Forest Health Monitoring

Borys Tkacz
USDA Forest Service

Issues with concerns of the health of the nation’s forests in the past led to calls for the creation of a means to measure and track forest conditions.  As the principal U.S. response, the Forest Health Monitoring (FHM) program was created to achieve these objectives.  FHM is a national program designed to determine the status, changes, and trends in indicators of forest condition for all forested lands in the United States on an annual basis (http://www.fhm.fs.fed.us ).

 
The FHM program uses data from ground plots and surveys, aerial surveys, and other biotic and abiotic data sources and develops analytical approaches to assess forest health issues that affect the sustainability of forest ecosystems.   FHM covers all forested lands through a partnership involving USDA Forest Service, State Foresters, and other state and federal agencies and academic groups.  There are many other state, local, and private forest health research and monitoring efforts as well, but this entry focuses on the national U.S. FHM Program

History

 
The FHM program grew out of concerns and debates related to forest declines and air pollution in the 1980s.  FHM came about when two programs: the National Vegetation Survey (part of the National Acid Precipitation Assessment Program) and the Environmental Monitoring and Assessment Program - Forests Component were combined with additional federal and state partners.   Initial efforts focused on development of sample designs and indicators of forest health.  Pilot studies facilitated the refinement of techniques and the development of field manuals, quality assurance plans, and information management systems.  Plots were first installed in 1990 in six northeastern states with additional states gradually added over succeeding years.  In the mid 1990s, FHM incorporated annual insect and disease damage estimates by developing national standards for aerial detection surveys being conducted by the Forest Health Protection (FHP) program of the USDA Forest Service and state partners.  In 2000, the FHM plot component was integrated with the extensive timber inventory conducted by the Forest Inventory and Analysis (FIA) program.  The FHM forest health plots are now Phase 3 of the FIA plot network.  The FHM program uses data from the Phase 3 plots as a critical part of Detection Monitoring. 

Major FHM Activities

• Detection Monitoring – nationally standardized aerial and ground surveys to evaluate status and change in condition of forest ecosystems;
  

• Evaluation Monitoring - projects to determine extent, severity, and causes of undesirable changes in forest health identified through Detection Monitoring;
  

• Intensive Site Monitoring – research sites designed to enhance understanding of cause-effect relationships by linking Detection Monitoring to ecosystem process studies and assess specific issues at multiple spatial scales;
  

• Research on Monitoring Techniques – research studies to develop or improve indicators, monitoring systems, and analytical techniques (such as, developing approaches to urban and riparian forest health monitoring, and early detection of invasive species);
  

• Analysis and Reporting – the synthesis of information from various data sources to produce issue-driven reports on status and change in forest health at National, Regional, and State levels.

Forest Health Indicators

 
The following are a suite of forest health indicators developed by the FHM program and currently being collected by the FIA program on the latest Phase 3 forest health plots:

• Crown Condition – amount, condition, and distribution of foliage, branches, and growing tips of trees.  The individual tree measurements include crown ratio, crown diameter, crown density, foliage transparency, crown dieback, light exposure, and canopy position.  Since 2000, crown diameter is estimated with models.
• Tree Damage – type, location, and severity of injury caused by diseases, insects, storms, animals or human activities.  Examples include: open wounds, cankers, signs of decay, and broken boles, roots, or branches.
• Tree Mortality – number, size, and volume of trees that have died since the previous measurement on a plot. 
• Down Woody Material – measurement of fallen trees, dead branches, and large fragments of wood on the forest floor.
• Soil Condition – data on erosion, compaction, and important physical and chemical properties (nutrient information, pH level, carbon and nitrogen, toxics, and bulk density).
• Vegetation Diversity and Structure – type, abundance and vertical position of vascular plant species. 
• Lichen Communities – lichen species distribution and abundance.
• Ozone Injury – severity of foliar injury on ozone-sensitive plants on ozone biomonitoring sites (not collected on Phase 3 plots).

Aerial Surveys

Aerial detection surveys are widely used for collecting data on biotic and abiotic damage to forested ecosystems.  FHP and its many state and federal cooperating partners have been conducting aerial surveys in some areas, for over 50 years.  These provide annual information on insect, disease, and weather related damage.  The information is used for regional and national reporting on insect and disease conditions and trends.  Aerial detection survey data are used by forest land managers, the public, and government officials.  The FHM program uses this data to evaluate tree damage that may be missed on periodically visited ground plots. 

 
To better serve all its customers, FHP and FHM have been working together to ensure that more consistent data are collected, national historical records are maintained, and that data standards and quality assurance procedures are developed and implemented among the states and FS Regions/Area.  Many cooperators are now using automated digital sketch mapping systems that link to aircraft global positioning systems.

Invasive Species Detection

 
Monitoring for invasive plant, insects, and diseases is fast becoming a large part of FHM efforts.  Once the most dangerous potentially invasive pests are identified, early detection programs are implemented to find incipient invasions before they have the opportunity to spread.   A risk-based approach is used incorporating knowledge of pest biology, susceptible hosts, suitable environment, and likely pathways of introduction to identify high-risk areas for invasions.  Sampling protocols are developed for cooperative surveys targeting specific invasive pests involving federal, state, and local partners.  Public information is disseminated to encourage reporting of suspected invasive pests and developed information management systems facilitate the rapid sharing of detection monitoring results.  

 
An example of a national invasive species detection survey is the one developed and implemented by FHM for the Sudden Oak Death Pathogen, Phytophthora ramorum. Once this new invasive pathogen was discovered in California in 2000, special detection surveys were initiated in Oregon and other states.  The discovery of a small, isolated infestation of the pathogen in southern Oregon has led to a limited quarantine and eradication project.  Surveys of susceptible forests in the eastern U. S. were initiated in 2003 and expanded to cover most high to moderate risk areas in subsequent years.  Four years of extensive surveys indicate that the pathogen has only spread to natural forest ecosystems in CA and OR, despite shipment of infected plants to nurseries throughout the U.S.  Current survey efforts are focusing on sampling high risk watersheds utilizing a very sensitive stream baiting technique.

Risk Mapping

The FHM program has recently completed a national risk assessment that maps potential future risk of tree mortality due to insects and diseases.  Risk was defined as an expectation that 25 percent or more of the standing live basal area of trees greater than 1 inch in diameter will die over the next 15 years due to insect and disease activity.  According to this assessment, more than 58 million acres of forest land are at risk.  This strategic assessment provides a useful tool in developing broad prevention strategies. 

Future Challenges

In the future, the FHM program will strive to enhance timely detection, analysis, and reporting of adverse changes in forest health to facilitate effective management responses.  To increase the understanding of the adverse changes in forest health, FHM will expand evaluations of the extent, severity and dynamics of forest stressors.  The continued development and enhancement of national and regional risk assessments will promote development of more effective prevention strategies. 

 Bibliography

Bechtold, W., Tkacz, B. and K. Riitters. 2007. The historical background, framework, and application of Forest Health Monitoring in the United States. International Symposium on Forest Health Monitoring, Seoul, Korea; January 31, 2007: http://fhm.fs.fed.us/pubs/misc/application_fhm.pdf

 
Coulston, J., Ambrose, M., Riitters, K., Conkling, B., Smith, W. 2005. Forest Heath Monitoring – 2003 National Technical Report.   USDA Forest Service. Southern Research Station, General Technical Report SRS-85.

 
Coulston, J., Ambrose, M., Riitters, K., Conkling, B., 2005a. Forest Health Monitoring – 2004 National Technical Report. USDA Forest Service. Southern Research Station, General Technical Report SRS-90.

 
Krist, F., Sapio, F., Tkacz, B., In press. A Multi-Criteria Framework for Producing Local, Regional, and National Insect and Disease Risk Maps. in: "Advances in Threat Assessment and their Application to Forest and Rangeland Management". Gen. Tech. Rep. PNW xxx. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station.

 
Riitters, K. and B. Tkacz. 2004. The U.S. Forest Health Monitoring Program. pp. 669-683 in Wiersma, B., ed. Environmental Monitoring. CRC Press, Boca Raton, FL. 792 p.

 
Stolte, K., Conkling B., Campbell S., Gillespie A.. 2002. Forest Health Indicators. Forest Inventory and Analysis Program, USDA Forest Service. FS-746. 23p.

 
Tkacz, B.M., Oak, S.W., Smith, W.D. 2006. National detection surveys for sudden oak death. In: Proceedings of the sixth annual forest inventory and analysis symposium: 2004 September 21-24; Denver, CO. Gen. Tech. Rep. wo-70. Washington, DC: USDA Forest Service. 126 p.

Posted 27 February 2008