Tag Archives: urban ecology

February 2018 in Review

Most frightening stories:

  • A general rule across many types of wildlife is that their range after urbanization decreases to between one-half and one-third of what it was before urbanization.
  • The Cuban sonic attacks are real. At least, the people who experienced them have real brain damage, even if we still don’t know what technology did the damage.
  • Cape Town will probably not be the last major city to run out of water.

Most hopeful stories:

Most interesting stories, that were not particularly frightening or hopeful, or perhaps were a mixture of both:

agent-based wildlife modeling in cities

This is an agent-based model of wild boars coming from wild lands into a city. We don’t have wild boar issues where I live, but raccoons and deer occasionally show up. I’ve lived places where black bears show up unexpectedly in urban areas, and that can cause a stir.

Pigs in space: An agent-based model of wild boar (Sus scrofa) movement into cities

Last decades saw a dramatic increase in wildlife populations within urban areas. Policymakers seek to minimize human-wildlife conflicts resulting from overabundance of species, such as wild boars (Sus scrofa). To this end, there is a need to understand the drivers governing infiltration of wildlife into cities. In this paper we study the availability and distribution of food resources in urban areas as driver of wild boar movement patterns. Based on the optimal foraging theory, we utilize an agent-based simulation model to investigate the ever-growing infiltration of wild boars into some cities. We apply the model to an artificial city that mimics the landscape of the city of Haifa. Manipulating food availability and relative resistance costs of different land-covers we demonstrate that infiltration of boars depends on population size of wild boars and on the amount and spatial distribution of attractors (e.g., food). Model outputs for likely sets of parameters demonstrate good correspondence to the reports of boar observations within the city of Haifa, Israel, where the porosity of the urban fabric and the connectivity of open space patches provide a trail network that makes food throughout the city accessible at a relatively low search-cost. Our results indicate that land cover and food patterns determine critically boars’ foraging movement and infiltration into the city. The proposed modeling framework provides a tool to investigate wildlife management policies that aim at reducing people-wildlife conflicts in cities.

mapping urban vegetation on a fine scale

This is an interesting paper about mapping urban vegetation on a fine scale based on photos.

Mapping vegetation functional types in urban areas with WorldView-2 imagery: Integrating object-based classification with phenology

Mapping urban vegetation is a prerequisite to accurately understanding landscape patterns and ecological services provided by urban vegetation. However, the uncertainties in fine-scale vegetation biodiversity mapping still exist in capturing vegetation functional types efficiently at fine scale. To facilitate the application of fine-scale vegetation spatial configuration used for urban landscape planning and ecosystem service valuation, we present an approach integrating object-based classification with vegetation phenology for fine-scale vegetation functional type mapping in compact city of Beijing, China. The phenological information derived from two WorldView-2 imagery scenes, acquired on 14 September 2012 and 26 November 2012, was used to aid in the classification of tree functional types and grass. Then we further compared the approach to that of using only one WorldView imagery. We found WorldView-2 imagery can be successfully applied to map functional types of urban vegetation with its high spatial resolution and relatively high spectral resolution. The application of the vegetation phenology into classification greatly improved the overall accuracy of classification from 82.3% to 91.1%. In particular, the accuracies of vegetation types was improved by from 10% to 13.26%. The approach integrating vegetation phenology with high-resolution remote sensed images provides an efficient tool to incorporate multi-temporal data into fine-scale urban classification.

habitat complexity doesn’t affect biodiversity?

There’s theory, and then there is collecting actual evidence to support a theory, which tends to be messy. In this case, the theory is that more complex habitats should support more diversity. They didn’t at least in this study of insects and spiders in Sydney.

Habitat complexity does not affect arthropod community composition in roadside greenspaces

Urban greenspaces including remnant patches of vegetation, backyard gardens and public parks provide important habitat for wildlife conservation. Maintaining and enhancing the conservation value of these spaces requires both an understanding of the biodiversity they support, and the factors, including habitat traits, influencing species occurrence. Roadside greenspaces, including road verges and median strips are often overlooked in current greenspace biodiversity studies. We quantified arthropod community assemblages in roadside and public park greenspaces, and determined if habitat complexity was an important trait influencing species composition in these areas. Using pitfall traps, we sampled ground dwelling arthropods along five major roads in the greater Sydney Region and in public parks. Whilst roadside greenspaces (road verges and median strips) and public parks supported significantly different arthropod assemblages, habitat complexity had no impact on community assemblage and neither factor affected the assemblage of key arthropods taxa including ants, beetles and spiders. Additionally, in public parks but not road side greenspaces we found an effect of habitat complexity on arthropod abundance; arthropods were more abundant in high complexity park sites. Our results highlight the unique arthropod community assemblage supported by roadside greenspaces, and suggest management practices like increasing habitat complexity may be important in some but not all urban greenspace types.

why our institutions are failing to deliver optimal green infrastructure

I think this article explains well why real green infrastructure is hard to achieve. Multiple goverhment agencies are responsible for bits and pieces of it, and even if they are acting efficiently within each of their limited missions, they are not coordinating to achieve goals efficiently as a whole. I see this plenty in my professional life dealing with water, parks and transportation agencies.

Lost in Transactions: Analysing the Institutional Arrangements Underpinning Urban Green Infrastructure

Urban development has altered surface-water hydrology of landscapes and created urban heat island effects. With climate change, increasing frequency of extreme heat events and in some areas, episodic drought and flooding, present new challenges for urban areas. Green infrastructure holds potential as a cost-effective means of providing microclimate cooling and stormwater diversion. Further, green open spaces when combined with the provision of equipment and facilities have the potential to promote physical and emotional well-being. However successful implementation may be predicated on co-ordinated efforts of multiple agencies. The Institutional Analysis and Development framework developed by Crawford and Ostrom is used in a case study to understand the institutional impediments, transaction costs and gaps in responsibility associated with the delivery of green infrastructure. Lessons learned are potentially transferable to other urban settings. Our analysis reveals areas of high transaction costs as well as a gap in the polycentric decision-making of agencies. The local government council is concerned with the well-being of its residents but has limited financial capacity. None of the agencies who deliver green infrastructure have responsibility for facilitating the indirect or preventative health benefits. Thus, a co-ordination problem among agencies can lead to suboptimal investments in green infrastructure.

 

January 2018 in Review

Most frightening stories:

  • Larry Summers says we have a better than even chance of recession in the next three years. Sounds bad, but I wonder what that stat would look like for any randomly chosen three year period in modern history.
  • The United States is involved in at least seven wars: Afghanistan, Iraq, Syria, Yemen, Libya, Somalia, and Pakistan. Nuclear deterrence may not actually the work.
  • Cape Town, South Africa is in imminent danger of running out of water. Longer term, there are serious concerns about snowpack-dependent water supplies serving large urban populations in Asia and western North America.

Most hopeful stories:

Most interesting stories, that were not particularly frightening or hopeful, or perhaps were a mixture of both:

quantifying ecological functions

Here is an interesting article on quantifying ecological functions. The main application appears to be wetland mitigation but the theory seems more general and could maybe be adapted to a variety of ecosystem restorations or creations.

Landscape consequences of aggregation rules for functional equivalence in compensatory mitigation programs

Mitigation and offset programs designed to compensate for ecosystem function losses due to development must balance losses from affected ecosystems and gains in restored ecosystems. Aggregation rules applied to ecosystem functions to assess site equivalence are based on implicit assumptions about the substitutability of functions among sites and can profoundly influence the distribution of restored ecosystem functions on the landscape. We investigated the consequences of rules applied to aggregation of ecosystem functions for wetland offsets in the Beaverhill watershed in Alberta, Canada. We considered the fate of 3 ecosystem functions: hydrology, water purification, and biodiversity. We set up an affect-and-offset algorithm to simulate the effect of aggregation rules on ecosystem function for wetland offsets. Cobenefits and trade-offs among functions and the constraints posed by the quantity and quality of restorable sites resulted in a redistribution of functions between affected and offset wetlands. Hydrology and water-purification functions were positively correlated and negatively correlated with biodiversity function. Weighted-average rules did not replace functions in proportion to their weights. Rules prioritizing biodiversity function led to more monofunctional wetlands and landscapes. The minimum rule, for which the wetland score was equal to the worst performing function, promoted multifunctional wetlands and landscapes. The maximum rule, for which the wetland score was equal to the best performing function, promoted monofunctional wetlands and multifunctional landscapes. Because of implicit trade-offs among ecosystem functions, no-net-loss objectives for multiple functions should be constructed within a landscape context. Based on our results, we suggest criteria for the design of aggregation rules for no net loss of ecosystem functions within a landscape context include the concepts of substitutability, cobenefits and trade-offs, landscape constraints, heterogeneity, and the precautionary principle.

more on movement ecology

I’m still digging into movement ecology, which has always fascinated me. Here is a comprehensive recent literature review on the subject.

Trends and missing parts in the study of movement ecology

Movement is important to all organisms, and accordingly it is addressed in a huge number of papers in the literature. Of nearly 26,000 papers referring to movement, an estimated 34% focused on movement by measuring it or testing hypotheses about it. This enormous amount of information is difficult to review and highlights the need to assess the collective completeness of movement studies and identify gaps. We surveyed 1,000 randomly selected papers from 496 journals and compared the facets of movement studied with a suggested framework for movement ecology, consisting of internal state (motivation, physiology), motion and navigation capacities, and external factors (both the physical environment and living organisms), and links among these components. Most studies simply measured and described the movement of organisms without reference to ecological or internal factors, and the most frequently studied part of the framework was the link between external factors and motion capacity. Few studies looked at the effects on movement of navigation capacity, or internal state, and those were mainly from vertebrates. For invertebrates and plants most studies were at the population level, whereas more vertebrate studies were conducted at the individual level. Consideration of only population-level averages promulgates neglect of between-individual variation in movement, potentially hindering the study of factors controlling movement. Terminology was found to be inconsistent among taxa and subdisciplines. The gaps identified in coverage of movement studies highlight research areas that should be addressed to fully understand the ecology of movement.

An idea that has always fascinated me is the idea that when designing a development or an even an entire urban area, you could actually lead with ecology, then layer hydrology, infrastructure, housing, and the other human elements on top of that. Sadly, I don’t think I know a single engineer or urban planner who would be particularly open minded to this idea.

models for movement and population ecology

This page has links to some academic/professional models of movement ecology and population ecology, such as predator-prey interactions. It’s something that interests me because with an accurate theory of how animals and plants function and interact in ecosystems over time, it should in principle be possible to design networks of urban, industrial, and agricultural areas that maximize ecological function.

Developing this knowledge would be step one. Of course, there would still be the small matter of our civilization deciding this is something it would like to do.

wildlife range in urban areas

Here’s an interesting study finding a general rule across many types of wildlife that their range after urbanization decreases to between one-half and one-third of what it was before urbanization.

Moving in the Anthropocene: Global reductions in terrestrial mammalian movements

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission.

One type of animal included in the study was deer in Pennsylvania. I also learned the name of the academic discipline that studies animal ranges and movements: movement ecology.