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Beyond the Trees: A Systems Approach to Understanding Forest Health in the Southeastern United States1

Geetha S. Iyer, Martha M. Monroe, and Jason A. Smith 2

This forest health guide for high school educators is available here:

The forests of Florida are diverse and indispensable. From the cypress swamps and longleaf sandhills along the Blackwater River to the mangroves that hug the Florida Bay, they form a network of temperate to subtropical ecosystems that shelter animals as small as bark beetles and as large as black bears.

Forests support humans as well, in both tangible and intangible ways. They are a source of aesthetic beauty and regional pride. They are an economic resource in sectors ranging from timber and fiber production to recreation and tourism—timber alone is a multi-billion dollar industry in the South. In addition to the monetary value of forest products is the value of the ecosystem services that forests provide. They hold together soil and filter water, photosynthesize and produce oxygen, recycle nutrients and store carbon, and serve as a gene bank for countless organisms. It is essential that these forests remain healthy and productive to benefit all the life forms that rely upon them.

A healthy forest is an intricately balanced system of interacting parts. Climate influences environment, environment shapes plant growth, plants provide food for numerous other organisms, and humans intersect with this system by harvesting and planting, fragmenting and reshaping, analyzing and appreciating forests for a variety of purposes. In some ways, forest health is in fact a human construct—that is to say, we define whether forests are healthy or not based on our viewpoints and concerns, manage forests to meet our various needs, and have impacted forests since we first built settlements near and within these ecosystems.

Historically, concerns about forest health overwhelmingly focused on the eradication of undesirable pests and disease-causing pathogens, such as insects and fungi, or environmental disruptions like fire, which could weaken or kill trees. However, damage, decay, and destruction are an essential component of healthy forests. Insects that feed upon trees are fed upon in turn by other animals. Fungi that rot away trees replenish the soil with nutrients that would otherwise be locked away in wood. In fire-dependent ecosystems, fires clear the undergrowth and make room for new trees to grow. So the death of individual trees in the forest is not always cause for alarm—in many cases, it is integral to the continued health of the entire ecosystem.

Death and decay are treated differently in more controlled ecosystems, such as those found in plantations, parks, and urban settings. For those who depend upon certain trees for products or aesthetic value, the priority placed upon healthy individual trees may define their perspective of overall forest health.

But there are some unambiguous threats to forest health. Non-native or exotic pests and pathogens are problematic in any ecosystem. These organisms have the ability to eliminate species and permanently alter ecosystems. For example, in the early 1900s, American chestnuts covered 25% of eastern forests, but within a few decades, 3.5 billion of those trees, over 80% of the existing population, were dead from a fungal pathogen that caused chestnut blight. Non-native insects such as the Asian longhorned beetle, emerald ash borer, and hemlock wooly adelgid are also wreaking havoc in the United States. The immense voids created by such insects and disease pathogens might be filled by invasive and exotic plants. Kudzu, Chinese tallow, climbing ferns, cogon grass, and Chinese privet top the list of invasive plants that are changing the ecosystems of the United States.

The situation appears even bleaker if abiotic threats to forests are also considered. Forest fragmentation by roads and development; land loss due to urban encroachment; improper fire management regimes; air pollution from ozone, sulfur dioxide, and nitrous oxides; runoff from concentrated animal feeding operations (CAFOs); and climate change are all factors that can weaken trees and forests.

Many of the problems associated with unhealthy forests originate from human actions, through mismanagement or misconceptions. This can be a source of hope, because while we may have caused these problems, increasing awareness and knowledge and changing our behaviors may help resolve these issues. Educating young people about the significance of healthy forests and the consequences of management activities is essential. Research and management are necessary components of maintaining or restoring forest health, but so too is an informed public. Monitoring imported goods for pathogens, managing forests through prompt harvesting and prescribed fire routines, encouraging native vegetation, creating better buffers against abiotic pollutants that we produce, and indeed producing less and conserving more, are important concepts that need to be understood as well as practiced to ensure the continued health of forests.

Forest health is an important topic for biology, agriculture, current issues, and environmental science classes. There are basic concepts and unanswered questions. There are historic successes, calamities, and current debates. Challenges affect urban and rural residents, private landowners, and public properties. Some dimensions are natural, while others are caused or magnified by people. It is a topic that includes variety and complexity while inviting multiple opinions and new discoveries.

There is no question that forests provide important ecological services and economic resources to Floridians. Similarly, there is no doubt that the health of our forests is at the mercy of how we manage our landscape and make decisions. The activities in this guide for educators help our students rise to these twin challenges.

Using This Material

Our conversations with teachers before developing this material revealed that while agricultural education teachers, AP biology teachers, and other environmental education practitioners understood the importance of forest health and wanted to teach their students about it, they were not equipped to do so given their existing curricula. Teachers who did cover forest health taught about forest insect pest and tree disease identification. They also addressed the role of fire in forests. Aspects that were missing from their curricula included the following:

  • The beneficial roles of insect pests and tree disease pathogens in a forest.

  • Management-related forest health issues.

  • The impacts of exotic and invasive species.

  • Forest fragmentation and urban encroachment.

This material supplements existing curricula and expands conceptual understanding beyond diagnostic and identification-based knowledge to a more in-depth understanding of the subject of forest health. It is not meant to be treated as an exhaustive compendium of forest health issues, but it does help learners:

  • Consider forest health from various viewpoints.

  • Understand interrelationships and feedback mechanisms in a forest system.

  • Visualize spatial and temporal mechanisms of forest system functions.

  • Appreciate the variety of threats to forest health.

  • Consider their role as future forest stewards.

The complete guide is available on EDIS at

These resources have been produced with assistance from the Florida Forest Service (formerly the Florida Division of Forestry), the USDA Forest Service, and the UF/IFAS School of Forest Resources and Conservation.


1. This document is FOR287, one of a series of the School of Forest Resources and Conservation Department, UF/IFAS Extension. Original publication date July 2011. Reviewed August 2017. Visit the EDIS website at
2. Geetha S. Iyer, graduate assistant; Martha M. Monroe, professor; and Jason A. Smith, assistant professor; School of Forest Resources and Conservation, UF/IFAS Extension, Gainesville, FL 32611.

Publication #FOR287

Date: 6/4/2019

    Fact Sheet


    • Jason Smith