Inoculation with rhizospheric microorganisms in tropical dry forests restoration increased microbial diversity but had no effect on seedling growth

Abstract

The diversity of soil microbial organisms is rarely considered in restoration scenarios, even though this diversity is an important component of the ecological complexity that we aim to understand. Plant growth promoting microorganisms can positively affect plants by providing nutrients regularly, producing phytohormones to stimulate root growth and development, and modifying the rhizosphere environment. The present study evaluated, over a 5‐month period, the effects of inoculation of Inga densiflora nurse seedlings with rhizospheric microorganisms taken from a neighbor forest habitat, in the context of an early‐stage ecological restoration project in a Tropical Dry Forest area invaded by Guinea grass (Panicum maximum). The inoculation's effect on two response variables was evaluated: (1) growth of the seedling (I. densiflora), and (2) the diversity of bacteria and fungi, with an emphasis on genera associated with rhizosphere that promote vegetation growth. Bacterial and fungal diversity were evaluated using the metabarcoding method and Hill numbers q = 0, 1, and 2. Significantly higher microorganism diversity was found in the rhizosphere of inoculated seedlings compared to non‐inoculated seedlings. However, no significant differences were found in the growth of inoculated versus non‐inoculated seedlings. This evidence suggests that, in the short term and through a restoration context, inoculating trees with microorganisms taken directly from a neighboring forest can increase bacterial diversity, and possibly also fungal diversity. While understanding the intricacies of these processes requires further study, this technique seems to be a promising approach for recovering the diversity of rhizosphere microbiomes during ecological restoration.