During secondary succession, which of these best describes why decomposing pioneer plants give way to larger, more complex plant species, such as hardwood trees? Increased amounts of sunlight are able to reach the ground while the pioneer species are decomposing. Increased soil temperatures from decomposing pioneer species help tree seeds germinate more quickly. Increased amounts of decomposing pioneer species remove nutrients that tree seedlings need to grow and mature. Increased amounts of soil from decomposing pioneer species allow plants with more extensive root systems to become established.