Excuse the rushed response, but Im in a hurry. A few things to consider:
1) why do you need to standarsdise these? Biologicaly, the interaction between forest type and temperture would be more useful, which can be used using a one way ancova with temp as your covariate.
2) If you HAVE to account for the difference in forest type, then I would suggest looking at the relative change in abundance at different temps. between forest types.