What do rocks have to do with plants?

For quite a few years now I have been fascinated by the effects rocks have on plants.  This might seem weird but rocks have major influences on soils which in turn influence plants.  Why you might ask?  Well it all has to do with rock texture.  Which probably leads you to another questions, what the heck is rock texture?  If you look closely at many rocks you can see particles, or crystals, that make up the larger rock.  Granite is a good example of a rock with obvious smaller crystals.

This is a close up of a granite counter top and clearly displays the different crystals present in the overall larger rock.  The entire image is granite rock, which is made up of black, white, and gray colored crystals.  The white crystals are quartz, the gray are feldspar, and the black are mica.  These crystals break off, or weather off, of the original rock to form sand for soil. 

These smaller crystals with time break off of the original rock to form particles that will turn into soil.  Water, chemicals, heat, cold, and so on all work together to weather, or break down, larger rocks into smaller crystals.  These larger rocks are known as parent materials and are most often in the form of bedrock or mountains.  Almost all of any given soil is made up of tiny weathered (or broken down) pieces of rock parent material.  So crystals or particles making up rocks are eventually broken down into soil.  The texture of any given rock corresponds to the texture of a soil.  For example, granite has a course texture and weathers into a course texture, or sandy, soil.  Other rocks such as basalt have a very fine texture and will weather into a very fine textured, or clay, soil.

Basalt has very tiny crystals that when weathered produce clay soils.  The crystals in basalt are so small they typically can not be seen.

 So rock texture determines soil texture, so what?  Soil texture then determines how much water a particular soil can hold.  Clay soils hold lots of water for a long time but absorb water very slowly.  While sandy soils absorb a lot of water very quickly but also dry out very fast.  Plants will colonize and grow best in the soils with textures that hold the right amount of water for them.

So how can you identify the soil parent material and what soil texture comes from it?
1. Find the most common type of rock at a particular location.
2. Looking closely at the rock, does it have larger or smaller crystals or particle sizes?
3. The larger the crystals/particles the more sandy the soil.  The smaller the crystals the more clay the soil will have.

The above rules generally hold true near mountains or where bedrock is close to the surface.  It does not hold true in a few cases.
1. If the predominate rock is limestone.  Limestone doesn't weather into soil particles, it rather is dissolved by water and washed away.  For this reason, limestone doesn't make soil texture like other rocks but certain types of soil will form from it.
2. If you are very close to a stream or river.  If you find lots of roundish rocks in the area, they are alluvial, or water, deposited.  In this case the soil will typically have a lot of clay.

If you find a lot of rocks in an area that look roundish like this you can know the area has alluvial, or water deposited, soil.

3. Areas with hardly any rocks are often wind or glacial soils.  Glacial soils will generally have a few very round rocks and occasionally very large round rocks.  These will also form special soil types but you can't use the rocks to identify the soil texture.  The Midwest is covered with these types of soils.

So using rocks can be very useful when trying to understand a habitat and determining how soil is influencing plants and animals.  In doing this the best book I have found in identifying rocks and their textures is "Smithsonian Handbooks: Rocks and Minerals".  This book has the clearest, most useful pictures of any rock and mineral book I have looked at.  It also has extremely useful information organized in a very easy to use and understand way.  One of my favorite features along with the great photos is the "grain size" information that goes along with each rock.  Grain size is the rock texture that we discussed above and fine grain size will result in fine clay soils, medium grain size a silt soil (half way between sand and clay), and a course grain size a sandy soil.

 

While this post discussed how to identify soils by looking at rocks I will have another post on how to identify soils directly by touch and later show how these things relate to the plant and animal life in a habitat.  Understanding and using rocks and soil textures are extremely useful when trying to find specific plants and even animals.  I personally have used rocks to help locate plants as well as places to find birds and animals.  But it works best for plants.

Medicinal herbal tea: Stinging nettles

In the interest of the Stinging Nettles project I am working on a coworker gave me some organic nettle leaf tea from traditional medicinals to try out.  Being that stinging nettles are full of all kinds of medicinal chemicals it would be very logical to expect nettles to have medicinal benefits.  Some of these medicinal chemicals are anti-inflammatory and have been shown to reduce joint point and allergy symptoms.  Another compound called formic acid is a known anti-bacterial.  Serotonin a hormone associated with feelings of love and happiness is also found in nettle.  As a medicinal product however, Nettles are mostly commonly prescribed to alleviate environmental allergy symptoms.

So with this all in mind, along with my allergies, I have tested out this tea several times in the past few weeks.  First off, the tea is a sort of brownish color with a slight green tinge to it.  Taste wise I would say it is neither bad nor good, but definitely easy to drink with no overpowering flavors.  Also, no real aftertaste.  I tried several different steep times ranging from three to ten minutes.  Medicinally ten minutes is probably most beneficial.  As for medicinal results I would say it definitely helps with mild allergy symptoms most of the time and will partially alleviate more harsh allergies sometimes.  As for making me feel happy or in love anything like that I don't know...  This is just my own personal experience but it aligns with much of the scientific research on the effects of stinging nettles.

As with all wild foods such as stinging nettles make sure you have absolute positive identification of the plant.  Check and cross check with experts, books, and the internet.  In the case of prepackaged herbal teas you don't have to worry about identification, its already been done for you.  Once the plant has been positively identified taste a small amount and wait several hours to make sure you do not have an allergic reaction.  Then taste again and wait awhile, if you don't have an allergic reaction go ahead and try it.

Simple aquatic insect sampling

Plastic mesh bags like the one above can be filled with leaves and placed in a pond or stream in order to collect aquatic insect larva and nymphs. 

For a number of years now we have been assessing local aquatic insect populations through a rather simple plastic mesh bag method.  The mesh bag, which is slightly larger then a sandwich bag, is filled with leaves, the openings tied shut, and then sunk in a few feet of water.  The bag can be submerged in any type of body of water, whether moving or still, the important part is that you have the ability to retrieve it.  It doesn't have to be deep to produce good results.  Also, make sure you place adequate weight in the bag (a rock will do) so the bag doesn't flow away.  Once the bag is placed on the bottom of a body of water it becomes habitat for immature insects as they colonize it over a period of a few weeks.  After a few weeks the bag can be opened up and the bugs sorted out out from the leaves.

Directions:
1. Obtain a mesh bag of some type.  Mesh bags that onions come in will work well.
2. Cut the mesh bag down to a more manageable size.  If you end up with multiple openings you can simply tie them shut.
3. Fill the bag with dead leaves.  Be sure not to pack them in too tightly.
4. Place a rock in the bag and tie it shut with string.
5. Submerge the bag in a few feet of water at most.  It is important to have the ability to retrieve it.  If it is too deep you might have to swim to get it.
6. Leave the bag underwater for about two weeks.
7. After about two weeks, retrieve the bags, open them up and carefully sort through the leaves to find small aquatic insects.  When transporting the bags from the body of water to where the leaves will be sorted out be sure to keep the entire pack in water.  If the leaf packs dry out the insects will die.  To avoid this place your leaf pack in a one gallon plastic bag or a bucket that has enough water in it to submerge everything.

These leaves are the contents from one of our leaf packs.  The leaves are taken out of the pack and sorted out carefully in trays or bowls filled with water from where the leaves were submerged.  Using a magnifying  glass, tweezers, spoons, and cheep paint brushed help in sorting through the leaves and looking for insects.

Sorting through the leaves in the bag can be quite interesting.  There should be all sorts of tiny creatures swimming around.  A magnifying glass, tweezers, spoons, and paint brushes help in carefully sorting through the leaves to find insects.  Most of the insects will likely be less then a half inch in length so look closely!

In the ponds around Phoenix we find an abundance of mayfly nymphs, dragon fly nymphs, scuds, and fly larva (diptera or "midges").

Mayfly nymph

Scud

Dragon fly nymph