Looking into the Iowa Deciduous Forests Past

In 1846 Iowa gained statehood and migrants rushed to the prairie taking advantage of free land made available by the government.  That same year, my German ancestors journeyed  across the Atlantic, through the eastern U.S. to the mighty Mississippi.  The country and forests look much different from what we have been discussing in previous blog entries on deciduous forests.  The Mississippi likely would have been the largest muddiest river they had ever seen.  Being the railroad would not have crossed into Iowa for four more years, migrants would have had to pass through the river bottomlands on foot or by wagon and cross the river by ferry.  Just thinking of crossing it would have been a daunting task.  Even if trails had already been blazed,  swamps, backwaters, islands, and mud in the bottomlands lining the mile or so wide river made crossing into Dubuque, Iowa from Illinois or Wisconsin quite an adventure.  The entire journey through bottomland muck and across the river could have been many miles.  Logging of the bottomlands would have begun at a larger scale 12 years prior to this time when the first sawmills were built in Dubuque, but the forests still would have largely been untouched by logging at this time.

A muddy bottomland forest.

First Steps in Iowa
Once crossing the Mississippi and setting foot in Iowa for the first time, it is likely migrants first entered an area covered with early successional Cottonwood and Willow forests along the river banks.  Being near the river, frequent flood disturbance and soggy soils would have maintained this forest type.  Heading inland, areas with slightly less soggy soils and less flood disturbance Boxelders, Ashes, Silver Maples, and Elms would have increased in abundance.  Elms of that time were very different from today.  Large, often several hundred year old Elms would have been common at that time.  Today however, Elms have been resorted into small understory trees only living a few decades at most due to the introduction of Dutch Elm Disease into the Midwest during the 1900's.  Further inland, less disturbed areas would have likely had more Sugar or Red Maple dominated forest than we see today.  Sugar and Red Maple, being a late successional climax species, would have likely been more abundant simply due to the lack of logging, allowing for succession to come to climax.

Moving upward, away from the river, more rarely flooded terraces would have had Oak-Hickory type forests.  Many types of Oaks would have been present including Swamp and Pin Oaks in wetter areas, White, Red, and Bur Oaks in the drier areas.  Bitternut Hickory would also have been in wetter areas and Shagbark Hickory in drier areas.  Some of the trees common below the terrace such as the Maples, Boxelder, and Elms would have also been present in this area, especially in moister locations.

Mature White Oak forest with widely spaced trees.  After coming out of the Mississippi River bottomland forests settlers likely found forests such as this one where wagons could easily move through the trees.  The floor of this forest is burned every few years, removing non-fire resistant vegetation.  Larger fire resistant oaks however survive the fires.

Entering the Prairie
Marking the end of the Mississippi river bottom, 200 to 300 foot steep limestone bluffs rise into the Tallgrass Prairie.  Moving up the bluff, the land became drier, and fire rather than flood became the major disturbance type.  All other species of trees slowly left the forest except for several species of Oaks.  White, Bur, and Red Oaks formed a woodland to savanna forest type.  These Oaks, due to their thick barks, easily survived the frequent prairie fires.  Non-fire adapted trees and shrubs, as well as smaller trees and seedlings of fire adapted species, were killed off by fire.  Larger Oaks however survived.  These forests were filled huge magnificent widely interspersed Oaks several hundred years old.  Today, most Midwestern forests are thick with vegetation and one could never imagine driving a wagon through them without running into a tree.  In 1846 however, the trees were so widely inter-spaced along the river bluffs that wagons were easily driven through.  Moving further from the river, trees likely became limited to valley and creek bottoms where they were protected from fire.  Ridge-tops, where it was driest and fires most frequent were primarily un-plowed prairie at this time.

Most free government issued homesteads were on these prairie ridge-tops.  This is simply because hills and valleys became less frequent and prairie became the most abundant ecosystem type the further away from the Mississippi you moved.  Prairie grass was so thick and tall it was difficult and dangerous to navigate through.  This grass was easy to get lost in and was home to buffalo and rattlesnakes, among other dangers.  Settlers often could not find their homesteads in this sea of grass.  So the Army Corp of Engineers at that time would burn the grass and mark the corners of the homestead.

An Oak Savanna, likely similar to what 1800's settlers would have seen.  These oaks have thick bark that  helps  these trees to survive frequent prairie fires.  

It is unknown how extensive Oak Savannas were prior to settlement.  These savannas contained relatively few Oaks, widely interspersed in the prairie grass.  Being Oaks were the most readily available building material these savannas were the first to be logged.  It is likely there were extensive savannas in Eastern Iowa, they were however logged prior to any scientific investigation.  The first settlers built their log homes, sheds, and barns out of these oaks.

Today, Oak Savannas are gone for the most part and only about one third of the overall Iowan forests remain.  These forests are almost all likely in earlier successional stages than they were in the mid-1800's.  This is simply due to the fact of logging and agricultural disturbance over the past 150 years.  Bottomland forests are about half what they were prior to settlement simply due to development within old bottomlands.  Oak-hickory forest types, once limited to bottomland terraces have expanded into uplands due to lack of fire disturbance.  But none of this is to be negative about Iowa's forests.  Though very different from what they were 100 plus years ago, they are still magnificent displays.

A large White Oak, similar to ones Iowan settlers would have seen in the 1800's.

August in the Sonoran Desert: Monsoon Season

The very large anvil portion of a large cumulus cloud from the Arizona Monsoon season.  Often huge anvils like this mean a strong monsoonal storm is coming.  Picture from:http://www.wrh.noaa.gov/fgz/science/monsoon.php?wfo=fgz 

So far this year monsoon season has been a flop.  We are towards the end of August with only an inch of rain or so in Phoenix, only 0.25 inches in the mountains west of Phoenix, and a fortunate 2 inches in the mountains east of Phoenix.  Other areas of the Sonoran Desert are also below the average summer rainfall totals, which are about twice or more than what we have received.  This is quite disappointing considering we haven't had good summer rainfall for several years now.  Us desert dwellers look forward to the break in the summer heat that rainfall provides.  But as is normal for the desert, there really isn't such thing as "normal" rainfall in the desert.  Fortunately, these poor rainfall reports could change to above average with a single large thunderstorm.

What is the Monsoon?
Monsoon season in the Sonoran Desert technically begins June 15th and ends September 30th.  During this time period, the normal dry heat of the desert is replaced with humidity from the Pacific Ocean and Gulf of Mexico.  Extreme summer heat in the desert causes rising air, creating a low pressure system pulling in this tropical humidity.  Wind patterns change as a result of this low pressure, shifting the normal dry western winds to humid winds out of the southeast.  This shifting wind pattern is where the monsoon gets its name, and means "wind-shift" in Arabic.  In order for rain to fall, high level humidity must be in place from the Gulf of Mexico (called the Bramuda High) and low level humidity must be in place from the Pacific Ocean and Gulf of California.

An anvil cloud, a type of cumulus cloud that results from hot rising humid air.  The flat top is a result of cooler air higher in the atmosphere.  There are no obvious cirrus clouds surrounding this cloud.    Picture from Wikipedia.

How to predict a monsoonal thunderstorm without the weatherman
1. High temperature around 100 to 108 degrees are optimal.  These temperatures heat moist air causing it to rise and form rain clouds.  This heated rising air is called convention and the resulting clouds are known as convection clouds.
2. High due points above 50 to 55 degrees, the higher the better.  This supplies the moisture to form clouds and rain due to rising air.
3. Winds generally coming out of anywhere from the south to east to north.  These winds are blowing humid air into low pressure systems and rise to form clouds.
4. Low level cumulus clouds, another indication of lower level atmospheric humidity.  These clouds should form with convection causing moist air to rise due to afternoon heat.  And of course, you need clouds for rain.
5. Large cumulus clouds that form flat-tops called anvils.  The larger the anvil generally the larger the storm.  Clouds wider then they are tall bring the most rain. Smaller, or tall skinny clouds with or without anvils and may appear to be leaning to one side, may bring small amounts of rain, or rain may never hit the ground.
6. High level cirrus clouds.  These clouds may indicate no rain if scattered.  Cirrus clouds are not always present, but a good storm will almost always have cirrus clouds proceeding it around the anvil.

Monsoonal thunderstorms in the Sonoran Desert are quite complex, it takes a lot of different things to be in place for a good storm to happen.  For example, if low level moisture is in place but high level moisture is not in place, clouds will form and some rain may fall from these clouds but may never reach the ground.  Clouds that form under these conditions often will be small, bent in one direction.  If however high and low level moisture are in place, rising humid air will form cumulus clouds lower in the atmosphere that continue to rise until they hit higher level cooler air.  This will result in an anvil cloud, which is a type of cumulus cloud with a flat top like an anvil.  This rising humid air hitting cooler air can form some pretty amazing storm clouds and at times some pretty amazing rainfall.

Monsoon Thunderstorms in the Desert
The drenching rain, spectacular lightning, and violent winds are something to behold.  Experiencing this type of storm will most definitely leave an impact on anyone.  Everything in the desert waits longingly for these storms.  In the dry hot months prior to monsoon season, the land becomes painfully dry, causing plants to shrivel up and die or go dormant.  Watering holes also dry-up, forcing many animals such as javelina and mule deer to stay near more permanent water holes in the mountains.  Mountain lions take advantage of these times by stalking prey near these watering holes, making life even worse for these thirsty animals.  Other animals and birds simply hide away from the heat, only coming out at night or limiting their activity all together.  Everything hides from the heat and dryness, waiting for rain.

An Ocotillo leafing out after some modest summer rainfall.   Most of the year this plant remains leafless in order to conserve water.  When it rains however, the plant quickly grows leafs.  These leafs remain on the plant until the soil drys out.  Once dry the leafs turn yellow and fall off, waiting to leaf out until the next rainstorm.

However, when a drenching rain hits, temperatures can at times drop from the 100's to the 70's or lower.  The ground becomes soaked. If rain comes hard and fast enough the washes fill with water, sending flash floods through the mountain canyons and into basins below, creating new and filling old waterholes to the brim.  With this water, life and energy return to the desert once again.  If you go hiking after a major rain, one of the first things you will notice is the new flurry of insect activity.  Ants will dig out highways in the washes.  Swarms of tiny mosquitoes will form (the one time of year you will want bug spray).  All sorts of gnats will also come out.  This also seems to awaken bird life feeding on these insects.  Animals that were limited to the areas around waterholes in the mountains the day before will once again venture out.  Even in the city, the most non-outdoorsy people will venture outside to experience the break in heat and dryness.  Several days after rainfall, plant life begins to awaken.  Dried out Triangle Leaf Bursage, Brittlebrush, and Creosotebush green-up and begin to grow again forming new leaves.  Ocotillos, which spend most of the year leafless form new leaves.  The Palo Verdes will also grow new leaves.  Annual plants like Prickly Poppies and Sacred Daturas will germinate and grow.

All this activity will slowly wane after days to weeks of time if rain doesn't return.  With the decline of monsoon season towards the end of September though, life does not return to the dull seemingly lifeless heat.  Rather, temperatures have cooled considerably and often more water remains across the landscape as we head into fall.

More information on the Arizona Monsoon: http://geoplan.asu.edu/monsoon.html

How to Map Soils

Looking at this landscape a little knowledge of soils can explain a lot of things.  Learn how to piece together landscape stories with the information on soil distributions and mapping in this blog entry.

Unless you are a little unusual, you probably rarely consider the soil we walk across.  But its OK to be a little unusual, the benefits can be great.  If when we are hiking, or even in our own backyard, we were to consider the soil we stand on and how different types of soil are distributed around us, the education we would receive would be great.  Far to often even seasoned research scientists will forget about the soil they walk over, even if it makes a huge difference to what they are studying.  It would literally pay for these scientists to have a little soil education.  By using the clues outlined in this article you can begin to piece together where specific types of soils are located, and begin to develop a story to how the land, plants, and animals came into their present state.  This also helps in understanding gardening or landscaping projects.  Every landscape has a story to tell, and very often that story starts with the rocks and dirt.  Here are the clues to look for:

Parent Material
What is the general type of rock that you find in an area?  A good rock book will help you figure this out.  Certain rocks will produce certain soils (click here for a previous blog on this subject).  Fortunately, there are only a handful of different types of rocks most soils are made out of.  Where I live in the Arizona Sonoran Desert the most common rock parent materials are granite, gneiss, basalt, and schist.  Where I grew-up and still visit often in Iowa limestone and sandstone are the most common rocks.  In Iowa however, rocks are usually not present and the parent material is glacial deposits (glacial till), alluvial (water deposited along rivers or streams), or loess (wind deposited).  The lack of rocks also is a good indicator of a particular soil type.  If there are no rocks try to use landform or landscape position to identify soil.

An example of landforms in the Sonoran Desert.  The foreground of this picture is a flat basin with only 1 to 2% slope.  In the middle of the picture is a long narrow hill called a banali.  In the distance are mountains.  Each of these landforms will have their own soil types.   

Landform
What types of landforms are near you or are you on?  Hills, mountains, basins, plateaus, plains, depressions, small rises will all produce different soil types.


Landscape Position
Where in the landscape do you find yourself?  This is similar to landform but more specific to where you find yourself on a particular landform.  Do you find yourself on a hillside, a hilltop, a flat plain along a river, a mountain?  Are you close to a mountain or far away from a mountain?  All these different areas will have different soils.  Also consider elevation.  Are their multiple plains, or flat areas, each with different elevations?  Each individual plain will likely have different soils.

This granite rock and the lack of other rocks in the area indicates glacial till as the parent material.  This rock was carried by a glacier from Canada to Iowa during the ice age.  The landforms in this picture also indicate different soils.  The flat area in the mid to foreground are one type of soil and the hill in the background has a different type of soil.  Behind where this photo was taken is another flat area, lower in elevation and with finer textured soil along the Cedar River, indicates another soil type.  Difference in vegetation does not indicate different soil types in this picture due to different disturbance histories.  The grassy area is disturbed by burning every few years while the forest is not burned.  

Slope
What is the general slope of the landform you stand on?  Again, this overlaps with landscape positions and landform, but helps you narrow down a particular area to a particular soil type.  Is the slope steep, flat, moderate?  Approximately, what is the percent of slope?  Consider landform or landscape position again, hilltops will have one particular slope, hillsides another, and basins or plains another.  Each will have a different soil type.

Soil Color
What is the soil color?  Refer to this previous blog entry to find more about what that soil color means.  One particular soil is going to have one general soil color.

Soil Texture
What is the soil texture?  Refer to this previous blog entry to find out how to determine and what that soil texture means.  One particular soil type is going to have one general soil texture.

Plant Communities
Generally, plant communities correspond directly to soil types.  Meaning, two different soil types are going to have two different plant communities.  The differences in plant communities may not be obvious.  Also, if there is a history of disturbance using plant communities as an indicator for soil becomes worthless.  For example, using plant communities as an indicator in deserts works extremely well due to the fact that deserts usually lack fire or agricultural disturbance.  In the Midwest however, fire is a normal part of prairie management but not of forest management.  And depending on when agricultural or logging disturbances in the Midwest happened will also determine what stage of succession a forest is in.  So depending on when and what type of disturbance has happened historically, one particular soil type may have several different plant communities.

So piecing all these things together, you can determine that an area has one particular soil type if: 1. the area is on a particular landform, 2. the area is on one particular landscape position on that landform, 3. that area also has similar parent materials, 4. The area also has a general soil color, 5. the area also has a similar soil texture.  Lastly, plant communities may or may not indicate a soil, depending on disturbance history.

This may seem like a lot of information, but with some practice this becomes a lot easier.  Landscape stories can be quite fascinating and often, most of the information you need is right under your feet.