Tag Archives: green infrastructure

ecosystem value of urban soil

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Soil is a critical part of a functional ecosystem, and yet most engineers and architects who work with soil in urban areas are not trained to really understand how soil works as part of an ecosystem. Soil scientists and agricultural engineers are, but they are not working in cities for the most part. Anyway, I like the premise of this article.

Towards an operational methodology to optimize ecosystem services provided by urban soils

Urban soils need to be taken into account by city managers to tackle the major urban environmental issues. As other soils in forest or agricultural environments, urban soils provide a wide range of ecosystem services. However, their contribution remains poorly assessed up to now, and as a result there is a strong lack of consideration by urban planning of the services they provide. Indeed, urban soils are mostly seen as a land surface (land area, two-dimensional system) and if they are characterized, it is almost exclusively for their potential contamination and their geotechnical properties. So, policy makers and planning operators rarely consider soils as a living resource, capable to fulfill essential functions. From the conclusions of previous studies, a selection of ecosystem services provided by soil and adapted to the specificity of urban context is proposed. This paper also aims at proposing the concept of the DESTISOL decision support system for urban planning projects upstream of the planning decisions, illustrated by an application example. It is based on an integrative approach linking soil quality indicators (e.g. physico-chemical and biological characteristics, fertility, pollution), soil functions and soil ecosystem services. The method leads to the semi-quantitative assessment of the level of ecosystem services that are either provided by urban soils or required to fit with the urban design.

February 2018 in Review

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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:

why our institutions are failing to deliver optimal green infrastructure

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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

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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:

living near a forest is good for your amygdala

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The amygdala is a part of your brain, and what is good for it is good for you.

“Our results reveal a significant positive association between the coverage of forest and amygdala integrity,” the researchers report. The amygdala is the almond-shaped set of neurons that plays a key role in the processing of emotions, including fear and anxiety.

Perhaps surprisingly, Kuehn and her colleagues found no such association from living close to urban green spaces such as parks, or near bodies of water. Only proximity to forest land had this apparent positive effect…

The study complements the already-strong psychological evidence of the benefits of living close to nature. Previous research has linked access to green space to longer lives, lower levels of aggression, and kids’ cognitive development. One study suggests it even makes for nicer people.

BIODIVERSITY AND ECOSYSTEM SERVICES IN URBAN GREEN INFRASTRUCTURE PLANNING

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I like this article from Italy a lot because it represents a practical approach to focusing on ecosystem services in urban areas.

BIODIVERSITY AND ECOSYSTEM SERVICES IN URBAN GREEN INFRASTRUCTURE PLANNING: A CASE STUDY FROM THE METROPOLITAN AREA OF ROME (ITALY)

Target 2 of the European Biodiversity Strategy promotes the maintenance and enhancement of ecosystem services < (ES) as well as the restoration of at least 15% of degraded ecosystems by creating green infrastructure (GI). The purpose of the this research is to present a GI proposal that combines the delivery of regulating services with the restoration and ecological reconnection of urban forests and trees in a densely urbanised context.

The project area covers about 3 000 ha in the urban sector of the metropolitan area of Rome and the GI components consist of 533 ha of areal green spaces and of more than 500 km of road verges. Planned interventions include forest restoration and tree plantations, with a varying service supply according to type and condition of the different components. Potential natural vegetation (PNV) models and dispersal potential of representative forest species, together with structural and functional vegetation models for the enhancement of air pollutants removal, guided the selection of the species to be promoted and of the planting pattern. Environmental benefits of the proposal include more than 30 ha of restored urban forests, about 15 000 planted individuals of native oaks, a sevenfold improvement in ecological connectivity and halved isolation between green spaces. On the other hand, the expected socio-economic benefits include almost 300 000 potential beneficiaries of the improved air quality and avoided costs for damages to human health that range between 40 700 and 130 200 EUR per year.

Notwithstanding their preliminary character, these estimates allowed the proposal to highlight the relationship between GI and public health. Moreover, they showed the economic and social effectiveness of nature-based solutions in comparison with further development of grey infrastructure. These results promote the definition of a national GI strategy in Italy.

November 2017 in Review

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Most frightening stories:

  • I thought about war and peace in November. Well, mostly war. War is frightening. The United States of America appears to be flailing about militarily all over the world guided by no foreign policy. Big wars of the past have sometimes been started by overconfident leaders thinking they could get a quick military victory, only to find themselves bogged down in something much larger and more intractable than they imagined. But enemies are good to have – the Nazis understood that a scared population will believe what you tell them.
  • We should probably be sounding the alarm just as urgently, if not more urgently, on biodiversity as we are on global warming. But while the case against global warming is so simple most children can grasp it, the case against biodiversity loss is more difficult to articulate.
  • A theory of mass extinctions of the past is that they have been caused by massive volcanic eruptions burning off underground fossil fuels on a massive scale. Only, not quite at the rate we are doing it now. Rapid collapse of ice cliffs is another thing that might get us.

Most hopeful stories:

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

  • You can get an actuarial estimate of your life span online. You can also search your local library catalog automatically whenever you consider buying a book online. Libraries in small, medium, and large towns all over the U.S. appear to be included.
  • “Transportation as a service” may cause the collapse of the oil industry. Along similar but more mainstream lines, NACTO has released a “Blueprint for Autonomous Urbanism“, which is my most popular post at the moment I am writing this.
  • It’s possible that the kind of ideal planned economy envisioned by early Soviet economists (which never came to pass) could be realized with the computing power and algorithms just beginning to be available now.

 

disappearing bugs

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This surprising study from Germany raises the possibility that a catastrophic loss of insects is occurring and that it could lead to ecological collapse.

More than 75 percent decline over 27 years in total flying insect biomass in protected areas

Global declines in insects have sparked wide interest among scientists, politicians, and the general public. Loss of insect diversity and abundance is expected to provoke cascading effects on food webs and to jeopardize ecosystem services. Our understanding of the extent and underlying causes of this decline is based on the abundance of single species or taxonomic groups only, rather than changes in insect biomass which is more relevant for ecological functioning. Here, we used a standardized protocol to measure total insect biomass using Malaise traps, deployed over 27 years in 63 nature protection areas in Germany (96 unique location-year combinations) to infer on the status and trend of local entomofauna. Our analysis estimates a seasonal decline of 76%, and mid-summer decline of 82% in flying insect biomass over the 27 years of study. We show that this decline is apparent regardless of habitat type, while changes in weather, land use, and habitat characteristics cannot explain this overall decline. This yet unrecognized loss of insect biomass must be taken into account in evaluating declines in abundance of species depending on insects as a food source, and ecosystem functioning in the European landscape.

I knew about the frogs, elephants, tigers, bees, and loss of larger animal species and biomass in general, but I hadn’t really heard this idea that insects are disappearing. I can see a silver lining to this – I can’t really create elephant or tiger habitat around my house, and frog habitat is a little tough, but insects – I can actually help the little guys. On a larger scale, there is the question of green infrastructure – can we deliberately design habitats in cities, larger reserves, and corridors connecting them to support as much ecological function as we can? I think so, but I don’t think our public officials, engineers, urban planners, scientists, and others in a position to do this are tuned into the issue or even very open to hearing about it.

trees and public health

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A new report from the Nature Conservancy makes the case for the value of urban trees to human health. They go through a number of economic valuation studies that are out there, and the literature on health benefits: air quality, heat stress, mental and physical health, climate change. Then they make a case that urban tree canopy in the U.S. is actually declining and that it is severely under-funded in most cities.

Also, on the tree front, here is a recent paper on the rate at which wood inside urban trees decays. I think one important concept with urban trees is to think of them as infrastructure that has to be maintained and replaced at some rate. They just don’t live as long as forest trees, because they are in stressful environments, performing functions for us, and getting worn out. And the cost of maintaining and replacing them is actually low, and their benefits high, compared to other types of infrastructure. But even though the engineering, planning and architecture professions have been talking a lot about green infrastructure for at least a decade, most of us still aren’t taking it seriously as infrastructure, and the construction industry, bureaucrats and politicians are not taking it seriously, if they have even absorbed the concepts at all. I think this is a case where wealthy private foundations or individuals could make an enormous difference if they wanted to, because the institutions to plant and maintain trees typically exist, but are just severely underfunded. So all I have to do is become a wealthy private individual and I will take care of this. Okay, a solution exists and I’ll get right on that.

The overlooked carbon loss due to decayed wood in urban trees

Decayed wood is a common issue in urban trees that deteriorates tree vitality over time, yet its effect on biomass yield therefore stored carbon has been overlooked. We mapped the occurrence and calculated the extent of decayed wood in standing Ulmus procera, Platanus × acerifolia and Corymbia maculata trees. The main stem of 43 trees was measured every metre from the ground to the top by two skilled arborists. All trees were micro-drilled in two to four axes at three points along the stem (0.3 m, 1.3 m, 2.3 m), and at the tree’s live crown. A total of 300 drilling profiles were assessed for decay. Simple linear regression analysis tested the correlation of decayed wood (cm2) against a vitality index and stem DBH. Decay was more frequent and extensive in U. procera, than P. acerifolia and least in C. maculata. Decay was found to be distributed in three different ways in the three different genera. For U. procera, decay did appear to be distributed as a column from the base to the live crown; whereas, decay was distributed as a cone-shape in P. acerifolia and was less likely to be located beyond 2.3 m. In C. maculata decay was distributed as pockets of variable shape and size. The vitality index showed a weak but not significant correlation with the proportion of decayed wood for P. acerifolia and C. maculata but not for U. procera. However, in U. procera, a strong and significant relationship was found between DBH and stem volume loss (R2 = 0.8006, P = 0.0046, n = 15). The actual volume loss ranged from 0.17-0.75 m3, equivalent to 5% to 25% of the stem volume. The carbon loss due to decayed wood for all species ranged between 69 to 110 kg per tree. Based on model’s calculation, the stem volume of U. procera trees with DBH ≥ 40 cm needs to be discounted by a factor of 13% due to decayed wood regardless of the vitality index. Decayed wood reduces significantly the tree’s standing volume and needs to be considered to better assess the carbon storage potential of urban forests.