To kill a tree completely, the roots need to be pulled out entirely. Here's an explanation of why pulling out the roots is necessary:

1. Importance of Roots:
The roots of a tree serve various vital functions. They anchor the tree into the ground, provide stability and support, absorb water and nutrients from the soil, and transport these essential resources to the rest of the tree. The roots also store energy reserves in the form of carbohydrates. Therefore, removing the roots is crucial to ensure the tree's death.

2. Cutting the Tree:
Merely hacking or making a simple jab at the tree trunk will not be sufficient to kill it completely. While these actions may damage the trunk and affect the tree's growth temporarily, they do not eliminate the tree's ability to regenerate. Trees have the ability to sprout new shoots from the remaining trunk or branches, allowing them to continue growing.

3. Choking the Tree:
Choking a tree refers to restricting its access to essential resources such as water and sunlight. This can be achieved through methods like girdling, which involves cutting a ring into the bark around the trunk to interrupt the flow of nutrients. However, while girdling may weaken the tree, it may not necessarily kill it entirely. Some trees can survive for a considerable period even after being girdled.

4. Pulling out the Roots:
Removing the roots entirely is the most effective way to kill a tree. The roots play a crucial role in the tree's survival, and without them, the tree cannot absorb water and nutrients or maintain its structural integrity. Pulling out the roots disrupts the tree's ability to obtain essential resources, leading to its eventual death.

Conclusion:
Killing a tree requires more than a simple jab or hacking at the trunk. Choking the tree or cutting the trunk may weaken it temporarily, but it often allows the tree to regenerate. To ensure the tree's complete death, it is necessary to pull out the roots entirely, depriving the tree of its ability to access water, nutrients, and structural support.