Analysis of the "Shelter Tree-Effect” of Natural and Exotic Forest Canopies on the Growth of Young Podocarpus falcatus Trees in Southern Ethiopia

background

The potential for plantations of fast-growing non-native trees to create suitable habitat for regeneration of native plant ecosystems has gained attention in the scientific literature. Previous studies often focus on the plantation species’ impacts on soil, but this study in the Munessa-Shashemene forest of Ethiopia proposes that light factors may be important as well. In this forest, native Podocarpus falcatus saplings actually perform better under the canopy of planted non-native Pinus patula and Eucalyptus saligna trees than in native forest, and this study hypothesizes that varying patterns of irradiance and sunflecks may explain this phenomenon. 

research goals & methods

To study the impacts of the different light conditions created by the non-native tree overstory on growth of the native tree understory, photosynthetic photon flux density (PAR) was measured. The study then connected the PAR patterns of the different overstories to photosynthetic carbon dioxide uptake by the native P. falcatus saplings.

conclusions & takeaways

The study found that the P. patula overstory created the most favorable conditions for the growth of P. falcatus saplings compared to E. saligna and the native tree overstory. The study found that the greatest impact of the P. patula trees was on the light climate for the P. falcatus saplings, and therefore this may be the primary explanation for the why the P. patula trees served as the most effective nursery species for P. falcatus.