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This study aimed to evaluate the dynamics, population density of tillers and stability index of Urochloa brizantha in silvopastoral systems composed of babassu palm trees in the Pre-Amazon region. Four systems consisting of different densities of palm trees (80, 131, and 160 palms ha-1) and a monocrop were evaluated. The rates at which the basal tillers appeared in systems with 131 and 160 palms ha-1 were similar to each other and were slower compared to the monocrop pasture and the system with 80 palms ha-1. Despite the variations, the stability index was always higher than 1.0, which infers a compensatory mechanism between tiller appearance and mortality rate, since monocrop pastures and systems with 80 palms ha-1 have a higher rate of tissue turnover with high rates of tiller appearance and mortality; in contrast, the system with 160 palms ha-1 presents high tiller survival rates. Both the 160 and 131 palms ha-1 systems indicate impaired canopy renewal, as seen in the low appearance rate of basal tillers due to shading. As such, the tillering dynamics of the systems vary according to the density of palm trees, and the smaller tree densities favor the tiller turnover in the first generations evaluated.

This study evaluated the agronomic, morphogenic and structural characteristics of palisadegrass (Urochloa brizantha) in silvopastoral systems (SSP’s) composed of babassu palms (Attalea speciosa) and grass monoculture in the Pre-Amazon region of the state of Maranhão, Brazil. The study followed a completely randomized design, with the arrangement in split plots with six replicates for the evaluation of agronomic characteristics and 30 repetitions for the morphogenic and structural characteristics. The plots were divided into pasture environments with different palm densities (monoculture, 80, 131, 160 palms.ha-¹), and the subplots were divided into the different seasons (rainy and dry). Total forage production was affected (P < 0.05) by the interaction between palm density and season. The rainy season, compared to the dry season, presented higher total forage production, whereas among silvopastoral systems, the one with 80 palms.ha-¹ presented higher production. The same pattern was found for leaf production. In the rainy season the production of culms increased, as did the ratio leaf.culm-1. Regarding the accumulation of dead material, the only observed difference was a smaller accumulation in the dry season for pastures with 160 palms.ha-¹. In the rainy season, the leaf elongation rate, leaf appearance rate, and final leaf length had higher values in the silvopastoral system with 131 palm.ha-¹, whereas during the dry season, these variables only differed in the monoculture system. Tiller elongation rate and the phyllochron were not affected (P > 0.05) by pastoral system during the rainy season, but in the dry period, higher responses were obtained in SSPs. Overall, SSPs with 80 palms.ha-¹ favored the agronomic characteristics of pastures. Morphogenic and structural characteristics were favored by increasing palm densities. Leaf senescence and duration were not affected by the system.