**3. Conclusions**

In the eastern Monte ecoregion of Rio Negro province, in accordance with the results found by different researchers in other arid and semiarid regions of the world, the presence of moss biocrusts shows important functions related to the sustainability of the system, and this underlines the need to preserve them and even increase their coverage, in a way to contribute to the maintenance of ecosystem functions and mitigate the risks of climate change.

We have seen that disturbances of different scales, from livestock trampling to the removal of the shrub layer that may occur due to the action of man or the occurrence of wildfires, can affect moss biocrust cover. In the latter case, the damage will depend on the intensity of the fire. The use of an effective way to achieve moss biocrusts for ecosystems restoration should probably be studied further.

Regarding the use of water, this kind of crusts would improve infiltration, and therefore, the availability of water for the seedlings that may emerge there, in addition to the benefit that humidity provides to biocrusts themselves by allowing them to rapidly photosynthesize at the slightest wetting. The soils of our region are mostly clayey, with heavy textures, which favors their water retention capacity (in fact, the producers of the region refer to them as "bearing" soils), and this can be increased by the greater infiltration and less evaporation provided by the moss biocrusts.

On the other hand, the precipitation regime in our system is mainly autumn-winterspring, which is different from other arid or semiarid ecosystems worldwide in which the main precipitation takes place in summer as torrential ones. The more extended period and the lesser rainfall intensity can contribute to water retention by these biocrusts, and this, added to the predominant soil's types mentioned, was reflected in the prolongation of the benefit that they contributed in terms of the lower evaporation that we found in pots with moss biocrust already extracted. These characteristics are also important when considering the reduction of water erosion risks in the system.

The greater humidity that moss biocrusts can conserve would also influence their possibilities of retaining seeds, and offering a favorable first environment for the emergence of seedlings and their initial growth. Perhaps, this humidity is the factor which reduces the risk of the seeds being blown away by the action of strong winds. Although we found beneficial results regarding seed retention, perhaps the benefit depends on the size and shape of the seeds that can fall within the biocrusts, and it would be necessary to determine if, at some point, the facilitation provided by moss biocrusts could be transformed into competition.

Apart from the researches previously mentioned that need to be deepened, our "black holes," in terms of regional information, are related to the contribution of moss biocrusts to nitrogen fixation and carbon sequestration, which should constitute future lines of research.

But there is no doubt that moss biocrusts should be taken into account when considering management practices for these systems, and the idea that their presence is a symptom of the "health" of these grasslands should be incorporated by both the researchers and producers.
