Response of a cryptic apex predator to a complete urban to forest gradient

2013 ◽  
Vol 40 (5) ◽  
pp. 427 ◽  
Author(s):  
Bronwyn Isaac ◽  
John White ◽  
Daniel Ierodiaconou ◽  
Raylene Cooke
Keyword(s):  
Urban Forest ◽  
Gradient Methods ◽  
Urban Systems ◽  
Tree Cover ◽  
Habitat Availability ◽  
Apex Predator ◽  
Apex Predators ◽  
High Resource ◽  
Independent Field ◽  
Normalised Difference Vegetation Index

Context Urbanisation is one of the most damaging landscape-scale disturbance processes leading to significant and potentially irreversible changes in biodiversity. How apex predators respond to urbanisation is poorly understood, largely because of their low density and low detectability. Given the important functional roles of apex predators in ecosystems, it is critical that research investigates how they respond to urbanisation, and how urban systems can be designed to better support apex predators. Aims The present research aims to examine how an avian apex predator, the powerful owl, responds to a complete urban–forest gradient in southern Victoria, Australia. Specifically, the research aims to understand the environmental attributes that drive habitat suitability for powerful owls across the urban–forest gradient. Methods Using a total of 683 independent field- and atlas-derived records of powerful owls across the study site, the research takes a presence-only modelling approach. The presence points were modelled against a series of geospatial variables that were determined a priori on the basis of the known ecology of powerful owls. Key results Potential powerful owl habitat declined in a dramatic fashion in response to increasing levels of urbanisation, ranging from 76% of the forest landscape to 21% of the urban landscape. Powerful owl habitat availability across the urban–forest gradient is positively influenced by tree cover, productivity (normalised difference vegetation index) and proximity to river systems and riparian vegetation. Conclusions Presence-only modelling has provided a useful way for investigating the response of an apex predator to a gradient of urbanisation. Although powerful owl habitat availability is negatively reduced by urbanisation, there is significant scope to manage urban landscapes to either maintain or improve the availability of habitat across the gradient. Implications High resource-requiring species, such as apex predators, have the capacity to be detrimentally affected by urbanisation processes. Presence-only modelling, however, provides a useful tool for investigating how these difficult-to-detect species are affected by urbanisation, and ultimately inform how landscapes can be managed to maximise habitat availability for apex predators.

scholarly journals Quantifying Tree Cover Loss in Urban Forests within Nairobi City Metropolitan Area from Earth Observation Data

2020 ◽  
Vol 3 (1) ◽  
pp. 78
Author(s):  
Francis Oloo ◽  
Godwin Murithi ◽  
Charlynne Jepkosgei
Keyword(s):  
Land Cover ◽  
Metropolitan Area ◽  
Land Surface ◽  
Urban Forest ◽  
Urban Forests ◽  
Earth Observation ◽  
Tree Cover ◽  
Observation Data ◽  
Vegetation Health ◽  
Earth Observation Data

Urban forests contribute significantly to the ecological integrity of urban areas and the quality of life of urban dwellers through air quality control, energy conservation, improving urban hydrology, and regulation of land surface temperatures (LST). However, urban forests are under threat due to human activities, natural calamities, and bioinvasion continually decimating forest cover. Few studies have used fine-scaled Earth observation data to understand the dynamics of tree cover loss in urban forests and the sustainability of such forests in the face of increasing urban population. The aim of this work was to quantify the spatial and temporal changes in urban forest characteristics and to assess the potential drivers of such changes. We used data on tree cover, normalized difference vegetation index (NDVI), and land cover change to quantify tree cover loss and changes in vegetation health in urban forests within the Nairobi metropolitan area in Kenya. We also used land cover data to visualize the potential link between tree cover loss and changes in land use characteristics. From approximately 6600 hectares (ha) of forest land, 720 ha have been lost between 2000 and 2019, representing about 11% loss in 20 years. In six of the urban forests, the trend of loss was positive, indicating a continuing disturbance of urban forests around Nairobi. Conversely, there was a negative trend in the annual mean NDVI values for each of the forests, indicating a potential deterioration of the vegetation health in the forests. A preliminary, visual inspection of high-resolution imagery in sample areas of tree cover loss showed that the main drivers of loss are the conversion of forest lands to residential areas and farmlands, implementation of big infrastructure projects that pass through the forests, and extraction of timber and other resources to support urban developments. The outcome of this study reveals the value of Earth observation data in monitoring urban forest resources.

Urban Trees and Water Use in Arid Climates: Insights from an Integrated Bioeconomic-Health Model

2018 ◽  
Vol 04 (04) ◽  
pp. 1850022 ◽  
Author(s):  
Benjamin A. Jones ◽  
John Fleck
Keyword(s):  
Ecosystem Services ◽  
Water Use ◽  
Forest Canopy ◽  
Urban Forest ◽  
Economic Value ◽  
Urban Trees ◽  
Tree Cover ◽  
Arid Environments ◽  
Value Of Water ◽  
Health Model

Managing outdoor water use while maintaining urban tree cover is a key challenge for water managers in arid climates. Urban trees generate flows of ecosystem services in arid areas, but also require significant amounts of irrigation. In this paper, a bioeconomic-health model of trees and water use is developed to investigate management of an urban forest canopy when irrigation is costly, water has economic value, and trees provide ecosystem services. The optimal tree irrigation decision is illustrated for Albuquerque, New Mexico, an arid Southwest US city. Using a range of monetary values for water, we find that the tree irrigation decision is sensitive to the value selected. Urban deforestation is optimal when the value of water is sufficiently high, or alternatively starts low, but grows to cross a specific threshold. If, however, the value of water is sufficiently low or if the value of tree cover rises over time, then deforestation is not optimal. The threshold value of water where the switch is made between zero and partial deforestation is well within previously identified ranges on actual water values. This model can be applied generally to study the tradeoffs between urban trees and water use in arid environments.

scholarly journals Reintroduced wolves and hunting limit the abundance of a subordinate apex predator in a multi-use landscape

2020 ◽  
Vol 287 (1938) ◽  
pp. 20202202
Author(s):  
L. Mark Elbroch ◽  
Jake M. Ferguson ◽  
Howard Quigley ◽  
Derek Craighead ◽  
Daniel J. Thompson ◽  
...  
Keyword(s):  
Population Model ◽  
Human Impacts ◽  
Adult Survival ◽  
Apex Predator ◽  
Vital Rates ◽  
Grey Wolf ◽  
Apex Predators ◽  
Negative Effects ◽  
Top Down ◽  
Species Abundances

Top-down effects of apex predators are modulated by human impacts on community composition and species abundances. Consequently, research supporting top-down effects of apex predators occurs almost entirely within protected areas rather than the multi-use landscapes dominating modern ecosystems. Here, we developed an integrated population model to disentangle the concurrent contributions of a reintroduced apex predator, the grey wolf, human hunting and prey abundances on vital rates and abundance of a subordinate apex predator, the puma. Increasing wolf numbers had strong negative effects on puma fecundity, and subadult and adult survival. Puma survival was also influenced by density dependence. Overall, puma dynamics in our multi-use landscape were more strongly influenced by top-down forces exhibited by a reintroduced apex predator, than by human hunting or bottom-up forces (prey abundance) subsidized by humans. Quantitatively, the average annual impact of human hunting on equilibrium puma abundance was equivalent to the effects of 20 wolves. Historically, wolves may have limited pumas across North America and dictated puma scarcity in systems lacking sufficient refugia to mitigate the effects of competition.

Socioeconomic Factors and Urban Tree Cover Policies in a Subtropical Urban Forest

2012 ◽  
Vol 49 (3) ◽  
pp. 428-449 ◽  
Author(s):  
Zoltan Szantoi ◽  
Francisco Escobedo ◽  
John Wagner ◽  
Joysee M. Rodriguez ◽  
Scot Smith
Keyword(s):  
Socioeconomic Factors ◽  
Urban Forest ◽  
Tree Cover ◽  
Urban Tree ◽  
Urban Tree Cover

scholarly journals Tree Species Diversity and Socioeconomic Perspectives of the Urban (Food) Forest of Accra, Ghana

2018 ◽  
Vol 10 (10) ◽  
pp. 3417 ◽  
Author(s):  
Bertrand Nero ◽  
Nana Kwapong ◽  
Raymond Jatta ◽  
Oluwole Fatunbi
Keyword(s):  
Land Use ◽  
Tree Species ◽  
Forest Cover ◽  
Food System ◽  
Food Policy ◽  
Urban Forest ◽  
Urban Forestry ◽  
Tree Cover ◽  
Land Use Types ◽  
The City

Urban and peri-urban forestry has emerged as a complementary measure to contribute towards eliminating urban hunger and improved nutritional security. However, there is scanty knowledge about the composition, diversity, and socioeconomic contributions of urban food trees in African cities. This paper examines the diversity and composition of the urban forest and food trees of Accra and sheds light on perceptions of urbanites regarding food tree cultivation and availability in the city. Using a mixed methods approach, 105 respondents in six neighborhoods of Accra were interviewed while over 200 plots (100-m2 each) were surveyed across five land use types. Twenty-two out of the 70 woody species in Accra have edible parts (leaves, fruits, flowers, etc.). The food-tree abundance in the city is about half of the total number of trees enumerated. The species richness and abundance of the food trees and all trees in the city were significantly different among land use types (p < 0.0001) and neighborhood types (p < 0.0001). The diversity of food-bearing tree species was much higher in the poorer neighborhoods than in the wealthier neighborhoods. Respondents in wealthier neighborhoods indicated that tree and food-tree cover of the city was generally low and showed greater interest in cultivating food (fruit) trees and expanding urban forest cover than poorer neighborhoods. These findings demonstrate the need for urban food policy reforms that integrate urban-grown tree foods in the urban food system/culture.

scholarly journals Mesopredators change temporal activity in response to a recolonizing apex predator

2019 ◽  
Vol 30 (5) ◽  
pp. 1324-1335 ◽  
Author(s):  
Carolyn R Shores ◽  
Justin A Dellinger ◽  
Eric S Newkirk ◽  
Shannon M Kachel ◽  
Aaron J Wirsing
Keyword(s):  
Activity Patterns ◽  
Niche Overlap ◽  
Lynx Rufus ◽  
Gray Wolf ◽  
Apex Predator ◽  
Apex Predators ◽  
Anthropogenic Landscapes ◽  
Mediated Effects ◽  
Top Predators ◽  
Temporal Overlap

Abstract Apex predators can influence ecosystems through density and behaviorally mediated effects on herbivores and mesopredators. In many parts of the world, apex predators live in, or are returning to, landscapes that have been modified by people; so, it is important to understand their ecological role in anthropogenic landscapes. We used motion-activated game cameras to compare the activity patterns of humans and 2 mesopredators, coyotes (Canis latrans) and bobcats (Lynx rufus), in areas with and without an apex predator, the gray wolf (Canis lupus), in a multiuse landscape of the northwestern United States. In areas with wolves, there was a significant increase in temporal niche overlap between the mesopredators owing to higher levels of coyote activity at all time periods of the day. Temporal overlap between mesopredators and humans also increased significantly in the presence of wolves. Coyotes exposed to wolves increased their activity during dawn, day, and dusk hours. The increase in coyote activity was greatest during the day, when wolves were least active. The direction of change in bobcat activity in areas with wolves was opposite to coyotes, suggesting a behaviorally mediated cascade between wolves, coyotes, and bobcats, although these findings would need to be confirmed with further research. Our findings suggest that mesopredators in human-dominated systems may perceive humans as less dangerous than apex predators, that humans may be more likely to encounter mesopredators in areas occupied by top predators, and that behaviorally mediated effects of apex predators on mesopredators persist in human-dominated landscapes.

scholarly journals Tree Cover for the Year 2010 of the Metropolitan Region of São Paulo, Brazil

Data ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 145
Author(s):  
Fabien H. Wagner ◽  
Mayumi C.M. Hirye
Keyword(s):  
Ecosystem Services ◽  
Spatial Resolution ◽  
Urban Forest ◽  
Sao Paulo ◽  
Urban Trees ◽  
Aerial Photographs ◽  
Metropolitan Region ◽  
Tree Cover ◽  
São Paulo ◽  
The World

Mapping urban trees with images at a very high spatial resolution (≤1 m) is a particularly relevant recent challenge due to the need to assess the ecosystem services they provide. However, due to the effort needed to produce these maps from tree censuses or with remote sensing data, few cities in the world have a complete tree cover map. Here, we present the tree cover data at 1-m spatial resolution of the Metropolitan Region of São Paulo, Brazil, the fourth largest urban agglomeration in the world. This dataset, based on 71 orthorectified RGB aerial photographs taken in 2010 at 1-m spatial resolution, was produced using a deep learning method for image segmentation called U-net. The model was trained with 1286 images of size 64 × 64 pixels at 1-m spatial resolution, containing one or more trees or only background, and their labelled masks. The validation was based on 322 images of the same size not used in the training and their labelled masks. The map produced by the U-net algorithm showed an excellent level of accuracy, with an overall accuracy of 96.4% and an F1-score of 0.941 (precision = 0.945 and recall = 0.937). This dataset is a valuable input for the estimation of urban forest ecosystem services, and more broadly for urban studies or urban ecological modelling of the São Paulo Metropolitan Region.

scholarly journals Mean and variance of greenness and pregnancy outcomes in Tel Aviv during 2000–14: longitudinal and cross-sectional approaches

2018 ◽  
Vol 48 (4) ◽  
pp. 1054-1072 ◽  
Author(s):  
Keren Agay-Shay ◽  
Yaron Michael ◽  
Xavier Basagaña ◽  
Èrica Martínez-Solanas ◽  
David Broday ◽  
...  
Keyword(s):  
Pregnancy Outcomes ◽  
Maternal Education ◽  
Vegetation Index ◽  
Low Birthweight ◽  
Tree Cover ◽  
Natural Environments ◽  
Limited Information ◽  
Cross Sectional ◽  
Tel Aviv ◽  
Normalised Difference Vegetation Index

Abstract Background Natural environments may have beneficial impacts on pregnancy outcomes. However, longitudinal evidence is limited and the associations with variance in surrounding greenness is unknown. Our objective was to evaluate these associations among 73 221 live births in Tel Aviv, Israel. Methods Longitudinal exposure to mean of greenness during pregnancy and trimesters were calculated using satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) Normalised Difference Vegetation Index (NDVI) data. In addition, exposure to mean and variation of NDVI from high-resolution satellite and percentage of tree cover [Vegetation Continuous Fields (VCF)] at 300-m buffer were evaluated in a cross-sectional approach. Generalized linear models were used to estimate the crude and adjusted associations. We explore the possible mediating role of ambient exposures and distance to ‘outdoor gyms’ located in parks. Results Crude beneficial associations between exposure to higher mean NDVI during pregnancy and pregnancy outcomes were observed [for birthweight, 3rd/1st tertile exposure increased the mean by 25.5 g, 95% confidence intervals (CIs): 15.4, 35.5] and decreased the odds of low birthweight, small for gestational age, preterm deliveries (PTD) and very PTD. Adjustment for individual and neighbourhood-level markers of socio-economic status (SES) attenuated all the associations. Strongest associations were observed during the first and second trimesters. Cross-sectional associations for mean greenness were similar with narrower CIs, and associations with NDVI were stronger than with tree cover and stronger for mean compared with variance of greenness. Associations were consistent for term births, different buffer sizes and for further adjustment to maternal education. Stronger associations were observed for lowest SES. Distance to ‘outdoor gyms’ and variance of greenness had the largest estimates of mediation. Conclusion This study adds to the limited information on when exposure to greenness is most beneficial, on the association with variance of greenness and the possible pathways. These observations require confirmation in other populations.

scholarly journals Spatiotemporal patterns of wolf, mesocarnivores and prey in a Mediterranean area

2021 ◽  
Vol 75 (2) ◽  
Author(s):  
Mariana Rossa ◽  
Sandro Lovari ◽  
Francesco Ferretti
Keyword(s):  
Wild Boar ◽  
Red Fox ◽  
Roe Deer ◽  
Fallow Deer ◽  
Apex Predator ◽  
Wild Ungulates ◽  
Apex Predators ◽  
Predator Prey ◽  
Behavioural Interactions ◽  
Temporal Overlap

Abstract Spatial and temporal occurrence can mediate behavioural interactions between apex predators, mesocarnivores and herbivores. Predators should adapt their activity to that of prey, whereas predator avoidance would be expected to influence activity patterns and space use of prey and smaller competitors. We evaluated interspecific spatiotemporal relationships in a prey-rich community including an apex predator (the wolf), three wild ungulates and several smaller herbivores/mesocarnivores, through camera trapping. All considered species (i.e. wolves and potential prey/smaller competitors: wild boar, fallow deer, roe deer, crested porcupine, red fox and European badger) were active especially at night and/or twilight. Among wild ungulates, the wolf showed the greatest temporal overlap with the wild boar and the lowest one with the least abundant and used of them, i.e. the roe deer. The main prey (i.e. the fallow deer) showed more diurnal activity and a lower temporal overlap with the predator in sites with high wolf activity than in low-activity ones. Among mesocarnivores, the red fox showed extensive temporal overlap with the wolf: the overlap between the two canids was greater in sites intensively used by this apex predator than in sites with low wolf activity, supporting a concurrent study which suggested a potential for facilitative—rather than competitive—interactions. Spatiotemporal relationships suggest complex interactions between the apex predator, prey and smaller carnivores, for which a substantial temporal or spatial association was often supported. Significance statement There is a growing interest in the influence of apex predators on ecosystems through their effects on the behaviour of prey and smaller carnivores, especially in the light of the ongoing recovery of large carnivores in temperate areas. Predators should synchronise their activity to that of prey; conversely, prey and smaller carnivores would be expected to avoid predators. In a rich community including the wolf, three wild ungulates and several mesomammals, we detected (i) a substantial temporal overlap between wolves and wild boar, porcupines and mesocarnivores; (ii) a negative temporal association between the predator and its main prey (i.e. the fallow deer) and (iii) a great temporal overlap between the wolf and the red fox. We provide a baseline to evaluate temporal changes of predator-prey-mesocarnivore behavioural interactions along with variations of carnivore-prey densities.

scholarly journals ANALYSIS OF URBAN FOREST CARBON SEQUESTRATION CAPACITY: A CASE STUDY OF ZENGDU, SUIZHOU

2017 ◽  
Vol XLII-2/W7 ◽  
pp. 1423-1426
Author(s):  
X. Yu ◽  
H. Wang ◽  
W. Cai ◽  
Y. Han
Keyword(s):  
Carbon Sequestration ◽  
Forest Ecosystem ◽  
Urban Forest ◽  
Management Strategies ◽  
Tree Cover ◽  
Forest Land ◽  
Carbon Sequestration Potential ◽  
Sequestration Potential ◽  
Forest Carbon Sequestration ◽  
Major Factors

Carbon-fixing and oxygen-releasing is an important content of forest ecosystem serving in city. Analysis of forest ecosystem carbon sequestration capacity can provide scientific reference for urban forest management strategies. Taking Zengdu of Suizhou as an example, CITYGREEN model was applied to calculate the carbon sequestration benefits of urban forest ecosystem in this paper. And the carbon sequestration potential of urban forest ecosystem following the returning of farmland to forest land is also evaluated. The results show that forest area, percent tree cover, and the structure of forest land were the major factors reflecting regional carbon sequestration capacity.

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