Producción CientíficaThe driest part of the Argentinean pampas is occupied by semiarid woodlands dominates by Prosopis caldenia Burkart (Calden). Calden pods are a highly valuable fodder supplement for livestock but its production is highly variable. Our objective was to analyze and model the temporal pattern in inter-annual variability of Calden pod production. Our key hypothesis is that weather conditions are the main determinant of the pod masting behavior. Tree size and climatic variables were evaluated as explanatory covariates using a zero-inflated log-normal modelling approach. The proposed final model structure incorporated 25 parameters, including four variance components, two intercepts for both the logistic and the log-normal parts of the model, and nineteen parameters associated with fixed effects. Climate had a strong influence on the flowering-fruiting Calden process and on the inter-annual variability of the final pod production at the tree level. Temperatures during bud breaking, flowering and fruit shedding, together with the precipitation from the final month of fruit shedding and the total amount of the prior vegetative cycle, were the main weather covariates that affect the processes

Arbuscular mycorrhizal fungi (AMFs, Glomeromycota) are biotrophic mutualistic symbionts of 80% of terrestrial plants. AMFs increase their hosts’ growth through their contribution to water and nutrient absorption from the soil to the plant roots. The different AMF taxa vary in their edaphic and nutritional preferences, the host species ranges and the seasonal changes in sporulation features. The increase in the world human population and the global demand for natural resources have acted as an important driving force for agricultural changes in Argentina in the last 150 years. Particularly, the Prosopis caldenia Burkart forests (or “Caldenales”) have suffered an important reduction in the last 10 years. Here, we studied AMF abundance and diversity in four land uses and their relationship with soil and vegetation characteristics. The land uses selected were native forest (Caldenales), Eragrostis curvula (Schrad.) Nees pasture, Medicago sativa L. cropfield and soybean (Glycine max (L.) Merill) cropfield. AMF spores were extracted from soil by the traditional method and were identified by their morphological features. Cluster analysis divided the land uses into two groups; Kruskal–Wallis tests showed significant differences in AMF abundance and richness between land uses; the AMF abundance and tree richness were negatively correlated, showing less abundance of AMF spores in the plots with the highest richness of tree species. Our results suggest that land use and vegetation richness have a strong influence on the AMF community. Agricultural activities would negatively influence the AMF species diversity but would not negatively affect the spore abundance.