There are pros and cons of each material. By the way, do you mean pine bark chips or the shredded wood that is a by-product of tree companies? (I've never heard of 'shredded' pine bark, is why I ask.)

Anyway, there is no question that the wood product lasts much longer....pine bark can last for years without breaking down. Shredded wood decomposes faster than the bark, but will return more elements to the soil as it does so.

Many of the tree companies are now using a different kind of chipper that creates very attractive little chips rather than that shredded stuff. Very nice looking. A real plus about the mixed wood chips is that they can often be had for free, as tree companies are very happy to find a place to donate their chips to, rather than pay to have them accepted into a landfill. This is my preferred mulching material, by far.

Pine straw deteriorates quite rapidly in hot sun, first losing its color before it turns into dust. Pine straw needs to be obtained when it is fresh or the life span will be shortened even more. Pine straw adds organic compunds to the soil as it degrades, as do all of these materials, but they may be of limited value to the growing plants. Pine straw may need to be refreshed twice a year, which is a pain in the pocket book.

Pine BARK lasts longest of all, since it is composed of lignins that even microorganisms can't break down. It maintains its color and consistency for a long time.

My personal preferrance, after many years as a professional and now as a (fussy) homeower is the mixed wood chips from tree companies. One good application can last for up to three years before needing a top dressing, in my experience. Probably less in your climate.

All three are great at buffering the soil from excessive heat, moisture loss, freezing temperatures, etc.

I checked a bag of the mulch which I got at Lowe's and it says "Shredded Pine Mulch." I just assumed it was shredded bark because the color and texture appeared to be bark.

Pine straw is better for inclines, since it tends to stay in place better, but it is acidic and will lower the soil ph a bit over time as it breaks down.

Fresh wood chips are fine as a mulch, but should not be mixed into the soil since they will require nitrogen as they break down, which is 'robbed' from the soil.This can be offset by the application of more nitrogen. Alfalfa pellets work well.

Cheers

My objection to bark is that it gets so hot. I go barefoot and bark mulch in sunshine is hot, even on my tough feet. That indicates to me the soil under it will be warmer and will dry faster. Plus, I like the benefit of the pine straw as it breaks down and becomes black soil.