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Chapter 6 - Summary & Conclusions

A Brief Project Reprise  |  Conclusion from The Analysis  |  Limitations of The Study  |  Strategies for Further Study  |  Land Use & Land Cover Dynamics  |  A Land Ethic

Conclusions from the Analysis

According to the statistics calculated from the land use and land cover change data, a total of 12.43 squares miles (7,952 acres or 1.94% of the total county area) of forest was lost, or converted to pasture lands in Carroll County from 1984 to 1999. These statistics also indicate that 2.46 square miles (1,574.4 acres or 0.38% of the total county area) of successional forest was regenerated from fallow pastures. The net amount of forest conversion or loss was calculated to be 9.97 square miles (6,380.8 acres or 1.56% of the total county area). Assuming these statistics to be accurate and precise, the net amount of forest conversion to pasture in Carroll County is approximately 10 square miles (9.97 square miles or 6,380.8 acres) over a time period of only 15 years.

The individual areas of clearcut were also analyzed based upon their contiguous area. Based on this analysis, it was determined that 1,098 different contiguous areas greater than one acre in area had been clearcut and converted to pasture over the past fifteen years. The average clearcut size was 7.24 acres. In addition, there were 24 clearcuts of an area greater than 50 acres. Eight of these clearcuts were between 100 and 200 acres with the largest clearcut being 232.82 acres or 0.36 of a square mile.

The spatial distribution of cleared forest areas in Carroll County were also analyzed by watershed; specifically, utilizing a 12 digit hydrologic boundary of the upper White River. Based upon this analysis, it was determined that forest conversion had occurred in 37 out of the 39 or 94.87% sub-watersheds present in Carroll County.

Comparative Evaluation of Forest Coverage

In order to offer a comparative evaluation of the results of this research with another documented source, U.S. Forest Service Forest Inventory and Analysis (FIA) Data for Carroll County is presented. According to the Forest Service FIA data, 218,400 acres or 341.25 square miles were classified as forest land and 187,200 acres or 292.5 square miles as non-forest land for Carroll County in 1995 (Rosson & London, 1997). Forest land is defined as land at least 10 percent stocked by forest trees of any size, or formerly having such tree cover and not currently developed for non-forest uses. The minimum area considered for classification is 1 acre. Forest land is further divided into timberland, reserved timberland, and woodland classes. However, this study is only concerned with the total amount of forest land. U.S. Forest Service FIA data is derived from statistical analysis of forest plots. Field measurements are conducted on a subset of permanent plots spaced 3 miles apart. Trees are measured on plots that were forested at the time of the current inventory or were forested at the time of the previous inventory (Rosson & London, 1997).

Previous forest inventory statistics for 1988 by Hines (1988) are also presented in order to attempt to establish a comparative trend in the amount of forest coverage for Carroll County for the time period considered in this study (Table 6.1). Additional research presented a U.S. Forest Service survey of Carroll County for 1978 (Quick & Hedlund, 1979). Unfortunately, the 1978 survey did not record data for the amount of total forest land or non-forest land. Instead, the 1978 survey focused on the amount of commercial forest, which is defined as forest land producing or capable of producing crops of industrial wood and not withdrawn from timber utilization (Quick & Hedlund, 1979). However, it should be noted that this definition has since changed and is now considered to be a component of the current definition of forest land.

Essentially, the 1978 survey does not include areas of woodland and reserved timberland, which the 1988 and 1995 surveys include as part of the total forest land, nor does it record non-forest land. Rosson & London (1997) define woodland as forest land that is incapable of yielding crops of industrial wood because of adverse site conditions, and reserved timberland as productive public forest land withdrawn from timber utilization through statue or administrative regulations.

In addition, it is pertinent to recognize that the U.S. Forest Service notes that there are important differences in the sampling methods and modifications of forest definitions utilized by the U.S. Forest Service between the 1988 and 1995 surveys (Rosson & London, 1997). The statistical sampling method and forest definition utilized in each survey are presented by Quick & Hedlund (1979), Hines (1988), and Rosson & London (1997). The Forest Service FIA statistics for Carroll County are presented in Table 6.1.

Table 6.1  Forest Coverage for Carroll County, Arkansas 1988 - 1995

Sources:  1988 Survey - Hines, 1988.  1995 Survey - Rossen & London, 1997.

According to the statistics in Table 6.1, the amount of total forest land has increased by 12,800 acres (20.0 square miles) while the amount of non-forest land has decreased by 13,000 acres (20.31 square miles) in Carroll County since 1988. The number in the rows and columns are not consistent due to rounding by the Forest Service. The U.S. Forest Service also acknowledges that the county totals are estimates and may not exactly match known totals for each category within the particular county (Hines, 1988).

The Forest Service FIA data calculated 218, 400 acres of forest in Carroll County for 1995. Based upon the classified satellite imagery, this study classified 238, 842.62 acres of forest in Carroll County for 1999, a difference of 20,442.62 acres over four years. It is important to note that the total land areas considered in each analysis are different. The Forest Service considers 405,600 acres, while this study considers 410, 079 acres, a difference of 4,479 acres. This is most likely due to the changing county boundary. There is also a difference of four years between these statistics.

The findings of this research present an opposite evaluation, with respect to trends in forest cover, than that of the Forest Service FIA Data. Based upon the FIA statistics in Table 6.1, there has been an increase of 12,800 acres of forest between 1988 and 1995. Based on the change detection method utilized in this project, there was a net forest loss of 6,380.8 acres or 9.97 square miles between 1984 and 1999. That is a difference of 19,180.8 acres or 29.97 square miles of forest. Again, keep in mind that the Forest Service data is derived from the statistical analysis of forest plots and this research employed the classification of satellite imagery. This research also covers a broader expanse of time, fifteen years as compared to seven years of the FIA data.

The forest area statistics for Carroll County from the U.S. Forest Service are presented only as a general reference to present a comparison between this research and that of the Forest Service. Due to numerous factors such as differing area statistics for the county as a result of changing boundaries, different sampling approaches and land class definitions utilized by the Forest Service over the considered time period, as well as differing years of assessment, it is difficult to evaluate and compare both quantitative trends of forest coverage for Carroll County. However, this issue poses an interesting topic for potential, further research and analysis.

The Forest Service FIA data provides an important assessment on the status of our nation’s forests. Obviously, the size and extent of the U.S. requires the use of such surveys. However, the utilization of increasing and innovative mapping technologies such as remotely sensed satellite imagery, GPS, and GIS are presenting new means for accurate assessment of the Earth and it’s resources. The Forest Service is beginning to research the collaborative implementation of such technologies in their forest surveys (Bergen et al, 2000).

Land Assessment

Once the areas of forest conversion were delineated, an additional assessment of these clearcut areas was undertaken to determine the wisdom of such land use practices. Three specific data layers were incorporated in a GIS analysis to determine land suitability as a result of its altered land use and land cover, these include slope, erodibility, and land productivity.

The assessment of the suitability or potential sustainability of the land on which land use and land cover change has taken place is an important consideration. The conversion of forests to pasture as a result of deforestation can potentially have adverse affects upon the landscape. Important components such as natural vegetative cover, slope, and the properties of soil help to maintain the balance of the landscape. These variables can be negatively impacted as a result of land use change.

A total of 12.43 square miles of forest was classified from satellite imagery as being cleared and converted to pasture in Carroll County between 1984 and 1999; of this area, 10.61 square miles, 85.4%, of the cleared forest was further classified as highly erodible, 6.43 square miles, 51.71%, of the forest was cleared on moderate to excessive slopes greater than 7 degrees, and 12.31 square miles, 99.03%, of the cleared forest was classified as not prime farmland.

Based upon this assessment, the clearing of forested areas on highly erodible soils and on slopes that range from moderate to excessive for the conversion to pastures, on land which has been classified as not prime farmland by the USDA, National Soil Survey Center, is occurring in Carroll County, Arkansas. Photograph 6.1 portrays a newly cleared area in which nearly all the vegetation has been removed. As a result of the datein which this photograph was taken, this area was not included nor classified in any of the analysis performed in this research.

Photograph 6.1  The Initial Stage of Forest to Pasture Conversion

Photograph by Author, 4/29/2000

 Photograph 6.2  Improved Pastures on Previously Forested Hillsides

Photograph by Author, 4/11/2000

Deforestation leaves significant amounts of thin topsoil as well as rock and stone exposed that is highly subject to erosion. Such land use practices are not considered to be the best management practices for landscape. The U.S. Army Corps of Engineers (1988) presents a list of best management practices (BMP’s) for different operations or land uses. Those listed for forestry applications relative to this study include:

     1. Limited clear cutting on steeper slopes

     2. Clearing on contours

     3. Temporary vegetative cover

     4. Critical area planting

     5. Stream side management zones

     6. Livestock exclusion

The utilization of such land use practices can greatly reduce the potential for soil erosion. Soil erosion has been recognized as a major contributor of non-point source pollution in our nation’s water resources. Not only do soil particles cause an increase in turbidity, they also transport nutrients and pesticides which have become attached to soil particles which end up in streams. A non-point source of pollution is a condition where pollutants enter a waterway through many points. Land use characteristics can have a major impact on local water quality (U.S. Army Corps of Engineers, 1988).

The introduction of improved pastures in Carroll County and surrounding Northwest Arkansas does, however, offer the potential to provide beneficial mediation to the landscape under proper management. Animal wastes from cow-chicken operations applied at moderate rates provide much-needed fertilization for tall fescue and bermudagrass pastures which can convert these poorly-suited lands into productive farms and ranches as well as reduce erosion. Though, due to the geographic concentration of poultry production, the ratio of poultry liter to available pasture land is often excessive. As a result, the litter may be applied at higher rates than the vegetation can absorb, such practices can be potentially hazardous to soil and water resources (Buchberger, 1991).

Nevertheless, under proper management practices, improved pastures can provide an enhancement to a landscape characterized by relatively infertile soils. Under ideal conditions, land owners can refurbish the land with improved pastures while retaining the aesthetic value of trees and the crucial role they play in the biosphere. This topic of forest conversion to improved pastures presents a complex paradigm comprised of important, local socioeconomic issues. Local economics and environmental consequences have become an intertwined component of numerous debates of which there are no easy answers.