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Initial Publication Date: March 13, 2010

Week 5: Monitoring Invasive Species

On This Page

Using ArcGIS to Analyze and Predict Invasions
Key Investigation Questions
Introduction
Launch ArcGIS and Orient the Map for the Investigation

Zoom_In

Investigate the Tamarix Invasion in the United States

Where is the Tamarix invasion the most severe?

Create a Spatial Query to Investigate the Extent of the Invasion
Focus on Arizona Tamarix

Identify rivers with Identify tool

Add Satellite Data to Connect Tamarix Spread with Vegetation Index
Add Elevation to the Map to Solve the Puzzle
Resources

Using ArcGIS to Analyze and Predict Invasions

salt cedar in landscape

Tamarix forest in riparian zone. Image courtesy of Steve Dewey, Utah State University, United States.

Key Investigation Questions:

How has the Tamarix plant's invasion proceeded over time?
What are the factors limiting Tamarix's spread through the entire United States?
How are scientists using Satellite imagery to aid in predicting Tamarix's next move?

Introduction

Tamarix, or saltcedar, grows as a woody shrub or small tree. It was introduced to the United States in the 1850's as an ornamental plant capable of erosion control. It successfully adapted and quickly spread into wetlands displacing native trees such as cottonwood, willow and mesquite. Now, Tamarix has invaded nearly all the watercourses and wetlands in the Southwest US. As one of the most successful and common invasive species in the United States, it has overtaken nearly one million acres of habitat. Since it can transpire as much as 300 gallons of water per day, it is capable of causing a wetland to completely dry up. Additionally, Tamarix has a tendency to increase the salinity of the soils in which it grows and it is of little or no value to wildlife. Although Tamarix is difficult to eradicate, in locations where it has been eliminated native vegetation and wildlife have returned and flourished.

Launch ArcGIS and Orient the Map for the Investigation

Launch ArcGIS by double-clicking its icon on your desktop or by clicking its icon on the Launch Bar (Win).
Choose File > Open, navigate to (path) and select the file C:/EYESINTHESKY2/WEEK5/Invasive_SpeciesAM. Then click open.
Once the map opens, turn on the US Rivers and Tamarix layers. Use the Zoom In tool to click and drag a box, around the contiguous United States.

Turn on the US Rivers and Tamarix layers by clicking in the checkbox next to their names.
Use the Zoom in tool to click and drag a box, around the contiguous United States.

Right click on the Tamarix layer and click on Zoom To Layer. The map will now be focused on the Western United States where the Tamarix invasion began.

Turn on the US States layer.

Investigate the Tamarix Invasion in the United States

Where is the present Tamarix invasion and how far has it spread across the United States?

Right click on the Tamarix layer, click on Selection, and then click on Make This The Only Selectable Layer.
Click once on the Select Feature tool in the toolbar.

On the map, click and drag to draw a rectangle around a group of Southwestern states.
When the tool is released, the selected Tamarix points are highlighted in blue. These points are selected because you chose the Tamarix layer as being the only selectable layer.

Clear the selections by clicking on the Clear Selected Features button
Right click on the US Rivers layer and repeat the selection process starting with making US Rivers the only selectable layer.
How do the results differ?
Show me the difference
Clear the selections by clicking on the Clear Selected Features button

Where is the Tamarix invasion the most severe?

Tamarix can be found throughout the Southwest United States. Some states have more of a Tamarix problem than others, but because Tamarix spreads easily and is very difficult to eradicate, plant biologists are keeping a close eye on the situation.

Zoom and Pan around the map to get a better idea of the extent of the invasion and to answer the following questions.

In which states has Tamarix been sighted?
Show me the answer

Hide
Tamarix has been sighted in the following states:
- California,
- Oregon,
- Idaho,
- Montana,
- Wyoming,
- Nebraska,
- Kansas,
- Oklahoma,
- Texas,
- New Mexico,
- Arizona,
- Utah,
- Colorado.
What relationship do you see between rivers and Tamarix?

Create a Spatial Query to Investigate the Extent of the Invasion

Query Southwest states to investigate the extent of the invasion.

Right click on the US States layer, click on Selection, and then click on Make This The Only Selectable Layer.
Click on the Select Feature tool.
Click inside the state boundary of Arizona.
After clicking inside the Arizona state boundary, Arizona (AZ) should now be highlighted (outlined in blue).
1. Right click on the US States layer, click on Selection, and then click on Make This The Only Selectable Layer.
2. Click on the Select Feature tool.
3. Click inside the state boundary of Arizona.
4. After clicking inside the Arizona state boundary, Arizona (AZ) should now be highlighted (outlined in blue).
Click on the Selection menu option at the top of the map view. A pulldown context menu will open.
Click on Select by Location.
In the Select By Location dialog box, set the "I want to:" pulldown arrow to "select features from."
In "the following layer(s):" Place a checkmark in the box in front of Tamarix.
Set the "that:" pull down arrow to "are within."
Set "the features in this layer:" to US States.
Click OK. The buffer dialog window will be displayed on the map.
1. Click on the Selection menu option at the top of the map view. A pulldown context menu will open.
2. Click on Select by Location.
3. Set the "I want to:" pulldown arrow to "select features from."
4. In "the following layer(s):" Place a checkmark in the box in front of Tamarix.
5. Set the "that:" pull down arrow to "are within."
6. Set "the features in this layer:" to US States.
7. Click OK. The Select By Location dialog window results will be displayed on the map.
Return to the map and right click the Tamarix layer.
Open the Attribute Table of Tamarix.
How many results have been selected?
Show me

Turn on the AZ Rivers layer.
Right click on the AZ Rivers layer and click on Zoom to layer to zoom into the state of Arizona.
Click on the AZ Rivers layer with the Identify tool to learn the names of the rivers in Arizona which are invaded by Tamarix.
In the Identifyresults box, scroll down to find the field "Name".

Right click on the AZ River layer with the Identify tool .
In the Identify results box, scroll down to find the field "Name".
List several rivers that have been invaded by Tamarix.
Other Tamarix invasions do not appear to be in streams. Since Tamarix needs wet conditions to survive its first year, what types of areas might also be suitable habitat for Tamarix?
Show me the answer

Add Satellite Data to Connect Tamarix Spread with Vegetation Index

By using the satellite data of vegetation health the scientists at NASA and USGS are able to use habitat preferences, such as moist soils and low elevations, to begin to predict where Tamarix plants were most likely to appear in the future.

Adjust the layers on the map for the investigation.

Turn off the US States, Countries and AZ Rivers layers.
Collapse the US States layer.
Turn on the vegetation index image file NDVI_6.1.09.TIFF.
Right click on the Tamarix layer and choose Zoom to Layer.
If necessary, adjust the layers so that the NDVI_6.1.09.TIFF, image is below the Tamarix layer.
Zoom and Pan to compare the location of the Tamarix points to the green regions of the image. Areas with healthy vegetation are prime locations for new invasions of Tamarix.

Plants are sensitive to their environment and so they serve as a good indicator whenever there is change. Scientists routinely produce global NDVI maps to help them monitor and investigate shifts in plant growth patterns that occur in response to climate changes, environmental changes, and changes caused by humans. Farmers and resource managers also use NDVI maps to help them monitor the health of our forests and croplands. So these maps are useful both for scientific research as well as societal benefit.

Notice that the in Arizona the Tamarix invasion prefers the lower elevations where there is more desert. It is found in the river corridors and other low lying wet areas.

Add Elevation to the Map to Solve the Puzzle

So far we have observed that Tamarix invasion patterns follow the river corridors and also other areas that appear to have healthy green vegetation in the satellite NDVI image. So, why doesn't Tamarix invade everywhere? What is the missing element in the puzzle?

Turn on the Elevation > 2km layer. Zoom To Layer.
Use the Zoom and Pan tools to look at the map. Are there many Tamarix sightings at elevations above 2 km? What climate conditions change at this elevation?
Turn the US Rivers layer on and off as needed and /or move the US Rivers layer above the Elevation layer.
Based on the data in the Satellite NDVI image, Elevation > 2km, and the US Rivers layers, predict the direction that you think Tamarix will move in the next few years in the United States.
Use the Identify tool, your selection skills and the layers in the project to answer the following questions;
1. Which US Rivers seem to be the most likely to be invaded?
2. Where would you send your land management team next?
3. What factors could be limiting the spread of Tamarix?
Quit ArcGIS. Do not save your work.

Resources

Tamarix Information from the Desert Museum of Arizona (http://www.desertmuseum.org)

More Information about Invasives (http://www.desertmuseum.org)

Tamarix Invasion White Sands National Monument

The Worst Weeds - database from Nature Conservancy

Plant conservation alliance alien plant working group

Illustrated Guide to Arizona Weeds

GIS aids in response to CA lake threatened by Pike

iMap Invasives - online mapping of invasives

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