Purpose To determine the quality of litter leachate and its availability as a nutrient source.
Hypothesis Carbon, Nitrogen and Phosphorus in organic and inorganic forms will leach from leaf litter covered in water, and soluble organic C, N and P will decay exponentially, while levels of inorganic forms increase.
Methods Can be divided into: Leaching-getting dissolved organic and inorganic nutrients into solution Filtering-sampling to determine levels of nutrients as decomposition occurs Analysis-analyzing nutrients, and interpreting what it means
I: Leaching Placed 1 gram of dried leaf litter material in 150 mL of deionized water for 24 hours. Filtered the resulting leachate to remove microbes, and then added a microbe inoculant.
II: Filtering For each time period, leachates were sampled and filtered to remove microbes. Leachate was sampled immediately after leaching (t0), and again after 2 days, 7 days, 14 days, and 35 days. Some of the samples from the last time period didn’t run properly and were re-filtered 42 days after leaching. Samples were acidified or frozen to stop decomposition.
III: Analysis DOC and DON were analyzed on a total organic/inorganic nitrogen and carbon analyzer made by Shimadzu. NH4+, NO3- and ortho-Phosphorus to be analyzed on a colorimetric autoanalyzer made by Astoria Pacific DOP to be analyzed by persulfate digestion for dissolved organic Phosphorus
The point in the timeline We’ve got most data from DOC and DON Started graphing, interpreting preliminary data
Carbon DOC leached in proportion to the amount of mass lost. %mass lost had a negative correlation to specific leaf mass: thinner leaves leached more carbon
Nitrogen DON leaching had a strong negative correlation to CN ratio-leaves with plenty of N leached more N. DON leaching was similar to DOC leaching. Maybe soluble N is linked to soluble C. Low soluble N availability may indicate low N in the ecosystem.
Synopsis of Methods Methods, so far, seem to work, and the first part of the hypothesis seems to be accurate. Organic carbon and nitrogen leach from leaves. In the future: Look at other ecosystem data to corroborate what this project seems to imply about the ecosystem. Look at more correlations between properties of plant and ecosystem type and DOC released from leaching. Incorporate other data.
What could change Add microbes before subsampling. Longer wait between first samplings. Play to strengths of different computer programs. Look into more procedures used by other labs. May throw out one data set………………