Effects of Megathyrsus maximus invasion and NPK fertilizer addition on the regeneration of native plants in dry seasonal forests

The modification of natural landscapes for agriculture is common in Brazilian semiarid regions. The cultivation of exotic species and the use of chemical fertilization, without prior soil analysis, negatively impact fertility and contribute to the abandonment of these areas. Nutritional imbalance favors invasion and consequently hinders succession processes. In this study, we investigated the impact of nutritional enrichment combined with invasion on native plants. The field experiment was completely randomized, in a 4 × 2 factorial (nutrient x invasion) and 6 replicates. Samples of soil and native leaves were collected and evaluated chemically and biochemically, respectively. The interaction between nutrients and M. maximus invasion did not alter soil chemistry due to leaching, high resource uptake, and soil activity. The presence of M. maximus increased competition under natural nutritional conditions, affecting the total soluble carbohydrate content in C. prasiifolia and the pigment and proline content in P. varians, as well as the enzymatic activity in response to oxidative stress in P. varians and S. maculata. Abandoned pastures with different soil nutritional conditions may favor the invasion of M. maximus in dry areas, outcompeting native species, compromising their establishment and development.