Biological Nitrogen Fixation (BNF) is a process where atmospheric dinitrogen (N2) is reduced to ammonium by the action of exclusively prokaryotic organisms. This process is of enormous biological importance as it is the main natural input of combined nitrogen into ecosystems. Among diazotrophic prokaryotes, rhizobia are a group of bacteria that fix nitrogen only in symbiosis with plants of the Leguminosae family. The purpose of this study is to investigate the symbiosis between rhizobia and the Teide broom (Spartocytisus supranubius), an endemic legume that is currently threatened and therefore protected due to the progressive decline of its populations. It is common to find specimens showing signs of loss of vitality, varying degrees of damage, decrepitude, a large amount of dead crown, and dried-out individuals. A large part of this situation is attributed to the impact of rabbits (Oryctolagus cuniculus). As the dominant legume in the Las Cañadas del Teide ecosystem, its decline could have negative consequences for nitrogen input into the ecosystem. This project proposes promoting biological nitrogen fixation (BNF) between rhizobia and Teide broom as a strategy for improving and restoring the current state of the Teide National Park ecosystem. To this end, the importance of BNF derived from the symbiosis of rhizobia with broom in the Park's soils will be studied, for which we propose several objectives. We will determine the contribution of the presence, decrease, or absence of nitrogen-fixing legumes to soil nitrogen content; we will estimate the size of the symbiotic rhizobia populations, their diversity, and the distribution of species or genotypes in the Park's soils; and we will assess the nitrogen-fixing efficiency of the strains. The study will examine the effect of organic nitrogen input from rabbit latrines on rhizobia populations (both quantitatively and qualitatively) and nitrogen fixation rates. It will also evaluate the effect of replanting with plants previously inoculated with efficient nitrogen-fixing rhizobia on adaptation and establishment during the first year in the field. Based on the results, a decision will be made regarding whether other actions, such as the use of rhizobia inoculants, should be added to the recovery protocols for broom populations in Teide National Park.