Several Andrews Forest LTER veterans recently published the paper "Productivity Is a Poor Predictor of Plant Species Richness" in the journal "Science", based on analysis from 48 meadow and grassland sites in five continents, including Lookout and Bunchgrass meadows in and near the Andrews Forest. Lead authors Peter Adler (Utah State Univ. and REU student at Andrews in 1993) and Elizabeth Borer and Eric Seabloom (Univ. of Minnesota, formerly at OSU) led a large team which found that the widely-cited theory that the number of species rises then declines with increasing productivity is not substantiated by field observations.
This is a product of NutNet, a network supported by the National Science Foundation (NSF) based at the University of Minnesota, that employs common observation and experimentation protocols to address a variety of ecosystem questions concerning the interplay of biodiversity and productivity. The long-term studies continue, and we look forward to further provocative findings.
You can read the article at http://www.sciencemag.org/content/333/6050/1750.full or an NSF Press Release at http://www.nsf.gov/news/news_summ.jsp?cntn_id=121691&org=DEB&from=news