Trees acts for their little thermal mass and large surface exposed to air, essentially IR radiation from the Sun can't much reach the ground or humans under tre

Trees acts for their little thermal mass and large surface exposed to air, essentially IR radiation from the Sun can't much reach the ground or humans under trees (if they are large and dense enough) and the part of the radiation touching trees get quickly dispersed in the air (climbing the atmosphere). The limited effect is that cities are dense and can't be made as forest so trees can't do nothing for buildings taller them them.