Measurements of temperature, red, far red wavelength of light and the ratio red to far red were made at every 10 minutes interval at marked points along a 15 m transect using thermometers and a Skye 660/730 Radiation Detector and Measuring unit (SKR100: SKR110) at Umudike, Nigeria. Readings were made during the dry and wet seasons under the forest floor of a secondary forest regrowth, under the crowns of Treculia africana, Dacryodes edulis, Irvingia gabonensis and in a 1 –year old abandonded farmland. Readings were taken at a height of 50cm above the ground. Plant species within 2.5 X 2.5m2 quadrats were enumerated every two months. Data revealed that there were variations within and between the red and far red wavelength at the studied sites. The ranges of the far red during the dry season were from -0.30 to 18.77; -0.42 to 10.18; -0.40 to 7.70; -0.60 to 1.36 and -0.39 to 0.31 in abandoned farmland, under the crowns of Treculia africana, Dacryodes edulis, Irvingia gabonensis and a secondary forest regrowth, respectively. The ranges during the wet season were – 0.88 – 16.79; - 0.86 – 5.54; - 0.86 – 4.26; - 0.70 – 3.38 ; - 0.83 – 0.12. The ranges of far red followed the same pattern. The ratio red to far red ranged between 1.7 and 1.8; 1.35 and 2.1; 1.4 and 1.8; 1.32 and 3.08 and 1.14 and 2.26. Simultaneous colonization of pioneers and climax tree species was not observed at the studied sites because of the poor dispersal appendages of most climax and pioneer tree species seeds within the studied areas. Grasses such as Alternathera sessilis were not observed at the secondary forest regrowth because adequate light for their seed germination was not available under the crown of the tree species. The grasses were abundant under the crowns of the plantation tree species especially Irvingia gabonensis. It was recommended that seeds of desirable tree species such as Khaya ivorensis and Entandrophragma cylindricum be germinated at the university nursery and the seedlings sold to farmers at cost lower than the cost of production.