Changes in Asymbiotic, Heterotrophic Nitrogen Fixation on Leaf Litter of Metrosideros polymorpha with Long-Term Ecosystem Development in Hawaii |
| |
Authors: | Timothy E Crews Heraldo Farrington Peter M Vitousek |
| |
Institution: | (1) Department of Biological Sciences, Stanford University, Stanford, California 94305, USA, US |
| |
Abstract: | We measured nitrogenase activity (acetylene reduction) of asymbiotic, heterotrophic, nitrogen-fixing bacteria on leaf litter
from the tree Metrosideros polymorpha collected from six sites on the Hawaiian archipelago. At all sites M. polymorpha was the dominant tree, and its litter was the most abundant on the forest floor. The sites spanned a soil chronosequence
of 300 to 4.1 million y. We estimated potential nitrogen fixation associated with this leaf litter to be highest at the youngest
site (1.25 kg ha-1 y-1), declining to between 0.05 and 0.22 kg ha-1 y-1 at the oldest four sites on the chronosequence. To investigate how the availability of weathered elements influences N fixation
rates at different stages of soil development, we sampled M. polymorpha leaf litter from complete, factorial fertilization experiments located at the 300-y, 20,000-y and 4.1 million–y sites. At
the youngest and oldest sites, nitrogenase activity on leaf litter increased significantly in the plots fertilized with phosphorus
and “total” (all nutrients except N and P); no significant increases in nitrogenase activity were measured in leaf litter
from treatments at the middle-aged site. The results suggest that the highest rates of N fixation are sustained during the
“building” or early phase of ecosystem development when N is accumulating and inputs of geologically cycled (lithophilic)
nutrients from weathering are substantial.
Received 4 February 1999; accepted 29 March 2000. |
| |
Keywords: | : asymbiotic nitrogen fixation chronosequence lithophilic nutrients soil development |
本文献已被 SpringerLink 等数据库收录! |
|