This study aims to develop site index for Teak (Tectona grandis) in Kanya Forest Plantation, Nigeria. Site index is defined as the total height of the dominant or co-dominant trees at an arbitrary index age, it is a method used for quantifying site quality for pure even-aged stands which is essential in growth and yield modelling. The data used in this study were obtained from six different age classes. Five sample plots each were selected across all age classes in which a total of 712 trees were measured, variables measured include total height, diameter at the base, middle, top, and diameter at the breast height were taken from 30 temporary sampled plots of 25x25m approximately from the centre, 180 dominant trees were selected from 712 trees. Basal area and volume of sampled trees were computed. Yield values obtained from the dominant trees are (B = 249.312 m3/ha, D = 196.128 m3/ha, F = 134.976 m3/ha, C = 119.328 m3/ha, E = 100.320 m3/ ha and A = 86.976 m3/ha). The results showed that B was the best and A was the poorest. Seventeen models were generated and paired sampled t-test was used for model validation, comparing the actual and predicted height. Two out of 17 were rejected (significant P<0.05). The first model Hd=12075.346-354.809(Age)+3.448(Age)2-135193.126(1/Age) is the recommended height estimation of Teak in Kanya Forest plantation for its best performance.

This study was conducted in order to estimate growth and volume production of Teak (Tectona grandis) in Kanya Forest Plantation, Nigeria. The plantation was divided in to six strata-based age classes (A=38, B=37, C=36, D=35, E=34, F=28, years). Five plots were randomly selected from each stratum. Trees within each plot were enumerated and measured. Variables measured include total height, diameter at the base, middle, top, and diameter at the breast height were taken from 30 temporary sampled plots of 25x25 m approximately from the center, 180 dominant trees were selected from 712 trees. Descriptive statistic was used to summarize the results while inferential statistic (correlation) was used to establish relationship growth and yield variables. Basal area and volume of sampled trees were computed using Excel as well as scatter plots, correlation analysis was achieved using SPSS statistical package version 20. The results of growth and yield values obtained from the dominant trees are (B=249.312 m3/ha, D=196.128 m3/ha, F=134.976 m3/ha, C=119.328 m3/ha, E=100.320 m3/ ha and A=86.976 m3/ha). The results showed that B was (37 years) the best and A (38 years) was the poorest. The results of correlation showed positive relationships with most of the tree growth and yield characteristics but negative relationships exist between age and some parameters that is to say as the age increases those parameters are decreasing.

This research was conducted to investigate mortality using logistic regression (Models) for River red-gum (Eucalyptud camaldulensis Dehnh) in Afaka Forest Reserve, Kaduna, Nigeria. Stratified random sampling and proportional sampling allocation were used in selecting plots and individual trees for measurements. Data on live and dead trees were recorded, variables measured are diameter, total tree heights, spacing and age of the stands within the plots. Diameter at the breast height (DBH) was measured using diameter tape while Haga Altimeter was used in taking the total height of the sampled stands. The Data collected were divided into four portions. Three portions (75%) for model calibration adopting logistic regression model, 25% were used for model validation of logistic model generated. Chi square test of goodness-of-fit, Negelkerke R 2 , Cox and snell R 2 Abubakar et al.; JSRR, 25(1): 1-9, 2019; Article no.JSRR.51395 2 values were used for model evaluation. The positive regression coefficients (16.737, 49.266 and 1.992) showed by Dbh, Height and age (as independent variables) indicated positive future mortality effects on the stands; as the trees ages and increases in size and height, the chances of mortality will increase. At the present age and sizes of the stands the fitted model shows no significant relationship between the current age, height and size of the stands, as such the notion held by the management of the plantation that Eucalyptus cannot grow for many years and in large sizes is not true. There is therefore, need for periodic re-measurement of the stands to evaluate future effect of the variables (Age, Dbh and height) on mortality. Original Research Article

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