The use of horses to drag logs has largely been a niche activity in small-scale forestry since the advent of heavy machinery, but researchers are intrigued by an area where it continues to this day on a truly industrial scale.
That region is Chihuahua, Mexico, where locals work in large-scale industrial community forests.
Researchers from Mexico and Florida set out to learn more about the scale and widespread persistence of horse skidding in the area.
The study team extracted information from the logging permit files of 59 communities in the Sierra Tarahumara, a mountainous region within the state of Chihuahua. They interviewed community leaders and foresters across 18 communities.
There were nine communities where logging could be considered large-scale, they reported in the journal Forests.
Six of them used animal traction for between 20% and 100% of their volume. All had sawmills integrated with their operations.
Over 10 years, the El Largo community alone extracted 3,169,019 cubic metres of wood from 123,810 hectares of forest, using only horses.
Those interviewed reported that horse skidding was more cost-effective than mechanized skidding, generated more employment, and had less impact on forests due to reduced carbon emissions.
“The widespread use of animal traction in large-scale industrial community forestry in Chihuahua demonstrates that horse skidding is not only a niche activity in small-scale forestry,” they said.
“Our data is preliminary,” they added, ” but we suggest that it highlights a need for further assessments of whether animal traction should be part of future efforts towards reduced impact, lower carbon emissions, and socially and economically just forest management.”
The study team, David Barton Bray, Elvira Duran, Javier Hernández-Salas, Concepción Luján-Alvarez, Miguel Olivas-García and Iván Grijalva-Martínez, said the historic use of animal traction for extracting logs began to fade as early as the 1930s, as diesel tractors began to replace horses and mules in the southern United States.
Between the 1940s and 1960s, horses and other animals for skidding were replaced by tractors and winches at all scales of logging, with an ongoing transition to purpose-built equipment.
Since the 1970s, there have been recurring reports of the persistence or return of horse skidding in small-scale forestry in many areas of the world.
However, the available scientific literature suggested it was entirely confined to a niche activity in small-scale logging enterprises.
Limited use of horse logging in small-scale forestry has been reported in Europe, Eastern Europe, Asia, and Latin America. The Czech Republic, Italy, and South Africa make more extensive use of horse skidding in small private forests or protected areas, and it is present in the Eastern and Southern United States, particularly Northern Alabama.
In the province of Osa, in Costa Rica, and Acre, Brazil, the use of animal traction in small-scale forestry in tropical rain forests has been documented.
However, overall, it played a negligible role in contemporary forestry.
So, what were the reasons behind its persistence in Chihuahua, the researchers asked?
Scientific literature on horse skidding in small-scale forestry suggested it had important ecological and economic advantages in certain conditions, the study team noted.
Studies from China, Africa, Iran, and the Missouri Ozarks showed very light residual damage to standing trees with animal traction. Trees growing close to animal skid trails, compared with mechanized skid trails, showed higher rates of growth. Soil compaction was also much lower with horses. Horses were also more maneuverable and flexible in handling varying timber dimensions, studies have found.
In addition, benefits have been found both in costs and in fossil fuel consumption, and thus carbon emission reductions.
A comparison of costs and fossil-fuel energy use between horse skidding (using both one and two horses) and tractor skidding in an Italian protected area found that tractor skidding was cheaper than horse skidding at extraction distances greater than 50 metres, assuming skid trails had already been built.
However, if new skid trails had to be built, one-horse skidding was cheaper than tractor skidding in distances up to 200 metres, although two-horse teams remained less expensive, even at greater distances.
It was found that horses, compared with tractors, took from 8 to 20 times less fossil fuel energy, with as much as 50% of that due to the transportation of horses in motor vehicles.
Horses, the study team said, were clearly a lower-impact alternative to tractors, and the costs were lower than those of tractor skidding when extraction distances were short and skid trails were not present.
The researchers noted that, in Chihuahua, not all of the forestry enterprises involved in the study used animals. Some combined animal and mechanical logwood extraction, and only a few reported a tendency to use more animal traction.
“Thus, the communities that use both may feel that they are at an optimal mix of the two technologies.
“The variables that may drive this differential use are not clear, although the degree of slope could be paramount among them.
“However, it is also possible that the Mexican national forest policy and a culture of industrial forestry that has encouraged the use of mechanical skidding may be causing some communities to overlook the advantages of horse skidding.
“Currently, horse skidding is characterized as an example of technological backwardness and elevated costs in forest management by the Mexican forest and environmental agencies, who have argued for the need to modernize the sector.
“However, our research suggests that great caution should be taken before merely characterizing horse skidding as backwards. Its purported backwardness may be more apparent than real in some circumstances.”
They continued: “The advantages and disadvantages of horse skidding in Chihuahua, Durango, and other states in Northern Mexico merit much further study and policy support.”
The researchers said they hoped their work would stimulate further research on the economic, social, and ecological advantages and disadvantages of animal traction in Mexico and elsewhere.
“Revaluing the use of horse skidding may be an important contribution to environmentally friendly and low-impact logging globally.
“The well-documented reduction in colateral damage in timber harvesting practices suggests that it could play an important role in practices of reduced-impact logging.
“Other advantages include a very low carbon footprint and social and household economic benefits of significant local employment.
“Our data is preliminary, but we think it argues for further assessments of whether animal traction has a role in promoting reduced impact, lower carbon emissions, and socially and economically just forest management.
“It may be that going ‘back to the future’ and re-evaluating the use of animal traction beyond small-scale logging will contribute to an expanded suite of forest engineering technology options, particularly in developing countries where employment generation is important.”
The researchers are variously affiliated with the Agricultural and Forest Sciences Department at the Autonomous University of Chihuahua; the Interdisciplinary Research Center for Integral Regional Development at the National Polytechnic Institute in Santa Cruz Xoxocotlán, Oaxaca; and the Department of Earth and Environment at Florida International University in Miami.
Back to the Future: The Persistence of Horse Skidding in Large Scale Industrial Community Forests in Chihuahua, Mexico
David Barton Bray, Elvira Duran, Javier Hernández-Salas, Concepción Luján-Alvarez, Miguel Olivas-García and Iván Grijalva-Martínez.
Forests 2016, 7(11), 283; doi:10.3390/f7110283