as part of work); (c) intentional interactions in gardens; and (d) intentional interactions in public urban greenspace.

3. Our results show that Singapore respondents spent about half as much time (25.8 hr/week) interacting with nature as Brisbane respondents (52.3 hr/week), and indirect interactions were the most prevalent across both cities.

4. Nature orientation, age, income and gender significantly predicted the duration of nature interactions in both cities, while self-reported health, education and ethnicity additionally predicted the duration of nature interactions only for Brisbane. Also, the relationship(s) between each factor and duration could differ in direction and effect size between the types of nature interactions.

5. As such, we conclude that there is much local variation in the dynamics of interactions between people and nature, and that focused studies are needed to develop effective interventions addressing declines in nature interactions in different locations.


Retrofitting

McNaughton, E.J., Beggs, J.R., Gaston, K.J., Jones, D.N. & Stanley, M.C. 2021. Retrofitting streetlights with LEDs has limited impacts on urban wildlife. Biological Conservation 254, 108944.

Artificial light at night (ALAN) causes a wide range of ecological impacts across diverse ecosystems. Most concentrated in urban areas, ALAN poses a particular risk to associated wildlife by disrupting physiology, behaviour and ultimately survival. This risk is predicted to shift as nighttime lightscapes in many cities undergo change. Globally, streetlights are currently being retrofitted with newer technologies that differ in the spectrum and intensity of their emissions, but there is a dearth of in situ urban experiments on the ecological impacts of this change. We monitored timing of dawn and dusk bird song; frequency of owl vocalisations; avian diversity, relative abundance and community composition; small invasive mammal and ground insect activity; and invertebrate relative abundance at 26 residential properties over an 18-month period that coincided with a retrofit from high-pressure sodium (HPS) to white light-emitting diode (LED) streetlights. Initiation time of dawn song was advanced or delayed for two bird species following the retrofit and backyard avian community composition was altered. Avian species richness, relative abundances of three bird species and ground insect activity increased in the presence of LED streetlights. No other retrofit effects were found. Our study suggests that retrofitting streetlights with white LEDs may lead to both positive and negative conservation outcomes for urban wildlife, but direct impacts are relatively small and may be mitigated by changes in lighting characteristics, such as dimming. Streetlight retrofits could provide an opportunity to reduce the impacts of ALAN on urban wildlife if intentionally designed with conservation benefits in mind.


Green exercise

Tan, C.L.Y., Chang, C.-C., Nghiem, T.P.L., Zhang, Y., Oh, R.R.Y., Shanahan, D.F., Lin, B.B., Gaston, K.J., Fuller, R.A. & Carrasco, L.R. 2021. The right mix: residential urban green-blue space combinations are correlated with physical exercise in a tropical city-state. Urban Forestry & Urban Greening 57, 126947. [Image from NASA]

Growing recognition of nature’s benefits to many aspects of human wellbeing has prompted the incorporation of both urban green and blue natural outdoor environments (NOEs) into cities. Amongst the many purposes of NOEs, promotion of physical exercise has been garnering interest, given the increasingly sedentary lifestyles of urban dwellers. However, studies rarely consider how different types of NOEs, let alone the combination of them, might affect the type and frequency of physical exercise conducted by urban residents. We use Singapore, a highly urbanised tropical nation with a considerable number of NOEs, as a case-study to address these gaps. We used a market research survey (n = 1519), geographic information systems, and generalised linear regression models to investigate the relationship between residential NOE cover, exercise-influencing sociodemographic factors, and outdoor exercise choice (i.e., if respondents exercised or not) and frequency of four types of physical exercises: walking, individual-based, team-sports, and overall exercise. For exercise choice, more people walked in areas with higher forest and scrub cover, and less in areas with just scrub. Less conducted individual-based exercise in areas with high unmanaged vegetation cover, and more conducted team-sports in areas with higher open-canopy managed vegetation cover. Amongst those who engaged in these exercises, managed vegetation cover is positively correlated with walking (open- and closed-canopy combined) and team-sports (open-canopy) frequency. Individual-based exercise frequency rose in areas with a mix of high open-canopy managed vegetation and blue space cover within 250 m from one’s home, and a mix of high managed treescape and forest cover 500 m from one’s home. Findings suggest that a specific mix of NOEs can promote the participation of different types of physical exercise. Integrating the right NOE types and combinations into urban residential spaces may thus help to mitigate sedentary lifestyles, boosting public health outcomes in city populations.