Data collection
In early August each year, percent cover of all vascular plants, bare
mineral soil, bryophytes and litter were estimated in the central 0.7 m
x 0.7 m area of each plot by the same observer (JC). 106 plant taxa were
recorded across all plots and years. We measured light availability and
volumetric soil moisture content (surface and subsurface) four times
throughout each growing season. We collected and mixed four soil cores
(10 cm deep) from each plot in June and July each year, extracted the
samples with 0.01 M KCl and measured extractable soil nitrate, the key
limiting resource at Cedar Creek (Tilman 1990). Appendix S1 includes
further details.