Monitoring techniques

monitoring phrag_EH

Melissa McCormick and Liza McFarland out sampling in the Wicomico River, MD. Photo credit: Eric Hazelton

Monitoring programs are an important, but often overlooked, part of non-native Phragmites management and control. Monitoring for early detection and then responding rapidly with proper management techniques can help reduce new non-native Phragmites invasions. In areas where non-native Phragmites is already established, monitoring plans should be in place to assess habitat response after management actions to help quantify the outcome of management efforts and provide insight for modifications to the management protocol.

To be effective, a detailed, site-specific, and achievable monitoring plan should be created prior to any management. In order to determine the effectiveness of management efforts, it is important to collect data in a structured way both before and after treatment. Collected data should be reviewed and analyzed to identify opportunities for modifying future management actions. This iterative approach to monitoring, analysis, and management will lead to the increased long-term effectiveness of management. Monitoring plans do not need to be overly complicated, and can be scaled to meet the skills and capacity of the manager. In some cases, pre- and post-management monitoring may be accomplished most efficiently by partnering with another organization, such as a federal or state agency, university, or local interest group.

Types of monitoring techniques

Photo points

Taking pictures of a fixed location through time allows you to visually track changes at that location. Photo points should be recorded with GPS coordinates and the compass direction of the photograph. Physical markers such as T-posts driven into the ground can aid in finding the exact location from which to take the photo.

  • Pros: quick, inexpensive,  visual
  • Cons: quantitative measurements (e.g., species diversity, stem density) are lacking

 

click to see examples

Aerial photos

 aerial photo--Ducks Unlimited MI

Aerial image where Phragmites has been highlighted in red. Photo credit (Ducks Unlimited, MI)

If you have aerial photos taken of the same area through time, you can track the extent of Phragmites either by hand or with geographic information system software such as ArcGIS or Quantum GIS.

  • Pros: quantitative measurements.
  • Cons: often expensive, requires software and trained staff.
Aerial photo of Rhode River, MD, from 1970 (left) and 2009 (right). Photo credit: Dr. Dennis Whigham

Aerial photo of Rhode River, MD, from 1970 (left) and 2009 (right). Photo credit: Dr. Dennis Whigham

 

Resources:

  • Maheu-Giroux, M. and S. de Blois. 2005. Mapping the invasive species Phragmites australis in linear wetland corridors. Aquatic Botany, 83 (4): 310-320. Abstract (Visit the Phragmites Research Group webpage to request a reprint)
  • Pengra, B. W., C. A. Johnston and T. R. Loveland. 2007. Mapping an invasive plant, Phragmites australis, in coastal wetlands using the EO-1 Hyperion hyperspectral sensor. Remote Sensing of Environment, 108(1): 74-81. Abstract

Field methods

witches broom resprout 2c

Phragmites “witches broom” regrowth after Glyphosate treatment of the stand at Harsens Island, MI. Photo credit: phragmites.org

Obtaining more quantitative data on species diversity, stem densities, water levels, etc. requires direct measurement. Type and frequency of data collection will depend on site characteristics and clearly articulated project objectives. Measuring plant species presence and dominance in quadrats (e.g. 1 m square) or along transects are common field methods. Field monitoring can also provide insight into non-native Phragmites management efficacy and follow-up needs. Even when the majority of a non-native Phragmites stand has been effectively killed with herbicide or other management techniques, it is likely that Phragmites seeds remain in the seedbank or some portion of the rhizome remains viable. Monitoring can include information about stand mortality, new Phragmites seedlings, or other observances such as “witches broom” regrowth, which can occur if there has not been a complete kill belowground. The “witches broom” growth form is one where many small stems grow from a single node that may be buried or exposed.

  • Pros: more detailed data that can be tested with statistical tools. Comparable among years and projects.
  • Cons: time intensive, requires training.