wood chips

In class, I think we were given some contradicting information. In the section about Heat Storage Capacity, Dr. Brown said organic matter has a low Cv, but later in the lecture she said woodchips would have a high Cv. Which one is it?

As per lecture slides (lecture #15 soil thermal properties), slide 19 - water has a high Cv, air has low Cv Thus an organic mulch such as wood chips, which as high porosity (i.e. lots of air) would have a low Cv

Apologies if there was any confusion during class discussion.