A Naturalist's Thoughts on Tree Rings

A tree is a woody plant with a single trunk that branches out at the top. Trees are perennial, meaning that they can live for many years. Tree height varies widely across the planet. Some California redwoods are more than 350 feet high, while the world's shortest tree, Greenland's dwarf willow, grows to be less than two and a half inches.

What causes tree rings?

The outer bark of a tree trunk consists of dead tissue, while the inner parts of the trunk are alive. New yearly trunk growth is added on between the inner old wood and the bark outside. Individual rings form because tree cells grow differently from the beginning to the end of a growing season. Each tree ring consists of two layers. A light-colored layer is formed when the tree grows rapidly in the spring; slower growth in the late summer and early fall causes a second, darker layer to form. Tree rings are only found in temperate climates. Tropical trees grow year-round, so they do not form rings.

When you look at a cross-section of a cut tree trunk, inner rings are the oldest. The rings' shape and width can tell you about the tree's life. Scars in the rings are usually caused by fire; if growth is limited by rainfall, wetter years tend to yield thicker rings. Narrow rings indicate tree stress, perhaps from drought or pests.

Photo credit: Lawrence Murray, via Flickr (cc by 2.0)

This information was first posted at the Audubon Naturalist Society. Come visit Woodend!

Ten Tips to Inspire Environmentalists

Climate change is profoundly and noticeably impacting the environment where I live. For the past few years, I've observed increasingly intense summer thunderstorms and accelerating tree death from a variety of causes. Despite an abundance of dragonflies this year (yay!), I've seen fewer butterflies, moths, and bees this summer. This loss has affected me deeply and left me feeling out of sorts. Discouraged about the general state of the planet's health and concerned for my eco-community specifically, I turned to a listserv of Maryland Master Naturalists for advice. Why keep plugging away at saving the environment, I asked, when things look so bleak? How do I keep my spirits up when I find myself discouraged?

Here are the ten best tips that I received for coping with environmental degradation and dealing with the feelings of loss and helplessness that can arise:

1. Remember that the Earth is resilient and will be here long after we are gone.

2. Recognize that it may take a number of adverse ecological changes before real, meaningful climate change legislation is enacted.

3. Get involved. Plant trees, keep bees, study native plants, aid pollinators. Every little bit helps.

4. Rejoice over small eco-victories.

5. Focus on what you can do for the planet and set a good example for others.

6. Speak out about climate change. Let your voice be heard and educate others.

7. Teach children to be environmental stewards.

8. Accept that some environmental change is inevitable. New, more adaptable species will arise to succession. This is part of life.

9. Know that you are part of a larger community of environmental stewards who are working to make a difference.

10. Events that we interpret as undesirable (such as tree death) have important environmental benefits too (bird habitat).

My thanks to the kind and generous Maryland Master Naturalists who responded to cheer me up. Keep fighting the good fight!

Image credit: tongdang, on freedigitalphotos.net

Project BudBurst

Has the dreary winter weather got you down? Let's plan for a fun way to celebrate spring! If you're in the U.S.**, join Project BudBurst and record your observations about the yearly stages, or phenophases, of select plants in your area. Choose from one of these 75 plants to study. You can track things like the earliest date you see leaves, flowers, or fruits and then report your data online. (** Not in the U.S.? You can still have fun predicting the timing of next spring's phenophases and recording your observations.)

Dr. Kayri Havens, Lead Botanist, and Dr. Paul Alaback, Lead Science Advisor, are keeping a Project BudBurst blog to accompany the website. I thought this blog snippet from Dr. Kay covered the objectives of Project BudBurst quite nicely:

"Thanks to all of you who are watching plants and submitting your observations! These data are helping us get a much clearer picture about how plants are responding to different climates around the U.S. This will help us predict how plants will respond to a changing climate."

At Project BudBurst, you can learn more about phenology, the science behind this study, download teaching materials about plants and plant identification guides, browse the map of recent observations, and more! And be sure to upload your plant photos to the Project BudBurst Flickr photo pool.

What is global warming?

Climate change is impossible to avoid. Scientists know that the Earth has been both colder (think Ice Ages) and warmer (the days of Titanoboa) at different times in the past. When people talk about the problem with climate change, though, they are talking about the recent, rapid increase in temperature across the planet. The majority of scientists think that the rate of change is unnaturally fast because of things people are doing, like burning fossil fuels (such as gasoline and coal).

Why does burning gasoline make a difference to the planet? When talking about climate change, it helps to remember that the Earth is a closed system. We only have so much carbon on our planet. Some of it is in solid form -- carbon-based life forms like you and me and the trees outside -- and some of it is in the atmosphere in gases like carbon dioxide (CO2) or methane (CH4).

When we burn fossil fuels, carbon that was in a solid form is released and enters the atmosphere. Atmospheric carbon can then be "breathed in" by trees, grasses, and other plants to enter a solid form again. This is a rather simplified version of the carbon cycle. (In the real-life model, there's a bunch of carbon "missing" -- unaccounted for in the cycle -- and no one knows exactly where it is going [although forests seem a likely place]. But that's a topic for another blog post!)

Image credit: NASA, revised version obtained through Wikipedia Commons

The problem with the carbon cycle is that we are changing the ratio of solid carbon to gaseous carbon. When we use drive a car, cut down trees, or burn coal to heat our house, we are moving carbon to the atmosphere. Carbon isn't leaving the atmosphere as fast as it's entering it. And that's a problem.

Carbon dioxide, along with other gases in the atmosphere, acts like a shield. The sun's rays deliver heat to the Earth's surface, but the heat gets trapped in the atmosphere. Just like in a greenhouse, this reflected heat bounces back down to the earth's surface. This warms the Earth, which is a good thing because it keeps us from freezing. But adding too much carbon dioxide to the mix makes the Earth's atmosphere trap too much heat, which causes temperatures to rise. This is known as the greenhouse effect.

Image credit: NASA (taken from a 2002 online press release)

Scientists that study the atmosphere can show that the levels of carbon dioxide in the atmosphere are steadily and rapidly increasing. No one knows for sure how the Earth will adapt to these changes.

Image credit: Dr. Pieter Tans, NOAA/ESRL (www.esrl.noaa.gov/gmd/ccgg/trends)

Think of the earth as a big mixing bowl. The sun's rays are beating down on the Equator, heating up the middle of the planet, while the poles are cold and snow-capped. These differences in temperature drive our weather.

Now, let's say that global warming has increased temperatures around the world. This may not seem like much of a problem at first, especially if you hate winter. But here are three specific concerns:

1) The Earth's weather is going to change. The polar ice caps are melting. The mechanism that drives our weather -- these differences in temperature across the globe -- has been altered. The ratio of the earth's liquid water to ice has changed. These changes are affecting the world's weather. And we have little control over the changes.

South Cascade Glacier, Washington State, United States.


Photo on top taken in 1928, photo on bottom from 2006. Note that the lower part of the glacier has melted by 2006.



Photo credits: 1928 - USDA/USGS; 2006 - USGS, cropped by Mama Joules)

Weather is not easy to predict as it is. Adding more confusion isn't going to help us develop good climate models. Although we have ideas, we don't know exactly how the weather is going to change from increased temperatures. As anyone who's watched a weather forecast knows, climate models can only predict so much.

Sometimes, a model completely fails to guess what's going to happen. Climate models are at risk of failure because so many factors (even the amount of volcanic ash in the sky) drive climate change. We know that weather can cause big problems -- things like typhoons, tornadoes, flooding, and drought. If we can't plan for the future, we will be unprepared for disaster when it strikes.

2) Some plants and animals may face extinction. The rate of temperature change might be too rapid for some species on Earth to adapt. Animals that currently live in the coldest climates on Earth -- like polar bears and penguins -- have no where else to go.

Photo credit: Dave Olsen, U.S. Fish and Wildlife Service

3) The composition of ocean water is changing. Melting polar ice caps create another problem -- they decrease the salinity of the Earth's oceans. The increase in planetary carbon dioxide is also changing the ocean's acidity. The plants and animals that live in the ocean are at risk from these changes. These changes may also affect the way that the ocean functions, like how it deals with pollution or how nutrients cycle through the marine ecosystem.

What can we do? These problems facing our planet can seem overwhelming. But here are some concrete things that you can do to make a difference:

Learn about the greenhouse effect and climate change. Over 7,000 blogs have chosen today, Blog Action Day 2009 to focus on climate change. Check them out!

Reduce your carbon footprint. Your carbon footprint is the amount of greenhouse gases (like CO2) that is being released into the atmosphere because of your behavior. If you carpool, turn off the lights, recycle, and shop locally, you will be reducing the amount of carbon entering the atmosphere.

Let your voice be heard! Join organizations that are working to understand climate change. As soon as you are old enough, vote! Support candidates that understand the environmental problems facing our planet.

Study science, math, and engineering. Scientists are already finding ways to sequester carbon (moving carbon from the atmosphere back into a solid form). Someone like you can invent a new and wonderful way to help address our planet's carbon problem!


(My thanks to Kerm and Itinerant Cryptographer for providing helpful comments on early drafts of this post.)

Website of the Week: Dig It! The Secrets of Soil

The Smithsonian National Museum of Natural History is currently featuring a new exhibit called Dig It! The Secrets of Soil.

What is Soil? Here's a handy definition I learned in graduate school -- Dirt is dead. Soil is alive. Soils are dynamic ecosystems filled with living things like insects, worms, bacteria, and fungi.

How do soils form? Check out this handy chart to learn more about the five soil formation factors: Climate (Is the surrounding area rainy or dry? Salty or devoid of minerals?) , Biota (Which plants and animals live and use the soil?), Slope (Did the soil form on a mountainside or in a valley?), Bedrock (What kind of rock has contributed to the soil?) and Time.

How many different types of soil are there? "Scientists recognize about 70,000 soil types in the United States alone ..." according to Paul Reich of the Natural Resources Conservation Service of the USDA, as quoted in this exhibit. His Global Soil Regions Map is shown on the NRCS Soils Website.

Check out the Educators Activity Page for fun ways to learn about soils both at the museum and at home. Learn More about soils by visiting these websites recommended in the exhibit.

(My thanks to Soils Professor Dan Richter for letting me know about this exhibit!)

Website of the Week: EPA Global Warming Kids' Page

Head on over to the EPA Climate Change Kids Site to read about climate change, view Climate Animations, and play a few games (I tried playing Checkers with Ozone the dog and learned that my game is a little rusty! I did better when I tried Hangman and took the climate change quiz).

P.S. Sorry this post is so short -- it's been a long week. Have a great week-end! :)