Effects of nutrients and sea-level rise on salt marshes of different soil types

The present thesis analyses the effects of the enrichment of the soil with fertilizer and sea level rise (SLR) on salt marsh vegetation. We simulated different conditions of the salt marshes under current and projected sea level rise. These habitats are colonised by various types of plants, we focused on species belonging to the genus Spartina. This plant seems to be particularly sensitive to eutrophication due to human activities, as experiments have documented a loss of habitat associated with altered nutrient conditions. We manipulated experimentally the types of sediment, the concentration of nutrients and sea level rise. We wanted to test whether eutrophication can affect the aboveground/belowground growth of the vegetation, and indirectly the erosion of the sediment, with potentially interacting effects with soil type and SLR in affecting the loss of the habitats and species. The study lasted from July to October. The data were analysed using Permanova. The results showed that the plants were placed in growth spiked sediment different from those raised in the untreated sediment. Furthermore, the sediment underwent a level of erosion differently depending on the growth of plants and the condition they were in the pots, current or future sea levers. These results suggest that the total salt marsh habitat is very sensitive to changes caused by human activities, and that excessive eutrophication, combined with SLR will likely facilitate further loss of salt marsh vegetation.

Impact of irrigation in the Po valley (Italy) on meteorological parameters through numerical simulation

Recent studies found that soil-atmosphere coupling features, through soil moisture, have been crucial to simulate well heat waves amplitude, duration and intensity. Moreover, it was found that soil moisture depletion both in Winter and Spring anticipates strong heat waves during the Summer. Irrigation in geophysical studies can be intended as an anthropogenic forcing to the soil-moisture, besides changes in land proprieties. In this study, the irrigation was add to a LAM hydrostatic model (BOLAM) and coupled with the soil. The response of the model to irrigation perturbation is analyzed during a dry Summer season. To identify a dry Summer, with overall positive temperature anomalies, an extensive climatological characterization of 2015 was done. The method included a statistical validation on the reference period distribution used to calculate the anomalies. Drought conditions were observed during Summer 2015 and previous seasons, both on the analyzed region and the Alps. Moreover July was characterized as an extreme event for the referred distribution. The numerical simulation consisted on the summer season of 2015 and two run: a control run (CTR), with the soil coupling and a perturbed run (IPR). The perturbation consists on a mask of land use created from the Cropland FAO dataset, where an irrigation water flux of 3 mm/day was applied from 6 A.M. to 9 A.M. every day. The results show that differences between CTR and IPR has a strong daily cycle. The main modifications are on the air masses proprieties, not on to the dynamics. However, changes in the circulation at the boundaries of the Po Valley are observed, and a diagnostic spatial correlation of variable differences shows that soil moisture perturbation explains well the variation observed in the 2 meters height temperature and in the latent heat fluxes.On the other hand, does not explain the spatial shift up and downslope observed during different periods of the day. Given the results, irrigation process affects the atmospheric proprieties on a larger scale than the irrigation, therefore it is important in daily forecast, particularly during hot and dry periods.

Soil quality in an experimental vineyard treated with biochar and compost

In order to increase fertility of agricultural soils, in the framework of circular economy, the use of soil amendments such as biochar, compost, and mixtures of the two, has been implemented in recent years. Although it has been demonstrated that their use can improve the physico-chemical characteristics of soil and plant yield, few studies investigated the effect of these amendments on the soil fauna, and consequently the biological quality of soils. This study aimed to provide information on soil fauna, in particular microarthropods , in plots of an experimental vineyard treated with different soil amendments (biochar, compost, and CB mix, i.e. a mixture of biochar and compost) compared to untreated plots. What emerged from this study is that taxa abundances are significantly increased in compost-treated soil samples compared to untreated and CB mix ones. The value of the QBS-ar index obtained in soil samples treated with CB mix is lower than in samples treated with compost, biochar, and untreated, although the difference was not statistically significant. The physico-chemical soil characteristics are, in general, significantly more favorable in samples treated with CB mix than in the control, although the soil fauna seems to be partially negatively influenced by the treatment with CB mix. In fact, the number of taxa, in particular the number of taxa most adapted to edaphic life, are significantly negatively affected by the application of the CB mix. Concluding, improved physico-chemical characteristics induced by soil amendments do not always correspond to a positive response of the soil fauna, at least with respect to the QBS-ar approach.