It’s hard to think of mulch as a controversial topic but, as with most things these days, we find people on both sides of an issue. And, as with most things these days, some of opinions are based on substance, others are not. In the southern U.S. some environmental groups are advocating a boycott of cypress mulch.
Cypress mulch is derived from baldcypress and pond cypress, which grow in ecologically sensitive wetlands in the Southeast. Cypress wood is highly valued for is natural decay resistance. Florida and Louisiana are the leading states for cypress harvesting for timber and other products. In Louisiana it is unclear if cypress is logged solely for mulch but cypress harvesting for mulch does occur in Florida. According to Dr. Jim Chambers, professor of Forestry at Louisiana State University and Chair of a governor’s science panel on forested wetlands in Louisiana, cypress mulch production is a sensitive issue. “Many of our cypress-tupelo forests are in a severe state of decline. As you can imagine, these forests are very important to south Louisiana for many reasons. Areas permanently flooded, areas that are flooded for substantial parts of the growing season, and areas subjected to salt water input cannot regenerate. The amount of forested areas with these conditions continues to increase as subsidence increases, coastal wetlands are eroded by storms and human impacts on hydrology continue to degrade many sites.”
The inability to regenerate new stands of cypress is an important concern and calls into question the sustainability of cypress harvesting on these sites. Chambers is working with environmental groups and others to develop a process to certify that mulch is produced from sustainable forest harvest operations
Another issue related to cypress mulch is a claim that is circulating in parts of Michigan (and perhaps elsewhere) that cypress mulch is linked to cancer. I conducted a search of the National Library of Medicine and National Institutes of Health literature database (www.pubmed.gov) on ‘cypress’ and ‘cancer’. The only hits I found were related to studies looking at falsecypress (Chamacyparis) extracts for anti-cancer properties, similar to taxol. The claims of cypress mulch and cancer may be an amalgam of the environmental concerns over cypress harvesting discussed above and concerns over use of mulch derived from CCA (chromated copper arsenate) treated wood, which is used for decking and other uses similar to cypress. Research has shown that leachate from mulch containing CCA treated wood can have elevated levels of arsenic and metals above established health standards.
We all know Linda’s fondness for wood chips as mulch. My personal favorite is ground red pine bark for its durability and natural appearance. The key is to look for renewable mulch products that are locally sourced.
Nice post, Bert. The point about avoiding wood chips made from CCA-treated timbers, or from shipping pallets for that matter, is critically important (the pallets often contain pesticide residues). Look for local, natural, recycled materials that would otherwise end up in the landfill. Arborist wood chips (my favorite) and bark left over from timber operations (Bert's favorite) are two good examples.