Sometimes a pasture makeover just isn’t possible. This is especially true in the wide open spaces of the west, where a single pasture can be as large as an entire farm in the Northeast. That’s when knowing your pasture’s potential becomes very important. By identifying an area’s Ecological Site, we can get a handle on the site’s potential and manage grazing to be sure that the site achieves everything it can.
What is an Ecological Site?
When we look across landscapes, it’s easy to see that some areas are different than others. Some places are hilly, some are flat, some are more arid, and they have different kinds of soils. All of those characteristics – an area’s location, soil properties, and climate – are the controlling factors determining the kind and amount of vegetation an area can produce. An ecological site is simply a term for describing a particular area’s characteristics. Ecological Sites are used by the Natural Resources Conservation Service and the Bureau of Land Management to divide the landscape into units for study, evaluation and measurement.
How does a site compare to normal?
Just like our doctors measure our basic health by checking our weight, blood pressure, heart rate, and temperature, and comparing them to what is “normal” for most people in our age group, rangeland health professionals compare a site’s health based on soil stability, water capture and storage, and the integrity of its plant community in comparison to what would be “normal” for that site.
“Normal” is just a description of what you might hope to find on a site with particular characteristics. For many Ecological Sites, there is are one or more “Reference Sites” to describe “normal”. The reference site is a place we believe is meeting its full potential. The reference site lets us know what we can expect when it comes to wind and water erosion, bare soil, and vegetation production.
For a grazier this information is important because it helps you decide if you need to make a change to your management. If you’re considering treatments, like subsoiling, seeding, or fertilizer, knowing your site’s potential will give you a better idea of the results you might expect, and whether it is worth the investment. If your site is functioning to its potential, changing your expectations and working with it may be the more economical choice.
The Comparison Process
To find out how your pasture measures up, you’ll do a “Rangeland Health Assessment.” This is the process of comparing a site to it’s reference site or, if a reference site is not available, of simply looking carefully at how the site is functioning. It is a qualitative, communication tool that requires some natural resource and land management experience. It can be used as a preliminary evaluation, to select monitoring sites, and to provide early warnings of potential problems and/or opportunities. Because it only looks at one moment in time, it cannot be used to identify problems, make management changes, or determine trends.
That sounds pretty dry, but a Rangeland Health Assessment is actually one of my favorite things to do because it involves taking a 30 minute-or-so walk in a pasture. First, we choose an area that is representative of our pasture as a whole. Choosing the “ugliest” or the “best” area in a pasture will simply skew the results and not give us an accurate picture. Evaluation forms take us through a variety of indicators, and we rate them in terms of departure from what we expected. We rate how far we are from expected on a scale of “None to Slight,” “Slight to Moderate,” “Moderate,” “Moderate to Extreme” and “Extreme to Total.” The best assessments are done with groups of people with different educational and experiential backgrounds. Talking about what we see as we go through the evaluation helps open our eyes to things we might have missed and communicate about our concerns and goals.
Here are a few examples of the things the evaluation form prompts us to look at. These pictures are taken from “Interpreting Indicators of Rangeland Health,” the handbook on Rangeland Health Assessments.
Here’s an example of the back of a completed evaluation sheet for a project I did in Boulder County, Colorado as part of a training with Josh Saunders of the Natural Resources Conservation Service. He made a preliminary visit to the 500-acre pasture to determine its ecological site, and brought the site description to the training for all of us to use as we compared what we found to the pasture’s potential. Then Josh compiled all the results of everyone’s evaluations and said, “It was an interesting site. I set my biotic as a slight to moderate departure. I believe that the site is functioning with respect to hydrology and soil/site stability. I feel that that there was more mortality than drought was causing, also, there appears to be slightly more build up of litter on the site. I feel that if anything, the nutrient cycling (ecological process) may be stagnating somewhat on this site. If you were planning on upping the stocking density on this site for a short period, I think that it would do it some good.”
If you’d like to know how your site measures up, check in with your local NRCS office. They can assist you, or give you reference sites and soil information to get started. They can also help you walk through an assessment process.