ABSTRACT

This study was conducted to assess the litter production and nutrient input of selected indigenous agro-silvicultural tree species at Forest Research Institute Of Nigeria. Outstation,Umuahia, Abia State. The study was carried out in Humid Forest Research Station, Forestry Research Institute of Nigeria (FRIN). Four trays (1 m x 1 m) were systematically positioned for collection ofleaflitter from three agroforestry plots ofGarcinia mannii, Ivringia gabonensis, and Abzelia africana species. Each tray had a plastic mesh (2mm) base and was raised on four legs which elevated the base to a height of 20cm from the ground. The trays were used in the study to collect leaf litter from all the selected agroforestry plots. Leaf litter were collected separately from each litter tray and placed in paper bags every 28th day ofthe month. The experiment was carried out using a randomized complete block design (RCBD) with three replications. Oven dried samples of the collected litter were then subjected to laboratory analysis to ascertain. The data obtained from the litter production and nutrient input studies was subjected to analysis ofvariance (ANOVA). The relationship between climate and litter production was determined with a Pearson correlation analysis. From the result, litter production for A africana ranged from 17.99 g in July to 50.29 g in September, for G. mannii it ranged from 34.47 g in August to 101.65 g in September while for I. gabonensis it ranged from 63.11 g in July to 105.72 g in September. Average organic matter (OM), organic carbon (OC), total nitrogen (TN), phosphorus (P) and potassium (K) were 205.25 %, 448.65 %, 36.51 %, 44.37 %, and 203.57 for A. Africana. In the leaflitter of G. mannii, 372.31 %, 1218.85 %, 30.29 %, 87.20 %, and 411.76 % were average OM, OC, TN, P and K obtained. In I. gabonensis, average OM, OC, TN, P and K were 409.22 %, 1185.06 %, 27.55 %, 60.58 %, and 193.18 % respectively. Effect of time and species difference was significant (p<0.05) to the leaflitter production and nutrient availability. Relative humidity (RH) was 82 %, 69 %, and 78 % for July, August and September respectively. The minimum temperature was 22.9 °C, 21.8 °C, and 28.7 °C for July, August and September respectively. The maximum temperature was 30.1 °C, 29.6 °C, and 30.5 °C for July, August and September respectively. The average monthly rainfall was 712, 136, 263 for July, August and September respectively. There was negative correlation between average rainfall data, relative humidity and the mineral constituent of the leaf litter. Weak correlation was observed between mineral constituent of leaflitter and minimum temperature while they had no correlation with maximum temperature. The order of nutrient availability in A. africana was OC>OM>K>P>TN. In Garcinia mannii, the order was OC>K>OM>P>TN while in Irvingia gabonensis the order was OC>OM>K>P>TN. There was significant positive correlation between litter production and mineral enrichment. Hence, all the leaflitter contributes highly to organic status ofsoil and its mineral status. The month of September was observed to be best in litter production and nutrient enrichment because it was dry season period and also there was increase in wind and other climatic condition that influence litter fall. Giving the outcome ofthis present study it is there necessary to recommend that I. gabonensis and G. mannii should be adopted as trees which its leaf litter may serve as an alternative organic nutrient source to the soil.