Nitrogen Uptake by Trees and Mycorrhizal Fungi in a Successional Northern Temperate Forest: Insights from Multiple Isoto
- PDF / 469,994 Bytes
- 14 Pages / 593.972 x 792 pts Page_size
- 94 Downloads / 194 Views
Nitrogen Uptake by Trees and Mycorrhizal Fungi in a Successional Northern Temperate Forest: Insights from Multiple Isotopic Methods Lucas E. Nave,1,2* Knute J. Nadelhoffer,1,2 James M. Le Moine,1,2 Linda T. A. van Diepen,3 Jules K. Cooch,1 and Nicholas J. Van Dyke1 1
University of Michigan Biological Station, 9133 Biological Rd, Pellston, Michigan 49769, USA; 2Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA; 3Department of Natural Resources and the Environment, University of New Hampshire, Durham, New Hampshire, USA
ABSTRACT 75% to less than 60%. Increasing N availability was associated with lower EM hyphal foraging and 15N tracer uptake, yet the EM-associated later-successional species Quercus rubra was nonetheless a stronger competitor for 15N than AM-associated Acer rubrum, likely due to the more extensive nature of the persistent EM hyphal network. These results indicate that successional increases in N availability and co-dominance by AM-associated trees have increased the importance of AM fungi in the mycorrhizal community, while down-regulating EM N acquisition and transfer processes. This work advances understanding of linkages between tree and fungal community composition, and indicates that successional changes in N availability may affect competition between tree taxa with divergent resource acquisition strategies.
Forest succession may cause changes in nitrogen (N) availability, vegetation and fungal community composition that affect N uptake by trees and their mycorrhizal symbionts. Understanding how these changes affect the functioning of the mycorrhizal symbiosis is of interest to ecosystem ecology because of the fundamental roles mycorrhizae play in providing nutrition to trees and structuring forest ecosystems. We investigated changes in tree and mycorrhizal fungal community composition, the availability and uptake of N by trees and mycorrhizal fungi in a forest undergoing a successional transition (age-related loss of early successional tree taxa). In this system, 82–96% of mycorrhizal hyphae were ectomycorrhizal (EM). As biomass production of arbuscular mycorrhizal (AM) trees increased, AM hyphae comprised a significantly greater proportion of total fungal hyphae, and the EM contribution to the N requirement of EM-associated tree taxa declined from greater than
Key words: mycorrhiza; hyphae; canopy; N; tree; competition.
15
INTRODUCTION Received 30 April 2012; accepted 20 November 2012; published online 18 January 2013
The effects of forest succession on nitrogen (N) availability and uptake by plants are important, because N limits plant productivity in temperate forests (Vitousek and Howarth 1991). Mycorrhizal symbionts play a major role in N acquisition for
Author Contributions: LEN, KJN, and JML conceived and designed the experiments. LEN, JML, LTAvD, JKC, and NJvD performed the experiments. LEN, KJN, JML, JKC, and NJvD analyzed the data. LEN wrote the manuscript; other authors provided substantive editorial advice. *Corresponding author;
Data Loading...
