Green Roofs for Endangered Birdlife in Boston, MA

Juliana Dolin – Pre-veterinary, Zachary Miller – Building Construction Technology, Sean Braley – Building Construction Technology

There’s no place like home, right? Imagine the comfort of your home, relaxing in a familiar territory, surrounded by family and friends. Now imagine that disappearing. Where would you go? What would you do?

This is the harsh reality for many animals as natural lands come down and concrete buildings go up. As urban expansion continues, open spaces diminish and with this several plant and animal species dwindle as well. According to the National Wildlife Federation, Smart Growth America and NatureServe (2005), over the next 25 years at least 22,000 acres of natural habitat and almost 1,200 species of both plants and animals will be lost due to metropolitan development (“Groups: Urban Sprawl”). The government lists 1,264 species to be endangered or threatened by extinction in the United States (“Groups: Urban Sprawl”, 2005). Over 300 of these species are in Massachusetts (“Massachusetts List”, 2014).

Special Concern Species and Lack of Habitat

In Massachusetts, several native non-predatory bird species are under “special concern” due to a decline in numbers caused by a lack of habitat requirements (“Massachusetts List”, 2014). A specie under “special concern” is defined as:

[N]ative species which have been documented… to have suffered a decline that could threaten the species if allowed to continue unchecked, or which occur in such small numbers or with such restricted distribution or specialized habitat requirements that they could easily become threatened within Massachusetts. (“Massachusetts List”, 2014)

The Common Moorhen is an example of a special concern bird directly affected by urban expansion. Mass.gov states the greatest threat to the specie: habitat loss. Massachusetts is an important home for the Common Moorhen. The bird has been found to breed and spend winters in our state. Moorhens depend on water sources, while also feeding on various vegetation (“Common Moorhen”, “Management Recommendations”, 2014). If a home was established for them within the city of Boston, the nearby Boston Harbor would suit the Moorhen’s water requirements, as the harbor holds fresh water from tributary rivers (MWRA, “About Boston Harbor).

The Blackpoll Warbler, another native Massachusetts bird, is also found on the list of special concern. Although they are migratory birds and fly South for the winter, Blackpoll Warblers breed in our state. However, these birds prefer to breed in small, young trees and are currently limited to 2 breeding grounds in the state (“Blackpoll Warbler”, “Populations Status”, 2014). The lack of available breeding grounds has limited their success in Massachusetts and has caused a decrease in Blackpoll Warbler numbers (“Blackpoll Warbler”, “Management Recommendations”, 2014). Another specie of Warbler, Mourning Warblers have suffered a 2.7% annual decline rate since 1980. Mass.gov states the cause to be a permanent loss of habitat to development (“Mourning Warbler”, “Population Status”, 2014). Like Blackpoll Warblers, Mourning Warblers depend on young tree, as well as raspberries.

The main cause for the decreasing numbers of these species is clear: urban development. As urban development increases, habitat availability decreases. Theobald, Miller and Hobbs state, “[n]ative vegetation is often removed during construction of buildings and roads and as a result of landscaping activities” (p. 26, 1997). This destruction of habitat indirectly affects the surrounding wildlife. The authors explain the importance of maintaining native vegetation in urban areas. The diversity of native bird species in these areas is highly dependent on the amount of native vegetation present (p. 26, 1997). Though it may not be obvious, the diversity of native species is important in the maintenance of surrounding areas, as well as other species.

Biodiversity

According to Anup Shah of Global Issues, our world’s declining biodiversity is an area of concern for many reasons (1998). Biodiversity boosts the productivity of the ecosystem with each specie, no matter how large or small, having a critical role to play. Shah continues to explain that a larger diversity of species in our world ensures the natural sustainability of all walks of life (1998). The loss of a single specie can create an imbalance in several chemical cycles, resulting in the loss of several more species. Therefore, the preservation of native Massachusetts birdlife is critical in terms of biodiversity. With a healthy ecosystem, wildlife is better equipped to survive natural disasters and prosper when threats arise. Biodiversity has always been and always will be critical to the survival and prosperity of our environment.

The loss of urban birdlife habitat calls for new areas to provide living space for birdlife. Instead of building new spaces for these species, why not incorporate a new design to existing structures? Installing green roofs in the downtown Boston area will create a natural habitat for endangered birdlife and prevent the loss of birdlife due to urban development, while also providing numerous environmental, social, and economic benefits to building owners.

Green Roofs

A green roof is defined as an “extension of the existing roof which involves a high quality water proofing and root repellant system, a drainage system, filter cloth, a lightweight growing medium and plants” (About Green Roofs, 2014). According to Simon Blackham, Green roofs comes in all different shapes and sizes, including but not limited to: extensive modular roofs, extensive built up roofs, intensive roofs, and biodiverse roofs (2014). We propose to use only biodiverse green roofs because these roofs are specifically designed to replace natural habitats that were displaced due to human developments. Biodiverse roofs are low maintenance and do not require irrigation which is just one of many reasons to install these types of roofs (Types of Green Roofs, 2014).

Environmental Benefits

According to Greenroofs.org, first and foremost, green roofs offer numerous environmental benefits to the public (2014). The primary benefit of green roofs can be seen in the reduction of the urban heat island effect. The urban heat island effect stems from the large amounts of concrete and construction materials present inside the “urban island”. Plantations on vertical and horizontal surfaces are able to cool down the city by absorbing the light that would otherwise be absorbed by the concrete and released as heat energy. Green roofs also absorb many of the greenhouse gasses that normally would be released into the atmosphere. Aside from the reduction of the urban heat island effect, green roofs also provide an effective way to manage stormwater (Green Roof Benefits, 2014).

The article Green Roof Benefits also claims that stormwater management can be very difficult in urban areas because of the larger than normal structures that occupy much of the urban area (2014). Water absorbed by green roofs can be stored in the plantations and then later released into the atmosphere through transpiration and evaporation. During peak stormwater flow periods, green roofs help in the delaying of the time in which runoff occurs. Green roofs not only provide environmental benefits, but they provide social benefits to the physical well being and mental health of the people who are affected by the roofs (Green Roof Benefits, 2014).

Social Benefits

When living in an urban setting, certain risks arise that are not as obvious as you would think. The article Aesthetic and Environmental Benefits says living and working in an urban environment surrounded by massive concrete structures can take a toll on the psychological health of people (2014). Just being near or looking at green roofs can provide benefits to mental health; the natural views can produce healthier, happier and more creative people. Green roofs in an urban environment can induce a sense of pride and increase levels of trust and civic participation, while also lowering the amount of vandalism, violence, littering, and aggression in people living in the city (Aesthetic and Environmental Benefits, 2014). The economic benefits of green roofs can be substantial as well (Economic, 2014).

Economic Benefits

Once past the initial costs of installing green roofing, long-term economic benefits add up, saving the building owner in many ways. According to the article Economic, “the initial extra short-term capital costs of green roof construction can be offset through long-term energy and maintenance savings” (2014). The economic benefits of the construction of green roofs are real reasons that municipalities and developers should consider implementing a greener strategy when planning their development. The US Green Building Council recently said that although the current initial investment when constructing a green roof is significant, the new advances in green design means that it does not have to be more than the construction of a non-green building. This is just more motivation for developers to implement green strategies when planning for their development, whether or not you have to pay a small amount more initially, the amount of energy that a green roof will save you in the long-run will essentially make you money (Economic, 2014).

Green Roofs as Wildlife Habitat

According to Stephan Brenneisen of the University of Applied Sciences Wädenswil, “Well-designed green roofs can provide habitat compensation for rare and endangered species affected by land-use changes” (2006). The Common Moorhen is a bird that has been directly affected by land-use changes. The ever changing urban landscape of the city of Boston has been driving birds such as the Moorhen out of the city for some time, and with the new developments in the construction and implementation of green roofs, the Moorhen will be able to use these roofs as a suitable habitat for breeding, feeding, and living. One factor of green roofs for birdlife habitat that must be taken into consideration in the depth of the soil and amount of water retention the soil will provide. In times of drought, when the animals, like worms, that the birds living on the roof feeds on dies, the birds will struggle to find food. This is why it is important to construct the green roof with a soil depth deep enough that water will be plentiful enough, even during times of drought, to keep ground-dwelling animals alive so that the birds may feed (Brenneisen, 2006).

Green Roofs as a Solution

In light of the many benefits green roofs provide urban environments, more can be done to enhance wildlife capacity and broaden the scope of influence that green roofs have on urban landscapes. To put it simply, green roofs need to be built and incorporated in greater volume. As Shah (1998) stated, the loss of urban wildlife habitat creates a need for new areas to provide living space. Considering that thought, one could argue that city parks and community garden centers provide enough proper habitat for local wildlife. At a glance, it seems likely that local green areas are home to wildlife, but on closer inspection it is clear that the fragmentation and lack of variance within these areas decrease their ability to support avian populations. Relying on existing park and garden areas to sustain urban wildlife is unrealistic. Fortunately, designers are becoming more aware of this issue as more data is collected.

A study by Eakin et. al., from the University of Michigan, concluded that out of twelve different site tests, only 36% of the total land area had green space cover, leaving a “potential mean green space cover” of 66% (Eakin et. al., 2013, slide 21). This means green space cover could be increased by 66%. Eakin et. al. continue to explain that green roof construction can increase green space by 300%, at certain sites (Eakin et. al., 2013, Slide 21).  Thus, emphasis should be put on the development of new habitats, utilizing existing structures and modern technologies, to maximize biodiversity and to make use of abundant rooftop space  (“Applications”, 2014).

The article “Green Roofs and Biodiversity” by Marinelli (2006) highlights studies from Germany, Switzerland, and London in which researchers provided evidence that green roofs can provide living space for plants and animals, including birds. One scientist from Switzerland, Nathalie Baumann, conducted research suggesting that “green roofs may be able to provide not only food habitat but also breeding habitat for ground-nesting birds” (Marinelli, 2006). These examples of habitat creation for endangered birds gives credibility to the idea that green roofs can sustainably support healthy populations of animals, in particular the Moorhen and Warbler species mentioned earlier, due to their lack of breeding grounds.

For the native Massachusetts species we are focusing on, Boston is the perfect area to install green roofs and begin the rehabilitation of these bird species in order to raise population numbers. As mentioned earlier, the Boston Harbor provides the water requirement for Common Moorhen birds. Additionally, since Massachusetts is the native breeding grounds for these species, incorporating their preferred plants will allow for comfortable mating and the establishment of colonies.

Since Mourning Warblers are a very secretive specie, they are often difficult to observe unless a male presents himself in song (“Mourning Warbler”, “Description”, 2014). If building owners publicize their contributions in establishing breeding grounds for the bird, tourists may be willing to pay in order to spend time among the Mourning Warbler. This will also economically benefit the building owner in the long run, while simultaneously educating the public about the benefits of green roofs. The more informed people are, the better equipped they will be in making decisions about green roofs.

Currently, the average cost of installing a conventional shingle roof ranges from five to seven dollars per square foot (Cost to Install, 2014).According to the United States EPA, the current cost of a green roof can range anywhere from ten to twenty-five dollars per square foot. Although the difference in price is not drastic, it is substantial enough to inhibit and deter people who would otherwise be interested in building green. Recently, however, cities and provinces have been offering incentives to residential and commercial building owners to further encourage and promote the building of green roofs. For example, since 2009, the city of Toronto, Canada,  has provided eligible green roof projects up to 75 dollars per square meter of roof area through their Eco-Roof Incentive Program,(Eco-Roof). To date, this program has helped fund over one-hundred green roofs across the city and has brought more attention to the benefits of green roofs. Additionally, in 2009, Toronto became the first North American city to have a bylaw to require the construction of green roofs on new developments (Eco-Roof).  

Educating Opposing Public Opinion

Williams, Lundholm, and MacIvor (2014) claim that a prominent dispute between pro-green roofers and their critics is that green roofs offer too small an area of habitat to make any real difference in conservation attempts. The authors explain that although the areas are small when you look at them individually, collectively they provide large areas of habitable land for several species in a given area. Furthermore, in the article titled Issues, arguments against green roofs include worries regarding waterproofing integrity and pesticide leakage from roof materials. The authors explain that water leakage and pesticide run-off is a rare occurrence which is often the result of using inferior, non-permeable membranes that can degrade over time. Additionally, building owners and designers question whether the cost of building a structure that can support the added weight of a green roof is worth the expense. Williams et. al. (2014) rebut the claim, stating that architects design buildings so that structural, load-bearing columns are directly under the part of the roof where the load is most concentrated (Williams et. al., 2014).

In summary, an inverse relationship exists between increasing human development and sustainable wildlife habitat. Urban environments are unnatural and lead to the displacement and decline of fauna and flora populations (Shah, 1998). This decreases diversity and disrupts symbiotic relationships within the natural environment (Aesthetic and Environmental Benefits, 2014). Green building, specifically green roofs, will help reduce the negative effects of urban sprawl and habitat fragmentation on avian populations in the greater Boston area.

 

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Evan

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