Feature Image - David Foster Presentation2

Dalhousie University Maps Urban Forestry for HRM

Managing Halifax’s Newly Planted Urban Forestry with Eos Arrow 100 and Esri Collector | David Foster, 2018 Esri Canada UC


Halifax Regional Municipality (HRM), with the help of Dalhousie University, needed to enforce a warranty period for trees planted within the past two years by contractors. Moreover, each year the contractors would plant more trees. Holding contractors responsible for trees that died from natural causes was nearly impossible, but it was also critical to understanding which trees fell in our out of the warranty stipulations for being replaced for free. To do this, a combination of researchers and city planners required a detailed, spatial, and highly reliable inventory of trees that could be updated over the course of each two-year warranty period. In this video, former Dalhousie University intern and current Ph.D student David Foster explains how the team used created this solution for urban forestry with Arrow 100 and Esri‘s ArcGIS Collector. The HRM is now able to hold contractors accountable, save the municipal region money, and ensure a healthy green environment.

Eos Positioning Systems video tutorial

Transcript for “Managing Halifax’s Newly Planted Urban Forestry with Eos Arrow 100 and Esri Collector | David Foster, 2018 Esri Canada UC”

My name is David Foster, and I am a Ph.D. student at Dalhousie University.

My research focuses on the effects of forestry on water quality specifically for drinking water purposes. But today I’m here to talk to you about another research that I’ve been doing at Dalhousie for a longer period, and it’s partnership with Halifax Regional Municipality (HRM). This partnership goes back to the mid-2000s when HRM was looking at creating a plan to guide the management of the urban forest, and they came to partner with Peter Duinker, a professor at the school for resource environmental studies at Dalhousie University. This partnership culminated in the co-authorship of the urban forest master plan in 2012 and was subsequently accepted by the HRM council as the guiding document on how to manage a Turin’s Urban forest. It included key findings of the age and composition of urban forests and also had some findings on risks both to and from the urban forests. This led to some critical recommendations on how to manage the urban forest including what and where to plant and also how to manage what’s already planted.

Just so we get an idea of what we’re talking about in terms of size and scale. The UF MP area includes where over 300,000 people live. HRM is over 17,000 hectares and has one of Canada’s highest canopy covers in an urban area at around 34, 4% of includes 7.4 million trees from an assessment done in 2016 by myself, 170,000 of these trees are growing in HRM Streets. There is public land adjacent to these streets that are owned and managed by the city, while this number may seem a little large there are still at least 94 thousand spots where we trees can be planted in HRM. The challenge the HRM faces is increasing that already admirable 34% by planting in these 94,000 spots.

HRM has a staff of under 20 in their urban forest department, and they are primarily involved in reactive interventions. As you see here in this picture, they’re removing a tree branch that’s fallen on a utility pole support cable.

Their planting regimen can be described as somewhat reactive because they only plant when somebody calls 311 and requests for a tree to be planted in front of their home or when an individual has had a tree removed for one reason or the other, they come back in some years and replant it. The staff are fully employed all year, and most of them are fully utilized.They also perform winter maintenance, by removing snow from public properties. Driving snowplows can be difficult if the roads are not cleared at winter.

To address these 94,000 plantable spots, we have to step up the planting game that’s currently going on in HRM, planting 300 trees a year doesn’t even come close to replacing the trees that we’re losing. We need to plant over a thousand trees a year, so we’ve moved to using contractors. So far we’ve had six contracts for planting from 2013 to 2018. If you notice the annual trends there has been relatively consistent growth in the numbers that are being planted but due to the recent increase in emerald ash borer mortality in central Canada, Ontario. The cost of trees have gone up, and the budget for the planting program is too high for the planned amount, we’ve had to cut back the number of trees that are planted.  In the meantime, we’ll see how that plays out as ash borer continues to ravage Canada.  Contractors are liable for a two-year warranty, and they must guarantee you that these trees will survive for two years. This is part of their contract if that tree dies of natural causes, i.e., you can’t determine that there was some external cause like snow plows they are liable to replace it. Examples of natural causes is an event that happens due to lack of watering; they must replace it. This implies that they have to take care of that tree usually in the form of watering which they almost never do because it’s cheaper to replace the trees that die rather than watering all of them, especially the ones planted in Halifax.

The partnership with HRM has been very fruitful for us at Dalhousie. They help in offering an internship for summer students. These students work on a variety of projects with different research objectives; they provide different knowledge resources for the city to better understand and manage the urban forest. There have also been other projects like the 2016-17 I tree assessment.

Designing an interesting tool to understand the benefits and costs associated with the urban forest has been a continued source of research for both the faculty and its students. This research’s primary goal is producing effective and better management practices for urban forests. These practices are the best tools.

In Halifax, a key piece of work for summer student interns work though is taking inventory of every newly planted tree in the city. I say every newly planted tree, but this category is solely for trees planted under the urban forestry program, this doesn’t include compensatory replacements that might have been planted by utility companies because of the “infrastructure work with tree” rule, and it most importantly doesn’t include new developments which are a massive source of new trees. We don’t have a properly structured mechanism of getting all of the information for yet, but we’re working on that and hoping that the evolving relationship with Halifax can get us all the information we need. This will help us develop a  linked spatial and tabular database. We are finding increasingly useful ways that this spatial database will help us with our management, but it’s critical that we have an Excel spreadsheet too. This is because partners like the municipality have little or no access to GIS(Graphic Information System) tools and also less familiarity and confidence with these tools.  They’re much more comfortable with the spreadsheet where they can easily filter out results and look for what they’re after. We’ve been doing this inventory since 2013 when the contracting plantings started.

An intern students summer project then was to come up with a method for taking inventory of all the trees.

She went a little low-tech with a map and pencil she because had low access to resources. She had to go out, see the trees, mark them on the map and go back to our desktop and input the data. This was very inefficient.

Gradually we’ve been digitizing this entire process to date when I think we’ve hit the sweet spot we’re using the Eos arrow 100 a sub-meter GNSS device paired with Ezra’s collector app allowing us to collect information in the field quickly, this data is immediately inputted digitally on the spot  and has reduced inefficiency in inventory taking.

This inefficiency caused a lot of opportunities for data entry error but has been resolved with the aid of the new system.

It’s important to note that the ATM’s urban forest program is a course supported by the council, the council approves annual expenditures and so to keep this funding going it’s important that every councilor sees the benefit of the program.

Any councilor that doesn’t see the benefit might not be inclined to vote for the kinds of funding that the program requires.

Let’s talk a little bit about infrastructure, robust large utilities like the picture on the left being in a city that has many transmission systems adversely affect tree planting. You can’t have growing up into the power lines; this will cause problems, so you have to manage those trees to reduce the impact of the trees on the power lines. The tower trees are usually blamed when there’s a power outage so ensuring the health of trees and making sure that there are no dead branches that could fall onto the power lines is paramount, and ensures the level of reliable electrical service does not decrease as a result.

When looking at trees, we’re not only looking at the trees themselves, but at the context in which they’re growing in, and one of the questions we asked is what infrastructure is over the top of those trees, so we’re looking at whether there is a power system. It looks like we’re only talking about the transmission wires, not the distribution ones that feed directly into your home. But the good news is that the majority of the invent we’ve taken don’t fall underneath power lines, this means there won’t be any conflict for us to worry about.

There are over a thousand trees that have been planted in the last six years that are under wide electrical systems, these systems are like in the previous slide wide and require a lot of work on the tree to make sure that there is no interaction between the branches and the wires.

Over a thousand trees are growing underneath narrower systems, like a single wire or something like transmission wires that are stacked vertically or using a Hendricks system.

Inert cables can be put over top of the wires, this protects the wires from any disruption, so we would, of course, encourage power utility companies to make use of tools like this to make it easier to grow trees around their property.

Take a look at the infrastructure at our feet, of course, this is our favorite place to plant a tree, and that’s what we call the tree lon. It’s a strip of grass between the road and the curb, you’ll see by the frequency of red and dark orange dots that most of the tree lines in that area are less than a meter wide. Looking forward to the future in a hundred years or less we’re looking more at trees that look like the ones on the right versus the ones on the left.

When we’re planning our streets, we should be planning for treaties that are large, healthy and have sufficient access to the resources that they need to thrive. I mean Halifax is an old city but some streets that are narrowing as little we can do about it, but when we’re planning for new developments, there should be proper planning.

To track up to four thousand trees simultaneously. The number is four thousand instead of six thousand because contractor inattention while transporting trees some of them died.

The trees are looked at after two years after planting because that’s the last time that that tree will be looked at before it eats the warranty period and any mortality that hasn’t been captured at that point won’t be within that warranty, so this requires robust records, I would argue a spatial inventory so that you can accurately track the status of each tree and communicate these results to the contractor. This is to ensure that they will place the right tree, but often these compilations don’t exist especially when there’s a management style where somebody manages more on paper. With this style of recording, it is kind of hard to see where these plantings have occurred and track them effectively.

What we’ve done with HRM has developed a drive-by inspection protocol.

How this works is that an intern student drives around in a car with municipal staff and the original contractor who did the planting. While those two come up with an agreement about which tree is dead and which tree is alive, the student uses a Zuri’s collector app and an EOS era 100 to identify and update the tree database in real-time, the database status is also updated as they drive and view other trees.

As a direct result of this new system of taking inventory, out of the 8800 trees that we’ve inventoried 7800 are still alive. This is a reasonably good planting success that’s and is under 10 percent mortality which in an urban planting environment is pretty reasonable however that number has been dragged down a bit by inattentive contractors who are focusing more on speed than quality.

Regarding the death rate of the trees, we’ve counted 800 trees dead within the within the total inventory program, and around 700 of those were counted within the Warranty Period.  This means that at an average cost of just under $400 a tree we’ve helped the city realize cost savings of a quarter million in terms of assets. This occurred because we ensured the trees were replaced within the warranty period.

Our well-executed inventory ensures that the trees will be properly counted and some conclusions about the work over the last six years between Dalhousie and in HRM are concrete.

It’s been more than at least a decade of work between the two bodies. Spatial inventories for urban forest planning has allowed us to better understand and just from a glance on how the project is spreading out.

What communities are being left out? Unlike now, Lower Sackville was not initially a high priority community this was because it’s a little further away from the HRM core. It is within the UM empty area and so just glancing at the map three years ago you would have asked why that community was not included, and the councilors were probably asking the same question. With a map like that just from a glance, you can identify areas that have been omitted. Something I didn’t have time to talk about that was also the species distribution and its importance.

Urban planners didn’t learn their lesson in the 50s when Dutch elm disease struck and wiped out massive proportions of urban canopies because we replaced those Elms in many instances with ash trees and of course we’re now realizing the folly of that.

I’m glad that we now understand this and that’s why in HRM we’re planting the minimum of 13 tree species per year

When we’re doing a planting, this type of inventory allows us to see where there are unfortunate trends happenings because too many of one species are getting planted in that area. Essentially, a resilient urban forest is one that’s able to survive the total loss of a single species and still provide a broad range of benefits to it to the citizens.

From an urban forest management perspective, there is a benefit here to contractor compliance; it’s an amazing cost saving for the city of $70,000. This the amount we’ve helped them recover in terms of assets, you can compare that with the price tag of the internship which is about forty-four thousand dollars a year, so it’s a net saving to the city.  The city also realizes all sorts of research benefits and partnership benefits from the University as well.

There’s also the relationship to infrastructure function. This type of a spatial inventory allows you to plan years into the future. For example; we have a tree here maybe we should start thinking about the type of electrical infrastructure overhead maybe we should start to think about the width of the tree lawn maybe we could widen that when the street comes up for recapitalization, perhaps we could widen it not the street or Sorry! We could perhaps widen the tree lawn leaking air to the streets arrow.

From an asset management perspective alone a tree inventory is incredibly important.

Our new urban forester Crispin wood lamented to me that with the onion dissipated early arrival of emerald ash borer he feels totally unprepared to provide really firm cost estimates of what it’s going to to do to the city and how much it will cost him to treat trees to prevent the infestation in, particularly valuable areas.

He can provide a good estimate from driving around, but with an inventory of all trees he could do a much better job of that, and of course, that inventory would have to be spatial for it to be useful in terms of the municipal postsecondary partnership that we’ve enjoyed with the municipality. It has of course been an excellent experience for students not only from the internship experience but the opportunity to work with municipal and experienced practitioners in the field of urban forestry, but it prepares them for what they might end up doing after their master’s degree at Dalhousie.

I hope the partnership has been of tremendous value to the municipality not just because of the realized cost savings but because there are all kinds of research opportunities that have generated innumerable recommendations for them on proper management.

Our recommendations guide them if they might want to plant trees, remove or replace. It has spawned incredible opportunities for our students.

I also know that Fredericton and Moncton have leveraged this opportunity with UNB. I hope that this model shows that universities and municipalities should continue to form partnerships in urban forest management. This is because urban forestry is still an emerging field that we’re still learning lots about it and I firmly believe that we can best manage this resource and have healthy urban forests for our people if we do the management together

Thank you Very much


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