The evaluation of interactions between the tree component and the crops allows the design of ecologically efficient agroforestry systems allowing economic sustainability. In this research, the phenological behavior of the Lactuca sativa lettuce under three levels of shade caused by different forest canopy structures and free exposure under conditions of the high Andean tropics was evaluated (2550 m.s.n.m). Canopies were classified into dense, gloomy heterogeneous (T1), heterogeneous gloomy intermediate density (T2), shady low linear plantation (T3), and full exposure (T4). At each level, the shadow accumulated with the ShadeMotion software, the carbon in the aerial biomass of the tree component, the structural complexity of the canopy, the photosynthetically active radiation RAFA and the main response variables on the crop were evaluated: total dry matter of the leaf and average daily increase in dry matter of the leaf at 19, 38, 57 and 76 days of development. The C in Mg ha-1 in the aerial biomass in the canopy was 2.8 at T1, 3.8 at T2, 81.03 at T3, and 0.0 at T4. The shadow accumulated in hours with overlap in each system varied between 1 and 1214 at T1, 1 and 871 at T2, 1 and 318 at T3 and 0 at T4. The RAFA (umol m2 s-1) it was 41 (±0,04) at T1, 84,91(±0,04) at T2, 701,46 (±0,82) at T3 and 1308, 02 (±0,09) at T4. No statistical differences were found in the total dry weight of the leaf at day 76 between the treatments T4 and T3 which accumulated 63.86 gr MS (±2.30) y 36.58 gr MS (± 1.25) respectively, these differed significantly from the treatments T1 with 7.20 gr MS (± 3.81) y T2 11.39 gr MS (± 1.90). The average daily increase in dry matter (gr/MS/día) at T4 (0.84±0.03) it was significantly higher than all the treatments, in T3 it was intermediate (0.48±0.02), but superior to the treatments T2 (0.15±0.03) y T1 (0.09±0.05). Agroforestry systems increase net primary productivity and are financially sustainable, require adequate distancing practices and pruning to reduce the impact of the canopy on the decrease in RAFA and the productive variables of horticultural crops.