growing the urban forest

This abstract in Restoration Ecology contains an interesting result: planting shrubs along with urban trees helps the trees. You might think the opposite, due to competition, but I have heard this before. One theory I’ve heard is that shrubs help establish beneficial fungi in the soil that pave the way for healthy trees. It shouldn’t be too surprising, when this is exactly the succession that will occur in an abandoned field over time, given enough rainfall and not too much fire.

Compost also helps trees, which might be surprising to some professional engineers but not to any amateur gardener (luckily, some of us are both!). Still, in urban stormwater management we engineers are often encouraged to plant trees and other vegetation, but to minimize organic matter because the same nutrients that trees need can become water pollutants if they find their way downstream. It’s a delicate balance. Civil, “environmental”, and geotechnical engineers aren’t good at finding it because it is not part of our typical training. We need the agriculture, forestry, and soil science types to help us with this.

Forests are vital components of the urban landscape because they provide ecosystem services such as carbon sequestration, storm-water mitigation, and air-quality improvement. To enhance these services, cities are investing in programs to create urban forests. A major unknown, however, is whether planted trees will grow into the mature, closed-canopied forest on which ecosystem service provision depends. We assessed the influence of biotic and abiotic land management on planted tree performance as part of urban forest restoration in New York City, U.S.A. Biotic treatments were designed to improve tree growth, with the expectation that higher tree species composition (six vs. two) and greater stand complexity (with shrubs vs. without) would facilitate tree performance. Similarly, the abiotic treatment (compost amendment vs. without) was expected to increase tree performance by improving soil conditions. Growth and survival was measured for approximately 1,300 native saplings across three growing seasons. The biotic and abiotic treatments significantly improved tree performance, where shrub presence increased tree height for five of the six tree species, and compost increased basal area and stem volume of all species. Species-specific responses, however, highlighted the difficulty of achieving rapid growth with limited mortality. Pioneer species had the highest growth in stem volume over 3 years (up to 3,500%), but also the highest mortality (up to 40%). Mid-successional species had lower mortality (<16%), but also the slowest growth in volume (approximately 500% in volume). Our results suggest that there will be trade-offs between optimizing tree growth versus survival when implementing urban tree planting initiatives.

air pollution and diabetes

Here is a long article citing evidence that air pollution is at least correlated, and quite possibly a contributing factor, to diabetes. The website is called diabetesandenvironment.org, so I don’t know if it is an unbiased source of scientific information. The scientific studies it cites are certainly real.

These authors suggest that oxidative stress, which involves an excess of free radicals, might be one mechanism whereby air pollutants could influence the development of type 1 diabetes. Ozone and sulfate can have oxidative effects. Particulate matter carries contaminants that can trigger the production of free radicals as well as immune system cells called cytokines (involved in inflammation), and may affect organs that are sensitive to oxidative stress (MohanKumar et al. 2008). Beta cells are highly sensitive to oxidative stress, and free radicals are likely to be involved in beta cell destruction in type 1 diabetes (Lenzen 2008)…

The children of mothers exposed to higher levels of air pollution while pregnant have a higher risk of later developing type 1 diabetes. This finding comes from the relatively unpolluted area of southern Sweden, and was found for both ozone and nitrogen oxides (NOx) (Malmqvist et al. 2015)…

A number of long-term studies have found that exposure to traffic-related air pollution is associated with an increased risk of type 2 diabetes in adults. For example, a study of African-American women from Los Angeles found that those who had higher exposure to traffic-related air pollutants (PM2.5 and nitrogen oxides) were more likely to develop diabetes (as well as high blood pressure) (Coogan et al. 2012). Adults in Denmark had an increased risk of diabetes when exposed to higher levels of the traffic-related air pollutant nitrogen dioxide (NO2)– especially those who had a healthy lifestyle, were physically active, and did not smoke– factors that should be protective against type 2 diabetes (Andersen et al. 2012). A study of adult women in West Germany found that women exposed to higher levels of traffic-related air pollution (NO2 and PM) developed type 2 diabetes at a higher rate. This study followed the participants over a 16 year period (at the beginning, none had diabetes) (Krämer et al. 2010). A long-term study from Ontario, Canada, found that exposure to PM2.5 was associated with the development of diabetes in adults (Chen et al. 2013). From Switzerland, a 10 year long study found that levels of PM10 and NO 2were associated with diabetes development in adults, at levels of pollution below air quality standards (Eze et al. 2014).

So does it make sense that we are obsessing over chemicals like trace agricultural pesticide residues in food and “microconstituents” in drinking water, rather than air pollution, which is 100% proven to be extremely harmful? I am not suggesting that we shouldn’t be concerned about all of the above, but in a world of finite resources and time we should calibrate our amount of concern and action to the biggest, most proven risks, while continuing to learn more about the others. The internal combustion engine is killing us and our children, slowly through the air not to mention through sudden, violent death on the ground.

A few more interesting air pollution notes:

  • China may have reached peak coal, with its consumption actually falling last year. World energy consumption has been known to fall during recessions, but this is supposedly the first time it has fallen during an economic expansion. The economics of renewables seem to be playing a significant role.
  • Air pollution kills more people worldwide than tobacco.
  • A Chinese documentary about air pollution called “Under the Dome” was seen by 300 million people in less than a week before it was censored in China. The film maker was partly inspired by a rare tumor her daughter developed in the womb that she links back to air pollution.
  • Confusingly, Under the Dome was also the title of a recent Stephen King novel and TV series. In Stephen King’s 1982 novel The Running Man, which he wrote under the pseudonym Richard Bachman, children are dying right and left of emphysema and cancer caused by air pollution. The government is covering it up and keeping people distracted and entertained with reality TV shows.

green roofs

Everybody kind of likes the idea of green roofs, but water professionals are not always 100% confident we understand them well enough to promise they will meet water quality and flooding regulations. But the studies are gradually trickling in. Here is a new one from Ecological Engineering:

Increasing recognition is being given to the adoption of green roofs in urban areas to enhance the local ecosystem. Green roofs may bring several benefits to urban areas including flood mitigation. However, empirical evidence from full-scale roofs, especially those that have been operational for more than several years is limited. This study investigates the hydrologic performance of a full-scale extensive green roof in Leeds, UK. Monitoring of the green roof took place over a 20 month period (between 30th June 2012 and 9th February 2014). The results indicate that the green roof can effectively retain and detain rainfall from the precipitation events included in the analysis. Retention was found to correspond significantly with rainfall depth, duration, intensity and prior dry weather period. Significant differences in retention values between the summer and winter seasons were also noted. Regression analysis failed to provide an accurate model to predict green roof retention as demonstrated by a validation exercise. Further monitoring of the green roof may reveal stronger relationships between rainfall characteristics and green roof retention.

Beyond questions on performance, there is a kind of chicken and egg problem where they are not used much (in the U.S., at least) because they are expensive and they are expensive because they are not used much. That is true of many emerging technologies. Of course, this “emerging” technology has been used in Europe for centuries, not to mention it is also popular with hobbits.

robots

Here’s a robot learning some tasks on its own. It’s interesting that my two year old human child is roughly around this same stage – he has thoroughly mastered a couple of these tasks, like putting a ring on a stick or a peg in a hole. He is still getting the hang of others, like sticking together legos and screwing on a lid. He has other skills though that I doubt the robot has, like making fart jokes and flirting with pretty girls (which sometimes go together at this age).

Robert Reich vs. Amanda Ripley

Interesting ideas. Free college, free child care, and universal health care are the kinds of bold ideas we need to be talking about to build a resilient 21st century economy.

I recently read The Smartest Kids in the World and How They Got That Way by Amanda Ripley. I liked the book because although it followed a plot of human interest and anecdote to keep the reader engaged, it had a hard core of data underneath. Data doesn’t always lead you down the path you expect, and sometimes it doesn’t tell you what you want to hear. For example, there is no clear evidence that better outcomes are linked to teacher pay, class size, or funding levels, three of the policies Robert Reich advocates above. What seems to make a difference is very high expectations of both teachers and students. Finland for example closed most of its teacher colleges, moved the few remaining into a few elite universities, and made them hard to get into and hard to successfully complete. Those who successfully complete them do get paid well, but there are other countries like Spain and Norway that also pay teachers well and don’t have nearly as good outcomes. High expectations can also come from parents, but they have to be academic expectations. Parental involvement is not that helpful if it is focused on sports and activities other than academics. Parental involvement outside of school, such as reading, is also very, very important. You come away from the book kind of scratching your head about how important school really is and whether any of it is really under your control as a parent, but at least you know the factors outside of school are important and under your control.

wind and solar

Here are some fun facts on the wind and solar revolution.

Rooftop solar is growing worldwide by 50% per year. In 1985 solar cost $12 per watt, but today’s prices are closer to 36 cents per watt. Every five hours the world adds 23 MW of solar—which was the global installed capacity in 1985.

In January of 2014 Denmark got 62% of its electricity from wind. In 2013 Ireland got 17% of its electricity from wind, and Spain and Portugal both exceeded 20% from wind. Today China gets more electricity from wind (91,000 MW) than it does from nuclear reactors. The United States is second in the world in installed wind turbines, with South Dakota and Iowa obtaining over 26% of their electricity from wind…

The renewable energy revolution will enable civilization to stop the growth of highly polluting fossil fuels. It will enable society to leave the majority of the remaining reserves of fossil fuels alone and unburned. Acceleration of this revolution helps in solving many problems and is a key to restoring and maintaining the life support systems of the earth.

money, debt, investment, and growth

It’s interesting how economists talk about money, debt, investment, and growth. If you’re not an economist, you have to tie your brain lobes in a few knots to make sense of it. This is Michael Spence from NYU:

high unemployment, high and rising debt levels, and a global shortage of aggregate demand are constraining growth and generating deflationary pressures. And now, as then, the level and quality of investment have been consistently inadequate, with public spending on tangible and intangible capital – a critical factor in long-term growth – well below optimal levels for some time.

Of course, there are also new challenges. The dynamics of income distribution have shifted adversely in recent decades, impeding consensus on economic policy. And aging populations – a result of rising longevity and declining fertility – are putting pressure on public finances.

Nonetheless, the ingredients of an effective strategy to spur economic growth and employment are similar: available balance sheets (sovereign and private) should be used to generate additional demand and boost public investment, even if it results in greater leverage. Recent IMF research suggests that, given excess capacity, governments would probably benefit from substantial short-run multipliers. More important, the focus on investment would improve prospects for long-term sustainable growth, which would enable governments and households to pursue responsible deleveraging.

Here’s what I think it means. “Global shortage of adequate demand” means people aren’t spending enough money to support productive activity in the economy. Either they don’t have the money or they are saving it instead of spending it. Of course, we need a productive economy to generate the jobs and wages that get people money to spend. So it’s a chicken and egg problem that can spiral downwards once it gets started (“deflationary pressures”). Governments also aren’t investing in productive activity, either because they are afraid of debt or aren’t taking in enough taxes, or both. “Available balance sheets” means they should just wish new money into existence (governments can do that!) and spend it on investments like infrastructure, education, and research that tend to support long-term growth, which would get people more money, which they could spend to support more productive activity, and so on in a virtuous cycle. Money isn’t really real, as long as we think it is real. Debt doesn’t matter, as long as we believe it does matter. Belief in money and fear of debt usually stops us short of the absolute physical limits placed on us by our physical environment.

Washington State drought

Washington State has a snowpack problem.

“Snowpack is down to just 16% of normal,” Inslee said. “This is an unprecedented low. Several mountain areas have already melted out and have little to no measurable snow left…. On the Olympic Peninsula, where there would normally be 80 inches of snow today in the mountains, the glacier lilies are blooming.”

No mandatory rationing has been ordered, but because conditions recently worsened, Inslee took the step to declare the statewide emergency. Fellow Democratic Gov. Jerry Brown of California declared a statewide drought emergency in 2014, and last month ordered municipalities across the state to cut water use by 25%.

In Oregon, Gov. Kate Brown has declared a drought emergency in seven of the largest counties. Seven other counties have requested that an emergency be declared. Combined, that’s about two-thirds of the state.

alternatives to minimum parking

Seattle has a brilliant, and in retrospective obvious, idea for an alternative to required minimum parking requirements for development. Instead of taking them out of the code entirely, allow developers or landlords to provide transit passes or car share memberships instead. This makes perfect sense. If you wanted to be more equitable, you could channel some or all of the money into a fund that low-income people in the neighborhood could use for transportation. For those who are just catching up, most cars sit parked most of the time and take up enormous amounts of space, generally equal or greater than the space taken up by housing. By reducing this wasted space, you create more space for housing, businesses, parks, or some combination. Depending on what you convert the land to, you can also reduce water pollution, flooding, and heat; reduce stress; improve physical health; improve appearance and property values; and maybe even grow some food. It’s an obvious win for everyone – why are we still letting car industry propaganda drive our culture and shape our cities?