Quite a few battles took place in heavily wooded areas, so suspect there are a number of examples of cav and infantry fighting in woods.
For instance Marbot wrote about the Battle of Hannau:
"At daybreak on October 30 the battle began. It was like a great hunting expedition. A few rounds of grape, the fire of the infantry skirmishers, and a charge in loose order by Sébastiani's cavalry dispersed the enemy's first line, awkwardly posted on the edge of the wood. But when we had advanced a little further, our squadrons could only act in the few clearings, and the light infantry pursued the Bavarians singly, driving them from tree to tree till they got out of the wood."
And later he says:
"The Emperor ordered the cavalry to make a general charge at a very difficult moment. Now, in such a case, it is not enough for a commanding officer, and especially when he is engaged in a forest, to send his regiment straight forward, as I have seen many do; he must cast a rapid glance over the ground to which his squadrons are coming, so that he may not lead them into swampy places. I marched, therefore, some paces in front, followed by my regimental staff, and having beside me a trumpeter who signalled, as I bade, the obstacles which the various squadrons would find in front of them. Although the trees stood wide apart, the passage through the forest was difficult for cavalry, because the ground was piled with men and horses killed or wounded, weapons, guns, and wagons which the Bavarians had left."
Source: http://napoleonic-literature.com/Book_3/V2C41.html
But I am sure there will be counter-examples of charges in forests making short work of infantry.
My own gut feeling is a forest is not an ideal place for cavalry, but nor for formed infantry. In particular, it must be a major challenge for command and control.
Cam