Dr Steward T A Pickett
Research What is Succession?
The Buell-Small Succession Study is a long term ecological study designed to document old field succession. The study was founded in 1958 by Murray Buell, Helen Buell, and John Small. It includes ten fields that were actively farmed until released for the study. Each year a team of researchers returns to the fields and measures the percent cover of plant species in permanently marked plots.
By looking at how the species in the plots and their cover change over time, researchers can learn how succession progresses in the fields. Understanding the succession of the BSS fields can help researchers determine how other abandoned fields in similar systems will change over time. Because the BSS data set is extensive in space and continuous in time, it can be used to answer a wide range of additional questions.
The Buell-Small Succession Study is named for its originators. Murray Fife Buell was Professor of Botany at Rutgers, The State University of New Jersey. He earned his Doctor of Philosophy degree under the great plant ecologist, William S. Cooper at the University of Minnesota. Helen Foote Buell earned her Ph.D. in phycology at the University of Minnesota. Although Dr. Helen Buell was not a member of the Rutgers faculty, she was an important member of the intellectual community in botany and ecology, and contributed significantly to the training of students and to research. Dr. John Alvin Small was a botanist on the faculty at Rutgers.
The study was begun in 1958, with the sampling of two fields abandoned the previous fall. That year was the first growing season after the dedication of the Hutcheson Memorial Forest Center (HMFC). Botanists and ecologists at Rutgers had been joined by colleagues and citizens to save Mettler's Woods, the last, old-growth, upland oak forest in New Jersey. In 1951 the United Brotherhood of Carpenters and Joiners contributed the crucial donation that enabled the forest and an adjoining agricultural land to be saved from development. The center was named for William L. Hutcheson, the past president of the union, and dedicated to the preservation of the old-growth woods, and to research and education. The fields abutting the forest were slated by Prof. Murray Buell, the first director of the HMFC, to be used for research on succession and other ecological, botanical, and zoological phenomena.
Murray Buell worked on the study until his death in 1975. John Small worked on the project until his death in 1977. Helen Buell worked on the project until the mid 1980's, but enthusiastically continued to share her energy and knowledge until she died in 1995. Dr. Steward T.A. Pickett, who joined the faculty of Rutgers in 1977, began to work on the project in the summer of 1978. He continues to lead the project, joined by plant ecologist Dr. M. L. Cadenasso, community ecologist Dr. P. J. Morin and plant ecologist Dr. S. Bartha. Dr. M. A. Leck was instrumental in conducting sampling in a new field in the 1980s. Although in the early days, the fields were sampled by the Drs. Buell alone, later joined by Dr. Small, the study soon grew too large for them to conduct by themselves. Over the years large numbers of graduate students in botany, zoology, and ecology, several undergraduates, post-doctoral researchers at Rutgers and even visiting scientists have assisted in the sampling. The continuation of the Buell-Small Succession Study would not have been possible without the expert and careful assistance of this array of dedicated scientists, many of whom volunteered their time or worked for a token amount.
Dr. Murray F. Buell's obituary can be found in volume 102 of the Bulletin of the Torrey Botanical Club, page 201.
Dr. John A. Small's obituary can be found in volume 105 of the Bulletin of the Torrey Botanical Club, page 70.
Dr. Helen F. Buell's obituary.
Plant community succession is one of the most ubiquitous of ecological processes. The change in structure and species composition of assemblages of plants after physical disturbances, or after release from agricultural management, has provided much grist for ecology. Indeed, the founding of the science of ecology in the United States is closely associated with studies of succession (Cowles 1899, Clements 1916, Cooper 1926). The differences in conditions and interactions that develop through succession provide major contrasts that plants and animals exploit. Thus, succession is one of the major sources of diversity in the living world. Life history and evolutionary contrasts between species, physiological and morphological strategies, assembly rules, and ecosystem processes are among the various ecological processes that assort along successional gradients. Differences in the successional status of different patches in a landscape are among the major sources of biological diversity.
Because succession perfuses so much of ecology, and because the change in communities is crucial to management and conservation, it has been important to learn how the process occurs. Fundamental to the understanding of succession is the need to know what the patterns of community change through time actually are. All else -- the understanding of mechanisms, the prediction of trends, the use of succession by managers -- depends on a sound knowledge of the patterns of change. In the early days of ecology, the only method available to discover the patterns of community change through time was to compare sites of different ages since disturbance or abandonment. This method, called either space-for-time substitution or chronosequence, assumes that the different sites are subject to the same conditions and have the same species available to them. If this crucial assumption is not met, the patterns may reflect permanent differences between the sites or other ecological processes rather than successional change. It was this assumption that the Buell's and John Small wished to test.
The Piedmont of New Jersey, where the BSS is located, shares with many other sites in that geomorphic province in the eastern U.S., soils that are problematic in some ways for agriculture, or location in the path of urban spread. Very intense use, erodability, or droughtiness characterize many Piedmont farms. Therefore, many Piedmont sites were abandoned from agriculture as a result of opening more hospitable soils in the Midwest and changes in the economic and social situation for agriculture in the east. Many fields in the Piedmont of central New Jersey were abandoned in the 1940's. These had been the subject of a study using space-for-time substitution (Bard 1950). The fields surrounding Mettler's Woods, held by descendants of Mynheer Cornelius VanLiew, the original Dutch settler who established the farm in 1701, were well cared for and reasonably productive. But the changing situation in the 1950's led to the selling of the farm and the subsequent abandonment of agriculture. The Buell's and Small wished to determine whether the results obtained by the chronosequence that Bard constructed in abandoned fields near HMF held when one examined specific fields through time.
The Buell's therefore decided to study succession in specific fields through time. Indeed, not only would the same fields be traced through time, but the very same study plots would be used. Based on consultations with a statistician in the early years of the study, the Buell's decided that 48 plots would be permanently marked in each of the 10 fields. These plots were 1 m2, and were rectangular to capture heterogeneity in the herbaceous and shrubby communities expected to dominate in the first decades of succession.
At around the time that the BSS was established, several controversies existed about how succession took place. One controversy dealt with the nature of the community. At one extreme, tightly unified communities were assumed to be the basis of succession, while at the other, the individual -- but interacting -- species populations were assumed to be the basis of succession. By examining permanent plots through time, the BSS could show whether communities came and went as wholes, or whether populations rose and fell through time based on their individual properties and capacities for interaction.
The second controversy is more subtle, and seems to be the one that most motivated the Buell's. Dr. F. Egler, noted ecological gadfly, had proposed that the species that would come to predominate in later successional communities were in fact present right from the start. This "Initial Floristic Composition" hypothesis was in opposition to the dominant assumption that species arrived in succession in order of their dominance. Egler's hypothesis apparently seemed unreasonable to the Buell's and John Small based on their experience. The only sure way to tell, however, was to look at specific permanent plots through time. It is just this design that the BSS employs.
The two controversies have in some ways been solved as a result of the BSS, other permanent plot studies in forests and fields, and judicious use of certain chronosequences and experiments. Consequently, contemporary succession theory incorporates aspects of the extremes of the controversies by recognizing when each of the patterns or processes occur. However, far from obviating the need to continue long-term, permanent plot studies of succession, new motivating questions have emerged that are appropriately examined by the BSS and other such studies. Questions that now rise to the top of the list of motivations for the study include those concerning 1) patterns of species assembly and assortment in time and space, 2) the role of functional groups in succession, 3) the place and significance of invasive exotic species in mid- and late-successional communities, 4) how species life histories and morphologies relate to their invasion and persistence, and 5) the role of episodic events in succession. Succession is driven by a suite of processes that occur to different degrees in all plant and animal communities. Because successional trajectories are so obviously dynamic, they provide a powerful stage for disentangling the web of interactions that characterizes communities and ecosystems.
There was a management rationale behind the abandonment of the fields adjacent to the old-growth Mettler's Woods. Allowing the fields to succeed from the herbaceous plants of agriculture to shrubby communities and ultimately to forest, would buffer the sensitive old woods from the external environment, and perhaps ultimately make a more secure forest environment. Therefore eight of the 10 fields in the BSS are adjacent to the old-growth forest. Other fields on the original property were to be used for demonstration or manipulative research. Manipulations would not be permitted in the old woods, and only sparingly in the fields of the BSS.