Litterfall nutrients and the soil nutrients under three indigenous tree species in the Nigerian rainforest Region

The study was conducted in the 3 senatorial districts in Delta State (Delta North, Delta Central and Delta South). From each senatorial district, 5 stands of each indigenous species of tree were selected, while 5 rainforest control plots were established from neighbouring rainforest cover of ≥ 80 years in age. Thus, samples of litterfall and soil were gathered from 15 trees, each from the indigenous species and the control plots, respectively. Two soil layers of 0-15cm and 15-30cm depth were determined under the trees, from where soil samples were collected, using a core sampler, while litterfall was gathered from March 2019 to February 2020 using litter traps. Standard laboratory procedures were adopted to analyse the samples collected. Descriptive, ANOVA and correlation statistics were employed to analyse the data using the 15.0 version of SPSS. The research statistically correlates litterfall nutrients with soil nutrients under isolated indigenous stands of Terminalia superba, Irvingia gabonensis and Newbouldia laevis trees in the Nigerian rainforest region. Results show that soil nutrients, litterfall nutrient contents and returns significantly differed among the tree species at a 5% confidence level, while soil nutrients correlated with litterfall nutrients positively. Since the isolated indigenous trees can add nutrients to rainforest soil, thereby improving its nutrients and sustaining its productivity, their incorporation into the agro-forestry practice as farm trees by farmers is recommended. This has implications for forest and environmental conservation.