Cynnamon Dobbs

A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers.

Urbanization contributes to the loss of the worlds biodiversity and the homogenization of its biota. However, comparative studies of urban biodiversity leading to robust generalities of the status and drivers of biodiversity in cities at the global scale are lacking. Here, we compiled the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). We found that the majority of urban bird and plant species are native in the worlds cities. Few plants and birds are cosmopolitan, the most common being Columba livia and Poa annua. The density of bird and plant species (the number of species per km2) has declined substantially: only 8% of native bird and 25% of native plant species are currently present compared with estimates of non-urban density of species. The current density of species in cities and the loss in density of species was best explained by anthropogenic features (landcover, city age) rather than by non-anthropogenic factors (geography, climate, topography). As urbanization continues to expand, efforts directed towards the conservation of intact vegetation within urban landscapes could support higher concentrations of both bird and plant species. Despite declines in the density of species, cities still retain endemic native species, thus providing opportunities for regional and global biodiversity conservation, restoration and education.

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.

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.

Above ground biomass and leaf area models based on a non destructive method for urban trees of two communes in Central Chile

La biomasa es considerada un importante indicador de los procesos ecologicos y de manejo que ocurren en la vegetacion urbana. Es dificil de medir pero facil de interpretar, pues refleja las condiciones del sitio y de los recursos edaficos, hidricos y de radiacion solar disponibles en el. En las ciudades, las practicas de manejo sobre los arboles afectan la distribucion de la biomasa en su interior y es necesario usar ecuaciones calibradas localmente para poder evaluar cada componente. Sin embargo, los metodos destructivos tradicionales, que se usan para recopilar los datos necesarios en la construccion de tales modelos, son poco aplicables en ambientes urbanos. En este estudio se utilizo el muestreo aleatorio de ramas (RBS), un metodo probabilistico no destructivo, y variables dendrometricas de facil medicion como DAP y altura total para estimar la biomasa aerea y el area foliar de arboles urbanos mas comunes en Santiago, Chile. Los resultados del estudio arrojaron estimaciones de biomasa aerea comparables, y dentro del rango de valores, a los reportados en la literatura internacional, para bosques y arboles urbanos. Las estimaciones para area foliar arrojaron valores mas razonables en comparacion con los datos de campo y referencias internacionales. Estas ecuaciones pueden ser incorporadas en los modelos forestales urbanos incluyendo estimaciones mas precisas y ajustadas a la realidad de America Latina. Aumentando la intensidad de muestreo de metodo RBS se podria usar como un metodo no-destructivo, replicable, para estimar diferentes tipos de caracteristicas en arboles urbanos.

Inequality in access to cultural ecosystem services from protected areas in the Chilean biodiversity hotspot

Experiences with nature through visits to protected areas provide important cultural ecosystem services that have the potential to strengthen pro-environmental attitudes and behavior. Understanding accessibility to protected areas and likely preferences for enjoying the benefits of nature visits are key factors in identifying ways to reduce inequality in access and inform the planning and management for future protected areas. We develop, at a regional scale, a novel social media database of visits to public protected areas in part of the Chilean biodiversity hotspot using geotagged photographs and assess the inequality of access using the home locations of the visitors and socio-economic data. We find that 20% of the population of the region make 87% of the visits to protected areas. The larger, more biodiverse protected areas were the most visited and provided most cultural ecosystem services. Wealthier people tend to travel further to visit protected areas while people with lower incomes tend to visit protected areas that are closer to home. By providing information on the current spatial flows of people to protected areas, we demonstrate the need to expand the protected area network, especially in lower income areas, to reduce inequality in access to the benefits from cultural ecosystem services provided by nature to people.

Urban ecosystem Services in Latin America: mismatch between global concepts and regional realities?

Latin America and the Caribbean (LAC) is one of the most urbanized and biologically diverse regions in the world but is often characterized by weak environmental governance and socioeconomic inequalities. Given large expanses of intact biomes, a long history of pre-Colombian civilizations, and recent urbanization trends, the urban ecosystem services (UES) concept has the potential to address issues of well-being for its citizens. We review relevant regional and global literature and use expert-based knowledge to identify the state of the art of the UES concept as applicable to green spaces in LAC and elucidate three overarching guidelines for management and future research needs: 1. LAC cities can be socio-ecologically unique; 2. Drivers of UES in LAC can be different than in other regions; and 3. Context and demand need to be accounted for when valuing UES. Overall, we show that research on UES is mostly from the global north and rarely accounts for the diverse and complex socio-political and ecological drivers of LAC’s urbanization processes. We find that, as in other regions, the biophysical context and land use policies play a major role on UES provision. However, socioeconomic inequalities and weak governance are key drivers in UES supply and demand in LAC. Context-specific information on how to promote, educate, and apply UES is particularly important, not only in LAC, but in other regions where inequities, rapid urbanization, and climate change effects are stressing socio-political and ecological systems and their adaptive capacities. Standardized approaches from developed countries should be used to complement - not substitute – LAC context specific approaches for studying and applying UES. We suggest that improved research funding and local governance can also provide critical strategies, information and the means for more effective management, planning, and equitable provision of UES.