VOLUME 14 NUMBER 2 (July to December 2021)

Ma. Patricia Joson¹, Mark Joseph Comia¹, Ma. Klarice Cureg¹, Ian A. Navarrete^1,2, and Severino G. Salmo III*^1,3

¹Department of Environmental Science, School of Science and Engineering,
      Ateneo de Manila University, Loyola Heights,
      1108 Quezon City, Philippines
²Department of Environmental Science, Southern Leyte State University –
      Hinunangan Campus, Ambacon, Hinunangan, Sogod,
      6608 Southern Leyte, Philippines
³Institute of Biology, College of Science,
      University of the Philippines, Diliman, 1101 Quezon City, Philippines

The lahar deposition from the eruption of Mt. Pinatubo in 1991 altered the mangrove mudflat in Sasmuan, Pampanga. Here, we assessed and compared the vegetation and sediment characteristics of mangroves composed of pre-eruption natural stands, post-eruption colonized stands (ca. 20 yr-old), and post-eruption planted stands (ca. 7 yr-old). Our results revealed that coarse sediments dominated more relative to the fine fractions, which may be related to the massive lahar deposition in the mudflat areas. In natural stands, the organic matter (OM) decreased at 80 to 100 cm depth that coincided with high coarse content but increased from 80 cm to surface implying post-disturbance OM accumulation. Both the colonized and planted stands have similar low OM at the bottom than the natural stands. Similar patterns were observed with bulk density (BD). The natural and colonized stands have comparable vegetation and sediment characteristics implying that mangroves subjected to post-disturbance colonization process may have similar attributes with a pre-disturbance stand in ca. 20 yrs. Although the deposition of lahar materials altered the growth of pre-eruption mangrove stands, the aeration and accretion provided by coarse fractions (on a usually asphyxiated and inundated sediment) may have facilitated mangrove colonization that led to the development of the colonized stands. To our knowledge, our study was the first to report the impacts of lahar in Philippine mangroves.