A New Old Tool for Battling Invasive Vegetation?

by Ron Rathfon

When Purdue acquired property in northeast Dubois County in 1953 to make the Southern Indiana Purdue Agricultural Center (SIPAC), they immediately set out to restore the farmed-out, cut over, burned over, and heavily grazed land (Figure 1).  Conservation practices in vogue at the time were employed.  Charles Deam (Indiana State Forester, 1909-1928) was a lone voice in the wilderness at this time, decrying the practice of planting exotic shrubs for conservation purposes, especially multiflora rose.  In 1952, Deam wrote to a botanist colleague:

“Last week another damn thing irritated me.  Our state forester has a million multiflora roses to give away for ‘living fences.’  I wrote the head of the Department of Conservation that he need not worry about a tombstone; he will be remembered O.K. by disseminating this pest all over Indiana.” (Kriebel 1987)

Deam’s opposition notwithstanding, 1,000 multiflora rose  were planted by SIPAC farm laborers and Purdue foresters along the edge of a tract of steep woods, presumably for erosion control, wildlife habitat, and maybe even as a “living fence” demonstration.  By 1960, we know that multiflora rose had become a nuisance in the understory of the young hardwood forest.  By this time it was also falling out of favor as the conservation shrub of choice, being replaced by Asian bush honeysuckles and autumn olive.  I found records in SIPAC archives detailing a multiflora rose control study using 2,4,5-T and amitrol herbicides in this tract.  Although the now-banned 2,4,5-T was effective, no follow-up treatment to completely eradicate multiflora rose was pursued.  By the time I arrived at SIPAC as a young extension forester in 1992, the timber was approaching maturity, but the multiflora rose had achieved complete dominance in the understory.  Before me was the task of preparing the site for a future timber harvest that involved controlling the rose.  The steep terrain and overwhelming density and height of the rose made conventional mechanical and herbicide treatments daunting and impractical.  Several attempts at controlled burning only top-killed the rose but did not consume the viciously-armed canes.  Fire only seemed to stimulate the rose and it regrew with a vengeance.  I gave up on trying to control the rose . . . that is, until the day the goats arrived. . .

As a young forestry student in the 1980s I was tutored in the history of our nation’s forests.  It was important for us to understand the past so as not to ever allow the mistakes of history to repeat themselves.  Ingrained into our forester psyche were black-and-white images of forest destruction resulting from rapacious logging, wildfire on a holocaust scale, and unmitigated livestock damage at a time when livestock free-ranged in eastern forests.

In the October 1945 issue of the Journal of Forestry, Daniel DenUyl (1945), Professor of Forestry at Purdue University, issued a rebuttal to proposed U.S. Forest Service forest grazing regulations for Region 9 (northeast and north central states). The regulations represented an uneasy compromise between forestry and livestock interests in the region’s “range wars.”  He summarized his research documenting the “stages of decadence” of pastured woods and the restoration of pastured forests through livestock exclusion.  He touted the fact that Indiana had been regulating grazing in forests for over 25 years through a voluntary program and that over 2,000 Indiana forest landowners were effectively regulating livestock grazing in the forest by exclusion as “classified” forest owners.  He definitively concluded his rebuttal, expressing a widely held view of forest grazing among foresters:

“The evidence and cumulative experience clearly show that livestock grazing will ultimately destroy the farmwoods. Continuous protection by complete exclusion of livestock is essential for continued woods production.”

The forestry profession’s uncompromising attitude was set and efforts to educate landowners and lawmakers on the destructive influence of livestock in eastern forests began to make headway.  J.H. Patric and J.D. Helvey (1986), U.S. Forest Service researchers documented a reduction in grazing in eastern U.S. forests from 180 million acres in 1938 to less than 25 million acres by 1982.  I began my forestry education at Penn State’s Mont Alto campus in 1982 and so began my indoctrination of the twin evils of forest grazing and wildfire. 

It may be debatable how much of the reduction in forest grazing was attributable to the landowner education efforts of foresters, to laws eliminating open range in the east, or  how much was just pure economics.  A study published in 1968 by Bjugstad and others (1968) illustrates the point.  They found that it took 180 acres of oak woodland in the Missouri Ozarks to maintain one cow and calf for six months.  The same cow and calf could feed well on 2 acres of well-managed pasture.  S. Clark Martin (1954) may have summed it up best at the Society of American Forester’s annual meeting held in Milwaukee in 1954 when he said:

“Even the farmer knows that starving cattle will not pay the grocery bill.”

Time for a change in thinking toward livestock in the forest?

It may be too early, but the time may soon come for foresters to rethink their historical opposition to livestock in the woods.  For many counties in Indiana, recent U.S. Forest Service Forest Inventory and Analysis (FIA) data show that from 35 to roughly 90% of forest sample plots are invaded to some degree with invasive plants (Oswalt and others, in review).  New alternative strategies and management tools need to be considered to soften the blow and stem the tide of non-native invasive plants. 

Foresters’ attitudes toward fire have evolved even over the course of my career. Prescribed fire is now widely used on public lands in Indiana and even on some private land, demonstrating its usefulness as a management tool.  Likewise, domestic animals may be able to provide valuable vegetation management services.  As with fire, uncontrolled, unmanaged grazing has already proved its destructiveness.  Carefully managed, prescribed grazing (PG) could prove a boon to forest managers.

Prescribed Grazing Defined

At this point I should define PG and will start by emphasizing what it is NOT!  PG is not fencing a woods and dumping a bunch of grazers and browsers in it simply because it has thick underbrush.  Nor is it livestock looking for a new source of forage in the forest.  We’ve already done that on a massive and unsustainable scale, as we have already discussed.

PG has been around for a few decades in the U.S.  Much of the research and experience using PG for non-native invasive plant management comes from western U.S. rangelands.  Karen Launchbaugh (2006), Rangeland Scientist with the University of Idaho defined PG as the “…the application of a specific kind of livestock at a determined season, duration, and intensity to accomplish defined vegetation or landscape goals.”  More recently, eastern U.S. researchers and land managers have looked to PG to help manage undesirable vegetation in a wide variety of management contexts, from power line rights-of-way maintenance to managing habitat vegetation for the endangered bog turtle in New Jersey.  Goats and sheep have been employed to help manage unruly, invasive vegetation in public parks, cemeteries, and historical sites.  Livestock are being called upon to help control kudzu in southern states.  The development of intensive rotational grazing techniques and mobile fencing systems allows entrepreneurs to provide prescribed grazing services to landowners (i.e., herd for hire).  However, such PG services are few in number in the eastern U.S. and research on effectiveness of PG to suppress NNIP species and impacts to non-target native vegetation in eastern hardwood ecosystems is almost non-existent.

. . . And so we return to my original story of trying to control multiflora rose in a woods at SIPAC and the day the goats arrived. 

Part 2 of this article will appear in the next edition of the Woodland Steward Newsletter. Ron Rathfon is an Extension Forester with the Department of Forestry and Natural Resources at Purdue University. Areas of focus include forest management, timber marketing, tree planting, oak regeneration and ecology, and invasive vegetation management.

Literature Cited

Bjugstad, A.J., D.A. Murphy, H.S. Crawford. 1968. Poor returns from Ozark woodland grazing. U.S. Forest Service, North Central Experiment Station, Research Note NC-60. 2 p.

DenUyl, Daniel. 1938. The development of natural reproduction in previously grazed farmwoods. Purdue Agricultural Experiment Station Bulletin No. 431. 28 p.

DenUyl, Daniel. 1945. Farm woodlands should not be grazed. Journal of Forestry Vol. 43, No. 10:729-732.

Kriebel, Robert C. 1987. Plain Ol’ Charlie Deam, Pioneer Hoosier Botanist. Purdue Univeristy Press. 183 p.

Launchbaugh, Karen and John Walker. 2006. Chapter 1: Targeted grazing – a new paradigm for livestock management. In Targeted Grazing: A Natural Approach to Vegetation Management and Landscape Enhancement. Karen Launchbaugh (ed.). American Sheep Industry Assoc. 199 p.

Martin, S. Clark. 1954. Grazing forestry relationships in the Missouri Ozarks. In: Proceedings, 1954 SAF annual meeting; Milwaukee, WI. Society of American Foresters, Wahington, D.C.: 203-205.

Oswalt, C.M., S. Fei, Q. Guo, B.V. Iannone III, S.N. Oswalt, B.C. Pijanowski, K.M. Potter. In Review.  A subcontinental view of forest plant invasions.

Patric, J.H. and J.D. Helvey. 1986. Some effects of grazing on soil and water in the Eastern forest. U.S. Forest Service, Northeast Forest Experiment Station, NE-GTR-115. 25 p.

Figure 1. “Farmed out” land acquired by Purdue University in northeast Dubois County in 1953 became the Southern Indiana Purdue Agricultural Center (SIPAC).Figure 2. Photos documenting effects of forest grazing from Purdue Forestry Professor Daniel DenUyl’s Purdue Agricultural Experiment Station Bulletin No. 431, published in 1938. The caption for the photos read:(top) “Young growth and vegetation in an oak-hickory woods in June, 1931.” and (bottom) “The same woods in June, 1933. After two years of grazing, tree reproduction has been eliminated and litter and soil conditions are unfavorable for the establishment and growth of tree reproduction.”