Final answer:
The most critical nutrients for forest growth are the macronutrients Nitrogen, Phosphorus, and Potassium, along with Calcium, Magnesium, Sulfur, and necessary micronutrients. In the tropics, Phosphorus is often the most limiting nutrient due to leaching caused by heavy rainfall.
Step-by-step explanation:
The most important mineral nutrients needed to support forest growth include three primary macronutrients: Nitrogen (N), Phosphorus (P), and Potassium (K), which are crucial for leaf growth, development of roots, flowers, seeds, and fruit, as well as for strong stem growth and water movement in plants. Three secondary macronutrients are also vital: Calcium (Ca), Magnesium (Mg), and Sulfur (S), with calcium being important for regulating nutrient transport and enzyme functions, and magnesium being integral to the photosynthetic process. Micronutrients such as Copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Zinc (Zn), and Boron (B) are essential but needed in smaller quantities. In the tropics, the most limiting nutrient is generally Phosphorus due to the high amount of rainfall that can leach nutrients away, leaving the soil nutrient-poor. This concept follows the 'Law of the Minimum', which explains that growth is limited by the scarcest nutrient relative to its needs. Hence, despite the presence of other nutrients, the absence or deficiency of Phosphorus can severely limit forest growth in tropical regions.