An aquatic wild plant as a keystone species in a traditional Philippine rice growing system: its agroecological implications

Lualhati  M. Noriel,; Cherukat  Balagopalan,

An aquatic wild plant as a keystone species in a traditional Philippine rice growing system: its agroecological implications

Cherukat Balagopalan | Lualhati M. Noriel

Abstract:

Martin K. and J. Sauerbom. 2000. An aquatic wild plant as a keystone species in a traditional Philippine rice growing system: its agroecological implications. Ann. Trop. Res. 22[1&2]:1-15. In the province of Ifugao, Northern Luzon, Philippines rice cultivation on irrigated terraces has been practiced since centuries ago. The traditional system is characterized by one harvest per year from permanently flooded fields.The macrophyte Najas graminea Del. is the most abundant submerged wild plant in this agroecosystem. It is argued that this plant can be seen as a keystone species, because of its crucial role in maintaining the organization and diversity of the aquatic community which also has impacts on the terrestrial community of the agroecosystem. This conclusion was drawn from two aspects studied: (1) The food web of the aquatic community depends on the presence of N. graminea since it provides Aufwuchs and detritus, on the surfaces of its leaves, to primary consumers such as crustaceans, the larvae of Ephemeroptera and Chironomidae, and Gastropoda which in turn serve as prey for a number of predators, mainly the larvae of Odonata, certain Coleoptera and Diplonychus rusticus (Fabricius). (2) The golden snail Pomacea canaliculata (Lamarck), a recent invader into Southeast Asian rice fields from tropical America and a serious pest of rice seedlings in modern production systems, caused no appreciable damage in the Ifugao rice terraces so far. The most probable explanation for that is the presence of a high biomass of wild aquatic plants mainly N. graminea and the floating fern Azolla pinnata R. Br. which serve as alternative food sources for P. canaliculata when the rice plants are most vulnerable to its attacks. Comparison of snail fauna in different fields before and seven years after the invasion of P. canaliculata showed that it had no clear negative impacts on the native species. Possible future impacts of the species on the agroecosystem are discussed.

References:

BIMBENET J.J., J.D.DAUDIN and E. WOLFF. 1985. Air drying kinetics of biological particles. In: Drying '85 (R. Toie and A.S. Mujumdar, eds.). Hemisphere Publishing Corporation. New York, pp: 178-185.
BRENNAN J.G., J.R. BUTTERS, N.D. COWELL and A.E.V. LILLY 1976. Food Engineering Operations. Applied Science Publishers, LTD, London.
CHIANG W.C. and J.N. PETERSEN. 1985. Thin layer air drying of french fried potatoes Journal of Food Technology 20:67-78.
DESROSIER N.W. 1970. The Technology of Food Preservation. AVI Publishing Company, Inc., Westport, Connecticut.
DIAMANTE L.M. and P.A. MUNRO. 1994. Drying characteristics of sweetpotato slices. In: Proceedings of the International Conference on Food Preservation and Security. National Academy of Science and Technology. Manila, Philippines. pp: 187-199.
DIAMANTE L.M., P.A. MUNRO and M.G. WEEKS. 1992. Fluidized bed drying of a biological material (casein): Effect of drying temperature. Paper presented during the 42nd National Convention of the Philippine Society of Agricultural Engineers (PSAE) held at Mariano Marcos State University, Batac, Ilocos, Norte, Philippines on April 22-24, 1992.
FELLOWS P.J. 1988. Food Processing Technology: Principles and Practice. Ellis Horwood Ltd. London.
FIELDS M.L. 1977. Laboratory Manual in Food Preservation. AVI Publishing Company, Inc., Westport, Connecticut.
GOMEZ K.A. and A.A. GOMEZ. 1984. Statistical Procedures for Agricultural Research. John Wiley & Sons, Singapore.
HOLDSWORTH S.D. 1971. Dehydration of food products: A review. Journal of Food Technology. 6:331-370.
JOHNSON A.H. and M.S. PETERSON. 1974. Encyclopedia of Food Technology. Volume 2. AVI Publishing Company, Inc. Westport, Connecticut.
LOZADA E.P. 1978. Principles of copra drying. In: Proceedings on the Seminar on Methods of Copra Drying. Philippine Coconut Authority. Diliman, Quezon, City.pp: 7-17.
MULET A., F. ROSELLO, F. PINAGA, J.V. CARBONELL and A. BERNA. 1985. Mecanismo y cinetica de secado de zanahorias con aire caliente. Rev. Agroguim. Technol. Aliment. 23:369-377.
SIEGEL S. and N.J. CASTELLAN, JR. 1988. Nonparametric Statistics for the Behavioral Sciences. MacGraw-Hill Book Co., Singapore.
TROUNG V.D., L.S. PALOMAR, C.T. MONSERATE and R.D. LAUZON. 1984. Coconut-based Food Products: Processing and Acceptance Studies. Terminal Report, PCARRD-Funded, ViSCA, Leyte
VACCAREZZA L.M., J.L. LOMBARDI, and J. Chirife. 1974. Kinetics of moisture movement during air drying of sugar beet root. Journal of Food Technology. 9: 317-327.
WATSON E. L. and J.G. HARPER. 1991. Elements of Food Engineering. Van Nostrand Reinhold Company, New York.
YUSHENG Z. and K.S. POULSEN. 1988. Diffusion in potato drying. Journal of Food Engineering. 7:249-262.