Studies on Fertility Indicators of Forest Soil under Different Tree Canopy Shades in a Tropical Low Land Rain Forest of Otuoke Bayelsa State, Nigeria

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Abstract

The study was carried out to investigate whether tree canopy shades have relationships with soil fertility indicators. Purposeful random- within- block sampling method was used. A homogenous forest stand with same site quality was purposefully demarcated into three sample areas of 1 hectare each in the order of limited canopy cover, and total canopy cover. An open field within the same terrain was also demarcated. A 10m×10m sub-samples were demarcated within each sample area and three sample plots were randomly selected from each sample area for investigation. Twenty trees (10/sample plot) within the nearest neighbour under limited and total canopy covers were randomly picked. Twenty leaves were collected from each sample tree for leaf area index measurement. Soil samples were collected from 0-30cm depth under each canopy shade and taken to the laboratory for soil and microbial load analyses. Chi- square test shows that microbial load was significantly (P<0.05) higher under close canopy than open field. Microbial population was 501 x 10-5 CFU under close canopy, 415 x 10-5 CFU under limited canopy and 201 x 10-5 CFU in open field. Results showed that closed canopy has the highest microbial load with mean value of 167 x 10-5, followed by limited canopy 138 x 10-5. Open canopy had the lowest microbial load 67x105. The coefficient of determination (R2) was 0.15 for closed canopy, and R2 was 0.21 for limited canopy shade. In all, there were weak positive correlations between tree canopy shades and soil microbial load.

Keywords: Fertility indicators, Forest soil,Tree canopy shade,Low-land rain forest,

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