Ecologists have long sought to understand and predict the composition of plant species, especially now, because climate and land use interfere with the way plants colonize and expand their communities. The study of predicting plant communities through time called plant sequences is one of ecology's oldest pursuits.
In 2016, Brian Buma, Ph.D., associate professor of integrative biology at the University of Colorado Denver, gathered a team of scientists to hunt and then extend eight long-forgotten, 103-year succession plans with a grant from National Geographic. The team discovered the sites and with the new tasks revived the world's longest succession study.
The researchers found that the original random assortment of plants spent a few decades fighting for dominance and sunlight before settling in a stable and almost unchanging society for the next 50 years, increasing the classic idea of inheritance.
The results were published in the journal Ecology .
Hunting for Square  In 1916, William S. Cooper, an early president of the Ecological Society of America, measured six plots of one square meter, called a square, on the edge of a glacier in Alaska's remote Glacier Bay National Park for to study how an ecosystem develops from the ground up. Cooper visited the square every five to ten years until the 1940s, when it was taken over by his student who maintained the record until his death in 1988. Unfortunately, his student never published the results, and for over 75 years Cooper's sites were forgotten and buried in layers of soil and vegetation in the Alaskan bush.
Fortunately, the famous ecologist kept a detailed journal of his observations of life in the small squares, along with maps and directions to them, but finding them would not be easy.
To begin with, Cooper north is not "t Buma is north. During the century since Cooper first cataloged the sites for his plots, the earth's magnetic pole has shifted about 12 degrees. Other landmarks have also changed: a large inlet has since shrunk to a small impressions of the coast, Koper's open fields are now incapable of vegetation, and one of the squares became a victim of erosion and, literally, fell into the sea.
Cooper drove in steel nails or reinforcements to mark the corners and stacked small stone hairs around them to mark their place. He marked the square places by pacing out the distance from large boulders, anywhere from 30 to 50 steps, and to varying degrees from the north. Notes like "Walk 12 steps from the big mountain, 27 degrees from north to a little worth "were common.
Unearthing 75 years of missing data
Armed with laminated photographs of the sites and surrounding the advice, Cooper's original handwritten magazines, a metal detector and a bit of luck, researchers spent eight days tracking down the plots and finding the last one within hours of leaving. Through extensive fieldwork, historical archives, remote analysis and dendrochronological methods, they were able to fill in the data for the missing 75 years.
"Nowhere in the world can you look through data and maps and images from a hundred years ago and have the detail required for this kind of scientific study," Buma said.
Upward chrono-sequence models
Before now, most ecologists have relied on chrono-sequence studies to study long periods of time, where researchers compare old sites with young places that are representative of the passage of time to study how societies have evolved. . But it makes a big assumption about how these sites differ because the old site might not look like the young site a hundred years ago, Buma said.
As a result, chrono sequence studies have known results that predict plants interact with each other over time to form predictable, successive paths. Cooper's Glacier Bay square shows the opposite.
Instead of a series of plants as chrono-sequence models suggested, the 103-year-old communities remained relatively the same. No other plants came in and the existing plants were reproduced asexually.
"It undermines much of the normal succession documents because it turns out that space is really important," Buma said. "There are many random things that happen early in the plot's history – where the seeds landed, for example – that still affect what we see today. It's like standing at the edge of a cliff and kicking a rock from the top. As it falls, the mountain can bounce off one way or the other, and you can get hundreds of different paths, even if the cliffs started from more or less the same location. " and spatial mapping for future researchers. Their goal is to observe whether the conclusions from Cooper's plot reflect the broader reality now.
"The plots can all end up the same way for a thousand years," Buma said. "But right now, during the first hundred years, we can say that each one is very different."
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B. Buma et al. The 100 year primary sequence highlights stochasticity and competition that drive community establishment and stability, Ecology (2019). DOI: 10.1002 / ecy.2885
Ecologist revives the world's longest-running succession study (2019, September 16)
retrieved September 17, 2019
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