Nearly everything Nina Wurzburger undertakes — at least regarding her research — pertains to woodlands.

She was raised on the central coast of California, where the Monterey pine woodland predominates the scenery. While journeying with her family, she recalls being captivated by the trees, woodlands, and vistas that appeared so distinct from those at home.

“I have always drawn inspiration from nature,” she remarked. “Every ecologist likely shares that sentiment.”

Now a faculty member at the Odum School of Ecology, Wurzburger continues to investigate why woodlands appear different. Her current inquiries examine how singular forests evolve over time due to human interference.

“At times, forests fail to recuperate,” she stated. “The factors that determine whether a woodland regenerates or not are frequently concealed underground.”

This work holds significant importance because as woodlands transform, people may forfeit the advantages they provide. They yield timber resources, cleanse toxins from water, create habitats, and absorb carbon dioxide from the air.

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Wurzburger is an ecosystem ecologist, a professional who examines the relationships between living and non-living entities in the natural environment.

“Numerous aspects are challenging to forecast if we overlook the interactions between the living and the non-living,” she noted. “The world we inhabit is profoundly shaped by those connections. For instance, atmospheric carbon dioxide influences climate, which subsequently impacts how flora develops and utilizes carbon dioxide.”

Presently, Wurzburger is engaged in three projects investigating dynamically changing forests. One focuses on fire in eastern U.S. woodlands, and how policy alterations have influenced outcomes.

Historically, fire constituted a natural component of the landscape. Indigenous people ignited fires for cultural or management purposes, leading these ecosystems to adapt alongside fire. However, as fire poses risks to individuals’ lives, homes, and livelihoods, policies transitioned to promote fire exclusion. According to Wurzburger, this alteration also resulted in a transformation of forests — and not for the better.

“Fire is a crucial element of ecosystems and their dynamics,” she asserted. “Now, there is an emphasis on reinstating fire in forests, aiming to restore them to their former state. But what occurs within the ecosystem when fire is reintroduced?”

Wurzburger and her team are investigating how prescribed burns influence the soil. Preliminary findings indicate that while burning decreases the overall carbon content in the soil, it may enhance long-term carbon retention. This could be mutually beneficial for forests.

“All carbon will ultimately be emitted back into the atmosphere. It’s merely a matter of the timescale,” she remarked. “If we can convert more carbon into a form that remains stable for a thousand years — as opposed to every year — we significantly enhance our ability to keep it out of the atmosphere.”

Indigenous, yet troublesome

If you’ve traveled to the Appalachians, you may have observed rhododendron flourishing densely across the mountains. If fortunate, you might have seen it in bloom. However, ecologists like Wurzburger have recognized that it has increased substantially over time, prompting them to explore its impact on the ecosystem.

Rhododendron is native and slow to grow, but it can be bothersome. It tends to thrive following disturbances that open up the forest canopy, allowing an influx of light, and it continues to flourish once the woodland has rejuvenated.

Longitudinal data indicates that when the American chestnut perished a century ago, rhododendron expanded its presence, according to Wurzburger. Its spread was further exacerbated by the decline of eastern hemlock due to the woolly adelgid, an invasive insect. Other studies have demonstrated that clear-cutting a woodland fosters a resurgence of rhododendron at higher levels than previously recorded.

“All these factors point to a human-induced disturbance regime that favors this shrub, so it’s imperative to comprehend its effects on the forest ecosystem,” she remarked.

Rhododendron has distinct fungal partners in its roots — only shared with related plants like azaleas, blueberries, and cranberries. A secondary project explores how the shrub and its fungi, which assist in nutrient acquisition, influence the movement of carbon from trees and shrubs to the soil. Wurzburger notes that underground processes are the most challenging to decipher.

“Soil is opaque, harboring numerous tiny microbes, and it exhibits significant complexity,” she stated. “That’s where all the intriguing questions lie, for me.”

West Coast incursion

A third new endeavor is situated in Big Sur, just south of Wurzburger’s hometown. This location features a mosaic of ecosystems — redwood forests, mixed evergreen woodlands with coast live oak and tanoaks, grasslands, and fire-adapted shrublands.

The forests in this region face threats from tree diseases and wildfires. Sudden oak death devastates tanoaks and true oaks, leaving behind substantial fuel in a landscape characterized by frequent fire occurrences. Coupled with prolonged drought, this environment becomes a tinderbox prone to increasingly powerful wildfires.

Into this landscape encroaches another opportunistic shrub, ceanothus. Like rhododendron, ceanothus is non-invasive but tends to dominate due to its advantageous traits suited for this altered habitat. It produces persistent seeds triggered by heat, leading to germination following a wildfire. It grows rapidly since its roots contain bacteria that fix nitrogen from the atmosphere, which it utilizes for growth.

When fuels such as dead trees ignite, there is generally an abundance of phosphorus found in the resulting ash. Besides extracting nitrogen from the air, ceanothus may leverage this phosphorus to further enhance its growth. It can reach around 8 feet in height within five years, outcompeting plants that cannot endure.

The forthcoming generation

During her undergraduate studies, Wurzburger majored in environmental science. She enrolled in a course on trees and woodlands and found it fascinating. Additionally, she was required to complete a soil science class, which surprised her with the volume of material dedicated to soil.

“Then I undertook the class, and it completely transformed my perspective,” she commented. “Now, nearly everything we pursue in the lab is somehow related to soil.”

In the upcoming years, Wurzburger will welcome four new colleagues who may share her enthusiasm for woodlands and soil. The Odum School is in the process of hiring new faculty members in ecosystem ecology — two focusing on terrestrial ecosystems and two on freshwater, marine, or wetland ecosystems.

“I’m incredibly eager to bring in a new wave of ecosystem ecologists addressing crucial global challenges,” Wurzburger noted, who is spearheading the hiring committee. “They have a unique opportunity to benefit from the legacy of the Odum School while steering us in a fresh direction.”

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