Logging in National Forests is a contentious subject that has a long, controversial history. With today’s post, I’d like to take advantage of a geospatial tool offered by the Forest Service to explore National Forest logging data. With this tool, we can see where and when particular timber harvests took place as well as determine the purpose of the harvest.
Let’s get started!
Forest Service Data Sets
First, we need to access the Forest Service National Datasets here. Take some time to scroll down and look at the different types of data sets available. In this list you can find data regarding invasive plants, mineral rights, National Grasslands, roadless areas, and even data on hazardous sites. Today, we are going to explore the Timber Harvests data set. Some of the questions we will seek to answer include:
- What types of harvests are most common?
- How many acres have been harvested?
- What can these data tell us about logging over time?
To answer these questions, we’ll be focusing on Daniel Boone National Forest in eastern Kentucky (Fig. 1).
First, let’s access the Timber Harvests data set. Near the top of the Forest Service National Datasets page you will find a search bar where you can type in “timber harvests” and click the GO button. The Timber Harvests data set returns and includes data for all of the US. There is an ESRI geodatabase, a shape file, and there is also a link to the metadata associated with the data. The purpose of the metadata is to provide a description of data attributes and give more context to the data. It is helpful to take a few minutes to explore the metadata, though the link for this particular data set does not give a full description for many of the attributes.
Under the Abstract column you will find a brief description of the Purpose of the data. These data do not contain all timber harvest activity because these data are self-reported by the Forest Service and spatial data is not necessarily required. So there may be more harvesting activities than what show up in these data.
Spatial Data
To access the spatial data that is available, we can go ahead and click on the “map service” link (Fig. 2). This will take us to an ArcGIS service directory where we can find links to the ArcGIS mapping tools, but also includes further detail regarding the timber harvest data layer. For these data, it is important to note that data is only visible when zoomed in past 1 : 750,000. We will keep this in mind, because if we are not able to see the harvest areas, it may mean that we have not zoomed in far enough.
Near the top of this page you can find a link called “ArcGIS Online Map Viewer.” Click on it. We are now in the ArcGIS online mapping tool (Fig. 3). From here we can explore the timber harvesting data layers.
The current map is called the base layer. We can select from several base layer options by selecting the “Basemap” button in the top left corner of the page. The Topographic map is the default layer, but you are welcome to try other base layers that fit with the kind of data you are sharing or your aesthetic preference. I suggest keeping the topo map as the default or one of the other maps that contains National Forest boundaries already.
Data Layers
If we look to the left of the screen, we fill find the side pane that contains the details of the data layers. EDW TimberHarvest1 is the layer we are interested in. But, this layer is greyed out, whereas the Topographic layer is not. The EDW TimberHarvest1 layer is greyed out because it is not visible at the current scale we are viewing the map at. So we know that we can zoom in until the layer name in no longer greyed out; at this point, it should be visible.
When we click on the EDX TimberHarvest1 layer name, the layer drops down to reveal each of the layers within it. By clicking on the names of each of these sublayers, we see how each is differentiated on the map by a particular color feature. The harvest data have been divided into decade time intervals based on when the harvest activity occurred and each time interval is represented by these sublayers. Looking at these layers, we can see that the data are divided into decade time intervals until we get back to about the mid 1940s.
Right now, all of these sublayers except the last are active because the boxes to the left of their names are checked. Using the map in Fig. 1, let’s zoom in to eastern Kentucky where we can find the boundaries of Daniel Boone NF. Alternatively, you can type “Daniel Boone National Forest” into the search window in the top right corner of the screen. (Zoom in enough that the layers in the side pane are no longer greyed out.)
Time Interval Data
Once the map loads, you should see shapes appear. These shapes represent stands where harvest activity has occurred. Each color represents one of the time interval layers. Let’s see how the harvest data has changed over time. Start by making sure the layers are active or inactive by checking or unchecking their box (Fig. 4) according to the following list:
- EDW TimberHarvest 01 Active
- Timber Harvest 2021 – Current Inactive
- Timber Harvest 2011 – 2020 Inactive
- Timber Harvest 2001 – 2010 Inactive
- Timber Harvest 1991 – 2000 Inactive
- Timber Harvest 1981 – 1990 Inactive
- Timber Harvest 1971 – 1980 Inactive
- Timber Harvest 1956 – 1970 Active
- Timber Harvest 1946 – 1955 Active
- Timber Harvest 1820 – 1945 Active
- Timber Harvest (All Years) Inactive
So the only sublayers that should be active are the layers depicting data from 1820 -1970. Now if we pan over the map of Daniel Boone NF, we see there were very few harvest activities conducted during this 150 year time period. However, we know that this was a period of some of the most aggressive harvesting in the history of the area. It’s much more likely that there is just a lack of spatial data for these harvest activities.
There is also a lack of available data for time intervals after 1970, but by selecting to only show the data layer for 1981-1990 we can see that a significant increase in recorded harvest activity. This pattern continues through the 90s.
Exploring Data Tables
We can now open up the data tables associated with these layers to learn more about the types of harvest activities that are taking place in the forest. If you hover your mouse pointer over the 1991-2000 data layer, you will see several small icons appear below the layer name. Clicking the first icon will reveal the legend for that layer, in this case, the color associated with that layer. The second icon will show the data table associated with the layer. Let’s click on the data table icon for the Timber Harvest 1991-2000 layer. A table will appear at the bottom of the screen that you can drag up to reveal more of the table. However, this table has all the data for the timber harvest events across the US. We only want to see data for Daniel Boone NF, so we need to filter out this data only.
Near the top right corner of the table, find the three lines that indicate the options menu and click on it, then select the Filter option. A window will appear. In the first drop down menu in this window (ACCURACY is the current menu option) scroll down to select ADMIN_FOREST_NAME. In the next menu select “starts with”, and in the third menu type ” Daniel” and click Apply Filter. This will only display data associated with Daniel Boone NF in our table and on the map. There should be 1223 features.
Harvest Activities
To learn what types of harvest occurred for this time interval, scroll right in the table until you find the category called ACTIVITY_NAME. This is the name of the harvest activity. We can scroll down and see Stand Clearfell, Natural Changes, Two-Aged Shelterwood Establishment Cut, and so on. If we click on the category name at the top, we can sort the data alphabetically in ascending or descending order. This will help to organize what we are seeing.
Scrolling further to the right, we will find a category named NBR_UNITS_ACCOMPLISHED. This is the number of acres in which the given activity took place. If we click on the category name we can sort the harvest units in descending order to determine which types of activity were associated with the largest acreage. We can also scroll just to the right right again and see the time associated with the harvest.
Further Exploration
I encourage you to continue exploring these data. See how many of the following questions you can answer with them.
- How many harvest activities were recoded for between 2001 and 2020?
- What type of harvest activity was associated with the largest acreage between 1991 and 2000?
- Were any harvest events associated with wildfire? How many?
You can also explore harvest activities in National Forest logging data near you. What other questions can you answer with these data?