ISA Certified Arborist Practice Exam

Which of the following factors influence tree growth?

1. Wind and rainfall

2. Light, water, nutrients, temperature, and soil conditions

3. Fertilizers and pesticides

4. Location and season

The correct answer is: Light, water, nutrients, temperature, and soil conditions

The growth of trees is significantly influenced by several key environmental factors that encompass the essentials for photosynthesis and overall metabolic processes. Light is crucial for photosynthesis, which is the process by which trees convert sunlight into energy. Water is another vital factor as it helps transport nutrients within the tree and is essential for photosynthesis itself. Nutrients provide the necessary building blocks for growth and development, while temperature can affect enzymatic processes and metabolic rates. Lastly, soil conditions, including pH and texture, can influence how well a tree can access water and nutrients. While wind and rainfall also impact trees, they do not encompass the full range of essential factors influencing growth. Fertilizers and pesticides are management practices that can enhance or protect growth but are not intrinsic factors influencing natural tree growth. Location and season can affect the overall environment of trees, but the specific daily and seasonal conditions that most directly impact the physiological aspects of tree growth are best captured by light, water, nutrients, temperature, and soil conditions. Therefore, the comprehensive nature of the second option makes it the correct choice when considering factors influencing tree growth.