Nitrogen fixation and accretion by wax myrtle ( Myrica cerifera) in slash pine ( Pinus elliottii) plantations

Abstract

The effects of wax myrtle ( Myrica cerifera L.) on the nitrogen cycle were examined in a 23-year-old slash pine ( Pinus elliottii Engelm. var. elliottii) plantation located near Gainesville, FL. These shrubs occurred naturally as an understory and had a crown cover of 8% of the study area. The potential rate of nitrogen fixation by wax myrtle was estimated to be 13 g N m −2 year −1, or 10.6 kg N ha −1 year −1 on a stand wide basis. Wax myrtle fixed substantial amounts of nitrogen throughout the year although winter rates were significantly less due to the greatly reduced activity of old nodules during that season. The average accumulation rate of nitrogen beneath wax myrtle was 1.5 g N m −2 year −1 in the soil and 0.9 g N m −2 year −1 in the forest floor. On a stand wide basis this amounted to an accretion of 1.9 kg N ha −1 year −1 in the soil and forest floor.