ForestGEO welcomes its 77th Forest Dynamics plot: Ichauway
ForestGEO recently welcomed its 77th Forest Dynamics plot – Ichauway – in the southeastern United States. We asked Principal Investigator Dr. Jeffery Cannon about the plot and how he got involved with ForestGEO.
How long have you been working at Ichauway? What is your background with forest science?
I have worked at Ichauway since completing my post-doctoral research in 2019. My research has always focused on how forests respond to natural disturbances. This interest has led me to addresses questions about how forests recover from tornados in the southeast, hurricanes in the coastal plain, and high-intensity wildfires in the western U.S. forests. In each of these forests (and many temperate ecosystems), the effects of frequent low-intensity fire are crucial driver of diversity and function and has been a secondary research focus.
How did you discover ForestGEO and get the plot involved in the network?
I first learned of the ForestGEO network during a research visit to the neotropical forests of Manaus, Brazil. In my research on wind disturbance, we measured tree strength by pulling on trees with a winch to simulate the torque from severe winds. Because of this work we were invited to Manaus to collaborate with the Instituto Nacional de Pesquisas da Amazônia (INPA) and test wind firmness in tropical trees. The work helped us learn that storm winds in the Amazon frequently reached speeds high enough to cause tree failure and may form a significant component of the disturbance regime in Amazon forests. The work was my first exposure to tropical forests and helped me see how long-term research infrastructure like ForestGEO sites can be a magnet for cross-disciplinary work that advances the conservation of ecosystems. Because of my interest in disturbance and fire I frequently mapped and tagged trees to study mortality and changing pattern. Establishing a ForestGEO plot at Ichauway seemed like a natural extension of my earlier work and would serve as a great place to study the effects of prescribed fire.
When was the Jones Center established, and how did it help in the transition to making Ichauway a forest dynamics plot? What does that partnership look like?
The Jones Center is a non-profit research and education center focusing on longleaf pine ecology and conservation. In the 1920s, the land was managed as a quail hunting retreat by Robert Woodruff, the president of the Coca-Cola company, and eventually dedicated to conservation research in the early 1990s. Throughout this time the land was managed with frequent prescribed fire which helped maintain and conserve the high biodiversity.
The Jones Center is home to several research labs covering many facets of longleaf pine ecology, and we co-advise and host graduate students from all over the southeastern region. Because of its unique position, there are many long-term studies on water, wildlife, and plant ecology that are ongoing. As a new faculty, I was eager to set up a long-term research study to address questions on ecology and management of longleaf pine. Because of my own interest in spatial ecology, regeneration dynamics, lidar, and fire, the ForestGEO framework seemed like a great way to answer our own questions locally, but also tie into a global research network.
How long did your first census take to complete? How big was the team?
Our first census captured over 18,000 trees > 1 cm and took a little over one year to complete. To expedite the plot establishment, we opted to take advantage of new mapping techniques using terrestrial lidar. We laser-scanned the entire area over a 3-day period and used tree-detection algorithms to map tentative locations and diameters for most trees. Armed with a preliminary map, over the next year, a team of 2-4 staff at a time measured and tagged trees, verified the locations, and identified species for all 18,000 trees even through the sweltering Georgia summer. I cannot imagine this pace would have been possible without the technological head-start we had.
Ichauway is one of two sites in the southeastern U.S. – what are the benefits of being able to compare these plots with each other, and with FDPs in other climatic zones?
Both the Ichauway and Ordway-Swisher FDPs are dominated by longleaf pine with an oak component. One big difference is that the Ichauway plot has a more abundant layer of oak saplings. Some of the oaks are fire-adapted and some are not. Because of these differences, the Ichauway plot will be a perfect place to study feedbacks between vegetation, fuel, and fire to better understand longleaf pine–oak sandhill communities. Comparisons among the two longleaf pine sites can ensure that some of our findings are general. But I think the real benefit will be in comparing our plot to other plots across the globe, especially those currently or historically impacted by fire.
How do you predict census data from this plot will vary from the others, specifically considering the regular prescribed burns?
Fire is a dominant driver of forest structure in longleaf pine systems, but we still have many questions about how hardwoods behave in a chronically disturbed system. Small patches of hardwoods exist that are constantly damaged by fire. Prescribed fire can kill the small aboveground stems are killed, fast-growing sprouts erupt from the abundant woody root mass underground and restore the patch which occurs as a phalanx of hardwood stems. So, we expect rapid turnover of smalls stems. But we still want to know whether patches are growing over time? Or is fire slowly eroding them? Does the impact of fire differ among species or sizes of patches? The answers to these questions about longleaf pine–oak woodlands can help us to better conserve, restore, and manage them.
You mentioned that some of the overstory pines at the site date back to the late 1800s -- how are you able to control what is burned?
Rather than posing a threat to adult trees, fire actually enhances longleaf pine persistence. Unlike the intense wildfires we see in the western U.S. and Canada, the fires in southeastern U.S. burned frequently but with low-severity fires. Historically, fires were ignited by lightning strikes or intentionally by Native Americans. If fires occur frequently fuel cannot accumulate, and fires burn in a slow, creeping manner. Most adult trees, and even saplings typically survive mild fires, and most trees are only vulnerable to fire at early juvenile stages. Longleaf pine has a growth form that makes it famously fire resistant even at very young stages. So, it is able to survive, and even regenerate despite frequent fire. Although the area has been burned consistently since the 1900s, the fires rarely affect established adult trees. Instead, by preventing the regeneration of other species, the frequent fires reinforce the dominance of the existing mature trees.
Icahuway FDP “is located within a global biodiversity hotspot of high conservation value” – can you expand on what this means?
Many longleaf pine woodlands are dominated by only a few tree species, but other aspects of the ecosystem make the ecosystem a global diversity hotspot, hosting an array of highly diverse plants and animals. Longleaf pine woodlands once dominated much of the southeastern U.S. Gulf coastal plain but have now been reduced to <3% of their historical range. The ecosystem depends on repeated fire to persist. Frequent, low-intensity fire kills small many small hardwoods that would otherwise shade out the diverse understory community. Frequent disturbance and high light conditions support high diversity of understory plants that can reach 40 species per m2, as well as an array of imperiled wildlife species such as the gopher tortoise, gopher frog, indigo snake, and red-cockaded woodpecker.
Many thanks to Dr. Jeffery Cannon for sharing more about our fascinating new plot!
Learn all the details about Ichauway here.