Riqueza y abundancia de artrópodos según estructura del tapiz en mejoramientos de campo natural

Changes in land use caused by agricultural activities are the main drivers of biodiversity loss in ecosystems. The natural field biome is the most important biome in Uruguay (64.3%), subject to these changes. In the 21st century, the transformations of this biome have accelerated. To evaluate the impact of natural field improvements on biodiversity, the richness of Cicadellidae, Delphacidae and Araneae and the abundance of arthropods were analyzed in the long term (9 years) in plots with: native field, 60 kg N/ha/year, 120 kg N/ha/year and field with Trifolium pratense and Lotus tenuis. The experiment was conducted in paddock number 18, located in EEMAC, Paysandú. In the experiment, 96 samples were taken with entomological nets (12 raids per sampling point) and 96 samples with aspirates, each technique occupied one square meter of surface. The data were analyzed using mixed models and Tukey's test (p-value ˂0.05) to compare the frequency of taxa in each treatment, the variable of analysis was the abundance of the different groups of arthropods, the abundance of Cicadellidae and Delphacidae was analyzed only in collections made with net. Both families were fitted in a simple regression model as a function of the independent variable forage height. Diversity indices: Specific richness, Shannon-Wiener and Simpson were estimated to compare the richness of Morphospecies of Cicadellidae, Delphacidae and Araneae captured with nets in each treatment. In the natural field the average Cicadellidae was significantly higher, while Delphacidae was statistically higher in plots with 60 and 120 kg N/ha. The abundance of spiders did not differ between treatments with netting, but was statistically higher in the 60 kg N/ha treatment than in the legume treatment with the aspiration technique. The average of Hemiptera, Halticus pygmaeus and Nysius simulans was significantly higher in plots planted with legumes with both collection methods. Cicadelids and Delphacidae varied as a function of the interaction between height and days post grazing. Delphacidae adjusted their distribution according to forage height, Cicadelidae showed association only in block 2. Significant regression was found between the predator Nabis capsiformis and the phytophagous Cicadellidae and Morphospecies 1 (Miridae), significant regression was also observed between Araneae and Cicadellidae. The richness of the taxa analyzed did not differ between treatments.