Pressione antropica sulla biodiversità del suolo dovuta a cambiamenti d'uso del suolo e alla gestione

Human activities, especially land use change and habitat degradation, alter global soil biodiversity. It is known that soil biodiversity plays an important role in ecosystem function. However, our knowledge of belowground biodiversity is still limited, at least compared to what is known about aboveground diversity. To enhance our knowledge, the main objective of the thesis is to explore the response to soil biodiversity to human activities. Understanding the extent of anthropogenic pressures on soil biota can provide a perspective for developing appropriate environmental management, restoration, and monitoring. In my thesis, I would like to figure how human activities impact soil biodiversity through controlled experiments and field surveys. I try to see the results in a miniature world. Firstly, I assess how soil organisms respond to atmospheric nitrogen deposition and the application of nitrogen fertilizers: a collation of published surveys of bacteria and arthropods which face urbanization pressures. Then I wanted further access to anthropic pressure and comparison between natural and anthropic ecosystems: with the research group that leader by my supervisor, we set a series of sampling of soil biota in different land uses and management to investigate the influence of human pressure on biodiversity. In Chapter 2.1, soil bacterial diversity and evenness showed a clear trend of time-dependent decline under repeated N application. Ammonium nitrogen enrichment, either directly or in relation to pH decrease, resulted in the main environmental factor related to the shift of taxa proportions within the urban green space soil bacterial community and qualified as a putative important driver of bacterial diversity abatement. In Chapter 2.2, the composition of the soil fauna underwent major changes under nitrogen deposition which were confirmed by the decline of biodiversity indices. A threshold effect appears to exist: low N addition (< 25 kg N ha-1) did not negatively affect soil fauna structure and composition, while in the range from these values up to 50 kg N ha-1. In Chapter 3, I find that the biodiversity indices are higher in the anthropized environment; biodiversity is more due to chance and less to genetic exchanges in anthropized ecosystems, it depends on selection, and it is more phylogenetic in natural environment. In chapter 4, I highlight the human activities impact of soil microbial community structure, but not for diversity. Some changes of microbial, particularly in unique systems may not be noticed at the diversity and richness but mostly at the compositional level. The soil organisms in the anthropic system maybe more dependent on soil nutrients compared to those in natural ecosystems. In addition, soil arthropods were more abundant in the anthropic ecosystem. In conclusion, this thesis provides information on the challenges and opportunities faced by soil biodiversity. These findings can be a scientific reference for the development of policies to ensure biodiversity conservation and long-term soil protection.