Document: CHR-3-82-17

Effects of disturbance on relationships between species richness and ecosystem processes: Using bryophyte communities as model systems.

MULDER, C.P.H.* ¹ and D.F.DOAK ²

Victoria University of Wellington, Wellington, New Zealand ¹
University of California, Santa Cruz, CA 95064 USA ²

Abstract:
The importance of high species diversity to the full functioning of ecosystems subjected to repeated disturbance or environmental variation remains unclear. We are using bryophyte communities to examine relationships between species richness and ecosystem processes in disturbed and undisturbed communities. Forty species of mosses and liverworts were collected from one valley near Akatarawa, New Zealand. Two-hundred and eight communities were created with seven levels of diversity (1, 2, 4, 8, 16, 24 or 32 species) and 104 unique mixtures. Pieces of each species were planted in random grid patterns in each 40 by 60 cm tray. Two replicates of each mixture were created; one replicate was kept under good conditions (high moisture and low light) while the other was subjected to repeated disturbance (drought, flooding and frost). Detailed spatial information will allow us to identify mechanisms underlying results. Unlike in vascular plant communities, pre-disturbance results showed no relationship between species richness and percent cover, and for only one species did its presence significantly increase percent cover. Decomposition of cotton strips could also not be explained by diversity or the species mixture but was negatively related to percent cover. Comparing these relationships in undisturbed communities with those in disturbed communities will allow us to determine whether the value of high species richness for ecosystem function emerges under environmental variation.

Keywords: species richness, ecosystem function, bryophytes

This abstract is being presented at: 11:45 AM in session:
Oral Session #2: Conservation Ecology.