Inventorying an ‘Industrial Flora’

Trade Hubs & Biological Invasions

An aerial view of the Port of Savannnah, showing stacks of shipping containers and three cranes on the Savannah River
Garden City Terminal is 11 miles upriver from Tybee Island, Georgia. The equivalent of 14 million shipping containers came through the Port in 2017. Photo by Billy Birdwell, U.S. Army Corps of Engineers, courtesy of Wikimedia Commons.

Shipping containers are stacked like Legos. From all over the world, they have arrived at the Garden City Terminal, at the Port of Savannah in Georgia.

About a third of the plant species growing there are also from around the world – they are non-native. Some are new to Georgia and the U.S. altogether. That’s a remarkably high proportion of non-native species, according to a recent study led by USDA Forest Service research ecologist Rima Lucardi.

“We conducted an ‘industrial flora,’” says Lucardi. “We inventoried the vascular plants present – all of the plants flowering or fruiting on the Garden City Terminal. It is a very different field site than what or where people may think or expect to conduct a botanical survey.”

At the Garden City Terminal, about 14 agriculture specialists with the U.S. Customs and Border Protection inspect millions of tons of imports each year. The equivalent of 14 million shipping containers came through the Port of Savannah in 2017.

Most of the Garden City Terminal is for shipping containers, both refrigerated and dry boxes, so the green spaces were small. The number of species collected, however, was in the expected range of the species-area curve. “This tells us that we did a good job capturing the flora present,” says Lucardi.

The research team included scientists from Arkansas State University, University of Georgia, and Columbus State University. For two years, the team collected plants from within the secure areas of the Garden City Terminal. Sampling began in August 2015 and ended in February 2017. During this time period, the researchers visited four times – in February, May, August, and November. When they located a plant that was flowering or fruiting, they collected and recorded it then put it in a plant press.

Travis Marsico, curator of the of Arkansas State University herbarium (STAR) definitively identified the plants, comparing them to other herbarium specimens. An herbarium is a library of pressed plants that have been carefully identified, curated, and labeled. Valuable information is recorded on the label – who collected the plant, when, and where.

“Herbaria are really important,” says Lucardi. “The herbarium at ASU is developing a collection of non-native and invasive plant specimens, which is so essential – if we continue to build up herbaria, we’re building up our ability to record, and therefore, understand and model plant invasions in both time and space.”

Once the industrial flora of the Garden City Terminal was identified, the researchers compared their results to other floristic surveys in the region. They also created a framework for engaging with private industry on this type of research.

Rima Lucardi and the rest of the team in the terminal with vacuums used to sample seeds
The sampling team poses with Milton King, supervisory agriculture specialist with USCBP. From left, Lauren Whitehurst (currently a PhD student at the University of Florida), King, Steven Hughes, Lucardi, Kevin Burgess, and Chelsea Cunard. Photo by Rima Lucardi, USFS.

The study is the first of its kind in the U.S. It was published in the journal PLOS ONE and is part of the journal’s special biodiversity collection.

Lucardi and her team conceived the idea of industrial floras. It reflects the unique set of plant species at such a site and, presumably, at other trade hubs. The team hopes to study additional trade hubs in the U.S. and beyond, as well as highway and rail corridors.

“This paper is a call to action,” says Lucardi. “The ‘usual’ sites botanists and plant ecologists study – places where rare and endangered species generally live – can be conserved if we also study and prevent exotic invasions. One of the major problems with a biological invasion is that by the time a species is creating a negative impact, both economically and environmentally, it’s already too late. Prevention, early detection, and rapid response are really key to conservation of biodiversity and positive economic returns.”

Invasions can start small. The redbay ambrosia beetle, for example, is smaller than a grain of rice. With a fungus that lives in its mouthparts, the beetle is killing redbay and sassafras trees across the South. It may have arrived in the U.S. through the Port of Savannah, according to previous research.

In terms of dollars and ecosystems, it’s much cheaper to prevent biotic invasions than to manage them.

In Georgia, for example, timber is a major export. If cogongrass is found on the harvest site, the timber must be fumigated before export, if it can be harvested at all. Cogongrass is among the ten worst weeds in the world because of its ability to spread quickly, alter ecosystems through fire and other mechanisms, and grow almost anywhere that’s warm enough.

A pressed plant - wispy roots attach to a thin stem that branches in the middle of the image. On one of the branches, a small purple flower
The specimen voucher for Latin American mock vervain (Glandularia tenera). “This plant was previously reported only from the Port of Mobile, Alabama, which is suggestive of a recent introduction at seaports in the southeastern U.S.,” says Marsico, who provided the image.

It was introduced to the U.S. multiple times, both as packing material in an orange crate that arrived in Grand Bay, Alabama, in 1912, and purposefully as potential grazing fodder for cattle by the USDA for several years in the 1920s. Lucardi has published extensively on cogongrass genetics, genetic diversity, and methods for controlling it.

The researchers did not find cogongrass growing at the Garden City Terminal. However 13 of the 25 grass species they did find were non-native, including a new Chatham County record of little lovegrass (Eragrostis minor).

“Trade hubs are hotspots of non-native plant diversity and possible sources of emergent plant invasions,” says Lucardi. “But our engagement and collaborations with industry shows us industry’s willingness to be proactive about the environment.

In Georgia, the Garden City Terminal and the entire Port of Savannah are managed by the Georgia Ports Authority, through a private-public partnership. “Georgia Ports Authority has been leading the way in terms of shared stewardship of trade,” says Lucardi. “They work very closely with U.S. Customs and Border Protection and they show up and contribute to quarterly meetings of the Savannah Pest Risk Committee.”

Lucardi has participated in the meetings since 2014, which brings together representatives of the USDA Animal and Plant Health Inspection Service, Georgia Department of Agriculture, Georgia Forestry Commission, the USDA Forest Service, U.S. Customs and Border Protection, and others. The USCBP Port Director or Assistant Director generally opens these meetings.

“Ultimately, this is an issue of bio- and agro-security. We hope other researchers will engage with industry, utilizing our framework, to cooperatively work to prevent and mitigate exotic invasions.”

Read the full text of the study.

For more information, email Rima Lucardi at rima.lucardi@usda.gov.

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