A Somewhat Inexact Science When we think of surveyors, we generally conjure up someone who pays attention to the most amazingly precise details of a land area. The surveying process involves declinations in millimeters rather than meters, so it may be rather surprising to discover that the technique is immensely useful in disciplines that require somewhat less exactitude. Vegetation surveying is one such example. Separating Out Plant Types Unlike standard surveying results, vegetation surveying is meant more to depict rough boundaries rather than strict lines of demarcation. This remains a valuable tool for botanists, environmentalists and other earth science types because of the ability to map out plant habitats with reasonable accuracy. Depending upon how the end product will be used, and by whom, the vegetation surveyor may be asked to do nothing more than indicate areas that possess any kind of vegetation as opposed to areas with none. At the other end of the spectrum, field observations will help determine exact species of plants as well as their density and location in relationship to other vegetative material and notable landmarks. Vegetation Surveying Objectives Surveys that take into account the mix of vegetation in a given area can be used to identify ecologically sensitive terrain—such as in wetlands—or map the spread of a particular type of plant. The collection of this information can be used to enhance other types of maps as well as stand on their own. Conducting vegetation surveys at regular intervals can help scientists understand the level of biodiversity in a given sector and see how it changes from one observation period to the next. This information is especially important when calculating the prospects of environmental changes due to natural or man-made events. Methodology of Surveying a Vegetation Sector Because this is an applied rather than an exact science, the surveying of vegetation requires a bit more latitude than the precision methods typical of the average land surveyor. Upon arriving at the survey site and roughly marking out the boundaries, the surveyor should first determine the range of species that lie within the target area. He or she may note that there are five different species of trees (oak, maple, birch, pine, and sycamore), four distinct kinds of low, flowering shrubs, plus three groundcover varieties. It is usually most convenient to mark off the target zone into quadrants or some other regular geographic shape. This will permit the surveyor and his assistant to keep accurate notes of what is contained where. Photography is oftentimes immensely useful, not only to capture the overall scene, but also to help identify individual plant types. If the area in question is meant to be studied over a long period of time—throughout the turn of the seasons, or perhaps over the course of years—it is wise to mark the exact spot where each camera shot is taken, so that the image can be accurately reproduced the next time a survey team arrives. In a field survey book, the surveyor draws each delineated area while noting the latitude and longitude at regular intervals. Within the square or rectangle, smaller divisions are created to form a grid pattern. This is the same methodology that archaeologists use to determine the exact placement of an artifact they have uncovered. Within each smaller division, the surveyor notes the placement and type of vegetation—in the NW corner, there is a pine tree; along the western border there is tall grass; at the center of the southernmost border there sit three oak trees grouped thusly. The use of a surveyor’s transit or total station can assist in determining vegetation height as well as laying out the grid. In this manner, you will know for certain that the aforementioned pine tree is eleven meters high. A year from now, when the next crew arrives to perform a follow-up survey, they will be able to grid off the area in exactly the same manner and also measure to see how much taller that pine tree has grown.
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A Somewhat Inexact Science
Land Surveys Pty Ltd are licensed surveyors and provide a complete array of surveying services in Perth & Karratha, Western Australia.
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