Human-nature interactions

Soga, M. & Gaston, K.J. 2022. Towards a unified understanding of human-nature interactions. Nature Sustainability, online early.

Interest in the direct interactions between individual people and nature has grown rapidly. This attention encompasses multiple academic disciplines and practical perspectives. A central challenge thus lies in creating a rich cross-disciplinary understanding of these interactions, rather than one that might become characterized by little conceptual, terminological and methodological unity. Here, to facilitate the former outcome, we bring together concepts and theories about direct human–nature interactions drawn from diverse disciplines within a unified conceptual framework. Using this framework, we discuss the linkages among key concepts and theories, identify important knowledge gaps and suggest directions for future research.

Horizon scanning

Sutherland, W.J., Atkinson, P.W., Butchart, S., Capaja, M., Dicks, L.V., Fleishman, E., Gaston, K.J., Hails, R.S., Hughes, A.C., Le Anstey, B., Le Roux, X., Lickorish, F.A., Maggs, L., Noor, N., Oldfield, T.E.E., Palardy, J.E., Peck, L.S., Pettorelli, N., Pretty, J., Spalding, M.D., Tonneijck, F.H., Truelove, G., Watson, J.E.M., WentworthJ., Wilson, J.D & Thornton, A. 2022. A horizon scan of global biological conservation issues for 2022. Trends in Ecology and Evolution 37, 95-104.

We present the results of our 13th annual horizon scan of issues likely to impact on biodiversity conservation. Issues are either novel within the biological conservation sector or could cause a substantial step-change in impact, either globally or regionally. Our global panel of 26 scientists and practitioners identified 15 issues that we believe to represent the highest priorities for tracking and action. Many of the issues we identified, including the impact of satellite megaconstellations and the use of long-distance wireless energy transfer, have both elements of threats and emerging opportunities. A recent state-sponsored application to commence deep-sea mining represents a significant step-change in impact. We hope that this horizon scanwill increase research and policy attention on the highlighted issues.

Concern for nature

Chang, C-C., Le Nghiem, T.P., Fan, Q., Tan, C.L.Y., Oh, R.R.Y., Lin, B.B., Shanahan, D.F., Fuller, R.A., Gaston, K.J. & Carrasco, L.R. 2021. Genetic contribution to concern for nature and proenvironmental behaviour. BioScience, online early.

Earth is undergoing a devastating extinction crisis caused by human impacts on nature, but only a fraction of society is strongly concerned and acting on the crisis. Understanding what determines people’s concern for nature, environmental movement activism, and personal conservation behavior is fundamental if sustainability is to be achieved. Despite its potential importance, the study of the genetic contribution to concern for nature and proenvironmental behaviors has been neglected. Using a twin data set (N = 2312), we show moderate heritability (30%–40%) for concern for nature, environmental movement activism, and personal conservation behavior and high genetic correlations between them (.6–.7), suggesting a partially shared genetic basis. Our results shed light on the individual variation in sustainable behaviors, highlighting the importance of understanding both the environmental and genetic components in the pursuit of sustainability. 

Pervasive impacts of artificial light

Gaston, K.J., Ackermann, S., Bennie, J., Cox, D.T.C., Phillips, B.B., Sánchez de Miguel, A. & Sanders, D. 2021. Pervasiveness of biological impacts of artificial light at night. Integrative and Comparative Biology 61, 1098-1110.

Artificial light at night (ALAN) and its associated biological impacts have regularly been characterized as predominantly urban issues. Although far from trivial, this would imply that these impacts only affect ecosystems that are already heavily modified by humans and are relatively limited in their spatial extent, at least as compared with some key anthropogenic pressures on the environment that attract much more scientific and public attention, such as climate change or plastic pollution. However, there are a number of reasons to believe that ALAN and its impacts are more pervasive, and therefore need to be viewed from a broader geographic perspective rather than an essentially urban one. Here we address, in turn, 11 key issues when considering the degree of spatial pervasiveness of the biological impacts of ALAN. First, the global extent of ALAN is likely itself commonly underestimated, as a consequence of limitations of available remote sensing data sources and how these are processed. Second and third, more isolated (rural) and mobile (e.g., vehicle headlight) sources of ALAN may have both very widespread and important biological influences. Fourth and fifth, the occurrence and impacts of ALAN in marine systems and other remote settings, need much greater consideration. Sixth, seventh, and eighth, there is growing evidence for important biological impacts of ALAN at low light levels, from skyglow, and over long distances (because of the altitudes from which it may be viewed by some organisms), all of which would increase the areas over which impacts are occurring. Ninth and tenth, ALAN may exert indirect biological effects that may further expand these areas, because it has a landscape ecology (modifying movement and dispersal and so hence with effects beyond the direct extent of ALAN), and because ALAN interacts with other anthropogenic pressures on the environment. Finally, ALAN is not stable, but increasing rapidly in global extent, and shifting toward wavelengths of light that often have greater biological impacts.

Lighting the night

Sánchez de Miguel, A., Bennie, J., Rosenfeld, E., Dzurjak, S. & Gaston, K.J. First estimation of global trends in nocturnal power emissions reveals acceleration of light pollution. Remote Sensing 13, 3311.

The global spread of artificial light is eroding the natural night-time environment. The estimation of the pattern and rate of growth of light pollution on multi-decadal scales has nonetheless proven challenging. Here we show that the power of global satellite observable light emissions increased from 1992 to 2017 by at least 49%. We estimate the hidden impact of the transition to solid-state light-emitting diode (LED) technology, which increases emissions at visible wavelengths undetectable to existing satellite sensors, suggesting that the true increase in radiance in the visible spectrum may be as high as globally 270% and 400% on specific regions. These dynamics vary by region, but there is limited evidence that advances in lighting technology have led to decreased emissions.

Connecting to nature

Oh, R.R.Y., Fielding, K.S., Chang, C.C., Nghiem, L.T.P., Tan, C.L.Y., Quazi, S.A., Shanahan, D.F., Gaston, K.J., Carrasco, R.T.L. & Fuller, R.A. 2021. Health and wellbeing benefits from nature experiences in Singapore may depend on strength of connection to nature. International Journal of Environmental Research and Public Health 181, 10149.

A growing number of policies and programmes in cities aim to increase the time people spend in nature for the health and wellbeing benefits delivered by such interactions. Yet, there is little research investigating the extent to which, and for whom, nature experiences deliver such benefits outside Europe, North America, and Australia. Here, we assessed the relationships between nature dose (frequency, duration, and intensity) and three mental wellbeing (depression, stress, and anxiety) and two physical health (high blood pressure, diabetes) outcomes in Singapore, an intensely urbanised tropical city. Our analyses accounted for individual factors, including socio-economic status, nature connection (nature relatedness), and whether people with poor health are prevented by their condition from visiting green spaces. Our results show that the association between nature dose (specifically duration) and mental wellbeing is moderated by a nature connection. Specifically, people with a stronger nature connection were less likely to be depressed, stressed, and anxious, regardless of the duration of their nature dose. For those with a weaker connection to nature, spending longer in nature was associated with being more depressed, stressed, and anxious. We did not find a relationship between nature dose and high blood pressure or diabetes. Our results highlight that the relationship between nature dose and wellbeing might vary substantially among cities.

Calibrating night-time imagery

Sánchez de Miguel, A., Zamorano, J., Aube, M., Bennie, J., Gallego, J., Ocaa, F., Pettit, D.R., Stefanov, W.L. & Gaston, K.J. Colour remote sensing of the impact of artificial light at night (II): calibration of DSLR-based images from the International Space Station. Remote Sensing of Environment 264, 112611.

Nighttime images taken with DSLR cameras from the International Space Station (ISS) can provide valuable information on the spatial and temporal variation of artificial nighttime lighting on Earth. In particular, this is the only source of historical and current visible multispectral data across the world (DMSP/OLS and SNPP/VIIRS-DNB data are panchromatic and multispectral in the infrared but not at visible wavelengths). The ISS images require substantial processing and proper calibration to exploit intensities and ratios from the RGB channels. Here we describe the different calibration steps, addressing in turn Decodification, Linearity correction (ISO dependent), Flat field/Vignetting, Spectral characterization of the channels, Astrometric calibration/georeferencing, Photometric calibration (stars)/Radiometric correction (settings correction – by exposure time, ISO, lens transmittance, etc) and Transmittance correction (window transmittance, atmospheric correction). We provide an example of the application of this processing method to an image of Spain. 

What moths see

Briolat, E.S., Gaston, K.J., Bennie, J., Rosenfeld, E.J. & Troscianko, J. 2021. Artificial nighttime lighting impacts visual ecology links between flowers, pollinators and predators. Nature Communications 12, 4163. [Image copyright: J. Troscianko]

The nighttime environment is being altered rapidly over large areas worldwide through introduction of artificial lighting, from streetlights and other sources. This is predicted to impact the visual ecology of many organisms, affecting both their intra- and interspecific interactions. Here, we show the effects of different artificial light sources on multiple aspects of hawkmoth visual ecology, including their perception of floral signals for pollination, the potential for intraspecific sexual signalling, and the effectiveness of their visual defences against avian predators. Light sources fall into three broad categories: some that prevent use of chromatic signals for these behaviours, others that more closely mimic natural lighting conditions, and, finally, types whose effects vary with light intensity and signal colour. We find that Phosphor Converted (PC) amber LED lighting – often suggested to be less harmful to nocturnal insects – falls into this third disruptive group, with unpredictable consequences for insect visual ecology depending on distance from the light source and the colour of the objects viewed. The diversity of impacts of artificial lighting on hawkmoth visual ecology alone argues for a nuanced approach to outdoor lighting in environmentally sensitive areas, employing intensities and spectra designed to limit those effects of most significant concern.

Lighting invertebrates

Lockett, M.T., Jones, T.M., Elgar, M.A., Gaston, K.J., Visser, M.E. & Hopkins, G.R. 2021. Urban street lighting differentially affects community attributes of airborne and ground-dwelling invertebrate assemblages. Journal of Applied Ecology, in press.

1. The introduction of artificial light at night (ALAN) into natural and urbanised landscapes is a known and highly pervasive disruptor of invertebrate communities. However, the effect of variation in intensity and spectra of ALAN on invertebrate communities inhabiting different spatial niches is little understood. Further, the remarkable ability of ALAN to continue to disrupt biodiversity even in chronically illuminated urban landscapes is not often acknowledged.

2. Here, we simultaneously sampled airborne and ground-dwelling invertebrate assemblages under and between urban street lights to explore the effects on community composition and abundance of (a) proximity to decadal (i.e. long-illuminated) nocturnal street lighting and (b) variation in the spectral output of light.

3. The two assemblages responded differently. For airborne invertebrates, night-time abundance doubled, and night-time assemblage composition was significantly different for traps under, compared with between, street lights. These differences in abundance were not affected by street light intensity, and were absent in day samples, suggesting that even weak ALAN may be causing short-term redistribution of nocturnal invertebrates. Further, the abundance (but not composition) effects of ALAN on airborne invertebrates increased when the street lights emitted a higher proportion of short-wavelength light.

4. In contrast, for ground-dwelling invertebrates, we found only marginal effects of proximity and spectrum of lighting on abundance and no effect on assemblage composition. However, more intense street lighting reduced abundance and altered composition at traps both under and between lights.

5. Synthesis and Applications. Public lighting managers must consider ALAN impacts on invertebrate communities not only when introducing ALAN to naïve environments, but also when changing lighting in areas that are highly urbanised and exposed to decades of ALAN. Further, lighting proposals and environmental monitoring of invertebrate communities must take into account the effects on both ground-dwelling and airborne assemblages, as these may respond very differently to the presence, intensity and spectrum of ALAN.

When the sampling stops

Zhang, W., Sheldon, B.C., Grenyer, R. & Gaston, K.J. 2021. Habitat change and biased sampling influence estimation of diversity trends. Current Biology, in press.

Recent studies have drawn contrasting conclusions about the extent to which local-scale measures of biodiversity are declining and whether such patterns conflict with the global-scale declines that have attracted much attention. A key source of high-quality data for such analyses comes from longitudinal biodiversity studies, which sample a given taxon repeatedly over time at a specific location. There has been relatively little consideration of how habitat change might lead to biases in the sampling and continuity of biodiversity time series data, and the consequent potential for bias in the biodiversity trends that result. Here, based on analysis of standardized routes from the North American Breeding Bird Survey (3,014 routes sampled over 18 years), we demonstrate that major local habitat change is associated with an increase in the rate of survey cessations. We further show that routes that were continued despite major habitat changes show reduced diversity. By simulating potential rates of loss, we show that the underlying real trends in taxonomic, functional, and phylogenetic diversity can even reverse in sign if more than a quarter of diversity is lost from routes that ceased and are thus no longer included in surveys. Our analyses imply that biodiversity loss can be underestimated by biases introduced if continued sampling in longitudinal studies is influenced by local change. We argue that researchers and conservation practitioners should be aware of the potential for bias in such data and seek to use more robust methods to evaluate biodiversity trends and make conservation decisions.