Invasive and Exotic Species

5. Monitoring

The purpose of monitoring is to evaluate the success of your purple loosestrife biocontrol program and to determine if you are meeting your purple loosestrife biocontrol goals. Monitoring activities use standardized procedures over time to assess changes in populations of the biocontrol agents, purple loosestrife, and the wetland communities.

Monitoring can answer questions about whether a) the beetles have become established at the release site, b) the beetle populations are increasing or declining, c) the beetles have spread from the initial release site, and d) the beetles are having an impact on purple loosestrife in the wetland plant community.

Monitoring methods can be simple or complex. Basic assessments can be done with a minimum of time and effort each year. The duration of monitoring can also vary, from a single year to demonstrate the biocontrol agents established, to multiple years to follow the population of the biocontrol agent(s), the decline of purple loosestrife, and changes in the overall plant community.

Qualitative monitoring

Qualitative monitoring is based on subjective assessments. It can include recording the presence or absence of insects, estimating the amount of plant damage, estimating the distribution or density of purple loosestrife at the site, or making observations about wildlife at the release site over time. Another qualitative assessment is before-and-after photographs (Figure 35), which is a photo record of the site before or at the time beetles are released that is repeated at one- or two-year intervals. Because of its descriptive nature, qualitative monitoring tends to be less time-, labor-, and supply-intensive than quantitative monitoring. The descriptive nature of qualitative monitoring does not readily allow for detailed statistical analysis; however, if sufficiently detailed qualitative data is collected, useful information can still be derived. Data obtained from qualitative monitoring may guide more intensive monitoring in the future.

Figure 35. Purple loosestrife infestation: a)before (1998) and b) after (2003) control by Galerucella beetles. (Left to right: UGA1291035 and UGA1291036)

Qualitative monitoring

Qualitative monitoring is based on subjective assessments. It can include recording the presence or absence of insects, estimating the amount of plant damage, estimating the distribution or density of purple loosestrife at the site, or making observations about wildlife at the release site over time. Another qualitative assessment is before-and-after photographs (Figure 35), which is a photo record of the site before or at the time beetles are released that is repeated at one- or two-year intervals. Because of its descriptive nature, qualitative monitoring tends to be less time-, labor-, and supply-intensive than quantitative monitoring. The descriptive nature of qualitative monitoring does not readily allow for detailed statistical analysis; however, if sufficiently detailed qualitative data is collected, useful information can still be derived. Data obtained from qualitative monitoring may guide more intensive monitoring in the future.

5.1 Monitoring Purple Loosestrife and its Biocontrol Agents

Before you begin your monitoring program, it is essential to outline your long-term monitoring objectives. It is important to know, before you begin, what and how much data will be collected. Be sure you have the necessary resources, trained personnel, and equipment to conduct the monitoring. Follow these additional steps:

Choose sites to monitor: Select sites that are accessible and have a dense infestation of purple loosestrife (Figure 36). Be sure the site will be available to you to monitor for at least three to five years after release. Begin monitoring where the insects were first released, as this is where the highest density of biocontrol agents are likely to occur and where changes to the purple loosestrife are more likely first to be detected.

Schedule monitoring activities: Schedule monitoring activities at the same time each year to enable comparison of year-to-year conditions. The recommended quantitative monitoring protocol outlined below requires monitoring twice each year: in the spring to monitor insect activity, and in the late summer to monitor distribution and density of purple loosestrife and other vegetation.

Figure 36. Purple loosestrife monitoring site. (UGA0021091)

Choose a monitoring method: Select a monitoring method and plan based on your monitoring goals, what information you want to gather, and the number of sites you intend to monitor. Consider the Questions to Ask (in box above) and the Monitoring Plan Questionnaire (see Appendix) to help determine the goals of your monitoring program.

Consider that:

• The better you define your biocontrol program goals and monitoring strategy, the better you will be able to evaluate your success.
• It is important to standardize monitoring procedures.
• Monitoring only becomes useful if methods are used consistently year to year.
• Even a full-scale quantitative monitoring protocol can be implemented withlittle effort. Once sites are established, time commitments usually require a few hours in the spring/early summer and a few hours in the fall for each monitoring site.

The recommended monitoring protocol described below is intended for select sites. If you manage a number of release sites, or if you do not have the time or expertise to complete the entire monitoring protocol as outlined, a more qualitative monitoring is recommended. A less intensive monitoring scheme is provided in Table 7. The categories involve “quick” scoring schemes of the number of biocontrol insects you observe, the amount of purple loosestrife defoliation, and photos taken at one- to two-year intervals. Included is timing for each activity.

Table 7. A rapid assessment scheme to monitor purple loosestrife and its biocontrol agents.

• Decide when to begin monitoring biocontrol agents: Monitoring should ideally begin the season before you release biocontrol agents (this provides baseline data) or, at a minimum, the year of your release. Galerucella easily colonizes a new site, especially if a large number (1,000 to 1,500 beetles) was initially released. Nanophyes, too, easily establishes itself at sites not colonized by Galerucella, although the population of Nanophyes is slower to build up than Galerucella. Hylobius may take two to three years after release to be detected (thus, if Hylobius is not found a year after the release, do not assume that it failed to establish: revisit the site for a few more years).

5.2 Detailed Purple Loosestrife Quantitative Monitoring

The detailed protocol outlined below is used for quantitative assessments of purple loosestrife and its biocontrol agents. It is a standardized monitoring protocol developed by the Ecology and Management of Invasive Plant Species Program at Cornell University (www.invasiveplants.net). The advantage of a standardized monitoring protocol is that it allows meaningful comparisons to be made among similar programs in different locations and regions, enables researchers and managers to evaluate the relative success of specific purple loosestrife biocontrol programs, and perhaps helps to understand why certain programs fail.

In this protocol, assessment locations are selected, a quadrat frame is put into place and marked with stakes, quantitative data are taken, and then the frame (but not the stakes) are taken to the next assessment location. Leaving the marking stakes in place allows the monitoring team to perform the same assessment at the same locations in subsequent years.

Follow these steps to begin a quantitative monitoring program:

1. Collect materials.

For each quadrat frame:

• Two 10-foot lengths of ¾-inch PVC or CPVC pipe, cut into two 1-m lengths and four 0.5-m lengths
• Four right-angle elbows and two straight-line connectors for the PVC or CPVC pipe
• PVC glue (a half-pint is enough for several frames)
• One can of spray foam insulation—optional (one can is enough for several frames)

Other materials, supplies, and tools:

• 1-meter measuring sticks
• 50-m measuring tape
• Four plastic or galvanized metal stakes (galvanized metal electric conduit or PVC pipe are inexpensive and readily available at hardware stores)
• Hammer
• Permanent marker
• Compass
• Handheld GPS receiver (if available)
• Camera
• Stopwatch
• Clipboard, pencils, and pen
• Forms 1 to 4 (see Appendix)

Figure 37 shows many of the materials needed for this monitoring method.

2. Construct a sampling quadrat.

Figure 37. Supplies needed to monitor purple loosestrife: a) meter-sticks, b) measuring tape, c) stopwatch, d) camera, e) compass, f) GPS, g) clipboard and writing instruments, and h) frame components. (UGA1291037)

We recommend using a two-piece quadrat frame composed of two short U-shaped halves that slide together to form a square. The frame can be filled with foam insulation to create a floating quadrat for use in flooded sites.

The inside dimensions of the finished frame should measure 1m by 1m. After cutting the pipe to the correct lengths, glue two elbows to each 1m-long piece (make sure the elbows are perfectly aligned with each other). Then, glue each elbow to a 0.5m-long piece to form two open U-shaped half-frames. Glue the connectors to the short sides of ONE of these half-frames (the connectors will hold the frame together while being used). Using a permanent marker, mark 10 cm intervals on each side of the frame pipe to assist with estimating percent cover.

3. Record site location.

Using Form 1: Purple Loosestrife Biocontrol Monitoring–Site Location (see Appendix), describe the monitoring site, and include a sketched map and a vegetation diagram. Record the position and numbers of the quadrats on the vegetation map.

4. Determine quadrat locations and set up the frame at field sites.

Quadrats should be placed at random into the purple loosestrife infestation. ALL quadrats must initially contain purple loosestrife; if necessary, shift the location of the quadrat so that purple loosestrife covers at least 30 percent of the quadrat. Various methods are available to randomize the quadrat placement. The easiest is a transect, a straight line running through the vegetation. Quadrats are placed at predetermined intervals (e.g., every 5, 10, or 20 meters) along the transect line. To do so:

• Locate the beginning of the transect at least 15 ft (5m) from an edge (i.e., roadside, streambank, field).
• Using the 50m measuring tape, stretch the tape in a straight line through the vegetation, being careful not to overly trample the vegetation.
• Secure the two ends of the transect with a stake to hold it in place while the quadrats are established.

At each site, have 5-10 quadrats. Keep in mind that more quadrats are better. Knowing how many quadrats you will have at a site, determine the distance between quadrats (e.g., 5, 10m) there will be along the transect.

• Starting from one end of the transect, locate the position of the first quadrat on the transect.
• Place the quadrat frame into the vegetation by sliding the arms of the first U-shaped frame through the vegetation and as close to the ground as possible, moving carefully to avoid disturbing any insects on the vegetation. Then, gently slide the second half of the frame into the vegetation from the opposite direction and attach it to the first half, completing the 1m2 frame. Avoid trampling vegetation in and near the quadrat.
• At one corner of the quadrat drive a 5-8 ft (1-2m) long plastic pipe or galvanized steel stake into the ground (galvanized metal electric conduit or PVC pipe are inexpensive and readily available at hardware stores). Mark each quadrat the same and note which corner is staked. This will allow exact placement of the quadrat in future years. Allow the pipe or stake to stick up high enough to be seen, but low enough to minimize vandalism. Write the quadrat number on each marker, and, if possible, record the GPS coordinates of each quadrat. Flagging tape will also help to relocate the quadrat in the future. Figure 38 shows a typical quadrat placement.

Figure 38. Quadrat set within a purple loosestrife infestation. (UGA1291038)

When you complete monitoring and recording data for the first quadrat, disassemble the frame and set it up at the next quadrat location along the transect. Repeat this until all the quadrats have been placed, marked with a stake, and the monitoring information is recorded. When the monitoring is complete for the site, remove the transect measuring tape, leaving only the quadrat markers behind. The same set of quadrats can be used year after year. This allows statistical analysis to be conducted on purple loosestrife density, the abundance of biocontrol insects, and the changes in purple loosestrife and other vegetation.

5. Monitor biocontrol agents.

Using Form 2: Purple Loosestrife Biocontrol Monitoring–Insect Monitoring and Instructions (see Appendix), evaluate the biocontrol agents on plants within each quadrat. The protocol involves the following:

• Visually count biocontrol agents: For each agent, count for one minute the number of beetles you see on plants in each quadrat. If more that one species is at the site, count one minute for each species. For Galerucella, where multiple life stages are present at a time, count for one minute, each, the number of adults, larvae, and eggs.
• Estimate feeding damage: In addition to counting insects, it is useful to look for signs of feeding damage. Estimate the amount of foliage that has been damaged or eaten by adults (and Galerucella larvae) feeding on foliage.
• Estimate cover of purple loosestrife: Looking over the quadrat, estimate the percent of the quadrat that is covered by purple loosestrife.
• Make observations: Observe the insects feeding and note their activity.

6. Purple loosestrife and other vegetation.

Purple loosestrife should be monitored before biocontrol agents are released. It is important to know the size and density of the purple loosestrife infestation before biocontrol is implemented as it gives managers baseline data against which future monitoring data will be compared. Monitor sites once a year or every other year. Purple loosestrife, and other vegetation, is evaluated within a quadrat set up as described above. Using Form 3: Purple Loosestrife Biocontrol Monitoring–Vegetation Monitoring and Instructions (see Appendix), do the following:

• Visual estimates: Visually estimate how much of the quadrat is covered with purple loosestrife and other vegetation such as cattails and shrubs, expressed as a percentage (Figure 39). Personnel may have to be trained in estimating cover percentage.
• Stem counts: Count the number of purple loosestrife and cattail (or other dominant vegetation) stems in the quadrat. Count the total number of inflorescences in the quadrat.

Figure 39. Estimating purple loosestrife coverage. (UGA1291039)

• Measure a sample of stems: Select the five tallest stems in the quadrat to measure. For each stem, measure height, number of inflorescences (on main stem and branches), and length of longest inflorescence. To count the number of flowers, remove the central 2-inch (5-cm) portion of the inflorescence and count the number of flowers and buds. These data enable you to evaluate how individual plants in the infestation are being affected by biological control.
• Make observations: Note any special features about the site or any changes at the site since the last examination, such as disturbance, fire, flooding, grazing, and bird nesting activity (or lack thereof).
• Monitor other vegetation: Use Form 4: Purple Loosestrife Biocontrol Monitoring–Associated Vegetation (see Appendix) to record other vegetation within the quadrat in the plant community. This form is used to track changes in the composition of the plant community as purple loosestrife declines.

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