Cross-Site Study Illuminates Strengths, Shortcomings in LTER Data
Robert B. Waide, Executive Director-NET
Although biodiversity is not officially recognized as one of the LTER core research areas, it is widely seen as an important focus of investigation throughout the Network. Studies of biodiversity are fundamental in understanding the ecological processes embodied by the five core areas. For this reason, site-level studies and experiments on the importance of biodiversity have always been common within the LTER Network. Recently the LTER Network has focused on developing a broader-scale understanding of the processes that lead to and maintain biodiversity and the influence that these processes have on ecosystem structure and function.
The VCR Coordinating Committee (CC) meeting in May 1995 provided a springboard for a discussion of the breadth of studies of biodiversity at LTER sites and the potential role that LTER could play in the field of biodiversity. Two activities were initiated at VCR, a survey of biodiversity research being conducted at LTER sites and planning for a workshop on biodiversity, which was held at the October 1995 CC meeting at the Cedar Creek LTER site. Here, representatives of each site presented results from the survey, which have been collected into an electronic document (with the help of John Porter of VCR). (Please see http://atlantic.evsc.virginia.edu/LTER_biod/)
A large number of potential studies were proposed at that meeting, but the issue that attracted the most interest was an examination of the relationship between productivity and species richness. There was general agreement that data available from LTER sites would be useful in examining this relationship. Mike Willig (LUQ) and I agreed to follow up this discussion with a proposal to the National Center for Ecological Analysis and Synthesis. This proposal, titled "An Analysis of the Relationship between Productivity and Diversity using Experimental Results from the LTER Network", led to a 10-day meeting at NCEAS in September, 1996. Please see http://www.nceas.ucsb.edu/fmt/doc?/nceas-web/projects/95WAIDE1 for the full proposal.
Representatives from 15 LTER sites and four other scientists gathered for that working group, to address these questions:
- What is the shape of the relationship between productiv- ity and diversity?
- Is this relationship consistent among systems? Among trophic levels?
- Do different mechanisms control biodiversity at different points along the productivity gradient?
- What is the spatial scale of diversity in different systems?
- Do these spatial patterns shift from low to high produc- tivity?
- How does diversity respond to manipulated shifts in productivity?
- What kind of experiment would we design to reveal the mechanisms underlying the relationship between biodiversity and productivity?
Each participant was asked to provide three kinds of data:
- Data from individual LTER sites that described the relationship between diversity and productivity over the available range of spatial scales and productivities
- Data from the literature that described the relationship between diversity and productivity over the full ranges of diversity and productivity that exist for each LTER biome worldwide
- Data on experimental manipulations of productivity at each LTER site and their subsequent effect on diversity
We immediately encountered problems in comparison of data taken at different scales, which required us to develop new analytical approaches to address the core questions. After 10 days we were tantalizingly close to uncovering what we believed to be scale-dependent patterns in the relationship between productivity and species richness. Two subsequent meetings (April and October 1997) by a subset of the working group were required to refine the analysis and complete manuscripts.
Seven manuscripts resulting from the workshop have been submitted to Ecology as a Special Feature, and workshop participants are preparing a manuscript to be submitted to Annual Review of Ecology and Systematics (thanks to encouragement from Judy Meyer). This latter manuscript will expand on the literature search compiled for the workshop and incorporate studies that focus on diversity as a driver of productivity.
The remaining challenge is to build on the results of the workshop to develop future cross-site studies or experiments that will shed further light on the relationship between productivity and diversity. I encourage those of you who may be interested in this topic to contact me so that we can begin a threaded discussion group.
Participants of the NCEAS Working Group, Santa Barbara, September, 1996
- Laura Gough, Arctic LTER
- Glenn Patrick, Juday Bonanza Creek LTER
- Clarence Lehma,n Cedar Creek LTER
- John C. Moore, Short Grass Steppe LTER
- Bruce J. Wallace, Coweeta LTER
- Glenn Motzkin, Harvard Forest LTER
- Jeff Herrick, Jornada LTER
- Katherine L. Gross, Kellogg LTER
- Gary Mittelbach, Kellogg LTER
- Scott L. Collins, Konza Prairie LTER
- Robert B. Waide, Luquillo LTER
- Michael R. Willig, Luquillo LTER
- Stephen B. Cox, Luquillo LTER
- Lee Turner, Niwot Ridge LTER
- Stanley I. Dodson, North Temperate Lakes LTER
- Maria Vernet, Palmer LTER
- Robert R. Parmenter, Sevilleta LTER
- Linda K. Blum, Virginia Coast Reserve LTER
- Mike Kaspari, University of Oklahoma
- Samuel S. Scheiner, Arizona State University West
- Craig W. Osenberg, University of Florida
- Michael L. Rosenzweig, University of Arizona