SITE INDEX ANALYSIS OF AN AGE SEQUENCE OF GMELINA ARBOREA PLANTATION IN JALINGO, TARABA STATE, NIGERIA

^*Yani J.P; ² Tella, O.I;  ³David D.L and ³Ali, B.D

^*Forestry Section Ardo-Kola Local Government Area, Taraba State-Nigeria

²Department of Forestry and Wildlife Management, Modibbo Adama University of Technology, Yola-Nigeria

³Department of Biological Sciences, Adamawa State University, P.M.B. 25, Mubi-Nigreria

E-mail: lammababs@yahoo.com    

ABSTRACT

Site index is a useful concept in analyzing plantation forestry. Among the numerous environmental factors affecting tree growth, the important relationship between soil and tree growth is most apparent. This is because evaluation of the site from soil characteristics has several advantages. Site index is essential in quantifying sites. A research was conducted to study site index of an age sequence of Gmelina arborea plantation. The parameters evaluated included soil and size characterization of the vegetation that affect tree growth into a unified classification and to quantify site of the plantations. The chemical properties of soils in the plantation revealed that soil pH was slightly acidic to alkaline as the soil depth decreases. There was a significant difference in terms of soil particle size distribution in the plantation at (P≥0.05 or P≥0.01). The percentage content of sandy, clay and silt soils was highest in sandy soil (63.13%) while the lowest was recorded in silt (18.31%). Site index equation with good fit from environmental factors selected for site investigation was formal using a multiple regression analysis of four functional forms namely- linear, semi-log, exponential and double-log, respectively. In conclusion, analysis using semi-log regression model seems to yield better in this type of plantation and the soil characteristics were significantly related to growth, although not the same everywhere.

Key word: Site index, age sequence, plantation, Gmelina arborea.