Land Use: A comparative Study Using Aerial Photos

Note: The materials for this laboratory can be purchased at Wards Natural Science (Item # 36 V 0957). This laboratory is based on information from this kit.

Things for you to print out are HERE.

Land use takes into account location, climate, soil type, topography, population, as well as trends in farming, forestry, conservation. Both man-made and natural features affect land use. Different soil types can affect the way land can be used (agricultural vs. commercial, for example).

Land use also depends on the population of people in the geographic location. In this study you will be examine aerial photographs of Pine Bush, NY (Read about the Pine Bush UFO sightings HERE). Pine bush is located about 90 miles north of New York City in Orange County, (41°36'32"N 74°17'55"W hr/min/sec; 41.6089 X 74.2986 decimal degrees). Two aerial photographs will be examined; one taken in 1963, the other in 2004. You will examine each photograph and determine how four types of land use have changed over time:

• Forested: Land covered with trees.

• Open Land: Undeveloped land including farm, field and meadows.

• Developed: Land put aside for urban usage (buildings, roads, parking lots)

• Water: Streams, ponds, lakes...

Procedure (Questions and or required procedures are highlighted in RED)

Work in groups of 3. Obtain the following from the front desk:

• One color photograph (2004) and one black and white photographs (1963).

• One transparent grid

• A set of colored pencils (green, brown, red, blue, black).

1. As a group, compare the black and white photo (1963) with the color photograph (2004). Be sure that you both agree as to the land use characteristics (forested, open land, etc.). What features are found on the 2004 photo that were not seen on the 1963 image?

2. Place a transparent grid over the 1963 of the photograph. Your group will survey one of the 2004 areas A1,A2,A3 (etc) and one of the 1963 areas B4,B3,B2 etc. On your PAPER grid identify the various types of land and make a mark on your PAPER grid according to the following color codes:

NOTE: the land use for the black area at the top or bottom of the 1963 photograph cannot be determined (Their color code will be black). There are approximately 130-135 unidentifiable squares on the 1963 photo. All squares can be identified on the color photograph.

If a road cuts through the grid, record it as "developed". If a river cuts through, mark it as "water". For all other squares identify which type of land dominates that square when deciding the code. MAKE SURE THAT EACH MEMBER OF THE GROUP AGREES AS TO WHICH AREAS ARE "FORESTED", "OPEN", etc.

3. For your chosen areas, identify the type of land use for each of the grids under the transparency and draw in the color code for each of the corresponding paper grids. You DO NOT have to fill each block on the grid; a colored "X" will be fine. Fill in all the squares on your grid. There are 200 boxes for each of the major survey areas.
4. Repeat steps 2-3 using the color 2004 color photograph.
5. I've compiled data for the entire survey of both photographs (needed for the following tables and calculations):

6. Add up the total number of unidentified blocks from the 1963 photo: ______________
7. Subtract the number of unidentified squares from 2000 to determine the number if identified blocks: ______________ The number of identified squares in the 2006 photograph is 2000.
8. For each type of land, divide each number from the above table by the number of identified blocks to determine the percentage use for each land type. Record the percentages in the following table:

9. Using Excel, chart the changes in percent land use between 1963 and 2006. Briefly discuss your results. What might be responsible for the observed changes?

READING TOPOGRAPHIC CONTOUR MAPS

 
Topographic maps of Pine Bush region.

The image above shows the features found on a geological survey map centered on Pine Bush. The map on the left depicts a conventional topographic map while that on the right shows a 3-D rendition. The 3-D map has a vertical exaggeration of 8X. Each contour line connects points of equal elevation. If you were to walk along a contour line you would remain at the same elevation. Index contour lines show the height above sea level. Without labels other than 400 feet it wouldn't be possible to read the above topographic map. The index lines in the above maps are labeled at 400'. Regular lines are not labeled. Normally, index lines are labeled every 100 feet, but the Pine Bush topography only ranges from In (A) I labeled some of the regular lines at the bottom of the map. On this map the interval between the contour lines is 20 feet. Note the hill at 440 feet in (A). Compare this area to the hill in the bottom left of (B). Correlate the relationship between the contour lines in (A) with the terrain shown in (B). If you're having trouble reading the map or just want more information on reading topographic maps, go HERE. Google maps for Pine Bush can be seen HERE.

TOPOGRAPHIC PROFILES

Profile for Pine Bush area.

The above image shows the profile centered around Pine Bush (circled in blue at the center of the maps). The maps show a MUCH greater area than the previous maps to include the mountains in the North West (like a satellite image). The map on the left (A) shows the terrain (vertical elevation magnified 8 times); that on the right (B) is a shaded topographic map. Contour lines are light brown. The profile transect shows the "cut" through which the profile (C) was calculated. The transect was drawn from the South East to the North West end of the map. Arrows show the relationship between map features and the profile itself.

MAKING A TOPOGRAPIC PROFILE FROM A CONTOUR MAP

1. If you didn't print out the contour map and prefer to work off a computer screen (recommended), use THIS link to open a new tab or window (right click) with the map.

2. Lay a strip of paper on the contour map and record the elevation where the contour line crosses the paper (see above). The river (Shawangunk kill) is at 300 feet. Mark the river on your paper strip. NOTE: South of the Shawangunk Kill very few of the 320 foot contours are seen (this sometimes occurs North of the river too. This is not a mistake. The river banks are very steep.

3. Lay the strip of paper on the x-axis of your graph paper and draw the profile as shown below.

3. Make five transects as shown above and prepare a profile for each.

Use the profile to explain the water shed, why land may be used or not used, and the effect topography could have on water quality (you'll probably need to do the Goggle on the interwebs to answer this question).

SOIL CHARACTERISTICS
Soil and dirt are not the same thing. Soil is a complex, living mixture of microorganisms, minerals, organic compounds, air, and water. Dirt is misplaced soil on the bottom of your shoe that no longer has a useful purpose. Soil formation starts when simple organisms, such as moss and lichens settle on a rock. Release of carbonic acid by these organisms begins to dissolve the rock and release minerals. At the same time, the structure of the plants begins to catch wind-blown dust which is added to the soil mixture. The mosses and lichens also begin to attract bacteria, fungi, protists, and animals that begin adding organic materials to the soil through their excretions and deaths. When the mat thickens higher forms of life (both plant and animal) can begin taking advantage of the site which leads to an acceleration in the rate of soil formation.

Surface materials, are transposed from the top layers of the soil to lower layers resulting in soil profiles (layers) called "horizons". From the ground surface to bedrock the soil horizons are named "A", "B", "C", and so forth. Each of these major layers may be subdivided into minor layers through the use of subscripts (e.g. A₀, A₁, etc; see below)

Horizon characteristics.

In general, the A horizon is formed as water moves fine particles leaving the coarse stuff behind. Microorganisms (bacteria, fungi, protists) and other decomposers (insects, roundworms, segmented worms, mollusks and the like) work on the larger particles and break them down into their organic components. This causes the A profile to have the richest supply of organic compounds and minerals. For this reason it is sometimes referred to as the zone of enrichment. Zone B is characterized by dense, fine particles. Zones A and B together comprise the true soil (solum). Zone C is the parent material. Zones M and G are the shattered and weathered remains of C. Soil development starts here. Anything below zone C is not parent material (zone D).

Properties of soils.

• Color: Dark soil color indicates a high humus content that is able to support growth. Red or yellow soils, on the other hand, are often high in iron content that is less capable of supporting growth.
• Texture: If the texture is too coarse or sandy it will be unable to hold water. Inability to hold water causes a loss of humus and an inability to support growth. If the soil is too fine it will impede water flow and aeration. In addition, fine soils hold too tightly to plant foods.

Topography affects soil horizons.
Topography is the study of physical features such as elevation and slope of the land. Even with the same climate, underlying parent material, and organisms to work the soil, landscapes with different topography will result in differing solum production and soil richness (see below).

Soil productivity.

• Nitrogen, potassium, and phosphorus are needed, but they have to be in the proper form or they won't be available to plants. Microorganisms (especially certain bacteria) are necessary to convert these elements into compounds that can be used by plants.
• Trace elements are also needed to support proper plant growth Iron, magnesium, boron, zinc, cobalt, and sulfur are often found in the form of salts.
• pH affects productivity by changing the charge of the soil. Soil charge allows it to hold on to nutrients. If it hangs on too tightly, it won't be available to plants. Too loosely and it'll be washed away when it rains.

The Web Soil Survey at the USDA and Natural Resources Conservation Service is located HERE. I assembled a soil survey for Pine Bush, NY from the USDA link. You can get  the full copy from HERE. An abbreviated synopsis is below....

Custom Soil Resource Report for Orange County, New York, and Ulster County, New York 

Preface
Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. 

Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. 

Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://soils.usda.gov/sqi/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (http://offices.sc.egov.usda.gov/locator/app? agency=nrcs) or your NRCS State Soil Scientist (http://soils.usda.gov/contact/state_offices/). 

Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. 

The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. 

How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. 

Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA.

The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape.

Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries.

Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research.

The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas.

Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape.

Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties.

While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil.

Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately.

Soil Map
The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit.

Full-sized soil map of Pine Bush. The area enclosed in yellow is a swampy area.

 
Map legend and information

 
Highlighted rows are the soil types found in the swampy area.

The soils in the swampy areas also make up more than 35% of the total soil types for Pine Bush. Why might this be and what does this say about the geological history of the Pine Bush area? (See the descriptions of the  soil types in the following panel.

Descriptions of soil types found in the swampy area. The Properties and qualities under the Description of the soil type is the most important section for interpreting the data for this lab.

Use this close-up map to examine the soil types in the swamp area.

Examine the soil types found in the swampy area of the map.  Using the information in the information of the descriptions of soil types found in the swampy area (image above this one), compare and contrast the soil taxa found in the swampy area (what do they all have in common; are there any that don't seem to belong and why?)

Using the USDA Web Soil Survey to explore ecological features.

1. Visit the USDA Web Soil Survey. The Web Soil Survey (WSS) provides soil data and information produced by the National Cooperative Soil Survey. It is operated by the USDA Natural Resources Conservation Service (NRCS) and provides access to the largest natural resource information system in the world. NRCS has soil maps and data available online for more than 95 percent of the nation’s counties and anticipates having 100 percent in the near future. The site is updated and maintained online as the single authoritative source of soil survey information.

2. Start the Web Soil Survey by clicking on the friendly green button at the top of the page.

3. 
   Choose the "Area of Interest (AOI)" tab if it's not already selected and then choose the Navigation method as "Forest Service" on the left-hand side of the screen. For this example I chose Ohio for the state and Wayne National forest. After pressing the View button the map is generated on the right (be patient. it could take a while). For this project you'll be working with Kentucky.

4. 
   Now zoom in on a particular part of the forest. Click, hold and drag the cross cursor over the map. You will see a light gray box. When you release the mouse button the map will zoom to that area.

5. 
   Here is the map zoomed in. Now we need to choose the area for analysis. Click the AOI (Area of Interest) button on the tool bar. Click and drag the mouse to select the AOI (the red box) for analysis. If your AOI is too large you'll see an error box. Close that and choose a smaller area.

6. 
   The program then zooms to the area of interest.

7. 
   Click the soil map tab at the top and the map is generated. The map symbols are described in the left panel. Click the next tab in line (Soil Data Explorer).

8. 
   Under the Soil Data Explorer click the "Suitabilities and Limitations for Use" tab if its not already selected. Then click on the "Vegetative Productivity" tab on the left side and then choose "Forest Productivity (Cubic Feet per Acre per Year). Other productivity indices that would be useful to explore include "Forest Productivity (Tree Site Index)", and each of the "Range Production" choices. Data may not be available for all options. If you click the View Description" button a short explanation window will open.

9. 
   At the bottom of this screen I chose "Virginia pine" from the drop-down box. The above map is generated showing the distribution of Virginia pines in the study site (blue is low density while brighter red and orange are dense stands). Other trees that have been found in the survey can also be explored. Copy each of the maps to a paint program or Word. You can also use the "Save page as..." function under the file menu for your browser. The tree maps are NOT included in the soil report you'll request from the USDA and you need them for the next series of questions. If you do not copy the maps you'll have to do this section over.

10. Choose the Shopping Cart tab at the top of the program to generate a FREE soil analysis of your study area.

Perform a similar analysis of a park in Kentucky. Include all of the tree species in the study area. In my example the dense stands of the Virginia pine appear to be associated with the ZnC soil type. The USDA Custom Soil Report for your area will explain the structures of the soils. Were there any similar trends in your soil-tree maps? List them. What might explain the associations? NOTE: "The Properties and qualities" section of the soil descriptions in your USDA soil report (the pages that look like THIS)