How ecosystems develop means of retaining soluble organic nutrients during primary succession and soil development, phosphorus input and cycling in Lake Tahoe, control of phosphorus eutrophication by addition of ferric chloride and alum, the process of humification and the control of carbon sequestration in soil, soil Nitrogen and Carbon mineralization in the Mojave desert, microbial decomposition of dissolved humic substances, ecophysiology and competitive relationships of Lepidium latifolium (tall whitetop) and other invasive wetland plants.