Losing a Louisiana Icon

Along with the American alligator and the crawfish, bald cypress trees (Taxodium distichum) and their swamps are one of the most iconic images of Louisiana. With their quirky “knees”, flared bases, and long lives, it is not surprising these trees have long supported and defined the culture of the state and the region. Fittingly, bald cypress is the state tree of Louisiana. However, within the past 150 years humans have changed the Louisiana landscape in ways that have caused bald cypress trees to die off faster than new ones can grow to replace them. As older trees die and waterways become increasingly developed and controlled, the future of this iconic Louisiana species has become uncertain.

A Louisiana cypress swamp in spring.

Why Are cypress swamps important?

Cypress trees are not only charismatic and aesthetically pleasing, but they provide us with several valuable services. Cypress swamps are powerful filters of water pollution. The nutrient pollution that enters our waterways from agriculture runoff can be removed by cypress swamps if given the opportunity to flow through their ecosystems. Cypress swamps also provide valuable wildlife habitat for birds, numerous amphibian and reptile species, and Louisiana black bears. Finally, cypress swamps help protect our communities along the coast, acting as critical buffers during hurricanes and tropical storms.

In Louisiana and across the South, cypress swamp acreage is expected to decline over time due to environmental changes.  Louisiana’s largest cypress swamp, the Atchafalaya Basin, will likely lose approximately 60,000 acres of cypress swampland in the coming years (Faulkner et al. 2009).

Why is the bald cypress in trouble?

Logging pressures: bald cypress is a desirable wood product

Cypress swamps were one of the last areas logged during the timber industry boom in the late 1800s because of the difficultly accessing the wet, muddy areas in which cypress grew. However, once logging companies figured out how to access cypress trees– mainly by draining swamps and dredging canals– virgin cypress forests were harvested at a rapid rate such that all were exhausted by the mid-1900s (Mancil 1972).

Cypress wood has a smooth grain, is light weight, and is naturally resistant to insects, disease, and water damage. These qualities have made it excellent for outdoor buildings and structures that are exposed to elements of the South. For these reasons, among others, cypress remains a desirable, expensive wood product today.

Loss of habitat

The city of New Orleans today rests where cypress swamps once thrived. Much of Louisiana’s original cypress swamp acreage was lost when European settlers developed the Mississippi River floodplain for agriculture. Louisiana has lost as much as 50% of its pre-settlement cypress swamp acreage (Smith 1993), with most of the remaining area existing in small patches.

As city populations grow and expand, Louisiana’s cypress swamps will continue to be threatened by development pressures.

Poor natural reproduction and slow growth

Before the landscape of the South was altered by agricultural, water levels changed dramatically in cypress swamps, ranging from deep flooding to dry soil surfaces. This pattern was important for natural regeneration of cypress trees. Cypress seeds cannot germinate and develop underwater. Thus, whenever the ground was dry for extended periods of time, it gave cypress seedlings an opportunity to establish themselves and grow. These days, humans have dramatically changed the flow patterns of rivers, floodplains, and swamps such that many cypress swamps are permanently flooded or permanently dry. In dry areas, cypress seeds can germinate, but cypress trees are slow growers and cannot compete with other faster-growing species.

Restoration issues

Most of the cypress in coastal Louisiana is not regenerating and many swamps have been converted to open water. Some artificial regeneration of cypress (i.e., planting) has been successful, but it is often a difficult, labor-intensive task (Connor and Toliver 1990). Invasive marsh rats called nutria enjoy young cypress trees as a source of food and often devour newly established cypress trees if they are unprotected (Myers et al. 1995).

One of the areas in the Atchafalaya Basin with natural cypress regeneration.

A recent example of a struggling swamp 

Logging pressures, loss of habitat, and poor natural reproduction have strongly influenced the largest cypress swamp in Louisiana – the Atchafalaya Basin. A 2009 study quantified the acreage of cypress swamp within the Atchafalaya Basin using satellite imagery. The researchers determined that within the Basin, about 43% (262,000 acres) of the area is cypress swamp. Of this area, only about 6% (15,224 acres) was classified by the researchers as capable of naturally regenerating. About 25% (60,602 acres) was classified as unable to regenerate either naturally or artificially (Faulkner et al. 2009). Initial over-harvesting of cypress trees, followed by permanent changes in swamp water levels have both contributed to the loss of habitat and poor natural reproduction within the Atchafalaya Basin.

A new cypress seedling.

What can we do about it?

Encouraging and supporting cypress restoration efforts is one method to help replace this classic Louisiana species. For those living in the South, volunteer opportunities for planting projects in areas needing new cypress establishment could also be an effective tool for maintain cypress swamps. More generally, strong public support for policies that protect and conserve wetlands will help curb encroaching development pressure on existing cypress swamps.

 

References:

Conner, W.H. and J.R. Toliver. 1990. Observations on the regeneration of bald cypress (Taxodium distichum (L.) Rich.) in Louisiana swamps. Southern Journal of Applied Forestry 14(3):115-118. https://academic.oup.com/sjaf/article-abstract/14/3/115/4793932?redirectedFrom=fulltext

Faulkner , S.P., P. Bhattarai, Y. Allen, J. Barras, and G. Constant. 2009. Identifying bald cypress-water tupelo regeneration classes in forested wetlands of the Atchafalaya Basin, Louisiana. Wetlands 29(3):809-817. https://doi.org/10.1672/08-211.1

Louisiana Department of Wildlife and Fisheries (LDWF). 2005. Cypress-tupelo-blackgum swamp. Conservation Habitats & Species Assessments. http://www.wlf.louisiana.gov/sites/default/files/pdf/document/32870-cypress-tupelo-blackgum-swamp/cypress-tupelo-blackgum_swamps.pdf

Mancil, E. 1972. An historical and geography of industrial cypress lumbering in Louisiana (Volumes I and II). LSU Historical Dissertation. https://digitalcommons.lsu.edu/cgi/viewcontent.cgi?article=3295&context=gradschool_disstheses

Myers, R.S., G.P. Shaffer, and D.W. Llewellyn. 1995. Baldcypress (Taxodium distichum (L.) Rich.) restoration in southeast Louisiana: The relative effects of  herbivory, flooding, competition, and macronutrients. Wetlands 15(2):141-148. https://doi.org/10.1007/BF03160667

Smith, L.M. 1993. Estimated presettlement and current acres of natural plant communities in Louisiana. Louisiana Natural Heritage Program, Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA. http://www.wlf.louisiana.gov/sites/default/files/pdf/document/32857-chapter-4-conservation-habitats-and-species-assessments/13_chapter_4_conservation_habitats__species_assessmen.pdf

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Whitney Kroschel

Whitney Kroschel

I am currently a PhD Candidate at Louisiana State University in Baton Rouge, LA. My research interests are generally in the fields of plant ecology, seed ecology, and wetland science. My dissertation research is evaluating the effects of flooding on tree species composition in forested wetlands.

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