Impacts of rainfall acidity on the germination and early seedling growth fo three forest tree species in two soil types in Mt. Makiling, Philippines
2006
Carandang, V.C .Q.
This study aimed to establish the sensitivity of three species found in the Makiling Forest Reserve to rainfall acidification. The species included Betis (Madhuca betis (Blanco) MacBride), Antipolo (Artocarpus blancoi (Elmer) Merr.), and Kalantas (Toona calantas Merr. and Rolfe) whose seeds were sown and maintained in two soil types namely, Makiling and Pansol soils. Simulated rainwater with the following pH levels were used in watering the seeds and seedlings: 2.5, 3.5, 4.5, 5.5, and distilled water serving as the control with a pH of 7.0. The sensitivities were established by examining the response of the said species to the aforementioned pH levels of simulated rainfall in terms of seed germination early growth of their seedlings, leaf anatomy and morphology, and seedling physiology. Germination value, root length, and epidermal leaf thickness were not significantly affected by rainfall acidity. However, height and diameter growth, shoot and root biomass, shoot root ratio, total chlorophyll content, number and size of stomata were found significantly affected by rainfall acidity. These parameters then are most useful as indicators of sensitivity to acid rain in the area studied. Root length, sturdiness quotient, leaf area, and palisade mesophyll thickness were both affected by rainfall and soil type. Less consideration is to be given to these parameters in the study of the sensitivity of plants to acid rain treatment. Of the three species studied, Kalantas was observed to be the most sensitive to changes in the acidity of simulated rainwater. The measurements obtained in all seedling growth parameters which were found to be significantly different showed more remarkable changes in Kalantas. For Betis, the differences within its seedlings in most of the parameters were found to be insignificant. Antipolo was intermediate between Kalantas and Betis.
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