Reading(s)
Lab Goals & Objectives
Identify Structural Indicators of Past Open Conditions: Recognize "wolf trees", large-diameter oaks featuring low, wide-spreading lateral limbs, surrounded by dense pole-sized saplings, and explain how these growth forms signal historical open-woodland or savanna environments that underwent fire suppression and woody in-filling.
Differentiate Midwestern Oak Communities Along a Canopy Continuum: Categorize woodland stands based on structural metrics, distinguishing open woodlands (30%–50% canopy cover) from closed woodlands (50%–80% cover) and closed-canopy forests (>80% cover). Quantify Canopy Closure Using a Spherical Densiometer: Apply standardized field protocols to measure % canopy closure across a gradient of thinned and unthinned woodland stands
Correlate Light Availability with Understory Functional Groups: Evaluate the empirical relationship between canopy openness and ground flora response, testing the hypothesis that 30%–50% canopy closure optimizes forb species richness and diversity while suppressing full dominance by tall C4 prairie grasses. Compare Fire Regimes on Grass vs. Forb Ratios: Contrast how disturbance frequency impacts understory composition, specifically how annual burning tends to promote C4 grass dominance, whereas biennial or variable fire intervals maximize forb richness
Analyze the Limitations of Fire Alone: Explain why low-intensity dormant-season surface fires primarily top-kill small woody stems (<10 cm DBH) and fail to kill larger overstory trees or reduce overstory stocking in fire-excluded forests.
Evaluate Overstory Thinning and Girdling Mechanics: Describe how mechanical girdling, stem injection, or harvest operations reduce overstory density to elevate photosynthetically active radiation (PAR) at the forest floor from ~3%–5% up to 50%.
Synthesize the Synergy Between Thinning and Prescribed Burning: Assess the "woody sprout trap" wherein canopy opening without fire triggers aggressive resprouting of top-killed trees and midstory shrubs and detail how follow-up prescribed burning suppresses woody competition, removes leaf litter barriers, and releases bound soil nutrients to stimulate herbaceous establishment.
Assess Site Vulnerability to Canopy Re-closure and Mesophication: Evaluate how soil depth, texture, and hydrologic restrictions (e.g., claypans, fragipans, shallow bedrock) induce seasonal droughtiness that naturally limits tree stocking and increases restoration feasibility compared to fertile, mesic soils. Evaluate Microclimate & Topographic Controls on Fire Behavior: Explain how aspect (south/west vs. north/east slopes) and landform (ridge tops vs. protected fire shadows/coves) interact with solar exposure, wind drying, and leaf litter flammability (pyrophytic oak vs. moist mesophytic litter) to dictate burn efficiency and overall restoration outcomes.
Reflection Prompt
This week, you transitioned from closed-canopy forests into restored oak woodlands managed via girdling, thinning, and prescribed burning. Synthesize your field observations, densiometer readings, quadrat vegetation counts, and course readings into a coherent 1-page single-spaced reflection addressing the three sections below:
Identify two specific data points from your lab group's measurements (e.g., a specific densiometer closure percentage in Plot X vs. Plot Y, or your forb vs. grass cover ratio in a specific 1 m² quadrat). Contrast these numbers with your visual observations of the canopy structure and midstory density at those exact plot locations.
Describe a specific "wolf tree" your group analyzed in the field. What physical indicators (branching architecture, surrounding sapling density) revealed its history? How do your group's densiometer readings and understory grass-to-forb ratios align with or contradict the management mechanisms discussed in your readings?
How do community or public values (e.g., viewing dense green forests as "healthy" vs. open woodlands with dead standing snags as "damaged") conflict with ecological restoration goals? How have your own personal definition and aesthetic appreciation of a "healthy forest" shifted as a result of walking through these thinned and burned sites?
Based on your observations of soil, aspect, or invasive sprout competition in the field, identify one specific restoration management challenge (e.g., controlling stump sprouts, managing fuel loads, or dealing with invasive species) that you feel unprepared to address.
Materials, Links, Logistics, & General Itinerary (subject to change as needed)
We will meet at Reith Village. Be prepared to walk off trail. The number of sites we are able to visit will depend on time. We will for sure visit woodlands by the Luckey's pavillion, Edwards's Wetland, the Shew Shop. If there is time we may also visit woodlands back by the gravel pit and a glacial kame. We will need densiometers and quadrats in addition to your lab notebooks and plant identification apps.