Using the term "evergreen" to refer to all conifers can be somewhat misleading. Not all evergreens are conifers, just as not all conifers are evergreen. Bald Cypress (Taxodium distichum) is a good example of a deciduous conifer, but you would never refer to as a deciduous evergreen!
The term "evergreen" can also be somewhat misleading when applied to pines (Pinus). Pine needles don't live forever, however what makes them effectively "evergreen" is that their needles persist for more than one year, never completely defoliating the tree. Many are noticing eastern white pines (P. strobus) in the St Louis metro area dropping a "significant" number of needles this fall, but is this cause for alarm? In "most" cases, this is a normal annual occurrence for white pines. Whereas most pines will overwinter with 2-3 years of needles, white pines lose all but the current year's needles in the early fall. This means white pines defoliate more than other pines annually, making their fall needle drop that much more noticable. In addition, some years will appear worse than others because any factor that causes additional stress on the tree will intensify the fall needle drop. Normal needle drop occurs only on the inner needles; if entire branches or needles at the tip of branches are dying then something else is stressing the tree like disease, mites or aphids.
If you have extra pine straw mulch, don't let it go to waste. Since a pine needle is actually a modified leaf, pine straw mulch benefits the landscape in much the same way as other decomposing leaves by recycling nutrients and maintaining soil organic matter without increasing the pH like hardwood bark mulch. And because pine straw knits together and hold in place better than bark mulches during heavy rain, it also helps in preventing soil erosion and is very resistant to compaction.
I love scientific terminology, and my newest marcescent (mar·ces·cent). This refers to deciduous trees that retain their dead leaves. This distinguishing feature seems to be very prominent in oaks (Quercus), beeches (Fagus) witch hazels (Hamamelis) and hornbeams (Carpinus). Marcescent leaves usually do not break off until mechanical forces like wind cause the dry and brittle petioles to snap, or when growth begins next spring. The expanding buds push the marcescent leaves off to cover the branches with new greenery.
I recently added the last "dregs" of my straw bale herb garden to the compost pile. Most of the bales had completely broken down, leaving behind a very rich looking black compost. One of the things I learned from this project is the unlikelihood of bales lasting more than one year. Many of the references available on straw bale gardening suggest they could be reused a second year…that just doesn't seem to be the case for gardeners in the St Louis Metro East. Which is not surprising given our high summer temperatures, humidity and rainfall…it all just speeds of the process of decomposition.