Fire frequency and other disturbance regimes are expected to change. C Effects of CO 2 on arthropod herbivores. Let's first review what can and cannot be gained from global change studies. There are two basic kinds of scientific research, experimental and empirical or observational. Then we can say most of the changes we observe are due to our experimental treatment because nothing else is different between them.
Empirical research relies basically on correlation and natural history.
When deciding what conclusions to draw from research results we must first think about the experimental population. In a CO 2 controlled growth chamber experiment with potted plants our population is limited to those plants, in those chambers, over the period of time the experiment is conducted. We have now accumulated a relatively large base of ecological research on elevated atmospheric CO 2 effects, which has produced often conflicting conclusions. There is some possibility of synthesis based on mechanistic interpretation within a hierarchical level. Across ecosystems, leaf-level data show the most consistency in qualitative patterns of response to elevated CO 2 .