Philippine Journal of Science
150 (S1): 539-550, Special Issue on Biodiversity
ISSN 0031 – 7683
Date Received: 04 Oct 2020
Foliar Carbon and Nitrogen Content and Stable
Isotopic Composition of Selected Philippine Flora
Roland V. Rallos*, Gerald P. Dicen, Andrea Luz G. Nery,
and John Leonard R. Labides
Agriculture Research Section
Philippine Nuclear Research Institute
Department of Science and Technology (DOST-PNRI)
Commonwealth Ave., Diliman, Quezon City
National Capital Region 1101 Philippines
*Corresponding author: rvrallos@pnri.dost.gov.ph
ABSTRACT
The elemental carbon and nitrogen content, as well as the stable isotopic composition of plants, can provide information on their nutrient dynamics and physiological characteristics. With applications ranging from paleoecology to ecological modeling, this information is critical in biodiversity conservation and management especially for highly dynamic ecosystems such as the Philippines’. Here, we determined the carbon and nitrogen content and their stable isotopic ratios in selected Philippine flora across different classifications and photosynthetic pathways. Fully developed leaves from different species of grasses, succulents, shrubs, and trees were collected and analyzed using isotope ratio mass spectrometry for carbon and nitrogen concentration and stable isotopic composition. Our results showed that trees had the highest carbon and nitrogen content, while grasses that utilized the C4 photosynthetic pathway were most efficient in terms of nutrient utilization as evidenced by their high C/N ratios. Foliar stable carbon isotopic composition of the surveyed Philippine flora was an excellent measure for distinguishing among photosynthetic pathways. The stable nitrogen isotopic composition was not distinct across plant classifications and showed indications of being sensitive to environmental factors, thus limiting its use for phylogenetic tracing. Our findings thus indicate that foliar carbon and nitrogen content and stable isotopic composition provide insights that cannot be easily achieved with other measurements.