What type of data would best help evaluate the effect of the hemlock woolly adelgid on trees?

To evaluate the effect of the hemlock woolly adelgid on trees, understanding the ecosystem's characteristics before the infestation provides vital baseline data. This context allows researchers to compare and contrast conditions before and after the adelgid's arrival, thereby assessing changes attributable to the pest.

For instance, knowing the health, diversity, and species composition of the tree population prior to infestation helps in determining how the adelgid affects these factors over time. If the ecosystem characteristics that supported healthy tree growth and biodiversity are altered, it becomes possible to identify specific impacts caused by the adelgid.

While assessing tree growth rates after infestation could indicate the damage done, it lacks the necessary context of pre-infestation conditions to establish a direct correlation. Information about the current adelgid population might reflect immediate pest status but doesn't reveal the long-term effects on the trees. Surveys of local bird populations may showcase secondary ecological impacts but do not provide direct data about the health of the trees affected by the adelgid.

Therefore, having a comprehensive understanding of ecosystem characteristics before the infestation is essential for effectively evaluating the full impact of the hemlock woolly adelgid on trees.