Some Techniques For Analysis Of Land Use Patterns in Northern Florida

Some Techniques For Analysis Of Land Use Patterns in Northern Florida Raymond A. Peterson University of Florida Those geographers interested in analyzing land use changes are finding it increasingly necessary to utilize modern techniques and to be cognizant of the contributions and limitations of aerial photographs and topographic and other maps. It is the purpose of this paper to comment on the extent to which aerial photographs and topographic maps may be used in the study of present and historical patterns of land use in the northern Florida area. Naturally, these are best employed in conjunction with observation and enumeration techniques. In addition, experience with four sampling procedures used in the field is evaluated. Aerial photographs of the northern Florida area are available for the years 1937, 1949, 1955, and 1961. These photos can be used for making historical comparisons of land use, although the number of categories is limited. The 1961 air photos were used to prepare base maps. Although much time was saved through the use of these air photos, one must recognize some of the shortcomings of aerial photography in a situation such as that existing in northern Florida. The first limitation of accuracy in land use mapping and coding on aerial photos becomes evident when field work is done by observation alone. While it is easy to differentiate corn, Pensacola bahia grass, and planted pines by observation, it is more difficult to ascertain, for example, whether the Pensacola bahia is in the Feed Grain Program and thus not actually used for unlimited grazing, or whether the planted pines are in the Soil Bank Program and thus a part of a farm unit or a part of a corporate plantation. Additional inaccuracies may result in land use mapping when crops with limited acreages or crops of a seasonal nature are considered, such as tobacco and truck crops. These crops may be practically surrounded in the field by other crops, out of view because of topography, or the land may appear idle even though it may have been used for a fall or spring planting. As a consequence, tobacco may be mapped as corn, and cropland may be mapped as idle land instead of seasonally idle cropland. ( 1 ) Such problems or hazards provide a good reason for combining field observation with enumeration techniques. (2) By the latter is meant interviewing the occupants of rural land and asking them to name the use of each parcel. By using both procedures a more satisfactory portrayal of present land use can be drawn, and the data can be much more useful for historical and comparative analyses. 34The Southeastern Geographer A few problems in interpretation arise when using photos from earlier flights. It is almost impossible to differentiate some categories of cropland from some categories of grazing land on these early pictures, and it is equally difficult to subdivide forest and woodland into "grazed" and "not grazed." Since flights are normally made during the winter months, little can be done to sub-categorize cropland. As a consequence, only three categories can be used, namely, (1) cropland and grazing land, (2) forest and woodland, and (3) other land. However, within these limitations land use maps can be drawn for each flight to analyze change over time. Government programs are factors which aid in explaining the present land use pattern. Unawareness of the content and extent of influence of these programs on the present land use structure might lead to gross misrepresentation , and improper analytical conclusions and historical comparisons . This is particularly true for land which may be mapped as idle. Idle land should be mapped as idle cropland, idle pasture, idle forest land, and so forth. (3) This type of mapping is quite feasible for the field worker who has acquainted himself with government programs, and uses the observation and enumeration method. After the land use has been mapped accurately, exact acreages of land in government programs can be obtained from the county office of the Agricultural Stabilization and Conservation Service. Topographic maps at a scale of 1:24,000 are companion tools to aerial photographs. The topographic map, provided it is of recent date, has several uses in land use mapping. It...