Tag Archives: urban ecology

How much ecological function can urban green space provide?

This is an important research question, I think, as the world becomes even more urbanized. Here’s a new study:

Vegetation Type and Age Matter: How to Optimize the Provision of Ecosystem Services in Urban Parks

As cities grow, urban greenspace assumes a more central role in the provision of ecosystem services (ESS). Many ecosystem services depend on the interactions of soil-plant systems, with the quantity and quality of services affected by plant type and age. The question, however, remains whether urban greenspace can be included in the same ecological framework as non-urban greenspace. Our previous studies have contributed towards filling this knowledge gap by investigating the effects of plant functional type (evergreen trees, deciduous trees and lawn) and plant age on soil characteristics and functionality in urban greenspace, offering also a comparison with non-urban greenspace. A total of 41 urban parks and five non-urban forest sites within and adjacent to the cities of Helsinki and Lahti (Finland) were included in this project. Path analyses presented in this contribution, combined with a synthesis of previous findings, offer strong evidence that urban greenspace functions similarly to non-urban greenspace. In particular, plant functional types lead to soil environmental modifications similar to those in non-urban ecosystems. Therefore, vegetation choice upon park construction/implementation can improve the quality and quantity of ESS provided by urban greenspace. However, although vegetation modifies urban greenspace soils with time in a fashion similar to non-urban greenspace, the vegetation type effect is greater in non-urban greenspaces. To conclude, our synthesis of previous studies provides science-based guidance for urban planners who aim to optimize ESS in urban greenspaces.

Urban Forestry and Urban Greening

Ecosystem services and ecological function are not exactly the same thing. Ecological function just is. Ecosystem services are what ecological functions do for people, and fit into the mainstream economic analysis framework. Part of the issue in studying this, I think, is scale. If you look only at one site, block, or park in a city, you might conclude that ecosystems services are negligible or un-measurable. If you look at the entire network and how it is connected, you might conclude that the effects are measurable and that there are policy and design choices that could make them better.

Biodiversity is something else again. More biodiversity is not always better, if it consists of more species of rats or coronaviruses, for example. But biodiversity may be a reasonable proxy measure for how the structure of a designed urban ecosystem translates to ecological function. This is useful if ecological function itself turns out to be difficult to measure. And I think the most useful measures might be biodiversity of animals such as insects (bees, butterflies) and birds. Because the plants in urban areas are mostly the ones that people put there. Biodiversity of plants can be improved through design choices, which is a good thing but in measuring that you are largely measuring inputs to the system rather than the resulting state of the system. Measure the animals, and you are measuring the resulting state of the system.

Measuring things that flit and flutter around might seem daunting. Well, you could try to do it with cameras and image processing of some sort. Or if you are interested in insects you can focus on larva, aka caterpillars. Tracking down bee and wasp nests seems a bit more risky, and you might also have a public relations problem trying to explain why more bee and wasp nests would be a good thing. But caterpillars don’t move fast, so trained people should be able to cordon off an area and find and identify them periodically. Let’s say you did this once a week for a year at several defined points in an urban area, especially if land use changes are occurring (or maybe some places they are occurring and some places they are not occurring.) Doing the same thing in nearby forests and/or farm fields might also add worthwhile data. Now you can do some data analysis and modeling, and maybe figure out design or policy choices that would help the little critters while also benefiting or at least not pissing off people or costing them any money. If you want to fund my half-baked research proposal, let me know.

what is green infrastructure

Here’s a paper that goes into the many definitions of green infrastructure across different disciplines, along with related concepts. I’ve certainly seen narrow definitions used in my own discipline of water resources engineering. Defining clearly what you mean by a term and sticking to that definition is actually a good thing, because it takes the power out of the words in the definition itself, and you are now defining the actual structure and/or function of something, and you can now have a conversation with someone else once they understand the definition you are using. Using words without a clear definition, or not being aware of alternate definitions or broader perspectives that are out there, is a problem, and unfortunately not an uncommon one.

2020 garden retrospective – now with more bug pictures!

Gardening and being around my small urban garden definitely brought me some comfort during the long Covid-impacted spring, summer, and fall. A silver lining of being forced to work from home was being able to work outside some. Anyway, below I’ll just tell my story in pictures.

Black Swallowtails are not rare but they are just fun to watch, and their big fat green caterpillars are fun for the young and young at heart. In addition to bicycle tires, they like the fennel and celery in the garden, neither of which I had to plant this year. The fennel is a hardy perennial with a deep taproot that also spreads aggressively by seed. In fact, I had to start pulling fennel aggressively this year except for a couple spots where I decided it was allowed. The celery (which I mistook for flat-leafed parsley at the farmer’s market years ago) seems to be self-seeding and coming back each spring. There was no parsley in evidence in the garden this year.

Black Swallowtail

We saw quite a few monarchs around. This one is on butterfly milkweed, which really started to take over parts of the garden this year. The monarch didn’t cooperate and spread its wings for a nice photo. This should be a host plant, but sadly we did not see any Monarch caterpillars in evidence. I feel good doing my small part in a small urban garden for this endangered species. We made a brief trip to Cape May, New Jersey in October during the fall bird and butterfly migration, and this is just an amazing thing to see – Monarchs just flitting by every few minutes, adding up to millions I would imagine over time!

Some other plants you can see here are purple hyssop (slightly past its prime) and the fennel just starting to bloom. In the background is the neighbor’s ornamental grass, which is interesting but getting completely out of hand. If I didn’t constantly hack at it my garden would be gone in a few years.

Monarch on Butterfly Milkweed

Here’s another (slightly more photogenic) Monarch on a sunchoke flower. The sunchoke, which I planted last year, started to get aggressive this year. I don’t really mind because they are shallow-rooted and easy to pull where I don’t want them. I did notice some squirrels digging them up in the fall and “squirreling them away” in neighbors’ gardens, lol. The sunchokes and hyssop in particular attracted lots of bumblebees which were fun to watch but did not cooperate for photos. Mountain mint was another plant that seemed to attract lots of bumblebees.

Monarch on Sunchoke

We had a bumper crop of milkweed bugs this year. They’re harmless and I think they are super cool, but I can appreciate they might be creepy to people who just don’t like bugs. This is what the butterfly milkweed looks like after it is done flowering and starts to grow seedpods. There was also a lot of common milkweed in the garden which I didn’t plant but leave alone whenever I see it. I notice that friendly neighbors and their gardeners tend to pull theirs, which I will not judge (in case any of you are reading this) but all the more reason for me to do my small part to support native plants and ecosystems.

Milkweed Bugs

Completing the butterfly milkweed life cycle, here the seed pods are bursting open and preparing to scatter their goodness to next year’s garden. The milkweed bugs are still around, but I noticed after about this point they just started to crawl away and scatter. I don’t know exactly where they go. The white flowers you can see here are garlic chives, which are super cool and attract lots of bees and harmless little wasps. They (the garlic chives, not the pollinators) are getting just a bit aggressive though.

Butterfly Milkweed Seed Pods

This giant pumpkin vine just volunteered, probably as a result of throwing last year’s Halloween pumpkin in the compost. Either that or the squirrel’s who shredded other peoples’ Halloween pumpkins (we have learned not to put ours out too early) might have buried the seeds. It didn’t grow any pumpkins though, maybe missing some key nutrient?

Volunteer Pumpkin

The spotted lanternflies invaded Southeast Pennsylvania with a vengeance this year. This is an invasive species from Asia that is almost certainly here for good now. They didn’t do any obvious damage to my trees (including this Asian persimmon) but we will see what the future holds. They don’t bite, unlike the mosquitoes we had in abundance. We mostly worried about one particular species of virus this year, but others like west Nile, Lyme disease, and Zika are still around, and with climate change I will not be surprised if tropical diseases like Dengue are on the way. Can we apply the new vaccine development technologies to work on some of these, please?

Spotted Lanternfly on my Persimmon Tree

We had lots of stuff in pots. From left to right here, Thai “holy” basil, Asian long beans, Thai “sweet” basil, sunflowers (“Autumn beauty”, which lived up to their name and I recommend, Thai jasmine. Lots of bell peppers also volunteered this year, but no hot peppers – in past years lots Thai red peppers have been in evidence.

Pots

Maypop was my “try again” species this year. With the last few winters being so mild, I am hoping to see it again this spring. The new species I decided to add this year was a low, evergreen groundcover called bearberry. I didn’t take good pictures of it, and anyway it is not photogenic at this point, but I have high hopes for its future.

Maypop

And finally, the dwarf Asian persimmon turned a nice shade of orange to wrap up the year. It is 3 or 4 years old, and flowered but did not set any fruit this year. My other tree is a dwarf Asian pear. It had some kind of leaf spot and looked a bit sickly much of the year, but it did set a fair amount of fruit, of which the score was humans 2, squirrels the rest. They were good, and that is an all time high score for the humans!

Dwarf Asian Persimmon Fall Foliage

bumble bee watch

If you have some free time or are looking for an outdoor project with kids, you can take pictures of bumble bees and upload them to this website. Scientists there can help you identify them and tell you if they are rare.

Bumble bees seem to like my anise hyssop, milkweed, and sunflowers especially. I tried to take a photo of one just now but it turns out they don’t always sit still for photos. There is only so much you can do for wildlife in an urban situation, but one thing you can do is plant to help bees and butterflies, then have friendly conversations with family, friends and neighbors when they ask what the heck you are doing in your “overgrown” garden and when your “weeds” make attempts to expand beyond your borders.

June 2020 in Review

In current events, the coronavirus crisis in the U.S. is spinning out of control as I write this in early July. I made a list of trackers and simulation tools that I have looked at. Asian countries, even developing countries, pretty much have it under control, Europe is getting it under control, and the U.S. and a few other countries are melting down. Some voices are very pessimistic on the U.S. economy’s chances to come back. So of course I’m thinking about that, but I don’t have all that many novel or brilliant ideas on it so I’m choosing to write about other things below. Most frightening and/or depressing story:
  • The UN just seems to be declining into irrelevancy. I have a few ideas: (1) Add Japan, Germany, India, Brazil, and Indonesia to the Security Council, (2) transform part of the UN into something like a corporate risk management board, but focused on the issues that cause the most suffering and existential risk globally, and (3) have the General Assembly focus on writing model legislation that can be debated and adopted by national legislatures around the world.
Most hopeful story:
  • Like many people, I was terrified that the massive street demonstrations that broke out in June would repeat the tragedy of the 1918 Philadelphia war bond parade, which accelerated the spread of the flu pandemic that year. Not only does it appear that was not the case, it is now a source of great hope that Covid-19 just does not spread that easily outdoors. I hope the protests lead to some meaningful progress for our country. Meaningful progress to me would mean an end to the “war on drugs”, which I believe is the immediate root cause of much of the violence at issue in these protests, and working on the “long-term project of providing cradle-to-grave (at least cradle-to-retirement) childcare, education, and job training to people so they have the ability to earn a living, and providing generous unemployment and disability benefits to all citizens if they can’t earn a living through no fault of their own.”
Most interesting story, that was not particularly frightening or hopeful, or perhaps was a mixture of both:
  • Here’s a recipe for planting soil using reclaimed urban construction waste: 20% “excavated deep horizons” (in layman’s terms, I think this is just dirt from construction sites), 70% crushed concrete, and 10% compost

Technosols

A technosol is an artificially created planting/structural medium from manmade materials, such as construction debris and compost. This article from Ecological Engineering journal says a mix of 20% “excavated deep horizons” (in layman’s terms, I think this is just dirt from construction sites), 70% crushed concrete, and 10% compost might work. If we truly want green cities, and we don’t want to reduce natural habitats to wastelands by harvesting materials from them to green our cities, this could be a good approach.

May 2020 in Review

You can’t say that 2020 has not been interesting so far. The Covid-19 saga continued throughout May. I certainly continued to think about it, including a fun quote from The Stand, but my mind began turning to other topics.

 

Most frightening and/or depressing story:

  • Potential for long-term drought in some important food-producing regions around the globe should be ringing alarm bells. It’s a good thing that our political leaders’ crisis management skills have been tested by shorter-term, more obvious crises and they have passed with flying colors…doh!

Most hopeful story:

Most interesting story, that was not particularly frightening or hopeful, or perhaps was a mixture of both:

  • There are unidentified flying objects out there. They may or may not be aliens, that has not been identified. But they are objects, they are flying, and they are unidentified.

native plant and pollinator gardening in Pennsylvania

This post has a ton of information on gardening with native plants and gardening for pollinators in Pennsylvania – sources of plants and seeds, recommended species and combinations of species for various conditions, and links to a variety of government and non-profit organizations that can provide even more information.

“supporting” ecosystem services in cities

This long article makes a distinction between services provided by natural and semi-natural areas in cities, and a concept of a city as a whole as an ecosystem that provides services. What it reminded me of, though, is the distinction between the UN’s definition of “regulating” ecosystem services and “supporting” ecosystem services.

• Regulating ecosystem services, such as control of stormwater discharge, mitigation of heat in urban areas, mitigation of noise, etc.

• Supporting ecosystem services, such as provision of habitats for urban biodiversity, provision of pollinators for urban farms, etc.

Journal of Landscape and Urban Planning

In the engineering world I inhabit, we have the regulating services reasonably well figured out. We don’t always do a great job of implementing and enforcing, and we exempt too many projects, but basically we have cost-effective standards and best practices for things like flood management and water pollution reduction.

The supporting ecosystem services are mostly not even on our radar. And that means that when we are designing for flood or water quality objectives, our designs are not as green as they might be if we took biodiversity and habitat into account. It might not even cost more to do that, but it would require a more expansive way of thinking. To do that, we would need to communicate effectively to the decision makers and then the rank and file just why they should care.

bye bye bumblebees

The latest charismatic species to be at risk of disappearing – bumblebees, according to Science. It’s a simple story – they just can’t handle the heat.

Climate change could increase species’ extinction risk as temperatures and precipitation begin to exceed species’ historically observed tolerances. Using long-term data for 66 bumble bee species across North America and Europe, we tested whether this mechanism altered likelihoods of bumble bee species’ extinction or colonization. Increasing frequency of hotter temperatures predicts species’ local extinction risk, chances of colonizing a new area, and changing species richness. Effects are independent of changing land uses. The method developed in this study permits spatially explicit predictions of climate change–related population extinction-colonization dynamics within species that explains observed patterns of geographical range loss and expansion across continents. Increasing frequencies of temperatures that exceed historically observed tolerances help explain widespread bumble bee species decline. This mechanism may also contribute to biodiversity loss more generally.

Science