Mystery graph: Hemlock woolly adelgid
Author
Sarah Morrisseau
Gulf of Maine Research Institute
Vital Signs Program
Question
How do scientists use graphs to understand how species change over time?
Overview
Use this activity to kick off a Vital Signs investigation focused on hemlock woolly adelgid (Adelges tsugae). Use your graphing skills to figure out and explain the introduction and spread of hemlock woolly adelgid in Maine from 1999 to 2010.
Science & Technology Standards (MLR)
A3 Constancy and Change Students describe how patterns of change vary in physical, biological, and technological systems.
B1 Skills and Traits of Scientific Inquiry Students plan, conduct, analyze data from and communicate results of investigations.
B1d. Use mathematics to gather, organize, and present data and structure convincing explanations.
B1e.Use logic, critical reasoning and evidence to develop descriptions, explanations, predictions, and models.
E2 Ecosystems.Students examine how the characteristics of the physical, non-living environment, the types and behaviors of living organisms, and the flow of matter and energy affect organisms and the ecosystem of which they are part.
E2b.Describe ways in which two types of organisms may interact including competition, and predator/prey.
Grade Level
7, 8
Setting
Classroom
Materials
Computer & projector
WCSH6 video:
(Direct link:
HWA news articles from May 2010:
Map of official HWA sites in Maine (2010):
Note: You need Google Earth on your computer to view this map
Time Needed
30-40 minutes
Activity Procedure
NOTE: For best results, play Oh Deer! Invasive Species Style to introduce the concept of species interactions and population change over time, and the skill of visualizing data and telling stories using simple graphs.
- Present to students the following “mystery graph” of real scientific data from the Maine Forest Service.
- Challenge students to explain what has happened over the 7 years from 2003-2010. Ask them to tell the “graph story,” just like they did during the Oh Deer! Invasive Species Style game. They may find their Oh Deer! graph trends and stories useful as they try to make sense of similar trends in this one.
- Give students enough time to think about, talk through, and maybe even write down what they think is happening over time. Mysterious story ramblings might go something like this:
- Something was pretty steady from 2003-2006
- In 2007 it started to increase pretty consistently until 2010
- Hmm. I wonder what happened in 2009...?
- Hmm. I bet it’ll be around 30 in 2011….
- Once students have been given a chance to look at and process the trends, give them more information about the graph usingcurrent events “hints.”
- Read this news article from May 2010 that explains the spread of HWA in Maine towns since 2003:
HWA attacking southern Maine
- Launch this map layer on Google Earth:
HWA in Maine, 2010
- Additional news resources:
WCSH6 video from York Maine in 2008:
Forest Service releases beetle to save hemlocks
Maine Forest Service to release predator beetles to fight HWA
- Based on what they learned from the news article, have students try to fill in the “mystery graph” with a title and legend:
It should look something like this:
- Have students tell the story (or improve the story they started in step 3)of what has changed over time.Draw on the Oh Deer! experience and news article/ video.
The graph storymay be written (1) in table form, (2) directly on the graph, or (3) using pictures depending on student choice or preferred learning style (examples are below):
This graph story comes straight from the Maine Forest Service website: The real story starts before the graph in 1999. Including it here can’t hurt. Of course, students won’t get to this level of detail.
(1)Example story in table form:
1999 / Hemlock woolly adelgid was inadvertently shipped to Maine from Connecticut on untreated nursery stock . The infested stock was treated and monitored for insect survival.2000 / Hemlock woolly adelgid infested outplanted hemlocks were found in new locations. Some of the hemlocks exhibited relatively heavy infestations indicating that they were infested when planted.
2001 / Again infested outplanted hemlocks were found in new locations. New infestations were found at sites treated in previous years
2002
2003 / Hemlock woolly adelgid was detected in Kittery and York, Maine forests. These sites are considered to be the northern edge of the general infestation in eastern North America. Spread was most likely from natural movement by wind, birds and/or mammals. Management tactics in this area focus on containment.
2004-2006 / No new reports of hemlock woolly adelgid.
2007 / Reports of hemlock woolly adelgid infested outplanted hemlocks, although much reduced, continue to come in. Maintain vigilance in checking your trees for this insect and report any suspected finds. Infestations in natural forest stands have been found in Eliot, Kittery, South Berwick,Wells and York.
2008 / Park Ranger, Janet Mangion, discovers hemlock woolly adelgid during routine road-side maintenance at Ferry Beach State Park in Saco. Press coverage of the detection yields reports of infested outplanted hemlocks in South Portland and infested forest hemlocks in Kennebunkport. Follow up surveys reveal a low-level infestation throughout Ferry Beach State Park.
2009 / No data from 2009
2010 / As of 2010 hemlock woolly adelgid has been found in forests of: Arrowsic, Boothbay, Boothbay Harbor, Bristol, Brunswick, Edgecomb, Eliot, Georgetown, Harpswell, Kennebunkport, Kittery, Ogunquit, Phippsburg, Saco, South Berwick, South Bristol, South Portland, Wells, Westport Island, Wiscasset and York. Many of these detections were reported by informed citizens.
(2) Example story in the form of an annotated graph:
(3) Example story in the form of a drawing:
2003Hemlock woolly adelgid was 2007 Four years later, hemlock woolly
found in just 2 natural forests in adelgid was found in 3 more Maine
Kittery and York.towns – South Berwick, Eliot, and Wells.
- Share and compare stories.
- Prepare to go look for HWA in your community during your own Vital Signs investigation.