FOREST ECOLOGY Instructor: M. AbramsFORESTRY 308

Community analysis of a mature white oak forest Valley floor forest

Introduction

Deciduous forests, or "summer-green" forests, dominate the eastern half of the U.S. (bounded by Minnesota, Texas, Florida, and Maine), and are bordered by prairies in the Central Plains and boreal forests to the north. Low soil moisture and prairie fires limit deciduous forests to the west, and low temperatures producing short growing seasons limit their extent to the north. Deciduous forests in the U.S. are dominated by oak, hickory, maple, beech, and basswood; all five genera occur in Pennsylvania. These forests typically occur on moist and fertile, well-drained sites. Dominant associations of deciduous forests include: beech-maple, maple-basswood, oak-hickory, and southern mixed hardwoods. Historically, white oak has dominated limestone, valley floor sites in central Pennsylvania. The purpose of this laboratory exercise is to survey the overstory and understory vegetation of a mature white oak forest situated on the limestone soils of NittanyValley. This exercise will allow you to quantify the composition and structure of a relatively, undisturbed mature forest. With this lab you will also come to realize some of the profound successional changes that are occurring in our area oak forests to due changes in historical disturbance regimes (suppression of understory fires).

Equipment

Compass, d-tape or Biltmore stick, 50' tape, 90' plot marker, chaining pin; bring pencil and paper.

MethodWe will be using stratified circular plots to survey mature trees, saplings and seedlings and shrub and herbaceous cover, using a minimum of 10 plots (but target 15 plots). Data collected for the mature trees is used to calculate density, dominance, frequency, and the Importance value of each surveyed species.

Each group (4-5 students) will pick a starting point at the forest edge and follow a compass bearing (transect) into the interior of the forest. Using either a systematic (every 20 paces) or a restricted random plot placement, a point will be marked that will be the 800 sq. ft. plot center for the overstory survey (tree larger than > 3 inches at dbh). The plot center should be at least ten feet away from a trail. For each “in” tree record the species and its dbh (in inches). Using the same plot center, conduct an understory survey and record species and number of all saplings (< 3.0 inches dbh and > 4.5 feet in height) in a 100 sq. ft. plot at each sample point. Next record species and number of all tree seedlings (< 4.5 feet in height) in a 50 q. ft. plot. Also estimate total cover of each shrub by species and total herbaceous cover in the 50 sq. ft. plot into one of the following cover classes:

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Class Canopy Coverage Midpoint1 0 - 5% 2.5%2 5 - 25% 15.0%3 25 - 50% 37.5%4 50 - 75% 62.5%5 75 - 100% 87.5%

Part I. Data analysis for overstory trees:

Using the data from all ten plots, calculate:1. The total frequency for each tree species as the number of plots in which it

occurred.2. The total density of each tree species per acre as the total number of individuals

for each species across all plots. Use cross multiplication to express your plot total area (e.g., 800 sq ft x 10 plots = 8000 sq ft) to a per acre basis. For example: (solve for X).

25 red maple trees = X red maple8000 sq. ft 43560 sq. ft.

3. The total basal area (ft2/acre) or dominance for each tree species per acre across all plots. Basal area (in square feet) is calculated as BA= .005454 x dbh2

Again, use cross multiplication to express your plot totals to a per acre basis.

4. Then calculate the relative frequency, density and basal area (dominance) for each tree species by dividing value for each individual species by the column total.

5. Finally, calculate the relative importance value by add the relative frequency, density and dominance for each tree species and dividing that number by three. The column sum for the 4 relative measures must add up to 100% (if not you made a math error. See the table below as an example you what you need to produce for your overstory data (keep in mind that this example used 20 plots, instead of the 10-15 plots you used).

Frequency Density Dominance Relative Relative Relative Importance

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(20 plots)(stems/acre) (ft2/acre) Frequency Density Dominance Value

Quercus velutina 20.00 81.52 47.785 23.53 23.58 51.05 32.72Sassafras albidum 15.00 85.87 11.63 17.65 24.84 12.44 18.31Carya glabra 9.00 45.65 10.02 10.59 13.21 10.68 11.49Quercus alba 7.00 36.96 14.07 8.24 10.69 15.03 11.32Prunus serotina 13.00 41.30 2.22 15.29 11.95 2.37 9.87Cornus florida 8.00 18.48 0.78 9.41 5.35 0.85 5.20Acer rubrum 4.00 16.30 1.70 4.71 4.72 1.83 3.75Quercus prinus 3.00 7.61 3.00 3.53 2.20 3.21 2.98Quercus stellata 2.00 4.35 1.045 2.35 1.26 1.13 1.58Amelanchier laevis 2.00 5.43 .261 2.35 1.57 0.26 1.40Fagus grandifolia 1.00 1.09 1.00 1.18 0.31 1.09 0.86Carya ovata 1.00 1.09 .087 1.18 0.31 0.07 0.52Total 85.00 345.65 93.65 100.00 100.00 100.00 100.00

Part II. Data analysis for understory vegetation:

1. Sapling and seedling regeneration: Estimate the number of saplings and seedlings per acre for each species and summarize the data in a table (see below). You will need to add up the total number of saplings and seedlings across all your plots and then use cross multiplication to express these data on a per acre basis. For example: 100 sq ft x 10 plots = 1000 sq ft; 50 sq ft plots x 10 plots = 500 sq ft

60 red maple saplings = X red maple1000 sq. ft 43560 sq. ft.

240 red maple seedlings = X red maple500 sq. ft 43560 sq. ft.

Example regeneration table. Data are express as # per acre

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LAB REPORTCalculations, summary tables, AND final report due: beginning of lab on the following week.

2. Shrubs & Herbaceous: Calculate the percent cover of shrubs and herbaceous species in the stand by averaging the midpoint percent canopy coverage in all plots. Again, create a summary table comparing shrub & herb cover in the two sites. a) convert cover classes to the midpoint (%) of the cover class:

Cover Class

Midpoint (%)

1 2.52 153 37.54 62.55 87.5

b) Mean cover =

example for Lonicera: (0+62.5+37.5)/3=33.3

Table XXX: Shrubs & Herbaceous Cover

Each group is responsible for doing all the calculations described above with the data your group collected. The report should be typed and organized in a neat format. Be sure to include a copy of your group’s field data with the final report.

1. Introduction and methods: in this section (1-2 paragraphs) you should summarize the problem we are trying to address with this study, and include a description of the sites we sampled and the rationale we used to select them. Finally, briefly describe the methods we used to collect the data.

2. Study area description, including location, topography, soils, forest condition and evidence of disturbance.

SunsetViac 1.67Paqu 5Lonicera 33.3

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2. Results: This part of the report should have two sections, Part I: Data Analysis for Overstory Trees, and Part II: Data Analysis for understory vegetation. Make sure you don't forget any of the steps! Do all the calculations with your group data and include one step-by-step example for each calculation. (Please arrange them in the order listed on the previous pages, i.e. Part I, questions 1-8, then Part 2 questions 1-3). Summary Tables: Create summary tables showing your group results.

3. Discussion & Conclusions (1-2 pages):

The questions below are designed to guide your discussion and should be addressed in fluent paragraph form; questions should not to be answered individually independent of each other.

Describe the overstory composition and structure of the mature stand at Sunset Park. Are the overstory dominants also the dominant understory species at Sunset Park? Also describe groundcover and tree regeneration (i.e. saplings & seedlings) in the stand. Do they vary much on a plot by plot basis. How do you explain the differences you observed? Cite numbers from your data to back up each of your assertions. Also in your discussion section, describe how the overstory condition has facilitated a compositional shift in the understory due to increasing shade. Describe the disturbance regime that led to this understory condition and contrast it with what might have occurred in presettlement forests. What implication does anthropogenic changes in disturbance regimes have for the future of Pennsylvania oak forests? What management techniques might be applied to create understory conditions that would allow the present overstory species to replace themselves following a major disturbance such as a clear cut?

Map of Sunset Park.

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