Species richness and stand stability in conifer forests of the Sierra Nevada.

Theoretical and empirical studies have long suggested that stability and complexity are intimately related, but evidence from long-lived systems at large scales is lacking. Stability can either be driven by complex species interactions, or it can be driven by the presence/absence and abundance of a species best able to perform a specific ecosystem function. We use 64 years of stand productivity measures in forest systems composed of four dominant conifer tree species to contrast the effect of species richness and abundance on three stability measures.

Salt spray as a microenvironmental factor in the distribution of beach plants at point reyes, California.

Measurements of salt spray were made weekly for 15 spring weeks with a grid of 50 traps in a 32 m longx24m wide plot of beach vegetation along the central California coast. The trap centers were 14 cm above the ground, the traps could swivel to continuously face the wind, and trap area (16 cm) was small in order to minimally affect wind flow. Regressions or analyses of variance of wind speed and direction, rainfall, tide level, plot topography, and plant distribution were performed against salt spray.

The effect of competition and salinity on the growth of a salt marsh plant species.

Young rhizome sprouts of the herbaceous perennial Jaumea carnosa were propagated from material collected in a salt marsh along the central California coast. The sprouts were transplanted to flats of sand sown with different densities of seeds of a representative glycophyte, Lolium perenne L. "Derby, turf type.