The quality of endozoochorous depositions: Effect of dung on seed germination and seedling growth of Neltuma flexuosa (DC.) C.E. Hughes & G.P. Lewis

Abstract

The qualitative component of the effectiveness of seed dispersal by endozoochory encompasses seed deposition. Neltuma flexuosa, a keystone tree of the Monte biome, is dispersed by several animals and in this paper we aimed to study the qualitative aspect of its dispersal. We studied the effect of the dung of Bos taurus (cow), Equus ferus caballus (horse) and Dolichotis patagonum (mara) on seed germination and growth of N. flexuosa seedlings. We conducted greenhouse experiments using dung or field soil as substrate, under two water regimes: pot capacity and pulsed irrigation; testing manually scarified seeds collected from trees. We observed that the effect of dung on the two key processes of plant regeneration was different and depended on the animal species: it either reduced or did not affect maximum germination, and promoted or did not affect seedling growth, compared to the soil. Horse and mara manure reduced germination, while manure from both domestic animals promoted seedling growth. The water storage capacity, drying rate and nutrient level of the substrates did not directly explain the results obtained. Overall, cow dung appeared as the best microsite for early regeneration of N. flexuosa, while mara manure was the most restrictive for this process.