Seedling survival and growth of native tree species in pastures: implications for dry tropical forest rehabilitation in Central Panama.
Griscom, Heather*,1, Ashton, P. Mark1, Berlyn, Graeme1, 1 Yale School of Forestry and Environmental Studies, New Haven, CT, USA
ABSTRACT- Our study tested the effects of herbicide application and cattle removal on the survival and growth of three central native tree species planted in pastures within the deforested, dry tropical forest region of Panama. We investigated whether enrichment planting may be a potential, complementing reforestation tool with natural regeneration. Three economically valuable tree species were chosen for the study; Cedrela odorata L., Enterolobium cyclocarpum(Jacq.)Griseb, and Copaifera aromatica Dwyer. Planted seedlings were monitored for survival, root collar diameter and height growth in four treatments within an active pasture. Environmental treatments were the following: (i) herbicide application and no cattle; (ii) herbicide application and cattle; (iii) no herbicide application and no cattle; (iv) no herbicide application and cattle. After 16 months, subsamples of seedlings within each treatment were harvested and measured for dry masses and leaf areas. Of the three species, C. odorata had the lowest mortality rates (58%), the greatest average diameter (DGR) and height growth rates (HGR) at 28 months (DGR = 3.42 cm y-1; HGR = 88.08 cm y-1), and the greatest average dry mass values and leaf areas after 16 months when seedlings were destructively sampled (dry mass = 906 g, leaf area = 3.16 m2). Cedrela odorata and E. cyclocarpum had significantly greater growth rates, biomass, and leaf area in the herbicide application and no cattle treatment (p<.05). The combination of these two management applications can increase the success of shade-tolerant, deciduous species used in enrichment planting within pasture environments in dry tropical regions. However, C. odorata grew significantly better than E. cyclocarpum in the presence of cattle.
Key words: tropical dry forest, Panama, Cedrela odorata, cattle pastures
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