Monday, August 19, 2013

Ecology as a Bridge

Last year, as some few followers of this blog may remember, I spent much of the year reading a textbook on biology--and posted some of what I learned, including posts on cells (Biology 101: Cells, 5/3/12), Cellular Respiration (5/10/12), and Photosynthesis (5/17/12).  In spite of the fact that I wrapped up the series early, I read through almost all of the book--almost everything except for the last section which was on ecology.  That was ironic because ecology was one of the things I was most interested in.  This year, as I was traveling--and up to the present, the book has been in a sealed box in a friend's basement.

However, as the last bunch of posts indicate, as I've been resting from my community travels, I've been going on a science reading jag.  I got very excited when I found a classic book on ecology and ecosystems at the co-op next to where I'm living.  The book is Ecology: A Bridge Between Science and Society, by Eugene P Odum.

This is a great introductory text.  It covers almost all the basics including Levels of Organization, emergent properties, The Ecosystem, biotic communities, the Gaia hypothesis, Energetics (which I'll write a bit more on later), various cycles (hydrological, nitrogen, phosphorus, sulfur, and carbon), soil as a resource (see my post on Soil Science, 7/20/13), Population and Community Ecology (including things like r- and K-Selection, carrying capacity, commensalism,  cooperation, mutualism, and a whole section on the lichens),  successional theory, and Major Ecosystem Types of the World.  Eugene Odum ends the book with a chapter focused on how the human race can become sustainable, which he calls The Transition from Youth to Maturity.  The book is written simply but with lots of clear information. I would recommend it to anyone who wants to get a basic understanding of ecology and ecosystems.

Eugene Odum's brother, Howard T Odum  was also an ecologist. I was able to get one of his books (Environment, Power, and Society) out from the library.  This book is focused on energetics and is a lot more technical and detailed than his brother's Ecology book.  I can imagine it would be useful if you wanted to study ecological energetics in depth, but I decided that it was too technical for what I was currently looking for.

If you are interested in permaculture or understanding how ecosystems work or even the biological and ecological understandings of today's multiple crises, I think that Eugene Odum's Ecology: A Bridge Between Science and Society is a great place to start exploring the concepts you need to understand.

Quote of the Day: "These scenerios are not predictions, since, as we have already stressed, no one (and no computer) can really predict the future; they are more like weather forecasts that have a certain probability of being right or wrong.
"...The logical consequences of placing value only on the individual are continued rapid expansion of world population and degraded life-support ecosystems.  Together these will lead to a less than satisfactory life for all but perhaps a few very rich people, since air, food, and water will be increasingly poor in quality and short in supply.
"The alternate scenerio ... is based on the assumption that we will turn more and more to the long-term view, with value placed on species (ours and all the others) and on maintaining healthy ecosystems worldwide. The logical consequences ... are reduced population growth (with stabilization in the next century) and healthy life-support systems, leading to favorable survival for all people and all life." - Eugene Odum



Tuesday, August 13, 2013

The Earth's Spheres

While reading books on meteorology and ecology, I've found references to the 'spheres' of the Earth.  One book mentions four spheres and another book mentions four spheres in one place and five in another.  In one place it's called 'the Earth system', in another 'the climate system', and a third just calls it 'Spaceship Earth'.

Some quotes: "As we study Earth, it becomes apparent that our planet can be viewed as a system with many separate but interacting parts or subsystems.  The hydrosphere, atmosphere, biosphere, and solid Earth and all of their components can be studied separately.  However, the parts are not isolated.  Each is related in some way to the others to produce a complex and continuously interacting whole that we call the Earth system."  - Lutgens and Tarbuck, The Atmosphere, p 4

"...there is a climate system that includes the atmosphere, hydrosphere, solid Earth, biosphere, and cryosphere. (The cryosphere is the ice and snow that exist at Earth's surface.)  The climate system involves the exchanges of energy and moisture that occur among the five spheres." - ibid, p 321

"The biosphere or ecosphere merges imperceptibly (that is, without sharp boundaries) into the lithosphere (the rocks, sediments, mantle, and core of the earth), the hydrosphere (surface and ground water), and the atmosphere, the other major subdivisions of Spaceship Earth." - Eugene Odum, Ecology: A Bridge Between Science and Society, p 31

As I've been reading books on geology, soil science, meteorology, and now, ecology (probably the subject of my next post), I've become more and more aware of how connected they all are.  I tried to get that across in my post on The Chemistry of the World, 8/2/13, where I talked about how plants use minerals from the Earth's crust (the lithosphere) and chemicals from the atmosphere (especially carbon dioxide and nitrogen) as well as water (from the hydrosphere) to grow from, and how we then get those same elements from the plants.  And, as I've talked about in my posts on composting (see for example, Thinking in Circles, 1/6/13), eventually we return those elements back to the earth.

It's interesting thinking about these spheres in terms of climate change as well.  The book on The Atmosphere listed the elements in the atmosphere by percentages and parts per million.  They listed Carbon Dioxide (CO2) as 0.036% or 360 parts per million.  The book has a copyright of 1998.  The news this year is that CO2 in the atmosphere has just reached 400 ppm.  The book also states that "...glacial ice is the Earth's largest reservoir of water outside of the ocean, accounting for 85 percent of the planet's fresh water.  ... As glaciers are composed of solid water, they are usually considered to be part of the hydrosphere.  Sometimes Earth's ice is placed in it's own 'sphere',the cryosphere (cryo is from the Greek for 'icy cold')."  It occurs to me with the rate that the glaciers are melting, that distinction may not be that relevant for long.

It's all only one planet and everything is connected with everything else--and everything changes everything else.  The boundaries between what we call living things and the systems of air, rock, water, and ice aren't as great as we might think.


Quote of the Day:  "The biosphere includes all life on Earth and penetrates those parts of the solid Earth, hydrosphere, and atmosphere in which living organisms can be found.  ...it should be emphasized that organisms do more than just respond to their physical environment.  Indeed, through countless interactions, life-forms help maintain and alter their physical environment. Without life, the makeup and nature of the solid Earth, hydrosphere, and atmosphere would be very different.  ...
"Humans are part of the Earth system, a system in which the living and nonliving components are entwined and interconnected.  Therefore our actions produce changes in all of the other parts." - Frederick Lutgens and Edward Tarbuck

Wednesday, August 7, 2013

Weather

A few years ago, I realized that I had a basic understanding of most of the sciences.  A big exception was meteorology.

I would look at those weather maps and glaze over.  High pressure area, low pressure area, warm fronts, cold fronts, occluded fronts, what did it all mean?  What was with all those different types of clouds?  And how could anyone even try to predict the weather?  (Unfortunately, this post won't try to explain how to predict the weather.  I will list some references that you can get more information about weather prediction from if you want to learn more.)  I vowed that at some point I'd study the atmosphere the way that I'd studied oceans, lakes, and rivers a few years ago, and biology last year.

This summer, at a time when I was having trouble finding more books on soil science, and after studying as much basic geology as I wanted, I decided it was a good time to study meteorology, the atmosphere, and the weather.

To begin with, what causes the weather, the winds in particular, and the complexity of the weather in general, is a variety of factors in the way that the sun heats the earth. The first and most basic factor is the shape of the earth, which is a sphere.  The sun's rays strike and heat up the atmosphere around the equator more than at either of the poles.  This is because the angle of the sun's rays is more direct in the tropics (close to 90 degrees at noon) than it is at the poles (where it might be, perhaps, 30 degrees).  So, as we all know, it's a lot hotter in the tropics than it is within the arctic circle.  When air is heated, it rises (ask someone who lives in a third floor apartment), and when it's cold, it sinks.  The warm air rising causes the air pressure to fall (the area becomes a low pressure zone) and the cold air sinking causes the pressure to rise (creating a high pressure area). 

If the earth were a simple ball and the sun revolved around it, this would mean air would be constantly moving from the tropics to the poles. (And air moving is, of course, wind.)  But the earth does revolve and this causes the winds to shift (in several zones).  In the northern hemisphere, this causes winds blow from west to east.  (I had learned that in New England, our weather usually comes in from the west--in this case, New York.  Now I realize that weather can travel all across the continent, beginning at the Pacific Ocean.  In Europe, the weather comes off the Atlantic and moves west.)  But the earth isn't a perfect little ball.  To begin with, two thirds of it is water, mostly the oceans.  The water takes longer to heat up and longer to cool down than the earth.  (Ask anyone who lives near the ocean.)  Then there are mountains and valleys--not to mention concrete cities that form little heat islands.  The upshot of all this complexity is our ever changing (and difficult to predict) weather.

When a warm, low-pressure area, encounters a cold, high pressure area, it creates a front.  (This was figured out during World War I by Norwegian researchers with battles on their minds.)  If warm air is in charge, it's a warm front.  If the cold air advances, it's a cold front.  If it's more complex, with cold air and warm air 'battling it out', it's an occluded front.

I could write a whole post on clouds--but I won't.  I've got a lot more things I want to write on (including more science).  The basics are that there are three main types of clouds, cirrus (high, wispy clouds made mostly of ice-crystals), stratus clouds (a layer of clouds, just hanging there--if it comes all the way down to the ground, you've got fog), and cumulus clouds (big, white, puffy--and often fair weather--clouds).  These are subdivided into ten categories: cirrus, cirrostratus, and cirrocumulus (the high atmosphere clouds), altocumulus and altostratus (the middle atmosphere clouds), stratus, stratocumulus, and nimbostratus (the low clouds), and cumulus and cumulonimbus clouds (which develop vertically, that is, up).  Obviously many of these clouds are combinations of the basic three. 'Alto' means high in Latin, but this describes the middle level clouds. More importantly, 'nimbus' refers to a rain cloud.  The nimbostratus are your ordinary rainclouds, the cumulonimbus are 'thunderclouds' bringing lightning, and often squalls, hail, and occasionally tornadoes.

This is just the slightest bit of meteorology.  I've been reading a lot of books on the subject, but there are two in particular that I'd recommend.  One is a textbook on the subject that I got out of the library:  The Atmosphere by Frederick Lutgens and Edward Tarbuck.  The other is a more readable (and sometimes humorous) treatment that was loaned to me by my brother, Spencer Christian's Weather Book by Spencer Christian with Tom Biracree.

I know I originally said that I was going to write three posts on science.  I'm still reading and learning and I want to write a few more.  Next, I'll talk about the earth's five spheres.


Quote of the Day: "The sun is the source of almost all the energy that has, is, and ever will be used on Earth... Because our world is solar powered, the sun is the engine of the global weather machine." - Spencer Christian

Friday, August 2, 2013

The Chemistry of the World

This post is a lot more geeky than most of my writings and most people won't lose much by skipping it.  On the other hand, if you want some insight into the way that the natural world works, you might find this post useful.

I'm going to start with four tables that will be the basis for my discussion.


Elements Essential to Human Beings
(by volume)

  • Oxygen
  • Carbon
  • Hydrogen
  • Nitrogen
  • Calcium
  • Phosphorus
  • Potassium
  • Sulfur
  • Sodium
  • Chlorine
  • Magnesium
  • Iron
  • Manganese
  • Iodine
  • Silicon
  • Florine
  • Copper
  • Zinc


Elements Essential for Plant Growth

  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Phosphorus
  • Potassium
  • Sulfur
  • Calcium
  • Magnesium
  • Iron
  • Zinc
  • Manganese
  • Copper
  • Boron
  • Molybdenum
  • Chlorine
  • Nickel
  • Silicon
  • Sodium
  • Vanadium
  • Cobalt
  • Iodine


Elements that Make Up the Earth's Crust
(by percentage)

  • Oxygen
  • Silicon
  • Aluminum
  • Iron
  • Calcium
  • Sodium
  • Potassium
  • Magnesium
  • Titanium
  • Hydrogen

Constituents of the Atmosphere
(by percentage)

  • Nitrogen
  • Oxygen
  • Argon
  • Carbon Dioxide
  • Neon
  • Helium
  • Methane
  • Krypton
  • Hydrogen



Let's start with the first two lists.  The elements essential to humans are very similar to the elements necessary for plant growth.  The order of some of the initial elements is slightly different and it's obvious that plants need a lot less chlorine and sodium than humans (in fact, some scientists question whether plants need sodium, or any of the last five elements on that list, at all).

The similarities between the first two lists shouldn't be surprising.  Humans get most of what we need from plants.  (See my posts on Biology 101: Photosynthesis, 5/17/12, and Biology 101: Cellular Respiration, 5/10/12, for the details of our essential chemical interactions.)  Where do plants get these elements?  The most important elements come from the air (atmosphere) and the water in the soil.  Plants take in carbon dioxide and water and use the carbon, hydrogen, and oxygen from them to create sugars.  (Again, see my post on Photosynthesis.) They then use these sugars as the basis to build more complex chemicals (for example, cellulose which makes up plant walls).

Plants also get nitrogen from the atmosphere--but not directly.  As I wrote in my last post (Soil Science, 7/20/13), the soil is filled with pores that contain air and water. Bacteria in the soil convert nitrogen (N2) to ammonium (NH4+), and then to nitrite (NO2-) and nitrate (NO3-).  These ions (as their called) are easier for the plant to take up.  (A small amount of the nitrogen in the atmosphere is converted by lightning into nitrous oxide--N2O--which gets carried into the soil by the rain and the plants can also take up.)  This process of conversion which is so important to plants is called the nitrogen cycle.  (There is also a carbon cycle and a hydrologic or water cycle that carbon and carbon dioxide as well as water go through.)

The rest of the elements come through the soil.  As I explained in my last post (Soil Science), soil is made mostly of broken down rock.  If you look at the table of elements in the earth's crust, you'll notice oxygen is the top element (and is, in fact, in one of the first three categories on all four lists).  But the next two mystified me for a while.  Silicon is at best a trace and relatively unimportant element for humans and plants and aluminum isn't used by them at all.  Then I discovered that silicon and aluminum are bound tightly to the oxygen in the compounds found in rocks.  However, the next five elements (iron, calcium, sodium, potassium, and magnesium) are, along with sulfur and phosphorus, the most important elements in living creatures (well, sodium isn't so essential for plants) after the basic carbon, oxygen, hydrogen, and nitrogen. It turns out that these elements aren't so tightly bound to the rock.  Ions (parts of compounds that are separated and thus have a charge) come loose.  The ions of these five elements (all metals) are positively charged and known as 'cations'.  (Negatively charged ions, such as chlorine, are known as 'anions'.)  One of the main reasons that humus and clay in soil (see my last post) are so important is that they have negatively charged areas that can hold these metal ions.  (This is known as the Cation-Exchange Capacity of the soil and is very important in understanding soil and plant nutrition.)  The roots of the plants exchange hydrogen ions (also positively charged) for these essential metal ions.

The whole thing is very delicately balanced and is, of course, circular.  (See my post on Thinking in Circles, 1/6/13.)  It makes me convinced that the whole earth is just one giant ecosystem.  Gaia.  We live here--and we live here because of the plants, and the rocks, and the soil, and the atmosphere.  It's all connected.

Next, the weather.


Quote of the Day: "We know from science that nothing in the universe exists as an isolated or independent entity." - Margaret J. Wheatley