Tree vegetation analysis and factors affecting regeneration of forest tree species within the Kanawan Negritos Reservation Area (KNRA) in Morong, Bataan, Philippines

The study mapped and measured the actual hectarage of Kanawan Negritos Reservation Area (KNRA) in Sitio Kanawan, Morong, Bataan, Philippines and its remaining forest using boundary coordinates by computer software Area.xlsx. Tree vegetation analysis was then conducted. The study also documented light and edaphic factors affecting seed germination, growth and survival of Anisoptera thurifera (Blanco) Blume and Parkia timoriana (DC.) Merr under nursery and field conditions. Using Point-Centered Quarter Method (PCQM), five 200 m transects were laid across study site. Trees with or = to 1.3 m from the ground (DBH) were sampled. Trees encountered were categorized into four groups: seedling, saplings, pole trees and standard trees based on girth classes. Calculations revealed that KNRA measures 186 hectares but only 28 ha remain with forest cover. Within the residual forest a total of 75 tree species belonging to 61 genera and 31 families were recorded. The most represented families were: Moraceae, Dipterocarpaceae, Sapindaceae, Malvaceae, and Lauraceae. The species with highest Importance Value (IP) were Shorea controta Vidal (Dipterocarpaceae) (IP=9.731), Macaranga tanarius (L.) Muell - Arg (Euphorbeaceae) (IP=5.659) and Canarium europhyllum (Burseraceae) (IP=4.538). Very high values of species diversity were calculated (H'=3.817, D'=0.968). The area was previously a dipterocarp forest and can now be classified as a young regenerating forest, composed primarly of sapling and many dipterocarp seedlings. There were 17 threatened species, including two critically endangered and four endangered species (listed in IUCN Red list of Threated Species and DAO 2007-01) and six endemic species identified as present in the area. This forest is a biological hotspot that needs utmost protection and conservation. A. thurifera had higher mean germination than P. timoriana both in nursery and field. Under nursery condition, partial shade have the highest and germination (56.5%) for both species (p less than 0.05). Full shade (46.3%) had almost same germination as the open area (43.3%). In the field, open area had the lowest mean seed germination (10.3%) while highest germination in partial (23.4%) and full shade (25%). The growth parameters differed between P. timoriana and A. thurifera, since they are different plant species and their growth was also defined by their district genetic characteristics. Regardless of the potting media used the two tree species survived better under full and partial shades. A. thurifera seedlings suffered high mortality under open condition. Though survival rate results on different potting media were not statistically significant, a trend established that soil amendments (Trichoderma, mycorrhizae and compost) gave positive results indicated by better survival and faster growth under partial and full shade condition.