Did You Know? Tree Are Always On The Job Filtering Earth's But Where Are Their Cheerleaders?!

by Jim Northrop, GSWA Volunteer

The Ashokan Reservoir in New York's Ulster County
is one of two reservoirs in the Catskill Water Supply
System delivering drinking water to New York City. Situated
approximately 73 miles north of the city, the Ashokan
supplies about 40% of NYC's daily drinking water needs.
Credit: flickr.com//photos/carbonnyc (D. Goehring)

Treating water pollution may be one of the most critical services that trees offer to the world. In "The Man Who Planted Trees," a 2012 book written by Jim Robbins, the author looks at the relationship between New York City and the forests just to the north of the city in the Catskill Mountains. These rolling woodlands form a catchment and filter area for the water that New Yorkers drink. In 1989, the U.S. Environmental Protection Agency ordered the city to build a new water treatment plant at a cost of $8 billion. Their concern was that microscopic intestinal parasites, and some other waterborne pathogens, would find their way into the New York City water supply.

However, city officials decided that the cheaper and better option was to protect the existing two-thousand-square-mile forested watershed that naturally filters water flowing into the city. That plan only cost about $1.5 billion, and the money was spent on such things as buying buffers of natural landscape around reservoirs to act as filters, and negotiating agreements with upstate cities and towns to limit development in watershed areas. While using woodlands to clean the water made economic sense on its own, maintaining tracts of native forest provided many additional ecosystem services, including wildlife habitat, recreation, and carbon dioxide absorption.

Deforestation anywhere can cause many problems for our water supply. Where freshwater once fell as rain (and was filtered by the forest and slowly released) there are now farm fields, lawns, and parking lots that pour polluted sediment into our streams and rivers. In fact, research shows that river basins with the greatest amount of farmland produce the most pollution-laden sediment, while river valleys with the most forest coverage produce the least. Nitrogen and phosphorus from agricultural fertilizers and poultry waste increase the proliferation of bacteria that, in turn, consume the oxygen dissolved in the water.

Deforestation along rivers and streams means that there are no woodlands to hold back the water, and so a faster flow is given to more water. Faster-flowing streams reduce the number and array of ecosystem services a waterway can provide. Broad streams with wooded banks flow more slowly than those without streamside forests, allowing more time for contaminants to settle out and be taken up by nearby trees and neutralized by microbes.

Re-forestation can help reverse these kinds of problems. In fact, trees could be used to remedy a lot of modern-day water pollution problems, including some of the worst kinds of human-created chemical waste, such as dioxin, ammonia, dry cleaning solvent, oil and gas spills, PCBs and other industrial waste. The trees take up waterborne toxic waste and then neutralize, metabolize, and/or vaporize it.

Hybrid poplar trees (Genus:
Populous) like those shown being
farmed in this photograph are often used
for phytoremediation. Phytoremediation
addresses environmental issues
through the use of plants capable
of mitigating pollution without
the need to excavate contaminated
material. Credit: National Renewable
Energy Laboratory.

Poplar and willow trees seem to be the most effective choices for scrubbing the runoff that washes into rivers and streams when rain falls across urban and rural landscapes. We have a problem in our cities and suburbs where pavement, driveways, and other impervious surfaces collect oil, lawn chemicals, pet waste, and industrial waste that subsequently washes into waterways during every rainfall event. Stormwater and sewage leaking from aged and broken sewer lines also carry viruses, bacteria, and protozoa capable of contaminating and killing shellfish, fish, and other aquatic life.

Because this runoff water comes from wide-ranging sources, it is difficult to capture and treat in a sewage plant. We cannot catch all of that stormwater and treat it conventionally ---- it would be too expensive. Perhaps the best way to get our streams and rivers cleaned up is to "tree-farm" our way out of the problem. Strategically placed in drainage areas where tainted water collects, willow and poplar trees could work their root zone magic and make very effective water filters.

There are many advocates in favor of "clear cutting" trees to make way for new houses and sports fields, but where are the advocates for our trees? Where are those who stand up in favor of keeping our trees, especially in situations where they really are needed? In the future, perhaps we should better understand and support the important role that trees play along our streams and rivers.

Did You Know? A “Crystal Ball” For Trees ---- Where Are Our Trees Headed?

by Jim Northrop, GSWA Volunteer

In 1982, a large glass-and-steel dome called “Biosphere 2” was constructed, intended for the human colonization of Mars. It failed for that purpose, but it has been useful for studying planet Earth because it allows researchers to control variables and play out different scenarios in a way that can’t be done in the real world.

The University of Arizona's Biosphere 2 earth systems
research facility in Oracle, AZ. Credit:
flickr.com/photos/tim846 (Tim Bailey, CC Attribution)

In 2009, according to Jim Robbins, author of the 2012 book The Man Who Planted Trees, two researchers moved twenty mature pine trees, five to six feet tall, into the dome and split them into two groups of ten. One group was placed in a chamber where conditions were equal to what they are today, and the other group was placed in conditions some seven degrees Fahrenheit warmer than it is now ---- roughly equal to the high end of the temperature rise scientists predict for the next century. Once the trees established themselves, researchers deprived both populations of water.

The human-induced drought killed the trees in the warmer chamber 28% faster than the trees in the chamber with normal temperatures. The conclusion of the researchers was that forest die-offs could increase by a factor of five if the climate warms seven degrees as predicted over the next century. Because droughts can kill trees faster when temperatures are warmer, they suggested that instead of one die-off in one hundred years, the number could increase by a factor of five! This is based on temperature increase alone. However, in addition to the effect of warmer temperatures on trees, we must consider the aggravating effect of warmer temperatures on disease and insects. In concert with water stress, disease and insects kill many more trees than drought alone.

Some scientists believe the earth is on track to see 20% of its tree species become extinct or be on their way to extinction by the end of the century. These scientists see droughts, heat waves, and forest fires of unprecedented ferocity, rapidly rising sea levels, and more storms with hurricane-force winds. While there have been mass extinctions before in the earth’s history, scientists say this one is different from the others. It is brought on largely by humans through their disturbance of the natural landscape, the introduction of exotic species of plants and animals, new pathogens (such as increased carbon pollution), and unsustainable exploitation of plant and animal species.

A view of trees damaged by black mountain beetles
(Dendroctonus ponderosae) in the Black Hills National
Forest in South Dakota. Credit: flickr.com (Chris M. Morris
CC Attribution).

To be more specific, giant forest die-offs have already begun in the Rocky Mountain West. In the last half century, the two-degree temperature rise that has occurred in the West has already begun to turn ecosystems inside out, and the anomalous behavior of insects is one of those changes. With only a small increase in normal temperature, tiny black mountain pine beetles (Dendroctonus ponderosae) now constantly fly from May until October, instead of a mere two weeks each year. They are attacking trees, burrowing in, and laying their eggs for fully half the year. There is evidence that the beetles are now attacking immature trees, and that they are switching to other tree species. In some high places where the beetles had a two-year life cycle because of cold temperatures, it has changed to a one-year cycle. This means that their populations can increase more rapidly during warm droughts when their host trees are most stressed, resulting in more beetles doing a lot more damage.

A dying forest is problem enough, but when large landscapes die they become contributors to a warming climate, a cycle called a “positive feedback loop.”  One of the most important things forests do for life on the planet is to capture carbon dioxide from the atmosphere and store it as plant tissue. Trees contain half of our terrestrial carbon stores, more than any other single source on land. Without forests, more carbon dioxide would remain in the atmosphere, causing more warming. When forests die or are cut down, they release their stored carbon dioxide into the atmosphere; in fact, such events are said to comprise 20% of annual carbon emissions.

While we cannot cure global warming, we may be able to slow it down. Understanding the causes and seeing whether we can adapt better to the effects is worth thinking about today as we face this inevitable change in nature.

Did You Know? ...About Spruce Trees

by Jim Northrop

For many American homes, the centerpiece of Christmas decoration is the Christmas tree, often a spruce tree, cut locally. Year-round, spruces are trees ornamentally popular with landscapers. They are admired for their all-seasons green color, and their tidy symmetrical growth profile. They have dense branches, but they are easy to decorate.

We should know that the spruce tree has more talents than just looking pretty. Spruce is very useful as a construction wood. It has many uses as lumber, ranging from general construction work, to crates, to highly specialized uses in wooden aircraft and as a "tonewood" in many musical instruments (including guitars, mandolins, cellos, violins and the soundboard at the heart of a piano, and the harp. The Wright Brothers' first aircraft was built of spruce.

Spruce is one of the most important woods for paper making, as it has long wooden fibers which bind together to make strong paper. Spruces are commonly used in mechanical pulping as they are easily bleached. Spruces are cultivated over large areas as pulpwood.

Interestingly, the fresh shoots of many spruces are a natural source of vitamin C. Captain Cook made alcoholic sugar-based spruce beer during his sea voyages in order to prevent scurvy in his crew. The leaves and branches, or the essential oils, can be used to brew spruce beer.

Native Americans in New England took the sap to make a gum which was used for various purposes, and which was the basis of the first commercial production of chewing gum. Also, the resin of spruce trees was used in the manufacture of pitch, at least until petrochemicals were found to be better for this purpose.

We have many varieties of spruce trees in the Great Swamp Watershed. Sadly, many of them were damaged or destroyed recently by Hurricane Sandy. The root systems of spruce trees are often quite shallow, making them quite susceptible to high winds. Their graceful presences will be missed for a long time, as it will take decades for new growth to fully replace them.

Editor's note: Some spruce trees, like the Norway spruce (Picea abies), were introduced to North America from Europe, and are now considered invasive species. As they invade an area, the Norway creates a new habitat that few native plants can tolerate. The soil surrounding stand of Norway spruce often becomes acidic and devoid of many important nutrients. Shade canopy also becomes very dense, preventing light from reaching native plants close to the forest floor.

Thankfully, homeowners and landscapers can avoid perpetuating the spread of invasive spruces by choosing to plant native spruce species instead. The red spruce (Picea rubens) is one of these native species. Its natural range stretches from the Canadian Maritimes through the Appalachian Mountains to western North Carolina. The red spruce thrives on moist, sandy loam, and also on dry rocky slopes. These trees can reach heights of 60 to 80 ft.