Influence of Native Trees on Soil Fertility at a Rainforestation Site in Mailhi, Baybay City, Leyte, Philippines

Abstract

The Philippines is one of the few countries in the world which was originally and thoroughly covered by rain forest. The conversion of natural forests to agricultural land uses has led to land degradation. Soil is a vital resource for human survival in that it is the medium in which most plants grow, it cleans and stores water, detoxifies pollutants, and plays a key role in the regulation of the Earth’s temperature. One of the intentions of rainforestation farming (planting of native tree species) is to regenerate soil fertility. However, the effect of native forest trees on soil fertility is still poorly understood. Hence, this study was conducted to evaluate the influence of native trees on the fertility status of the soil in Mailhi, Baybay City, Leyte, Philippines. Two adjacent sites were evaluated and sampled. These were the 22-year-old rainforestation farm and the nearby coconut plantation. At each site, a 20 m x 20 m plot for sampling purposes was established which was divided into four parts. In each part, four (4) composite soil surface samples were collected from a soil depth of 0-20 cm using a soil auger. Each of the four composite samples came from three (3) subsamples. The subsamples were mixed, and one-half kilogram was placed in properly labelled plastic bags and brought for processing and laboratory analysis. Results revealed that the rainforestation farm did not have an effect on water holding capacity and soil pH but significantly increased the organic matter and total N contents of the soil, when compared with the nearby coconut plantation. On the other hand, available P and exchangeable K were lower in the soil under native tree species compared to the coconut plantation. The results indicate that indeed, the native trees in the rainforestation site have caused important changes to the fertility status of the soils.