. Research methods in ecology. Plant ecology. SUCCESSION '^^\ to follow. For this, the use of the permanent quadrat is imperative, as the sequence and structure of the stages can be understood only by a minute study of the shifting and rearrangement of the individuals. Permanent mi- gration circles are indispensable for tracing movement away from the pioneer areas by which each stage reaches its maximum. Denuded quadrats are a material aid in that they furnish important evidence with respect to migration and ecesis. By means of them, it is possible to determine the probable devel-. Fig. 70. Al
. Research methods in ecology. Plant ecology. SUCCESSION '^^\ to follow. For this, the use of the permanent quadrat is imperative, as the sequence and structure of the stages can be understood only by a minute study of the shifting and rearrangement of the individuals. Permanent mi- gration circles are indispensable for tracing movement away from the pioneer areas by which each stage reaches its maximum. Denuded quadrats are a material aid in that they furnish important evidence with respect to migration and ecesis. By means of them, it is possible to determine the probable devel-. Fig. 70. Alternating gravel slides on Mounts Cameron and Pals- grove, from the comparison of which the initial development of the talus succession has been reconstructed. opment of stages which reach back a decade or more into the past. In the ex- amination of successions, since cause and effect are so intimately connected in each reaction, it is especially important that general and superficial observa- tions upon structure and sequence be replaced by precise records, and that vague conjectures as to causes and reactions be supplanted by the accurate determination of the physical factors which underlie them. 329. Method of alternating stages. The period of time through which a primary succession operates is usually too great to make a complete study possible within a single lifetime. Secondary successions run their course much more quickly, and a decade will sometimes suffice for stabiliza-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Clements, Frederic E. (Frederic Edward), 1874-1945. Lincoln, Neb. , University Pub. Co.
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