In the western Amazon Basin, recent intensification of river-level cycles has increased flooding during the wet seasons and decreased precipitation during the dry season. Greater than normal floods occurred in 2009 and in all years from 2011 to 2015 during high-water seasons, and a drought occurred

Hoarding food is an important strategy of rodents in desert environments characterized by unpredictable and poor food resource availability. In the Monte Desert, Prosopis produces abundant food, unevenly in time and space, in the form of pods and seeds. Sigmodontine rodents (Graomys griseoflavus,Akodon molinae, Eligmodontia typus and Calomys musculinus) use Prosopis propagules extensively, and they could be predators or dispersers depending on how they handle and where they leave the propagules. The objectives of this study were: (1) to know what rodent species transported propagules; (2) to evaluate what hoarding pattern was used by species that transport propagules (larder and scatterhoarding); and (3) to analyse in which condition were propagules left by the rodent species, both at the food source and in caches. Our results showed that all four species transported propagules, with G. griseoflavus and E. typus being the species that carried more seeds. Our study supported the evidence that food caching is common among species and that many species both larderhoard and scatterhoard food. Graomys griseoflavus and A. molinae, the largest species, larderhoarded more than did the smaller E. typus. These results uphold the hypothesis that larger species will show greater propensity to larderhoard than smaller species. Considering the interaction between seed-hoarding patterns and plants, E. typus was the species that could most improve germination because it scatterhoarded propagules and left seeds out of pods. In contrast, G. griseoflavus could have a negative impact on plant populations because this was the species that predated more seeds and larderhoarded a high percentage of them. The smallest C. musculinus was the species that transported propagules least, and left them as seeds inside pods or pod segments mainly at the food source, which makes seeds more vulnerable to predation.

Relationships between Prosopis flexuosa (Fabaceae) ABSTRACTThe fate of Prosopis flexuosa seeds dispersed by cattle is dependant on the spatial pattern of dung deposition and foraging movements. We hypothesised that cattle-use site classes explain the response variables related to seed input and fate of seeds, seedlings and saplings (small plants more than one year old). We defined sites with heavy cattle traffic ("trails" and "periphery of trails"), sites used for resting and foraging ("under Prosopis"), and sites where isolated individuals only walk ("under shrubs" and "bare soil"). Considering the established cattle-use site classes, our specific goals were to quantify and compare: (1) seeds transported in cattle dung; (2) seedlings 10 months after dung deposition; (3) established saplings; and (4) germinated and remaining seeds, and seedling survival in dung immediately after dung deposition. In a grazed field at Ñacuñán (Mendoza, Argentina) we worked in four similar areas, each consisting of 25-ha plots 2 km apart. Space use by cattle caused differential seed input: "under Prosopis" and in the "periphery of trails" animals deposited the largest amounts of dung and seeds. Ten months after dung deposition, the highest number of seedlings occurred on "trails", "under Prosopis" and in the "periphery of trails". In the long term, the highest number of established saplings occurred only in the "periphery of trails". The number of seeds germinated immediately after fruit production and dung deposition was very low. Survival of seedlings sprouting from dung-germinated seeds did not exceed one week. On "trails" and in the "periphery of trails" the persistence of seeds in dung was low because of dung disintegration by the action of cattle trampling. The seeds that did not remain in dung were probably the source of seeds that will germinate in the next wet season (i.e. 10 months after dung deposition). With different effects depending on cattle site activity and on the stage of the P. flexuosa plant (seed, seedling, or sapling), defecation and trampling appear to be important processes in the seed dispersal cycle. In this sense, cattle could benefit the establishment of P. flexuosa.

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