Academic history

4. Mechanisms of Brazilian pepper success in South Florida

Fruiting Brazilian pepper.

See Publication list below for reprints.

For my dissertation, I examined some of the mechanisms that potentially contributed to the success of the invasive exotic Brazilian Pepper (Schinus terebinthifolius Raddi) in different ecosystems of South Florida.

In the laboratory of Dr. L. Sternberg (University of Miami), I contrasted water uptake and gas exchange patterns of this exotic with native species in four different ecosystems (a coastal pine forest, mangrove forest, upland rock forest, previously rock-plowed agricultural area) in Florida. Gas exchange of the exotic was not significantly different from native species but water uptake patterns of the Brazilian Pepper showed this exotic to be tolerant of saline conditions within coastal areas. The exotic was more tolerant of soil flooding compared to native pineland species. This work is significant as it provides insight into how this invasive exotic has been able to succeed in its introduced habitat.

5. Nutrient and salinity responses in mangroves: implications for ecosystem biodiversity

Anthropogenic inputs into coastal ecosystems are becoming increasingly common (e.g. in the form of runoff from terrestrial areas, sewage spills, etc.) especially along the densely populated shorelines of eastern North America. However, little is known about the effects of continuous long-term low-impact pollution on plants or animals, forest structure, and ecosystem processes.

One component of my research was to compare the responses of three mangrove species (Rhizophora mangle, Avicennia germinans, Laguncularia racemosa) under differing nutrient and salinity regimes to gain a better understanding of the ecological and physiological tolerances of each species. Research was conducted both in the field as well as in a shadehouse setting. I found that each mangrove species was physiologically adapted to different salinity and nutrient levels and interspecific differences potentially affected their distribution and overall abundance within the community.

Findings from this study have long-term implications on biodiversity as increases in nitrogen availability will effectively reduce populations R. mangle (at low salinities) and L. racemosa (at high salinity) in favor of A. germinans. My field observations also support these findings as long-term research has shown a shift from mixed species communities to A. germinans dominated forest.

Shadehouse experiment at the Smithsonian Marine Station. Plants were grown in a fully factorial experimental design of 3 nutrient and 5 salinity regimes (total = 15 setups).

Examining Avicennia germinans (black mangrove) leaves.

6. Effects of Ischnodemus variegatus on the invasive exotic West Indian marsh grass (Hymenachne amplexicaulis)

The West Indian Marsh grass (Hymenachne amplexicaulis) is an invasive exotic of wetland ecosystems in Florida. Originally imported as a forage crop from South America, this grass now forms large monospecific stands in Myakka State Park. Approximately 5 years ago, park staff observed significant damage on this grass, caused by the non-native Ischnodemus variegatus. This piercing-sucking insect is believed to be from South America but little is known about its ecology and distribution.

In collaboration with Dr. W.A. Overholt and Rodrigo Diaz (UF graduate student), we set up an experiment to quantify the effects of the insect on the ecology and physiology of H. amplexicaulis. It was hoped that this insect could potentially be a viable biocontrol agent of the grass. We found plants infested with I. variegatus were only 77% the size (above + belowground biomass) of control plants although the photosynthetic rates of both treatments were not significantly different. It is possible the insects increased marsh grass photorespiration and/or affected its carbohydrate synthesis, resulting in smaller plants.

Published in Florida Entomologist (Overholt et al. 2004)

7. Ecology of the giant land crab: baseline information for population management

Ovigerous C. guanhumi in the surf.

The purpose of this research was to examine the population structure and distribution of these crabs in the mangrove forests over a temporal scale. As the giant land crab is being harvested for consumption and is locally extinct in areas of South Florida, it was hoped that this baseline data from Central Florida would provide information for the future management and population restoration of this protected species.

In collaboration with Dr. Bjorn Tunberg (Smithsonian Marine Station) and with the help of an undergraduate intern (Christina Pugliese, Univ. of Florida at Gainesville), we set up a 4 m x 5 m plot and trapped all individuals within. We discovered the giant land crab population to be approximately 50:50 male:female. Although most of the crabs trapped (n=33) were mature, only one female trapped (1 out of 16 females) was gravid. In October 2002, a mass migration of females was observed depositing eggs into the Atlantic Ocean during the new moon. This event has never been observed before and together with our population data, is currently being prepared for publication.

Teaching allows me to share my passion for biology. My goals are to stimulate interest in biology and to motivate my students to continue their quest for knowledge in science When my students leave the class, my hope is that they will continue to pursue a lifelong interest in biology and the world around them.

From 1999-2001 (3 years), I was the instructor for the Fall and Spring Biology Honors laboratory classes. The benefit of the Honors class was the freedom that accompanied the smaller class size. Due to the advanced nature of the class, I was given the latitude and freedom to design the curriculum.

I believe in interactive learning and require the active engagement of my students. To encourage active and enthusiastic participation, I encourage all my students to explore their biological interests and bring them into the classroom. I am strongly in favor of adding a hands-on dimension into the staple textbook-classroom learning as most people learn better when they are able to touch and feel the objects they are learning about. Therefore, I try to take my students outdoors (in small groups with a lot of personal attention) and have them connect with what they were studying. Where possible, I have integrated field trips and independent student projects into regular course material as I feel that it important to be connected with what one was studying. In my class, we have explored sawgrass communities in the Everglades, examined disturbed and native pineland communities, conducted plankton tows in Key Biscayne and studied the soil, pelagic and benthic community in the local area ponds. Additionally, we have also used the University of Miami's Gifford Arboretum as a learning resource. I was the curator of this living collection of over 400 vascular plant species for 2 years (1998-1999).

I am committed to providing the best learning experience to every student in my class and bringing out the best in each person. My lectures are structured to be informative and easily assimilated. All of my students find my office door always open and that I am readily available to work with them outside the classroom. Frequently, I have held weekend extra study sessions on both the individual and group levels when students have requested help-my philosophy is that if they are willing to invest the time in the subject, I am glad to promote that interest by being there for them.
As part of their scientific training, some of my students carry out small, semester-long scientific projects aimed at answering simple hypotheses. They are required to design a project in an area of interest, carry it out to completion, and assess their findings. The students learn self-discipline, the rigors of the scientific method and most come away with a newfound appreciation for research. Many of my students have been greatly encouraged by their own abilities and sought to carry out further research.

In science, it is not sufficient to do only research.
One also must be able to share that knowledge either by presenting the work in front of others or by writing it up for public viewing. In addition to scientific writing, my curriculum also requires students to research a topic or an organism, and present the information learned in the form of a web page. I encourage them to choose a topic of their interest and then present it in a way that is readily understandable (from grades K-12). Over the course of the semester, with my help and that of a web-designer, we meet weekly out of class and learn to design web pages. Some of this work is currently online at: www.bio.miami.edu/studentweb01.html.

Below are some pictures taken with the Spring 2000 Honors class on a field trip to Everglades National Park:

South Florida pine rocklands dominated by the Dade County slash pine (Pinus elliottii).

Brown water snake

American Alligator

Sawgrass marsh with pine rocklands in the background. If you look carefully, you will see two deer in the middle of the marsh.

Mentoring:

Over the years, I have taught graduate students both field collection and stable isotope techniques. With undergraduate students, my primary task is to expose them to as many different research options as possible. I show them various research techniques to help them decide their research interests. For example, one of my students completed a research project with me on the carbon stable isotope ratios of native and invasive plants growing under saline and freshwater conditions. Another student completed a project on the differences in diurnal photosynthetic patterns of Clusia rosea (C4 plant) and Quercus virginiana (C3 plant) using the portable gas exchange meter (Li6400, LiCor, Lincoln, NE). Both of my previous interns, Rosalie Leonard and Onour Moeri, and now pursuing graduate degrees in biology at the University of Toronto and University of Florida respectively.

In brief, I believe in exposing students to research and the environment from an early stage. I was privileged to be exposed to research as a sophomore in college and that experience has significantly shaped my interests and pursuits.

Publications

Ewe S.M.L., Sternberg L. da S.L. and D. L. Childers (accepted) Seasonal plant water uptake patterns in the saline southeast Everglades ecotone. Oecologia

Ewe S.M.L. (accepted) Are Rhizophora mangle propagules of different sizes prematurely lost from the plant equally viable? Florida Scientist

Ewe S.M.L. and Sternberg L. da S.L. 2007. Water utilization patterns of the invasive exotic Schinus terebinthifolius contrasted against native species in two coastal plant communities. Journal of Coastal Research. 23(1):255-264. [pdf proof]

Ewe S.M.L., Gaiser E.E., Childers D.L., Iwaniec D., Rivera-Monroy V.H. and Twilley R.R. 2006. Spatial and temporal patterns of aboveground net primary productivity (ANPP) in the Florida Coastal Everglades. Hydrobiologia. 569:459-474. [pdf]

Sobrado, M.A. and Ewe S.M.L. 2006. Linking hypersalinity to leaf physiology in Avicennia germinans and Laguncularia racemosa coexisting in a scrub mangrove forest at the Indian River Lagoon, Florida. Trees. 20(6)679-687. [pdf]

Ewe S.M.L., Overholt W.A., Kirton L.G., Lai E-M., Ahmad I., and Ulaganathan S. 2006. Foreign exploration for biological control agents on three invasive plant species from Asia. Wildland Weeds. 3:19-21. [pdf]

Lovelock C.E., Ball M.C., Feller I.C., Engelbrecht B.M.J., and Ewe S.M.L. 2006. Differences in plant function in phosphorus and nitrogen limited mangrove ecosystems. New Phytologist. 172(3):514-522. [pdf]

Lovelock C.E., Ball M.C., Feller I.C., Engelbrecht B.M.J., and Ewe S.M.L. 2006. Salinity and nutrient effects on hydraulic conductivity of mangroves. Physiologia Plantarum. 127(3):457-464. [pdf]

Ewe S.M.L. and Sternberg L. da S.L. 2005. Growth and gas exchange patterns of the invasive exotic Schinus terebinthifolius contrasted with native species under controlled saline conditions. Trees. 19(2):119-128.[pdf]

Overholt W.A, Ewe S.M.L., Diaz R., Morgan E.C. and Moeri O.E. 2004. The effect of Ischnodemus variegatus (Hemiptera: Lygaeidae) feeding on photosynthesis and growth of Hymenachne amplexicaulis (Poaceae). Florida Entomologist. 87(3):312-316. [pdf]

Herwitz S. R., Levia D.F. and Ewe S.M.L. 2004 Transpiration rates of the understory annual Impatiens capensis (Balsaminaceae) in response to the autumnal change in canopy leaf area. Flora: morphology, distribution, functional ecology of plants. 199(6):524-530.

Ewe S.M.L. and Sternberg L. da S.L. 2003. Seasonal gas exchange characteristics of Schinus terebinthifolius in a native and disturbed upland community in Everglades National Park, Florida. Forest Ecology and Management. 179:27-36.[pdf]

Ewe S.M.L. and Lovelock, C.E. 2003. Photosynthesis, growth and primary production of mangrove trees. In: I.C. Feller (ed). Mangrove ecology: a field manual focused on the biocomplexity of mangrove ecosystems.

Ewe S.M.L. and Sternberg L. da S.L. 2002. Seasonal water-use patterns of the invasive exotic, Schinus terebinthifolius, in a native and disturbed community. Oecologia. 133:441-448.[pdf]

Ewe S.M.L. 2001. Ecophysiology of Schinus terebinthifolius contrasted with native species in two South Florida ecosystems. University of Miami, Coral Gables, FL. 194 pp. Download at: FIU Digital Commons.

Ewe S.M.L., Sternberg L. da S.L and Busch, D.E., 1999. Water use patterns of woody species in pineland and hammock communities of South Florida. Forest Ecology and Management. 118: 139-148.[pdf]

Non-refereed publications:

Ewe S.M.L., Overholt, W.A. and Lee, D. 2005. Foreign exploration for biological control agents of three invasive species from Asia. Report submitted to: Florida Department of Environmental Protection. [pdf]

Childers D.L., Ewe S.M.L., Rondeau D., Grahl T. 2005. Water quality, hydrology, soil and macrophyte dynamics in the Southeast Everglades: a multi-year study. A report submitted to Everglades National Park.

In preparation/review:

Sternberg L. da S.L., DeAngelis D., Ewe S.M.L. and Wilhelm-Miralles F (in review). A dynamic model of ecosystem shifts at the saline/freshwater vegetation ecotone. Ecosystems.

Ewe S.M.L. and Sternberg L. da S.L. Seasonal gas exchange of the invasive exotic, Schinus terebinthifolius versus native plant species in mangroves and pinelands of Florida. Trees.

Ewe S.M.L. and Sternberg L. da S.L. Gas exchange and growth patterns of invasive exotic Schinus terebinthifolius and native species under controlled flooding.

Ewe S.M.L. and Lovelock C.E. Leaf isotopic (d¹³C and d¹⁵N) patterns of three mangrove species in response to nitrogen and phosphorus enrichment at different salinity levels.

Ewe S.M.L., Lovelock C.E. and Feller I.C. Vegetative and reproductive phenology of fertilized black mangroves (Avicennia germinans) in a nitrogen-limited system.

Ewe S.M.L., Tunberg B. and Pugliese C. Ecology of the giant land crab, Cardisoma guanhumi, in the Indian River Lagoon, central Florida, USA.