Answer:
Fredric Clements and Henry Gleason both published papers addressing the process of ecological succession in the early 20th century. Both men developed theories concerning succession, and they differed greatly. Clements’ Plant Succession An Analysis of the Development of Vegetation (1916) stated the succession is a universal process of formation development. He believed through his research and observations succession was a series events. Clements stated that the types of vegetation in an area are directly related to climate. The climate is in complete control of the form and variety of vegetation that occurs during plant succession. Christopher Elliot’s paper describes this idea perfectly, “For Clements, climates are like genomes, and vegetation is like an organism whose characteristics its genome determines” (2007). This quote demonstrates how firmly Clements believed that climate was the main driving factor in what type of vegetation would arise during succession. The final step in vegetation succession he referred to as a climax. Another major point in Clements paper is that vegetation grows, as what he denoted as a unit. Meaning the entire vegetation develops together as a single unit like an organism. This is known as the super-organism theory. Clements theorized that some type of organized process was needed for plant succession proceed and be successful. Clements described the process as complex. When Gleason’s paper The Structure and Development of the Plant Association was published a year later in 1917 he casted some doubts on Clements paper. Gleason and Clements had similar views on the understanding of plant succession. However, Gleason favored a more simplistic view of plant succession. He disagrees with units being organisms and the series of events with a climatic end. He also believed that there was more than just one factor that affected ecological succession. Gleason did not believe that climate alone was responsible for the types of vegetation, but other variables could be equally responsible. Gleason developed the individualistic concept in contrast to Clements who theorized the community acted as a whole. However, this does not mean that Gleason dismissed the community as a factor in plant succession, but just recognized individuals’ greater impact. This point was described in Crawley and et.al’s paper that revisited Gleason’s theory (2002). Both Clements and Gleason’s approaches to define plant succession are similar in their core beliefs, but differ greatly in the details. The holistic theory versus the individualistic theory differs because of where the researcher focused and how they choose to examine the large concept of plant succession.
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