Given the bulk of the forestry work in New Jersey is driven by Farmland Assessment on smaller parcels, it’s fair to say that we tend to focus more on forest structure within individual tracts to meet those goals, and have less need to evaluate statewide forest metrics too closely. Working for New Jersey Audubon, part of my job has become advocating to a variety of audiences for statewide healthy forests, and why active management is better than benign neglect. A tool that I have leaned on heavily to do this is the landscape level data available through the US Forest Service’s Forest Inventory & Analysis (FIA) program.
We’ve seen excerpts of this data in the periodic publications distributed by the New Jersey Forest Service and US Forest Service, but I hadn’t become well acquainted with the FIA program until I worked for the Northern Research Station in the early 2000’s. The FIA program we see today has evolved and expanded from a limited inventory of select areas initiated in the 1950’s, and now covers the entire country. FIA inventory plots are stratified across the landscape, and field crews measure fixed radius, nested plots to collect the data. In recent years, the program goal was to revisit these plot locations every five years, thereby capturing the small changes to stand dynamics over time.
The compiled data can be retrieved via FIDO (Forest Inventory Data Online) at: http://www.fia.fs.fed.us/tools-data/.
FIDO has a number of standard reports available, and custom retrievals can be scaled down to the county level – although sampling error tends to become more significant at these smaller scales. Figure 1 is an example of a typical statewide report using the 2013 data (the most recent available data tends to be a year or two behind).
Since the majority of my forestry work at NJ Audubon is tied to wildlife habitat objectives, I use the FIA data to look for trends that might correlate with statewide wildlife issues of importance. While we’ve all probably – least anecdotally – referenced the uniformity of our forest age structure as an anthropogenic caused anomaly, what jumps out from the FIA data is how it’s trending. With our total forest cover remaining relatively constant since recovering from maximum deforestation around 1900, recruitment of new stands peaked about 70 years ago (646,879 acres initiated in the twenty year window between 60 – 79 years ago), and now continues to drop steadily. At the current rate of new stand initiation (or lack thereof), we can expect that by about 2030 there will be no new even-aged stands of trees regenerating (from a statistically significant perspective). That’s a stark contrast to even the most conservative estimates of what a naturally occurring age class distribution would be for our main forest types in this region. This trend correlates strongly with many wildlife species that are declining, and it will be interesting to see how this progression unfolds.
Another interesting trend is the ongoing shift in species composition. From the data we can see that advanced regeneration of red maple, sugar maple and sweet birch have become the three most numerous trees in north Jersey; despite being only minor associate of the overstory. In south Jersey, red maple is second in frequency only to pitch pine, occurring at a rate of about one maple for every two pitch pine. Furthermore, since the eighties, we’ve realized (statewide) a fourfold increase in the number of red maple greater than 13″ DBH. The species continues to occupy more and more growing stock in larger size classes, and it appears that trend is likely to continue. After seeing this data, I pay a little more attention to red maple saplings during intermediate treatments than I used to.
Overall, the FIA data seems to be pointing to a forest trajectory that is one of reduced diversity and value (both commercial and ecosystem). It suggests that we are developing a different forest mosaic (both age class distribution and species composition) than we’ve had in the past. While there may be numerous reasons for this, chief among them has to be our flawed property tax abatement policy and cultural bias against intensive silvicultural treatments. Will that ever change?
So, even though you think the FIA data may not be helpful for your day to day work – it’s worth checking out. Having a better awareness of the statewide forest trends has definitely influenced my decision making on individual properties. It might affect how you advise clients and manage properties too!