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15 N natural abundance of vascular rainforest epiphytes: implications for nitrogen source and acquisition
Author(s) -
STEWART G. R.,
SCHMIDT S.,
HANDLEY L.L.,
TURNBULL M. H.,
ERSKINE P. D.,
JOLY C. A.
Publication year - 1995
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1995.tb00547.x
Subject(s) - epiphyte , rainforest , nitrogen , botany , abundance (ecology) , biology , ecology , relative species abundance , chemistry , organic chemistry
The foliar natural abundance of 15 N was analysed to compare the potential nitrogen sources of vascular rainforest epiphytes and associated soil‐rooted trees. Leaves of epiphytes collected from six rainforest communities in Brazil, Australia and the Solomon Islands were depleted in 15 N relative to the trees at each site. Epiphyte δ 15 N was as low as ‐6.4% o , while trees were generally enriched in 15 N (0.7 to 3.5% o ). These results indicate either that epiphytes use nitrogen sources depleted in 15 N or that discrimination against 15 N is an intrinsic function of epiphyte physiology. At three sites, epiphytes could be grouped into those having both low δ 15 N and low leaf‐nitrogen content and those possessing both high δ 15 N and high leaf‐nitrogen content. The second group had δ 15 N values in the range sometimes attributable to N 2 fixation (‐2 to 0%o). There was no correlation between growth form and δ 15 N. It is concluded that epiphytes may utilize 15 N‐depleted nitrogen from atmospheric deposition and N 2 fixation.