Litterfall and Nutrient Returns in Isolated Stands of Persea gratissima (Avocado Pear) in the Rainforest Zone of Southern Nigeria

This study assesses litterfall and nutrient returns to the soil in isolated stands of Persea gratissima in the rainforest zone of southern Nigeria. The study examined litter production, the concentrations of nutrients in litterfall, the returns of nutrient elements to the soil via litterfall, the relationship between litter production nutrient returns via litterfall, and determined the seasonal variations in litter production and the returns of nutrient elements via litterfall respectively. Data collection was on litterfall which was collected from February 2010 - January 2011. Data collected were statistically analyzed using the SPSS 15.0 version. Average litter production was 60.23 g/m²/yr and 77.31 g/m²/yr for the Persea gratissima and adjoining rainforest. Results of the Independent Samples T-Test revealed that there are significant differences between Persea gratissima and adjoining rainforest in litter production and returns of nutrient elements via litterfall. Except for Nitrogen, the concentrations of nutrient elements were similar. Results of Pearson’s bivariate analyses showed that significant positive relationships exist between litter production and nutrients returned to the soil through litterfall at the 5% levels. However, litter production and the returns of nutrient elements vary with the seasons of the year, but the trend in the seasonal patterns of nutrient returns from Persea gratissima and adjoining rainforest is similar for K, Ca, Na and Mg. Persea gratissima return nutrients to the soil through litterfall, therefore its production should be encouraged to help in improving the soil nutrient status in rainforest areas.Keywords: Isolated tree stands, litterfall, nutrient returns, Persea gratissima, Southern Nigeria, Tropical rainforest