Dave Kendal

The role of social values in the management of ecological systems.

The concept of value is central to the practice and science of ecological management and conservation. There is a well-developed body of theory and evidence that explores concepts of value in different ways across different disciplines including philosophy, economics, sociology and psychology. Insight from these disciplines provides a robust and sophisticated platform for considering the role of social values in ecological conservation, management and research. This paper reviews theories of value from these disciplines and discusses practical tools and instruments that can be utilised by researchers and practitioners. A distinction is highlighted between underlying values that shape peoples perception of the world (e.g. altruistic or biospheric value orientations), and the values that people assign to things in the world (e.g. natural heritage, money). Evidence from numerous studies has shown that there are multiple pathways between these values and attitudes, beliefs and behaviours relevant to ecological management and conservation. In an age of increasing anthropogenic impacts on natural systems, recognising how and why people value different aspects of ecological systems can allow ecological managers to act to minimise conflict between stakeholders and promote the social acceptability of management activities. A series of practical guidelines are provided to enable social values to be better considered in ecosystem management and research.

A cultivated environment: Exploring the global distribution of plants in gardens, parks and streetscapes

Plants cultivated in gardens, parks and streetscapes are becoming increasingly important to peoples’ experience of biological life, and have been the recent focus of research in ecology, invasion biology, human geography and sociology. However patterns of distribution have not previously been explored at a global scale. In this study, global patterns in the distribution of cultivated floras were explored to determine the significance of biophysical and social factors driving species distributions. The taxonomic similarity of 72 published species lists was examined, covering a wide geographic and climatic range and a variety of land uses. Cultivated floras across urban and rural settlements were found to be very different and unsurprisingly to be strongly filtered by temperature. However we found that human behaviour may overcome other physical drivers of plant distribution such as rainfall in some instances. Social factors were also found to be important. Having a different dominant language (a proxy for cultural background) and difference in GDP per person (a proxy for household income) were also related to the dissimilarity of cultivated floras. Differences in both the social and physical environment are related to floristic differences between cities. However, we recognise that other factors identified in the literature but unsuited to meta-analysis, may also influence the composition of cultivated landscapes. These include changes in policy relating to the provision of street and park vegetation, the availability of plants from nurseries and the preferences of influential gardeners and landscape designers. The significance of the relationship between temperature and species composition suggests that cultivated floras are likely to change in response to climate change. The high level of dissimilarity observed between settlements suggests that patterns of potential naturalisation of cultivated plants are likely to be more complex than currently accepted.

Global drivers and tradeoffs of three urban vegetation ecosystem services.

Our world is increasingly urbanizing which is highlighting that sustainable cities are essential for maintaining human well-being. This research is one of the first attempts to globally synthesize the effects of urbanization on ecosystem services and how these relate to governance, social development and climate. Three urban vegetation ecosystem services (carbon storage, recreation potential and habitat potential) were quantified for a selection of a hundred cities. Estimates of ecosystem services were obtained from the analysis of satellite imagery and the use of well-known carbon and structural habitat models. We found relationships between ecosystem services, social development, climate and governance, however these varied according to the service studied. Recreation potential was positively related to democracy and negatively related to population. Carbon storage was weakly related to temperature and democracy, while habitat potential was negatively related to democracy. We found that cities under 1 million inhabitants tended to have higher levels of recreation potential than larger cities and that democratic countries have higher recreation potential, especially if located in a continental climate. Carbon storage was higher in full democracies, especially in a continental climate, while habitat potential tended to be higher in authoritarian and hybrid regimes. Similar to other regional or city studies we found that the combination of environment conditions, socioeconomics, demographics and politics determines the provision of ecosystem services. Results from this study showed the existence of environmental injustice in the developing world.

Harnessing diversity in gardens through individual decision makers

Goddard et al.’s [1] review is a welcome contribution to the study of the ecological effects of urban gardens in western developed countries. However, we disagree with their proposition that gardens should be ‘managed collectively’ to enhance native urban biodiversity. This may in fact be counterproductive as the very high vegetation diversity observed in gardens is the result of many individual decision makers. Instead, we argue that the key to biodiversity conservation in urban gardens is developing a greater understanding of the factors driving both the positive (high diversity) and negative (low proportion of native plants) ecological outcomes of peoples’ gardening practices. Both research and practice should focus on understanding and harnessing the extraordinarily high species and structural diversity that result from current gardening practices in ways that enhance broader ecological functioning.

Quantifying Plant Colour and Colour Difference as Perceived by Humans Using Digital Images

Human perception of plant leaf and flower colour can influence species management. Colour and colour contrast may influence the detectability of invasive or rare species during surveys. Quantitative, repeatable measures of plant colour are required for comparison across studies and generalisation across species. We present a standard method for measuring plant leaf and flower colour traits using images taken with digital cameras. We demonstrate the method by quantifying the colour of and colour difference between the flowers of eleven grassland species near Falls Creek, Australia, as part of an invasive species detection experiment. The reliability of the method was tested by measuring the leaf colour of five residential garden shrub species in Ballarat, Australia using five different types of digital camera. Flowers and leaves had overlapping but distinct colour distributions. Calculated colour differences corresponded well with qualitative comparisons. Estimates of proportional cover of yellow flowers identified using colour measurements correlated well with estimates obtained by measuring and counting individual flowers. Digital SLR and mirrorless cameras were superior to phone cameras and point-and-shoot cameras for producing reliable measurements, particularly under variable lighting conditions. The analysis of digital images taken with digital cameras is a practicable method for quantifying plant flower and leaf colour in the field or lab. Quantitative, repeatable measurements allow for comparisons between species and generalisations across species and studies. This allows plant colour to be related to human perception and preferences and, ultimately, species management.

Assessing the drivers shaping global patterns of urban vegetation landscape structure

Vegetation is one of the main resources involve in ecosystem functioning and providing ecosystem services in urban areas. Little is known on the landscape structure patterns of vegetation existing in urban areas at the global scale and the drivers of these patterns. We studied the landscape structure of one hundred cities around the globe, and their relation to demography (population), socioeconomic factors (GDP, Gini Index), climate factors (temperature and rain) and topographic characteristics (altitude, variation in altitude). The data revealed that the best descriptors of landscape structure were amount, fragmentation and spatial distribution of vegetation. Populated cities tend to have less, more fragmented, less connected vegetation with a centre of the city with low vegetation cover. Results also provided insights on the influence of socioeconomics at a global scale, as landscape structure was more fragmented in areas that are economically unequal and coming from emergent economies. This study shows the effects of the social system and climate on urban landscape patterns that gives useful insights for the distribution in the provision of ecosystem services in urban areas and therefore the maintenance of human well-being. This information can support local and global policy and planning which is committing our cities to provide accessible and inclusive green space for all urban inhabitants.

Green space context and vegetation complexity shape people’s preferences for urban public parks and residential gardens

Abstract Landscape preferences shape decision-making and drive the ecological outcomes of urban landscapes. We investigate how people’s landscape preferences are shaped by the green space context (public park vs private residential garden landscapes) and by physical features such as vegetation complexity. A postal questionnaire was sent to households near seven urban parks in Melbourne, Australia. Results showed that landscapes were grouped into four categories based on patterns of preference response. Landscapes with moderate vegetation complexity were placed in separate categories distinguished by green space context (parks vs gardens), while very simple and very complex landscapes were placed in different categories irrespective of green space context. Surprisingly, dense vegetation was highly preferred by respondents. As areas of dense vegetation also provide complex habitats for wildlife, this highlights the possibility of developing policies and designing landscapes that can benefit both people and nature.

Local Assessment of Melbourne: The Biodiversity and Social-Ecological Dynamics of Melbourne, Australia

Melbourne, Australia is a city rich in biodiversity. It contains a high proportion of open space and supports a large number of flora and fauna species, both indigenous to the region and introduced from around the world. The high levels of biodiversity are partly the result of historical planning decisions that did not deliberately consider biodiversity yet inadvertently favoured many plants and animals. However, Melbourne is currently at a tipping point whereby continued urban growth is likely to result in a loss of biodiversity if it is not explicitly and carefully considered in planning, policy and management. Enhancing biodiversity into the future will be aided by a reconciliation of underlying tensions between (1) growth and conservation and (2) the management of ‘native’ and ‘exotic’ vegetation that are currently embedded in a range of governance structures and public attitudes. This would enable the implementation of urban design that promotes biodiversity across the city as a whole.

The Grass is Greener on the Other Side: Understanding the Effects of Green Spaces on Twitter User Sentiments

Green spaces are believed to improve the well-being of users in urban areas. While there are urban research exploring the emotional benefits of green spaces, these works are based on user surveys and case studies, which are typically small in scale, intrusive, time-intensive and costly. In contrast to earlier works, we utilize a non-intrusive methodology to understand green space effects at large-scale and in greater detail, via digital traces left by Twitter users. Using this methodology, we perform an empirical study on the effects of green spaces on user sentiments and emotions in Melbourne, Australia and our main findings are: (i) tweets in green spaces evoke more positive and less negative emotions, compared to those in urban areas; (ii) each season affects various emotion types differently; (iii) there are interesting changes in sentiments based on the hour, day and month that a tweet was posted; and (iv) negative sentiments are typically associated with large transport infrastructures such as train interchanges, major road junctions and railway tracks. The novelty of our study is the combination of psychological theory, alongside data collection and analysis techniques on a large-scale Twitter dataset, which overcomes the limitations of traditional methods in urban research.

Temperature variability influences urban garden plant richness and gardener water use behavior, but not planting decisions.

Urban environments are being subject to increasing temperatures due to the combined effects of global climate change and urban heat. These increased temperatures, coupled with human planting preferences and green space management practices, influence how urban plants grow and survive. Urban community gardens are an increasingly popular land use, and a green space type that is influenced by unique climate-human behavior interactions. Despite ongoing rapid temperature changes in cities, it is unknown how gardeners are adapting to these changes, and to what extent changes influence planting decisions and patterns of urban plant diversity. In this study, we monitored the variation in daily air temperatures and measured plant species richness at the garden and garden plot scale in 11 community gardens in Melbourne, Australia. We surveyed >180 gardeners to better understand the relationships between temperature variation, garden plant species diversity, and gardener management practices. We found that garden scale temperature variability is driven by regional context, and temperatures are more stable in landscapes with higher impervious surface cover. Gardeners agreed that climatic/temperature changes are influencing their watering behavior, but not their plant selection. Instead plant selection is being driven by desired food production. Yet, when comparing two bioregions, temperature did have a measurable relationship with garden plant composition in the region with more temperature variation. Temperature variability negatively related to plant species richness within garden plots, providing evidence that plant survival is related to climate at this scale in such regions. Although gardeners may be able to water more in response to regional climate changes, gardeners are unlikely to be able to completely control the effects of temperature on plant survival in more variable conditions. This suggests the inner city with more stable temperatures (albeit potentially hotter for longer due to heat island) may accommodate more species diverse gardens.