Exclosure

Exclosure – (ex-clo’-sure) n. – an area protected by various devices against the entrance of animals and insect pests – from Webster’s New Universal Unabridged Dictionary.

Photograph taken by Lew Hunnicutt.

In February of 2000 Dr. Lew Hunnicutt, who was then in charge of Stewardship, Education and Research for us, set into motion on Selah a research project quite ambitious for a small staff and operation such as Bamberger Ranch Preserve. The project in Lew’s own words was to “Monitor Range Condition and Trend.” It was long range, a minimum of 5 years but our expectations were 10, maybe even 20 years! In 2001 and 2002 Lew, assisted by Margaret Bamberger and a very capable volunteer, Patrick Garnett, monitored and photographed the existing exclosures. As a result of their efforts, a very good baseline set of records exist. Unfortunately, in 2003 Dr. Lew left us to return to his roots, college level teaching. The regular monitoring required of the project soon escaped our attention.

I have admonished everyone here over and over, “Never initiate an action that you are unable to sustain,” whether it is a business, a marriage, a trail or a research project. Without Lew Hunnicutt, we did not have the time or knowledge to sustain the project; although Margaret led newly hired Ranch Biologist, Steven Fulton, to the exclosures and together they recorded observations and took photographs. However before the next scheduled visits, Margaret was diagnosed with cancer and her involvement was no longer possible.

Before moving to 2009, let me describe for you just what and how and for what purpose the exclosures were installed. Once again, in Dr. Lew’s own words excerpted from his plan:

“The condition of rangeland (i.e. excellent, good, fair, or poor) is a direct result of the management practices imposed on it. Determining condition alone is not enough; we must also monitor the direction of change in condition over time (rangeland trend). Trend can be upward (positive), stable (positive or negative), or downward (negative). This dictates to us whether or not our animal management program is beneficial or detrimental to a particular range, site, pasture, etc. If detrimental (downward trend), changes can be implemented to move a site back toward an upward trend.

In order to monitor condition and trend on the ranch, 13 exclosures (more to be added in the future) were constructed in February of 2000. Each exclosure was constructed using 2, 20-foot cattle panels pulled into a circle with the overlapping ends wired together. Each exclosure was then wired to 3 t-posts driven into the ground for support. The 13 exclosures were divided among 5 different range sites (a classification of land based on soil type and properties) across the ranch in areas determined to be important from an animal use standpoint. The purpose of each exclosure is to keep out large ungulates (cattle, deer, and goats), while still allowing use by small animals (rabbits, quail, etc.). Baseline date (i.e. species composition, extent of cover versus bare ground, height of vegetation, etc.) was documented at each exclosure. A permanent photo point was also placed at each exclosure site. This photo point was simply another t-post driven into the ground in close proximity to the exclosure. To collect photo point data, a camera is placed on the top of the post with the lens pointed in the direction of the “tail-of-the-t” of the t-post. The picture is taken then the camera is turned 180 degrees to capture a photo in the opposite direction. This insures that the same areas will be photographed during each data collection period. The purpose of photo points is to look at changes in the land over time. Photos can be compared with previous years to determine the trend (upward, downward, stable) of the site. The key to using photo points is to not get in a hurry. It is impossible to draw conclusions after only a few years. It takes a minimum of 5 years and it is even better with more years worth of photo data before conclusions are drawn about the trend.

We will visit each exclosure at least twice (more as needed) during the year to document species composition, forage quantity inside and outside each exclosure, and to take photo point photos. The visits will occur during the growing (May/June) and dormant (Jan/Feb) seasons for many of the plant species found on the ranch that are of major importance to large ungulates. This data will allow us to monitor condition and trend over time. This is a long term study, basically never-ending, project.”

Over the past 5 years while rounding up cattle or guiding a hunter, Scott Grote, Ranch Operations Manager, made a few casual observations of the exclosures. Nothing was recorded.

Now fast forward through 2004-2005-2006-2007 and 2008. In late August 2009 Steven Fulton, Ranch Biologist, with me and my dog, Cory, tagging along visited, inventoried and photographed all exclosures.

Like tree rings divulge age and weather, the exclosures, along with our weather and livestock records give us valuable information.

Photograph taken by J. David in June of 2009.

See what may occur if rangeland is not managed. Grazing cattle or browsing deer are management tools. Inside the exclosure, woody species have essentially taken over. The tall plant is a Hackberry tree which will eventually provide bird food. Primary vegetation is Greenbriar, a preferred plant for deer, but currently over represented throughout the ranch. There is also a very large spreading Agarita which I would describe as somewhat invasive. There were 3 forbs: Orange Zexmania, Vetch Sp, and Shepherds Purse; some Texas Wintergrass; and K.R. Bluestem, but overall the cover inside was 65% woody with 156” height; while outside the exclosure under managed (grazed) conditions, the cover was grass.

Photograph taken by J. David.

Here on this adobe site there is not much difference inside or outside our exclosure. The ground cover is 45% inside and out of the exclousre with grass cover 6 to 8 inches inside. The grasses are primarily Seep Muhly, Little Bluestem and Tall Dropseed. Steven indentified two forbs, Queen’s Delight and Navaho Tea, and a succulent, Twisted Leaf Yucca, which hadn’t been recorded in those first three years.

Photograph taken by J. David.

Grass cover was estimated at 95% and 10 to 12 inches tall within this exclosure with K.R. Bluestem being most abundant followed by Little Bluestem, Silver Bluestem, Side Oats Grama and some Tall Dropseed. One forb, Vetch Sp, was noted as well as Greenbriar, a woody. It appeared that grass production was beginning to mulch itself.

Photograph taken by J. David.

This is on our Redlands Range site. A small, perhaps a 50 acre area in which Post and Blackjack Oak dominate. There are very few other oaks in this area. 85% cover, 6 to 8 inches high and mostly grass was identified within the exclosure. They being K.R. Bluestem, Little Bluestem and smaller amount of Sideoats and Indiangrass. There were no identifiable forbs, outside the exclosure grazing and hoof action had hampered our ability to identify anything. We noted that in 2003 this location held a nice diversity of grasses and forbs. Please read on through the next exclosure for comments about this as well as other thoughts on our exclosure project.


Photograph taken by J. David.

I was unable to identify which exclosure this was so I passed the question to Steven Fulton, our Ranch Biologist, with the comment, “Tell me about this one.” The following is Steven’s written reply:

“My first impression of this pasture as I approached this exclosure was that it is overgrazed. However, when our 30 inch deficit in rainfall of the past two years is thrown into the equation the condition of this pasture begins to make more sense. The physiological response of many of our native plants is to retreat into a state of dormancy when faced with severe drought. Our seemingly dead grass is only dead above ground; the life of the plant persists in the roots. Cattle removing dead grass blades and stems should not change the species composition of this grass community. Inside the exclosure, the dominant species is Little Bluestem. To determine the degree of overgrazing (if any) in this pasture, a return visit after a wet period is warranted. I expect to see the pasture composed mostly of Little Bluestem, meaning that overgrazing has not occurred. However, if the grass community shifts to less desirable species (threeawns) then overgrazing has occurred. Let’s pray for a wet fall and spring so I can answer this question about overgrazing.”

I’m not pleased with this, my first report on the exclosures. However I am enthusiastic about the project. It was very interesting to see the changes at each site and to look at Lew Hunnicutt and his volunteers’ comments and inventory of the plants. Now that we are back and involved with this research, I expect to be much more thorough when monitoring and collecting data. . . . . What can we say about all of this at this time?

• Well, we could tell which sites cattle preferred.


• It was wrong to conclude any site was overgrazed due to poor management since we had two serious drought years with no water in 4 pastures. So, in spite of reducing our cattle herd by 60%, cattle had to be grazed in pastures that had water.


• There was a lot of dormant grass that has begun to green up since recent rains.


• Rangeland unmanaged will result in woody species that begin taking over.


• As a precursor to climate change, we may learn which plants can adapt.


• It would be more valuable if we had checked our project in a more normal climate year, but what really is normal?

As Lew Hunnicutt said – “the project has more value if extended 20 years,” and it’s our goal to do just that.