Overview of the Lakeshore Nature Preserve Plots

I run my Disturbance Ecology Labs at UW-M as CUREs, in which students use permanent research plots in campus natural areas to ask and answer research questions. With my students, I established a network of long-term experimental research plots designed to investigate how white-tailed deer (Odocoileus virginianus) and invasive plant species interact to shape forest understories. These plots serve as a dedicated space for researchers and students to study the complex ecological pressures – such as selective browsing and competition from non-native species – that define the forests of southern Wisconsin.

Plot Locations and Setup

There are eight permanent 25-by-25 foot plots distributed across four distinct woodland sites within the Preserve. At each site, two adjacent plots were established to ensure nearly identical environmental conditions, allowing for accurate scientific comparisons.

The four research sites include:

Frautschi Point Woods: Northeast and Northwest sites
Second Point Woods: Southeast and Southwest sites

Figure 1: Lakeshore Nature Preserve research plot locations. Yellow boxes mark the eight permanent 25-by-25 foot plots (two per site) across four woodland sites within the Preserve. Inset shows Preserve context relative to UW-Madison landmarks including Picnic Point and Eagle Heights.

Experimental Design: The 2 x 2 Factorial Study

To distinguish whether ecological changes are driven by deer, invasive plants, or a combination of both, the project utilizes a 2 x 2 factorial design.

1) Invasive Species Management: In 2023, invasive plants were removed from four plots using mechanical cutting and targeted herbicide, while the other four were left unmanaged as controls.

2) Deer Exclusion: In 2024, stainless-steel fencing was installed around four plots to prevent deer from browsing, while the remaining four remained accessible.

The following table illustrates how every treatment combination is represented across the eight plots:

Understanding the Recovery Process

It is important to clarify that our monitoring of “ecological recovery” refers specifically to these research plots, rather than the Preserve as a whole.

In these sites, recovery is defined by the restoration of natural processes, such as nutrient cycling and native seedling recruitment, rather than an immediate visual change. This process is often a slow, “messy” transition where resources like light and moisture are redistributed from invasive species back to a diverse community of native plants. By tracking these subtle shifts – from the return of spring wildflowers to the restoration of complex soil food webs – we can observe the forest moving toward a resilient, healthy state that can thrive under modern conditions. This long-term perspective allows us to distinguish temporary setbacks from forward progress.

Screenshot 2026-04-08 at 11.33.36 AM.png

Screenshot 2026-04-08 at 11.52.07 AM.png

Figure 2. Deer exclosure plot. A fenced experimental plot that prevents white-tailed deer access, isolating the effects of herbivory on understory vegetation through comparison with adjacent unfenced controls.

Course-Based Undergraduate Research Experiences (CUREs)

Course-Based Undergraduate Research Experiences (CUREs) mirror the way professional scientists conduct ecological research. Rather than following traditional “cookbook” laboratory exercises with predetermined outcomes, undergraduate students across multiple University of Wisconsin-Madison courses engage in authentic discovery through the following pillars:

Scientific Practices: Students take ownership of the research process by forming their own original questions and developing field methods to test them within the plots.
Discovery: Because these plots are part of an ongoing, long-term experiment, the results are not known in advance. Students frequently uncover ecological patterns and interactions that provide new insights into forest dynamics.
Real-World Relevance: Student findings provide immediate value to the Preserve, helping land managers and scientists understand the specific pressures – such as deer browsing and invasive species – facing southern Wisconsin forests.
Collaborative Science: Working in interdisciplinary teams, students combine their interests in botany, soil science, entomology, and ecology to analyze the complexities of the forest ecosystem.
Cumulative Progress: This research is a multi-generational effort. Each new cohort of students builds upon years of data collected by previous classes, allowing for the study of long-term ecological changes that occur over seasonal seasons.

Through this hands-on approach, students develop professional skills in scientific reasoning, field research, and data analysis while contributing meaningful, real-time knowledge to the field of forest ecology.

Student Research Gallery

The following research projects, conducted by undergraduate students at the University of Wisconsin-Madison, utilize the Preserve research plots as a long-term platform for ecological discovery. These studies contribute vital data toward our understanding of how forest understories respond to management and environmental pressures.

Interactive Effects of Deer Browse and Invasive

Species on Invertebrate Dynamics

Authors: Tamara Case, Will Ranger, Mackenzy Groth-Price, Jaen Muñoz, and Jude Whale

This study investigated how the simultaneous pressures of white-tailed deer (Odocoileus virginianus) browsing and invasive plant dominance influence forest-floor invertebrates. By using Berlese funnels to extract organisms from leaf litter samples, the team discovered a significant interactive effect: while individual treatments had little impact, the combination of excluding deer and removing invasive plants led to a five-fold increase in detritivore (organisms that feed on dead organic matter) populations. These findings suggest that restoring healthy soil food webs requires addressing both stressors concurrently.

Screenshot 2026-04-11 at 11.54.22 AM.png

Evaluating Spring Ephemeral Diversity Under Invasive Pressure

Author: Maxton Strait

This project examined how management strategies affect the diversity of spring ephemerals, the first native wildflowers to bloom each spring. Through systematic vegetation surveys within the Preserve research plots, the researcher found that while management effects were not immediately detectable in the first year, site-specific environmental conditions significantly influenced plant diversity. The study highlights that the recovery of native wildflower communities may be a gradual process, potentially delayed by the long-term “legacy effects” of historical deer browsing and the initial disturbance of removing invasive shrubs.

Screenshot 2026-04-11 at 11.55.30 AM.png

Invasive Plant Impacts on Soil Organic Matter Accumulation

Authors: Anika M. Johnson and Aundrea Taylor

This research explored how invasive species, such as common buckthorn (Rhamnus cathartica) and honeysuckle (Lonicera spp.), alter soil chemistry. The study revealed that plots dominated by invasive vegetation contained higher levels of soil organic matter compared to plots where invasives had been removed. This counterintuitive finding likely reflects the rapid decomposition rates of invasive plant litter, which can fundamentally shift nutrient cycling in the forest. The results emphasize that removing invasive plants is only the first step in a long-term process of restoring natural soil functions in the Preserve.

Screenshot 2026-04-11 at 11.56.46 AM.png

The Impact of Field-Based Research on Student Engagement

Authors: Elliot Oquist and Adam Gundlach

Beyond ecological data, this project assessed the educational value of using the Preserve as a “living laboratory.” Through pre- and post-course assessments, the researchers found that participating in authentic, long-term experiments significantly increased student confidence in scientific reasoning and their overall interest in forest science. Additionally, student-led vegetation surveys reinforced a key ecological pattern: as the abundance of invasive species increases, the richness of native plant species consistently declines, providing real-world evidence for the necessity of ongoing restoration efforts.

Deer Impacts on Temperate Forests

White-tailed deer (Odocoileus virginianus) are a native and iconic part of the Wisconsin landscape. However, in urban-adjacent areas like the Preserve, deer populations often reach levels that significantly influence the health and future of the forest [1, 2]. In fragmented woodlands near Lake Mendota, deer densities frequently surpass 35 deer per square mile, exceeding the land's natural carrying capacity by 2-3 times. This creates chronic pressure on the forest understory, leading to several long-term ecological changes [3].

Selective Browsing and Regeneration Failure

Deer are selective browsers, meaning they actively choose to eat high-protein native species while avoiding others. This preference targets the very trees needed for the forest's future, such as sugar maple (Acer saccharum) and northern red oak (Quercus rubra).

Stalled Growth: Chronic browsing often leads to “regeneration failure.” Monitoring in Dane County reveals that saplings in heavily browsed areas rarely grow taller than three feet (0.5 - 1 meter) even after 5 to 10 years. This “stalls” the replacement of the forest canopy, leaving a gap between the aging overstory and a sparse midstory [4, 5].
The Rise of Fern Meadows: As deer reduce the diversity of native wildflowers and shrubs by 40% to 60%, they leave behind unpalatable species like sensitive fern (Onoclea sensibilis) and Canada mayflower (Maianthemum canadense) [1, 7]. Over time, these plants can dominate the landscape, forming “fern meadows” that lack the biodiversity of a healthy forest.

Trophic Cascades: Impacting the Entire Food Web

The effects of high deer density ripple through the entire ecosystem in what is known as a trophic cascade. This term describes a chain reaction where changes at one level of the food web – such as an overabundance of deer – trigger significant changes at multiple other levels.

Spring Ephemerals: These are the first native wildflowers to bloom each year, such as trout lily (Erythronium americanum), which provide essential early-season food for pollinators. In high-deer areas, these populations can drop by 50% to 75% due to repeated feeding [3, 6].
Soil Life and Detritivores: A simplified forest floor provides less habitat for detritivores – the small soil-dwelling organisms, including many invertebrates, that break down dead leaves to recycle nutrients. Studies show these populations can decline by 30% to 50% under high-deer regimes [9].
Bird Communities: This cascade even impacts the trees. Ground-nesting birds, such as the ovenbird, experience roughly 40% lower nesting success in deer-altered forests because there is less vegetation to conceal them from predators [8, 10].

Beyond Eating: Soil and Carbon Dynamics

Deer also influence the forest through “non-consumptive” mechanisms – physical actions that do not involve feeding.

Soil Physical Changes: Frequent deer activity leads to soil trampling, which increases soil “bulk density” (the weight of soil in a given volume) by 15% to 25% [9]. This compaction makes it harder for water to soak into the ground and thus stresses the roots of native plants.
Nutrient Hotspots: Deer waste creates localized spikes in soil nitrogen. This often favors nitrophilic (nitrogen-loving) invasive species over sensitive native wildflowers that are adapted to more stable, nutrient-lean conditions [1, 4].
Carbon Storage: By shifting the forest floor from woody stems to ferns – which break down differently – deer browsing can actually reduce soil carbon storage by 10% to 20% [11].

The Path to Recovery

Research in the Preserve highlights that excluding deer is a vital first step, but recovery is a slow process due to “legacy effects.” For example, even after deer are removed, it can take several years for the essential fungi (mycorrhizal colonization) that help tree roots absorb nutrients to fully return to the soil.

Regional models suggest that to prevent irreversible shifts to low-diversity states, deer densities may need to be maintained at fewer than 20 deer per square mile – a target that is difficult to reach in urban areas [4]. Our long-term research plots allow us to track these complex transitions and determine the best ways to guide the forest back toward a resilient and healthy state.

Invasive Species Impacts on Temperate Forests

Non-native plants have become a dominant presence in the understories of Madison-area forests, including the Preserve. Species such as common buckthorn (Rhamnus cathartica), Morrow’s honeysuckle (Lonicera morrowii), and garlic mustard (Alliaria petiolata) often form dense, single-species stands that fundamentally alter the ecosystem [12]. These plants typically establish along urban forest edges and trails where disturbances facilitate their spread, eventually displacing native vegetation and reducing overall biodiversity [14].

Competitive Advantages: Light and Phenology

Invasive shrubs often gain a competitive edge through “early leaf-out.” Buckthorn and non-native honeysuckles typically produce leaves two to three weeks earlier than native deciduous trees like the sugar maple (Acer saccharum). By doing so, they intercept critical spring sunlight, casting a dense shade that suppresses the germination of native seedlings and eliminates the spring wildflowers that rely on that brief window of light [12, 13].

Chemical Warfare: Allelopathy and Soil Disruption

Some invaders use chemical strategies to hinder competitors, a process known as allelopathy. A primary example is garlic mustard (Alliaria petiolata), which releases natural chemical compounds called glucosinolates into the soil [15].

Root Inhibition: These chemicals can inhibit the root growth of native species by 30% to 50%.
Fungal Disruption: Glucosinolates also disrupt mycorrhizal fungi – beneficial soil fungi that form symbiotic relationships with native plants to help them absorb nutrients and water [12, 16].

Altering Soil Biogeochemistry

Invasive species do more than just occupy space; they change the very chemistry of the forest floor.

Nutrient Feedback Loops: The rapid decomposition of buckthorn leaf litter elevates soil nitrate and organic matter levels. This creates a “feedback loop” that favors further weedy invasion while stressing native plants adapted to stable, nutrient-lean conditions [12, 13].
Moisture Depletion: Dense thickets of invasive honeysuckle can deplete soil moisture during dry periods, placing additional stress on native hardwoods.
Legacy Effects: These soil changes often persist as “microbial legacies” for two to four years after the invasive plants are removed, which can slow the return of native wildflowers [15].

Trophic Cascades: Disrupting the Food Web

When invasive plants dominate, the impacts ripple through the entire ecosystem in a trophic cascade.

Invertebrate Decline: Invasive-dominated understories often show a 20% to 35% reduction in invertebrate diversity because their foliage is often lower-quality food for native insects [1].
Impacts on Detritivores: Population of detritivores frequently decline where native leaf litter is replaced by invasive debris [13].
Wildlife Shifts: As the forest structure simplifies, interior forest specialist birds and small mammals often decline, replaced by “edge species” that thrive in disturbed habitats.

Structural Damage: Girdling Vines

Climbing vines such as porcelain berry (Ampelopsis brevipedunculata) and oriental bittersweet (Celastrus orbiculatus) present a unique threat. These vines can climb high into the canopy and girdle mature trees – tightly wrapping around trunks and branches until they cut off the tree’s circulation. The added weight also makes mature trees more susceptible to branch breakage during storms.

Management and the NR 40 Rule

To combat these threats, the City of Madison and the Preserve staff utilize integrated management approaches, including mechanical removal, targeted herbicide spot-treatments, and prescribed burns. These efforts are guided by Wisconsin’s NR 40 rule, the state’s invasive species law that classifies non-native species as “prohibited” or “restricted” to mandate their control and prevent further environmental harm [12, 17, 18].

Through the long-term research plots in the Preserve, we are tracking how these interventions help break the cycle of invasion and restore the complex natural processes that sustain a healthy forest.

Invasive Species of the Preserve

The following species represent the primary non-native plants managed within the Preserve. While many of these are established throughout southern Wisconsin woodlands, their distribution within the Preserve varies. We categorize them as ‘Core Invasives’ – those that are common and widespread across the landscape – and ‘Localized or Emerging’ species, which are currently restricted to specific patches or are in the early stages of establishment.

Common and Widespread (Core Invasives)

These “core” species have severely dominated the understory of Madison-area forests for decades, with some occupying 70% to 80% of southern Wisconsin woodlands.

Common Buckthorn (Rhamnus cathartica): A dominant shrub (10-25 feet) that suppresses native seedlings through intense shading. It is highly successful because it “leafs out” 2-3 weeks earlier than native trees [17]
Garlic Mustard (Alliaria petiolata): An herbaceous biennial that exhibits allelopathy by releasing glucosinolates. These chemicals inhibit native root growth by 30% to 50% and disrupt essential soil fungi [17]
Invasive Honeysuckles (Lonicera spp.): This group – including Morrow’s, Bush, Amur, Tatarian, and the climbing Japanese honeysuckle – collectively dominates the shrub layer. They achieve 10x higher seedling densities than natives and deplete soil moisture during dry periods [24]
Oriental Bittersweet (Celastrus orbiculatus): A woody vine that can grow over 60 feet. It is known to girdle mature trees – wrapping tightly to cut off circulation – and adds significant weight that leads to structural damage [17]
Black Locust (Robinia pseudoacacia): A tree that changes soil nutrient conditions by “fixing” nitrogen, often favoring other weedy invaders over native hardwoods [13]
Wild Parsnip (Pastinaca sativa): Common in open areas and trail edges; its sap causes severe skin irritation and blistering when exposed to sunlight [25]
Siberian Elm (Ulmus pumila): A fast-growing tree (40-70 feet) that establishes quickly in disturbed soils along trails and forest edges [13]
Common and Cut-leaved Teasel (Dipsacus spp.): Tall, spiny plants that form dense stands in open areas, producing thousands of seeds that compete with native grasses [17]
Reed Canary Grass (Phalaris arundinacea): A tall grass that forms extensive, single-species stands in wetlands near Lake Mendota, reducing native diversity [17]
Purple Loosestrife (Lythrum salicaria): A prolific wetland invader that replaces native vegetation essential for local wildlife [17]
Norway Maple (Acer platanoides): A shade-tolerant tree that can establish beneath existing canopies, casting a shadow so deep that native seedlings cannot survive [13]
White Mulberry (Morus alba): A concern for forest edges that can hybridize with the less common native red mulberry [26]

Present but Localized/Patchy

These species are currently found in smaller numbers or specific “hotspots.” Staff monitor these areas closely to prevent these plants from becoming widespread.

Tree-of-Heaven (Ailanthus altissima): A rapidly growing tree that forms dense stands in disturbed areas; its crushed leaves release a strong, distinctive odor [17]
Princess Tree (Paulownia tomentosa): Found in forest openings and gaps where sunlight reaches the soil; it produces vast amounts of wind-dispersed seeds [13]
Porcelain Berry (Ampelopsis brevipedunculata): A vigorous vine that forms dense tangles over native shrubs in sunny edges, shading out the plants beneath [17]
Himalayan Balsam (Impatiens glandulifera): Localized to moist soils and streambanks where it competes for space and sunlight [27]
Japanese Stiltgrass (Microstegium vimineum): An emerging threat in the Preserve that forms dense mats over the forest floor in moist, shaded areas [17]
Giant Hogweed (Heracleum mantegazzianum): Currently rare in the Preserve, but strictly managed because contact with its sap can cause severe, permanent skin burns [17]

What Recovery Looks Like (and What It Doesn’t)

Ecological recovery in the Preserve research plots is best understood as a change in processes, not just a change in appearance. In the first few years after management, the most important signals of recovery are often hidden: subtle shifts in who is recruiting into the understory, how nutrients move through the soil, and which species are beginning to claim microsites that were unavailable for decades. Rather than a rapid transition from “weedy” to “pristine,” the plots are expected to pass through a series of transitional states that can look messy or even degraded while underlying conditions are actually improving [20, 21].

One early hallmark of genuine recovery is a reopening of ecological space. When deer access is reduced and invasive shrubs are removed together, light, moisture, and nutrients are redistributed from a small set of stress-tolerant dominants to a broader suite of native species. In practice, this often shows up first as an increase in the number of species present – even if each one is still rare – rather than as a lush carpet of vegetation. Small cohorts of tree seedlings, scattered spring ephemerals, and a more structurally varied litter layer signal that the system is beginning to diversity, even if total biomass or visual “greenness” has not yet rebounded [1].

A second indicator is the re-establishment of feedbacks that favor natives over invaders. Before treatment, many Preserve stands are locked into feedback loops where invasive shrubs create the very conditions that help them persist: dense shade, nutrient pulses from fast-decomposing litter, and simplified structure that withstands heavy deer browse. As those shrubs are controlled and browsing pressure is reduced, the direction of feedbacks can slowly flip. Native litter begins to accumulate, microhabitats for fungi and invertebrates become more complex, and small patches of regeneration are less likely to be wiped out by a single disturbance event [20, 22]. None of these changes is dramatic on its own, but together they indicate that the system is moving into a different stability domain.

Recovery also has a temporal signature that differs among plant functional groups. Fast-growing herbs and graminoids often respond first, followed by shrubs and, only much later, long-lived canopy trees. In the Preserve research plots, it is realistic to expect that a few years of data will show improvement in ground-layer richness or invertebrate communities without yet capturing meaningful changes in overstory recruitment or soil carbon pools [23]. Rather than interpreting these lags as failure, it is more accurate to see them as evidence that different components of the forests are operating on different clocks, all of which must be monitored to understand the full trajectory.

Finally, the research plots highlight that recovery has a direction, not a fixed end point. The Preserve will not return to some idealized “pre-settlement” forest. Instead, it will move toward a new configuration that reflects current climate, land-use history, and ongoing urban pressures. In that context, success looks less like recreating a particular species list and more like restoring key functions: sustained regeneration of native trees, a seasonally diverse wildflower layer, complex litter that supports robust detrital food webs, and understories that can absorb disturbance without flipping back into invasive dominance.

While these observations are specifically focused on the research plots within the Preserve, they provide a broader framework for understanding forest restoration across southern Wisconsin and other temperature deciduous forests. By documenting these complex recovery trajectories, our findings offer scalable insights that help scientists and land managers navigate the universal challenges of deer overabundance and invasive species to restore long-term ecological resilience throughout the region.