Did you catch the article on Forest Inventory in the latest Winter Edition of the Steward newsletter? If not, check it out here. Below, you’ll find some supplementary information to accompany Matt Fitzpatrick’s informative article;
Fixed Radius Plot Sampling Forest Inventory
Fixed Radius Plot Sampling is a type of forest inventory that’s used to sample trees based on how many fit within a randomly placed, predetermined sized plot. The size that the plots are made depends on how accurate you want the inventory to be. In this case I used 1/5 acre plots (52 ft radius). If you used this plot size and had exactly 1 plot per acre on your inventory then every tree counted in your plot would represent 5 trees throughout the entire acre. This inventory had 33.09 acres and 32 plots, so it’s close to that but not exact. In this inventory I separated the full 33.09 acres into 3 separate stratums. Each stratum is treated as its own individual tract of land and only added to the other strata’s in the grand summary. This is done because the more alike the trees are in your inventory, the more accurate it will be. For example, if you have a 10 acre tract and 3 acres of it are mostly riparian species and you do an inventory treating it as one tract of land, then the riparian species will be multiplied and distributed throughout the entire 10 acres, which is not accurate because there just on the 3 acres. A thing to keep in mind when looking over the total trees is that it only represents the total amount of trees that are 10 inches and above in diameter, which is also known as saw timber. Obviously these totals are not going to represent exactly what’s present, but the inventory I did was pretty intensive compared to the majority of inventories done, so I think these numbers aren’t that far off from reality.
Excel Document Key
- Field Sheet- Digitized copy of the sheet that the field information was taking on.
- Grand Summary- Summary of all the information from all 3 strata’s.
- Strata Cruise Summary- Summary of all the information from individual strata.
- S&S- (Stand and Stock) formula sheets for determining amounts for each species in each stratum.
- DBH- Diameter of a tree at breast height (4.5 ft)
- Saw Timber- Timber suitable for sawing into lumber. Dbh requirements vary from area to area, in this inventory its 10 inch and up.
- Basal Area- The area of a given section of land that is occupied by the cross-section of tree trunks and stems at their base, used to examine a forest’s productivity and growth rate, among other things. Measured in square ft.
- Board Foot – Specialized unit of measure for the volume of lumber. One board-foot equals: 1 ft × 1 ft × 1 in
- Forest Stratification- Separating an area of forest into different categories (strata’s) based on age, stand structure, species, and location.
- Cull- A defect in a tree that in most cases results in a loss of board feet.
Download the Spreadsheet here;