Despite the lush plant growth, the soils of tropical rainforests are generally nutrient-poor. This is because the high temperatures and abundant rainfall in these regions cause rapid decomposition of organic matter, which releases nutrients into the soil. These nutrients are then quickly taken up by plants, or leached away by the heavy rains. In addition, the dense vegetation in rainforests prevents sunlight from reaching the soil, which inhibits the growth of nutrient-fixing bacteria.