Microbial biomass, soil ammonium and nitrate in a secondary successional chronosequence.

Abstract

We studied the microbial biomass, soil ammonium and nitrate in a secondary successional chronosequence. We wanted to know if nitrite, amino-N, or total microbial N content in soils vary with forest stand age. We also wanted to know if there was a relationship between amino-N and ammonium and if there was a relationship between amino-N and nitrate. To assess the soils, we collected a total of 90 samples from the burn plot chronosequence on the University of Michigan Biological Station (UMBS) property. Soils were collected from the 1911, 1936, 1948, 1954, 1980 and 1998 burn plots. Soils were sieved and picked through to remove fine roots and other debris such as twigs and pebbles that could interfere with our date. Soils then were taken to the lab to be homogenized and weighed out. The soils were then separated into fumigated and non-fumigated samples and KCL extractions and chloroform tests were run on the samples. We found that there was no significance across the chronosequence in nitrite, amino-N or total microbial N related to forest age stand. We also found no significant relationship between amino-N and nitrate but we did find a significant relationship between amino-N and ammonium. Future studies should be run to understand how microbes are affecting nutrient cycling in secondary successional chronosequences and the types of microbes present.