Despite the importance and increasing knowledge of ecological networks, sampling effort and intrapopulation variation has been widely overlooked. Using continuous daily sampling of ants visiting three plant species in the Brazilian Neotropical savanna, we evaluated for the first time the topological structure over 24 h and species-area relationships (based on the number of extrafloral nectaries available) in individual-based ant-plant networks. We observed that diurnal and nocturnal ant-plant networks exhibited the same pattern of interactions: a nested and non-modular pattern and an average level of network specialization. Despite the high similarity in the ants’ composition between the two collection periods, ant species found in the central core of highly interacting species totally changed between diurnal and nocturnal sampling for all plant species. In other words, this “night-turnover” suggests that the ecological dynamics of these ant-plant interactions can be temporally partitioned (day and night) at a small spatial scale. Thus, it is possible that in some cases processes shaping mutualistic networks formed by protective ants and plants may be underestimated by diurnal sampling alone. Moreover, we did not observe any effect of the number of extrafloral nectaries on ant richness and their foraging on such plants in any of the studied ant-plant networks. We hypothesize that competitively superior ants could monopolize individual plants and allow the coexistence of only a few other ant species, however, other alternative hypotheses are also discussed. Thus, sampling period and species-area relationship produces basic information that increases our confidence in how individual-based ant-plant networks are structured, and the need to consider nocturnal records in ant-plant network sampling design so as to decrease inappropriate inferences.

Amaranth is a broad leaf pseudocereal native to South and Central America and can be used as a source of high protein grain, as a leafy vegetable and has the potential to grow as fodder. The objective of this work was to evaluate some characteristics of amaranth agronomic interest (Amaranthus spp), as the best way of propagation of the crop, whether by planting of seedlings or direct seeding, and also to determine the most suitable depth of sowing of amaranth. Three treatments were established to conduct the first experiment, seedling versus no-tillage using the BRS-Alegria variety: the first (T1) was the planting of seedlings with 15 days old, previously produced in a greenhouse, on the day of establishment of the experiment in the beds; the second (T2) was the direct sowing in the soil on the day of establishment of the experiment in the beds; and the third (T3) was the transplanting of surplus seedlings from the first treatment, after two weeks of establishment of the experiment in the beds. The T1 treatment was the one that presented the best performance in the attributes of lap diameter and dry mass of plants, being not different, only, at plant height, in relation to T2 treatment. The treatments T2 and T3 presented the same performance for all attributes studied. The second experiment was carried out with the objective of evaluating the best sowing depth for the Amaranthus varieties: BRS-Alegria, Diócus, Princes, Verde (Amaranthus cruentus) and Inca (Amaranthus caudatus), under zero millimeters soil), five millimeters, and ten millimeters deep. The BRS - Alegria, Verde and Diócus varieties showed the best results when tested at 0, 5 and 10mm depth, with the average of plants emerged at 15 days after sowing, of 71.4; 65.9 and 61.0 respectively. The worst results were found in the Princes and Inca varieties, with average values of emerged plants of 51.3 and 47.2, respectively. As for the seeding depths, the best were 10 and 5 mm, with plants emerged after 15 days, of 86.9 and 77.9, respectively. The worst result was for the 0mm depth with an average of 13.3 emerged plants.