No abstract

The effectiveness of heavy metal-tolerant microorganisms for supporting plant growth needs to be understood before it can be used as a soil bioremediation agent. The purpose of this study was to determine the effect of heavy metal tolerant microorganisms on the growth of “Narra” seedling (Pterocarpus indicus Wild). Three heavy metals-resistant (Pb, Cd, and Cu) rhizobacteria from a copper (Cu) mined-out site in Marinduque, Philippines showed plant growth promotion in vitro. A treatment combination of formula inoculant A (CuNFbM 4.1, MGR 333), B (CuNFbM 4.1, MGR 333, PbSM 2.1), and O (Uninoculated); compost (0%, 4%); and lime + inorganic fertilizer {without or with lime and inorganic fertilizer (LF0; LF1)} were applied to Narra seedlings planted on 445 mg/kg Cu-contaminated soil. Lime (2 mg/ha) and the recommended dose of soybean inorganic fertilizer were used as positive controls to evaluate the ability of inoculations and composts to promote the growth and used as positive controls to evaluate the ability of inoculants and composts to promote the growth and copper accumulation of narra in greenhouse experiments. All treatment combinations resulted in significant differences in plant height, leaf number, stem diameter, shoot and root dry weight, as well as, shoot, root Cu content, and plant Cu uptake of 13-week-old “Narra”. Inoculated “Narra” could thrive better in mine-degraded soil containing 445 ppm Cu with 4% compost. Inoculant B demonstrated the best plant performance while Pseudomonas synxantha (PbSM 2.1) probably increases the plant’s growth due to 1-aminocyclopropane-1-carboxylate (ACC) deaminase it produces. Accumulation of Cu was higher in the root compared other plant parts. More research is necessary to elucidate the mechanism of plant growth promotion and heavy metal re mediation by P. synxantha.

This study analyzed the water quality dynamics in the coastal zone of Boracay Island in relation to anthropogenic activities and natural factors. Seven sites were studied where possible sources of nutrient inputs on spatial and temporal basis were identified. Water samples were evaluated using the Philippine Department of Environment and Natural Resources (DENR) regulatory standards. The coastal water quality was generally influenced by nutrient loading coming from untreated and partially treated waste water from households and commercial establishments not connected to the sewerage system of the island. Natural cleansing mechanisms attributed to activities of autotrophs in the coastal water and biogeochemical processes of mangrove swamps are operational. Coastal waters adjacent to mangrove swamp impoverished of mangrove trees showed poor water quality, while coastal water adjacent to mangrove swamp with relatively good mangrove cover exhibited good water quality. The months of February to June with highest number of tourist arrival proved to be the critical periods. Lugotan Cove close to Mangrove Swamp 6 impoverished of trees was the critical area in the Island. Puka Beach close to Mangrove Swamp 1 with good mangrove cover showed the cleanest water quality, followed by Long Beach with most of the commercial establishments connected to the sewerage system.

Patterns of distribution and diversity of springtails along an elevational gradient in the canopy and forest floor of Mt. Makiling, Philippines were determined, this being the first study conducted on springtail diversity along an elevational gradient and also the first published report of canopy arthropods in the Philippines. Springtails were extracted from soil samples from the floor and those suspended in the canopy of three natural forests at different elevations (tropical lowland evergreen rainforest, lower montane rainforest, and tropical upper montane forest). We predict that elevation and forest strata will have significant effects on the springtail assemblages. A total of 2,287 springtails representing 31 morpho-species and eight families were collected from the study. Across the elevation gradient, mean species richness and mean abundance consistently decrease as elevation increases, but only the mean abundance of the lowland forest is significantly different from that of the lower and upper montane forests. Diversity t-test (p-values less than 0.05) revealed significant differences between different sites and strata. Clustering analysis using the Bray-Curtis similarity index revealed separate groupings of the lowland forests to those of the montane forests. Lastly, the results of PERMANOVA showed that both elevation and strata were found to have significant effects on the overall assemblage of springtails. This study suggests that forest floor species assemblages are closely related to each other unlike those of the canopy, where only the upper montane and lower montane are similar. The results of this study affirm our main hypothesis that springtails (as a group) respond significantly to both elevation and strata in a tropical forest in the Philippines.