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Vegetation Monitoring

Why measure forest vegetation?

The key focus of this study is monitoring how vegetation responds to changes in deer densities and different forest management actions.  We will intensively monitor understory vegetation – herbs, shrubs and tree regeneration – because these plants respond most rapidly to management actions and determine future forest conditions.

Two types of vegetation surveys will be conducted for the study. First, 50 permanent plots were established in each study area to track landscape-level changes over time. Second, plots will be established in areas where forest management treatments are planned. These treatment-area plots will evaluate the effectiveness of the management actions in establishing tree regeneration and their impact on the species composition of the forest understory.

Vegetation monitoring will:

  1. Document forest conditions in the study areas at the beginning of the project,
  2. Identify changes over time in the species composition, abundance, size and distribution of vegetation in the study areas,
  3. Evaluate existing, and potentially develop new, vegetation-based measures of deer impact on vegetation, and
  4. Evaluate the response of understory vegetation to various forest management treatments.

Plot Layout

Each randomly-located plot consists of five 1/24th-acre subplots 120 feet apart. Nested inside each subplot are a 1/300th-acre microplot and a 1/1000th-acre microplot. Data from this study can be compared to USDA Forest Service (FIA) and DCNR (CFI) inventory plots. 

Figure 1. Plot layout with five 1/24th-acre subplots with 1/300th-acre and 1/1000th-acre nested microplots. One set of microplots is fenced to exclude deer.

plot layout

All trees over 5 inches in diameter are identified and measured on the 1/24th-acre subplot, and all plant species are identified and measured on the microplots. A fifth microplot (northeast of the plot center) will be fenced to measure how the vegetation in the area changes in the absence of deer.

Permanent Plots

Fifty permanent plots were established in each study area, for a total of 200 plots. Plots were randomly located on the landscape to obtain a representative sample of the vegetation. These plots will be revisited every two years to track landscape-level changes in vegetation over time.  

Figure 2. Randomly-located permanent plots (yellow triangles) on the Bald Eagle study area.

50 permanent plots

Treatment-area plots

Forest management treatments – such as shelterwood harvests, controlled burns, and herbicide applications – will be monitored on each study area.  Between 20 and 30 plots will be located in each treatment area depending on size of the treatment.  Similar to the subplots in the permanent plots, these plots will consist of a 1/24th-acre overstory plot with nested 1/300th-acre and 1/1000th-acre microplots. 

These plots will be measured before the treatment is applied and two–three years afterwards. These plots will allow us to evaluate the effectiveness of the treatments in establishing tree regeneration and their impact on plant species composition.