Selecting FIA data

For initial exploration of the data, we will first get FIA plots from MI, MN, and WI. We are downloading data directly from DataMart for most up to date information. A harvest is defined as either a 10 in the TRTCD1 column and/or 25% BA removed per acre without any other disturbance reported.

To clean the data, we are only selecting FIA data that was measured in 1997 or later, when annualized data began. Finally, we are selecting plots that:

1. Have accessible forestland
2. Are not reserves
3. Are of private ownership
4. Are single condition class
5. Are greater than or equal to 2000 gross BF per acre (initial)
6. Are natural stands (not planted stands)

Reporting Harvest likelihoods over 20-year timeframe for major forest types

Using the Best Practices formula but with avg time between measurement dates rather than invyr

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\(\color{forestgreen}{\text{For Maple / beech / birch group the harvest likelihood is: 62.18%}}\)

\(\color{forestgreen}{\text{For Oak / hickory group the harvest likelihood is: 37.36%}}\)

Forest Types

Total number of plots is \(\color{red}{\text{4748}}\)

Forest transitions over time

Total number of plots that did not transition is \(\color{red}{\text{4302}}\)

Breakdown of FIA plots

This table subsets to sites with initial gross board foot volume being greater than or equal to 2000.

Map of FIA plots

Change in BAA by forest type

\(\color{red}{\text{For Maple / beech / birch group, the number of clearcut plots (i.e., removed at least 70% BAAC) is **29** and the number of thinned plots is **395**.}}\)

\(\color{red}{\text{For Oak / hickory group, the number of clearcut plots (i.e., removed at least 70% BAAC) is **23** and the number of thinned plots is **186**.}}\)

Harvest behaviors by change in QMD

Percent TPA removed

The red portions of the histograms represent trees that were removed, whereas the grey portions are the trees left to grow. If the red to grey ratio is consistent across the diameter classes, that suggests a thin throughout. If the red to grey ratio is higher in the higher diameter classes, that suggests a thin from above and if the red to grey ratio is higher in the lower diameter classes, that suggests a thin from below.

Histograms of Previous BAA across Longleaf forest sub types

\(\color{red}{\text{For Maple / beech / birch group, the mean BAAC for all plots is **121.63 sqft/acre** and the mean for harvested plots is **123.01 sqft/acre**.}}\)

\(\color{red}{\text{For Oak / hickory group, the mean BAAC for all plots is **115.57 sqft/acre** and the mean for harvested plots is **121.38 sqft/acre**.}}\)