Hawaii Kohala Volcanic Soils

We are studying a network of sites along an extreme rainfall gradient that ranges from 200 mm to 3500 mm/year over a short distance of 12 km due to orographic moisture interception by Kohala Mountain in Hawaii. This climate sequence is ideal for studying soil development because the effects of rainfall on soil properties can be isolated from other environmental factors. Unlike most gradients that span arid to wet tropical climates, soil forming factors other than rainfall vary minimally across these sites: Parent material and topography are constant and there is minimal variation in vegetation and climate factors other than rainfall. These unique circumstances make this gradient a powerful model field system to understand the effects of rainfall variation on soil development and ecosystem biogeochemistry, as demonstrated by the seminal work done in these areas by our collaborators Peter Vitousek (Stanford) and Oliver Chadwick (UCSB). In spite of the wealth of ecosystem and soils research conducted at these sites, there is little known about soil microorganisms in these soils and no community characterization using DNA sequencing. We will sequence soil 16S rRNA genes from 13 different locations along the gradient. At each location we have samples from each of three depths (0-15 15-30, 30-50 cm) and four field replicates for each depth at most locations.