True or False: Excess or insufficient water is a likely cause of tree decline within the first year after installation.

The statement is true because both excess and insufficient water can significantly impact a tree's health, particularly within the first year after planting. During this critical establishment phase, trees are developing their root systems and adapting to their new environment.

If a tree receives too much water, it can lead to waterlogged soil, which reduces oxygen availability to the roots. This condition can cause root rot and introduce various pathogens that hinder tree growth and overall health, leading to decline. On the other hand, insufficient water can cause stress as trees struggle to take up adequate moisture, resulting in wilting, reduced leaf area, and ultimately, decline.

Thus, the establishment period is crucial, and managing water levels is vital to ensure that newly planted trees thrive rather than face decline due to water-related issues.