TSS was introduced in Nigeria and Ghana in the 1940s. In contrast to the MUS, the forests under management did not have enough regeneration potential, and therefore canopy openings were done several years prior to harvesting in order to promote adequate regeneration. Canopy opening by felling or poison-girdling selected trees was prescribed over a 5-year pre-harvest period. In practice, every tree not considered to have economic value was killed, resulting in severe canopy openings (65-80% of total basal area). This drastically increased light levels, leading to growth of vines and other light-demanding weeds instead of the desired regeneration of hardwood species. The system as practiced was not very effective. TSS could potentially work only in forests where light-demanding species are the desirable species and where climbers and weeds are not a big problem. In addition, the TSS is often too expensive for low-yielding forests (Dawkins and Philip 1998). The TSS was gradually abandoned in Ghana and Nigeria in the late 1970s and polycyclic methods were adopted. Variations of the TSS are sometimes utilized in tropical forests, generally as an initial treatment preceding other management operations.
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