Differential Seedling Establishment of Woody Plants along a Tree Density Gradient in Neotropical Savannas

Background

This study examined the recruitment and survival of an initial seedling assemblage and three cohorts of recruits of woody plants located along a tree density gradient in the savannas of central Brazil. It considers the problem low levels of woody regeneration in savannah landscape, addressing two main issues, shortage of seeds and difficulties to saplings to survive. The study focuses on trying to understand how differences in canopy (by its effect on the availability of soil moisture and herbaceous cover density) affect germination and survival of the saplings, and test the behavior of different cohorts of regeneration under 3 levels of canopy density.

Conclusions & Takeaways

The paper finds that increased seedling survival occurs under a closed canopy which is related to a less decreased stress on saplings from irradiating conditions (and drying) and possibly less competition for resources than in pasture because less density of pasture grasses could improve the availability of water. In the case of tree recruitment the differences between open and closed savannas are attributed to the low availability of seeds and high mortality in open savannas. Also the leaf litter, which is more abundant in closed savannas, plays a role in the release of nutrients that favor the regeneration. Finally, the paper concludes by stressing the importance of preserving sites of closed canopy as a conservation strategy in the savannas and highlights the potential use of this information in the process of restoration.