Seed dispersal is important for the assembly and maintenance of diversity in plant communities. Yet, patterns of seed dispersal are notoriously difficult to study because current techniques to link dispersed seeds and/or seedlings to their mother are costly and available only for few plant species. This limits the scope and accuracy of ecological and evolutionary studies that require linking mother plants to their offspring in the field. A new technique that uses Nitrogen stable isotope markers (15N) is proposed here to help breach such a methodological gap. The method consists of spraying the leaves of plants with 15N -labeled urea. Preliminary work shows that 15N signals are reliably passed from mother plant to seeds and retained in seedlings, providing reliable mother-offspring markers. Field experiments will be conducted to test and validate the use of this labeling technique. Tests include the use of different 15N doses to differentially label individual plants or groups at a location, and the ability to use bulk-processed seeds from labeled plants to reduce costs.
The use of stable isotopes has promoted major advances in the study of food webs, physiological ecology, and ecosystem function. Yet isotopic techniques have not been used to study seed dispersal and recruitment. This method will have broad appeal because it allows labeling of plants in the field, has the rigor of molecular approaches, and could permit the cheap analysis of many samples. This technique will be particularly relevant for the long-term and long-distance monitoring of seeds.
