Record ID No. |
2555 |
Author(s) |
Kranabetter J M., MacKenzie W H. , 2010 |
Affiliation |
British Columbia Ministry of Forests and Range, 4300 North Rd., Victoria, British Columbia, V8Z 5J3, Canada. Marty.Kranabetter@gov.bc.ca |
Title |
Contrasts among mycorrhizal plant guilds in foliar nitrogen concentration and delta 15N along productivity gradients of a boreal forest |
Source. Vol.(no):Page |
Ecosystems. 13(1):108-117p. |
Categories |
Mycorrhiza General |
Subjects |
Biochemistry |
Sub-subjects |
Nitrogen metabolism |
Host |
Orthilia secunda, Pyrola asarifolia |
Organism |
Rubus parviflorus, Viburnum edule |
Country |
Canada, N America |
Abstracts |
The distribution of plant species in boreal forest understories is hypothesized to reflect mycorrhizal guilds and associated adaptations for organic nitrogen (N) acquisition. In this study of a natural edaphic gradient, where supply rates of inorganic N increase with site productivity, we noted a decline in understory ectomycorrhizal, ericoid, and arbutoid plant communities on productive sites, in contrast to a positive response by most arbuscular species. We then assessed the rate of change in foliar N concentration (Nconc) and abundance of 15N ( delta 15N) of select plants from these mycorrhizal guilds. Two arbuscular plant species (Rubus parviflorus and Viburnum edule) had the sharpest increases in foliar Nconc with enhanced supplies of NH4+ and NO3-, but with no differences in foliar delta 15N. An ectomycorrhizal species, Abies lasiocarpa, and ericoid species, Vaccinium membranaceum, had parallel increases in both Nconc and delta 15N with soil N supply. The foliar delta 15N of two arbutoid plants (Orthilia secunda and Pyrola asarifolia) were as enriched as ectomycorrhizal sporocarps, likely indicating N transfer from mycorrhizal networks. The depletion of foliar delta 15N by ectomycorrhizal and ericoid plants on poorer sites likely reflected a high degree of N retention and photosynthate demand by fungi, whereas arbuscular plants may have had a less significant delta 15N response because of a more passive role by fungi in scavenging organic N. The results suggest differences in how mycorrhiza exploit diverse soil N supplies (recalcitrant and labile organic N, NH4+, NO3-, and parasitized N) could be an important factor in boreal plant community composition. |