Monitoring Restoration Efforts at Woodlands Trail and Park

 
 

Funding & Support: CSUCI IRA Fund, CSUCI ESRM, Barataria Terrebonne NEP, Change Happens Foundation

Collaborators: Woodlands Trail and Park & Lambrinos Lab Oregon State University

Defining desirous levels of ecological functioning for our coastal wetlands

Context:

In March of 2007 the first of my ESRM 392: Service Learning in New Orleans classes from California State University Channel Islands spent Spring Break touring around the greater New Orleans area rebuilding homes and assisting with wetland restoration efforts.  As part of our now-annual trip we assist with the monitoring, control of the invasion of woody plant species from Asia, and restoration of native cypress-tupelo swamp across the Woodlands Trail and Park site in Belle Chase, Plaquemines Parish, Louisiana.  This site, open to the public, is one of the the last significant stands of native bottomland hardwood forest south of New Orleans.  Our now on-going effort to support the non-profit Woodlands Trail and Park focuses on invasive species management.  In effect, our only chance to maintain this community is to exclude the invaders threatening to displace our native vegetation.


Invaders Unleashed:

Hurricane Katrina gave this entire forest a “crew cut,” effectively turning a darkened, closed-canopy swamp region into a high-light shrub community.  Left to its own devices, such a forest would normally recover a mature canopy within a decade or two.  Unfortunately, the presence of aggressive invaders threatens to alter this recovery pattern, possibly eliminating many of the native plant species and more or less converting this forest into something akin to a bamboo forest in southeastern Asia.

Our three woody species of concern are: Sapium sebiferum (Chinese tallow), Melia azederach (Chinaberry), and Ligustrum sinense (Chinese privet).  In addition, native Rubus spp. (blackberry) exploded post-Katrina and we are also following the dominance of this plant.  These invaders have been spreading throughout coastal Louisiana for decades, but dramatically expanded their range and density thanks to seed dispersal via the winds and habitat opening of Hurricanes Katrina and Rita in 2005.


Trends To Date:

Privet and Chinaberry appear to reach their peak densities within 8m of the trail, suggesting control measures focusing on 10m swaths away from the trail may be successful in suppressing their abundance.  More problematic is Chinese tallow.  Individuals along Trial A peaked near the trail, but (unlike privet and Chinaberry) tallow on Trail B reached maximum abundance at the furthest distance into the woodland that we surveyed (16m).

In general our focal invader species are common throughout the site and all of southern Louisiana.  While these invaders had established themselves as of 2007, their vegetative growth appeared to be suppressed by the often very thick blackberry canopies that had developed across much of this landscape post-Katrina.  2008 saw the beginning of invaders pushing through this suppressing cover of blackberry.  Between 2007 and 2008 we saw some recruit invaders having grown more than 3m, with many, many sub-meter recruits ready to bolt during the summer of 2008.  We were depressed to find all invader species having more or less grown through the suppressing blackberry canopies by 2009, with Chinese tallow particularly exploding in height.

Going On The Offensive:

2009 also brought with it some good news.  Our wetland crusader Katie Brasted at Woodlands Trail managed to wrangle up enough funding to allow us to start our first pilot restoration effort on approximately 20 acres (8 ha) of our overall 600 acres (240 ha).  My long-time collaborator Dr. John Lambrinos of Oregon State University and I established an array of monitoring plots in September of 2009 (where we learned how fun it is to try to see through the pouring rain while swiping at mosquitos, watching our high-tech mapping equipment flood and die, and discovering the cajun word for “humidity’) just as we were starting our targeted herbicide chopping, spraying and killing efforts.  This was followed by a series of community planting efforts by many groups over the course of the next several months.  This effort “backfilled” in the forest with native seedlings.  By Spring of 2010 we saw a marked decrease in invaders in treated regions and the beginnings of more animals in the plots where we had removed invaders.  This initial success has renewed our hope that with enough resources and continued community support, we still have a shot at keeping these invaders at bay long enough to allow our native, closed-canopy forest to recover.  We look forward to continued progress and improving native seedling survivorship this coming spring.


Stay tuned for our Spring 2011 update in early summer...