30 research outputs found

    15N natural abundance of vascular rainforest epiphytes: Implications for nitrogen source and acquisition

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    The foliar natural abundance of 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 N relative to the trees at each site. Epiphyte δN was as low as ‐6.4%, while trees were generally enriched in N (0.7 to 3.5%). These results indicate either that epiphytes use nitrogen sources depleted in N or that discrimination against N is an intrinsic function of epiphyte physiology. At three sites, epiphytes could be grouped into those having both low δN and low leaf‐nitrogen content and those possessing both high δN and high leaf‐nitrogen content. The second group had δN values in the range sometimes attributable to N fixation (‐2 to 0%o). There was no correlation between growth form and δN. It is concluded that epiphytes may utilize N‐depleted nitrogen from atmospheric deposition and N fixation. Copyrigh
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