Philippine Journal of Science
153 No. 6A: 2003-2018, December 2024
ISSN 0031 – 7683
Date Received: 19 Mar 2024
Earthworm Species Diversity across an Elevational Gradient in Mt. Sawtooth and its Neighboring Highlands in the Zambales Mountain Range, the Philippines
Ericka Jane A. Angeles1,2* and Carmela P. Española2
1University of the Philippines Integrated School, College of Education, University of the Philippines Diliman, Quezon City, National Capital Region 1101 the Philippines 2Institute of Biology, College of Science, University of the Philippines Diliman, Quezon City, National Capital Region 1101 the Philippines
*Corresponding author: eaangeles1@up.edu.ph
Angeles EJ, Española C. 2024. Earthworm Species Diversity across an Elevational Gradient in Mt. Sawtooth and its Neighboring Highlands in the Zambales Mountain Range, the Philippines. Philipp J Sci 153(6A): 2003–2018.
ABSTRACT
Earthworm species diversity was determined across an elevational gradient in Mt. Sawtooth and nearby highlands in the Zambales Mountain Range, part of the Tarlac province, Philippines. This study documented 34 earthworm morphospecies with one exotic species, Pontoscolex corethrurus, and 33 morphospecies belonging to the family Megascolecidae. Megascolecid earthworms were assigned to the following genera: Pheretima, Pithemera, Pleionogaster, Archipheretima, and Polypheretima. Two main clusters of earthworm assemblages were identified based on Jaccard’s index – a cluster characterized by low species richness and dominance of P. corethrurus, as well as a cluster characterized by diverse megascolecid earthworm genera. Most megascolecid earthworms were found in sites with broad canopy cover, high soil moisture, and high relative humidity with low air temperature, low soil temperature, and low soil pH. Anthropogenic disturbances such as reforestation using non-native tree species may have negatively affected the earthworm diversity in lower elevations, as these activities can modify soil properties and destroy natural habitats, making the conditions ideal for the invasion by P. corethrurus. The diversity of megascolecid earthworms in higher elevations was attributed in part to the geological history of the Zambales Mountain Range.