Volume 23 Nos. 1 & 2
Acidity, conductivity and ionic trends of rainwater in acid deposition monitoring sites in Los Baños, Laguna and Quezon City, Philippines
This study aimed to establish trends of levels of acidity (pH), conductivity (EC), and concentrations of anions (SO4 2-, NO3-, Cl-) and cations (NH4+, Na+, K+, Ca2+, Mg2+) in rainwater on urban and rural acid deposition monitoring sites in the Philippines. The results of the study will be significant in establishing local acid deposition baseline data to prove or disprove acid deposition occurrence in the Philippines and to provide useful inputs for decision-making aimed at preventing or reducing adverse impacts of acid deposition. The investigation was conducted in Los Baños, Laguna (Los Baños site) and Quezon City (Metro Manila site), categorized as rural and urban sites, respectively, under the Acid Deposition Monitoring Network in East Asia (EANET) protocol. Weekly monitoring, collection, and laboratory analysis of samples were conducted using standard analytical methods and EANET quality assurance and quality control (QA/QC) procedures. Time series analysis of data from 2001 to 2009 for both sites showed a general decreasing annual trend for all parameters. Seasonal trends were observed to be consistent with annual trends. Correlations between the parameters analyzed are outside the scope of this study and should be the focus of further assessment of the state of acid deposition in the Philippines.
Trace metal speciation by sequential extraction in marine sediments of Calancan Bay, Sta. Cruz, Marinduque, Philippines
Heavy metal contamination is one of the many serious environmental problems affecting the society. Determining only the total metal concentration in sediments is not enough to gauge the potential impact of some heavy metals to aquatic organisms and human beings. To determine what chemical forms of the metals are bioavailable and have the potential for toxic effects, metal speciation is recommended. Through metal speciation, ways to abate the impact of heavy metals to the immediate community could be designed effectively.
This study on trace metal speciation was conducted in the municipalities of Sta. Cruz and Torrijos, province of Marinduque, particularly in Calancan Bay which used to be a repository of mine tailings generated from copper mine operations. The distribution of Copper (Cu), Lead (Pb), Arsenic (As), and Chromium (Cr) in the sediments collected from the Calancan Bay, Sta. Cruz, Marinduque, Philippines was determined by employing Tessier et al. speciation scheme to assess the geochemical mobility as well as the potential bioavailability of these heavy metals.
This study established current metal levels in the sediments collected from Calancan Bay, Marinduque; spatial variability in metal concentrations within the study area; and bioavailability of metals in sediments of Calancan Bay using the sequential extraction technique. The implications of the geochemical mobility of the heavy metals found in the sediments of Calancan Bay were also discussed and correlated to provide a better understanding of the environmental impacts of the presence of the tailings causeway in the bay. Copper present in sediment samples was found mostly in the organic fraction, while Pb was found to associate with the Fe/Mn oxides and hydroxides. As and Cr, on the other hand, were found in the lithogenic fraction of the sediment.
Growth performance of three eucalyptus (Eucalyptus deglupta x E. pellita) hybrids on half-sib progeny trial in Northern Mindanao, Philippines
Half-sib progeny trial as one essential aspect of Forest Tree Improvement to produce quality planting materials is limited in the Philippines. Using three F1 hybrid parents and 74 surviving F2 half-sib progenies of Eucalyptus deglupta x E. pellita hybrids, the economically important traits such as percent survival, total height, diameter at breast height and volume were evaluated. Comparison of the means using T-test analysis detected nonsignificant differences between border and inside trees. Outcome of the analysis of variance revealed that the three F2 half-sib progenies perform poorly due to the occurrence of inbreeding depression (ID), as reflected in a non-significant variation within and among the families in all phenotypic traits used, except in Total Height and Volume. Correlations indicated that future selection using either of the traits studied, particularly those with the highest value except for PS, can result in better volume harvest. Ranking analysis proved the superiority of EDP1F2. It was followed by EDP3F2 then EDP2F2. Results suggested that while ID negates the phenotypic superiority of Eucalyptus hybrids, application of appropriate silvicultural practices can correct its adverse effect.
Assessment of tree species diversity and structure of selected government reforestation projects
This study investigated and analyzed the composition and structure of three government reforestation projects: Paraiso Reforestation Project (PRP) in Piddig, Ilocos Norte; Nassiping Reforestation Project (NRP) in Gattaran, Cagayan; and Marinduque Reforestation Project (MRP) in Boac and Torrijos, Marinduque. Purposive sampling was applied using 50 m X 50 m sampling plots established within the plantations considered mature or old.
A total of 165 species belonging to 120 genera and 49 families were recorded in the three reforestation projects. Swietenia macrophylla King was found either dominant or co-dominant in the three reforestation sites but pose a potential threat for bio-invasion.
The diversity level in PRP, NRP, and MRP based on Shannon-Wiener Index were computed at 2.77, 3.01, and 3.13, respectively. By comparison, the values of diversity index ranges from Moderate to High based on modified Fernando Biodiversity Scale (1998). The computed values for Simpson’s Index of Dominance for PRP, NRP, and MRP were 0.84, 0.90, and 0.88, respectively, indicating the dominance of only few tree species in the entire community, notably the tree species such as S. macrophylla, Reutealis trisperma (Blanco) Airy Shaw, Tectona grandisL.f., Adenanthera intermedia Merr., Gmelina arborea Roxb., Vitex parviflora Juss., andPterocarpus indicus Willd forma echinatus.
Out of the 165 species, there were 101 indigenous, 38 endemic, and 27 introduced species. Among the species listed as endemic or indigenous, a total of 21 species recorded in the three study sites were listed in the National List of Threatened Philippine Plants of which four species are Critically Endangered including R. trisperma and Toona calantas Merr. & Rolfe, six species are endangered, seven species are Vulnerable, and four species are listed as Other Threatened Species. Most of the species listed are timber-producing trees and economically important for furniture and high quality lumber.
Genetic diversity of Limuran (Calamus ornatus Blume var. philippinensis Becc.) populations from three sites in Luzon Island, Philippines using Random Amplified Polymorphic DNA (RAPD) markers
Genetic variation within and among populations of Limuran (Calamus ornatus Blume var. philippinensis Becc.) from Bataan, Camarines Norte, and Quezon were determined using Random Amplified Polymorphic DNA (RAPD) analysis. From the 19 primers used, 11 were polymorphic where a total of 182 alleles were detected. The total genetic diversity among populations and mean genetic diversity within population values were 0.4003 and 0.3724, respectively. The computed Wright’s Fixation Index WFI (Fst) was deemed moderate (0.0698) and could imply that the populations are relatively distant from each other. The dendrogram generated from the observed polymorphisms showed that the Bataan population, which has the highest genetic diversity among the three, was grouped singly. Statistical analysis of the genetic diversity and population genetic structure showed that the three populations have moderate variation. Results of the study can be used in the maintenance and/or improvement of Limuran in the Philippines.
Expression of dominance as influenced by soil fertility in Imperata cylindrica-Saccharum spontaneum vegetation formation
The study was a two-year experiment involving six 4m x 4m plots in mixed Imperata cylindricaand Saccharum spontaneum grassland formation, with application of 14-14-14 NPK fertilizer as the treatment. It aimed to determine which of the two grass species would express vegetative dominance over the other when soil gains in fertility. Results showed that Saccharum spontaneum gained dominance when fertilized, with increase in height, plot cover, number of shoots, and biomass production and the consequent reduction in number of shoots and biomass production in Imperata cylindrica. The results supported the current grassland succession models that are based on field observation, which suggest thatImperata and Saccharum tend to occur in mixture in denuded sites but Saccharum tends to express dominance over Imperata in more productive sites. Frequent disturbance to biomass inImperata-Saccharum formation, such as harvesting or by fire, can prevent Saccharum from attaining competitive dominance over Imperata. The consequence is for Imperata to maintain its dominance because of removal of competition pressure from potentially larger plants like theSaccharum, shrubs, juvenile trees, and associated persistent vines. This study recommends further studies on the ecology of Philippine grasslands to establish basic information for more effective land management and site capability evaluation.