(Deer) X (Invasives)² : Interactive Effects in the Herb Layer of Suburban Forests

Project Overview

This is a project funded by the National Science Foundation Ecology program (DEB1257833, March 2013 – Present)

Project Investigator: Dr. Janet Morrison at the College of New Jersey 

Biological invasion by non-native plant species and its impact on the resident plant community is a complex, multifactorial process that begs for a conceptual framework approach. The proposed study puts into one interconnected system the experimental effects from two co-occurring, dominant invasive species: Alliaria petiolata (ALPE, garlic mustard) and Microstegium vimineum (MIVI, Japanese stilt-grass) on the resident herb layer community of suburban forests – and on each other’s demography and invasion. It also includes effects from generalist herbivory by overabundant deer on both species’ invasion processes and on the plant community. This is a multi-year field experiment in 6 forests, with 40 16-m² plots in each. After a year of baseline data collection, half were fenced to exclude deer, and crossed with an invasive seed addition treatment (NONE, ALPE, MIVI, or ALPE+MIVI), which started small stands that develop on their own in the plots. Community variables (richness, cover, woody plant growth, invasive cover), demographic measurements on the two invasive plant species, deer pressure, and key environmental variables are measured each season by teams of undergraduate researchers. The six forests are similar but span a range of deer pressures.

Location

The study is taking place in central New Jersey (Mercer County), at the heart of the suburban/exurban matrix, with deer densities estimated at 30/km². The area is a typical urbanizing landscape 60 km from Philadelphia and 95 km from New York City. The research is being conducted on six properties controlled by two of the area’s most important land owners/managers, Mercer County Department of Parks and Friends of Hopewell Valley Open Space.

Each forest site has the following requirements:

1) Sufficient size to accommodate the 40 plots;

2) ALPE and MIVI present, but with non-invaded areas for the experiment;

3) Similar soil types and only gentle slopes;

4) Upland with closed, hardwood canopy of similar successional age and composition;

5) Contribution to a range of ambient deer pressure;

6) Similar earthworm densities;

7) A diverse mixture of native species in the herb layer.

We chose 12 forests initially that met criteria 1-4, collected data for criteria 5-7 in those 12 forests, and identified the final 6 study forests.We are interested in how deer pressure interacts with the invasive species effects, so I selected forests with a range of ambient deer pressure, measured by browse along 300 m of transects, foliage coverage by native shrubs at 40 points/forest, deer pellet fecal accumulation rate (FAR), and hunting history.

Timeline

1. Six forests that met basic criteria for project research were selected. (2008-2009)
2. 240 plots were set up and permanently marked. (Fall 2009)
3. 15 112-m2 deer pellet plots per forest to record fecal accumulation rate (FAR) to estimate deer density. (2010)
4. Recorded pre-treatment deer browse recorded for woody species. (2012)
5. Recorded pre-treatment Fall and Spring percent cover of every herb layer species in 4 1-m2 subplots per plot, in all 240 plots. (2012)
6. Record pre-treatment shrub cover, deer pellets, soil characteristics, earthworms. (2012)
7. ALPE and MIVI seeds collected for addition treatments and ALPE and MIVI added seeds to designated plots (Fall 2012)
8. Fall and Spring census (percent cover of herb layer) collected for 2012-2015
9. Woody browse data collected for 2012-2015
10. Shrub cover data collected for 2012-2015
11. ALPE/MIVI browse data collected 2013-2015
12. PAR data collected 2013-2015
13. ALPE/MIVI counts data collected 2013-2014
14. Leaf Litter data collected summer 2013-2014
15. Woody heights data collected Fall 2013-2015
16. Worm data collected Summer 2014-2015
17. Soil Water Potential data collected Fall 2014
18. Soil PFLA data collected Sumer 2015
19. Soil analysis data collected Summer 2015
20. Leaf Chemistry data collected Fall 2015

Protocols

Photo Archive

Related Publications and Conference Presentations

(All co-authors were TCNJ undergraduate students)

Research with Undergraduates

• Current Students:
  • Devyani Mishra
  • Gina Errico
• Former Students:
  • Kiara Proano (Fall 2015-Spring 2018)
    
    
    I started shadowing in Dr. Morrison’s lab sophomore year and became a credited research student a year later. Along with learning the effects of invasive species and deer population on native species, I’m conducting my own experiment. I was always curious about the soil activity that isn’t visible to the eye. What is happening beneath the soil? What are helping these plants grow? We know that soil consists of all sorts of fungi that help in plant development, but I specifically wanted to learn more about the functions of mycorrhizal fungi. The presence, whether it’s high or low, of these fungi have the ability to alter plant root structure. Learning more about this function will help me better understand the way certain plant species in our study sites grow. These last two summers I took part in TCNJ’s Mentored Undergraduate Summer Experience continuing my research with Dr. Morrison. I spent eight weeks, with three of my research peers, collecting data from our study sites. This was my first time really getting my hands dirty for the lab experiment, and there was just something about spending hours outside with your face in the dirt with others. We would wake up early together, eat together, and end our day together. I’ve learned how rewarding and fun it is to work alongside bright students who have similar interests as you.
  • Nicole Potter (Spring 2016-Spring 2018)
    
    
    I first became interested in Dr. Morrison’s lab at the end of the fall semester of my sophomore year (fall ’15) after I took ecology. During this class, we had to conduct our own experiments and I really enjoyed the process as well as the field work that we had to complete. I shadowed the lab the next spring semester and officially joined the my junior year! I am currently in the process of conducting my side project for my biology capstone. I am interested in the competitive relationship between native and invasive plants. I’m specifically interested in Microstegium vimineum (MIVI) and its relationship with various native and invasive plants. MIVI is native to Japan and so I want to look at how MIVI interacts with other herbaceous pants that are native to Japan and plants native to North America. I’m interested in whether MIVI is able to experience increased recruitment in the presence of plants native to Japan or plants native to North America. For my experiment, I am looking 2 vines native to North America (Parthenocissus quinquefolia and Vitis) and 2 vines native to Japan (Celastrus orbiculatus and Lonicera japonica).
  • Anna Zauner (Fall 2016-Spring 2018)
    I joined the lab Sophomore fall because I am very interested in learning more about the ecosystems that surround us. After doing work in the field I have become very interested in the earthworm population in our forests. I am working on a side project now that is looking more in depth about the relationships between earthworms and microbes in our forests. I hope to get some conclusive results for this project and learn something new about the earthworm community.
  • Daniela Nattes (Spring 2017-Spring 2019)
    
    Daniela Nattes has began shadowing in Dr. Morrison’s lab since her second semester of Sophomore year, and was smitten with the field work. Already an avid biology and botany enthusiast, she is aiding in data collection in the Fall 2017 semester and establishing her side project. While still in its early stages, the main component of her potential project would be focusing on fungal infections and its effect on the growth of native and invasive species. Looking to the future, she hopes to continue her studies to graduate school.
  • Scott Eckert (Fall 2014 – Spring 2017)

    
    I am currently using structural equation modeling (SEM) to represent how deer herbivory and invasion of a non-native grass, Microstiguem vimineum, commonly known as Japanese stilt-grass, affect the recruitment of tree seedlings in New Jersey suburban forests. The data I am using are from the factorial field study, with the experimental treatments being the novel addition of stilt-grass and implementation of fencing, being conducted by Dr. Morrison along with the help of all of student researchers. It is important to model the forest as a system, because the forest is a living system. As such, other statistical methods may not capture some of the interactions that occur in nature.

  • • Ryan Goolic (Fall 2013 – Spring 2016)
      
      Ryan Goolic has been involved with the Morrison Lab since his Freshman year and is approaching his Senior capstone experience.  As a Freshman, Ryan started as a Biology Education major, but being part of an ecological research team shifted his interest.  Now, he is a Biology major with a minor in Environmental Studies.  For his capstone experience, Ryan will be looking at the interactive effects of invasive earthworms and invasive plants.  In forest ecosystems around and north of TCNJ, earthworms were decimated during the last ice age.  Through means of human interaction, exotic earthworms from around the globe were able to establish themselves in places where they had not existed for thousands of years.  While earthworms in gardens can be beneficial, the way that they cycle nutrients can be detrimental to forest ecosystems and be a mechanism for invasion of non native plants.  Specifically, Ryan will be studying the effects of Asian, European, and native earthworms on the growth of the European garlic mustard and Japanese stiltgrass.  This will be a greenhouse experiment and will have implications for the co-evolution and co-invasion of the earthworms and plants in the Morrison Lab study sites.
    • Marisa Grillo (Fall 2014 – Spring 2016)
      
      I am in the process of researching and planning my side project.  I want to study woody shrubs because they are in their own layer within the understory between the small, herbaceous plants and the tall trees.  Shrubs are also important for birds and other wildlife, providing shelter and food (seeds and berries). I will review the data that have already been collected throughout the experiment in order to compare deer browse and the effect of caging on native and non-native woody shrubs.  I will use these data to develop an experiment to investigate native and non-native woody shrubs within this study.
    • Elizabeth Matthews (Fall 2014 – Spring 2015)
      
      In my side project, I am interested in the effect that the invasive vine, Lonicera japonica (LOJA) has on native plants in suburban forests. In our study sites we noticed that LOJA only grows across the forest floor and dominates laterally. My focus so far has been looking through percent cover data specifically in lower-deer-pressure forests to see if different levels of LOJA correlate to differing levels of native species. Through regression analysis, I found that where levels of LOJA were high, levels of Aster divaricatus (ASDI) were low. The opposite effect was seen Rosa multiflora (ROMU); it appears that LOJA may use ROMU as a substrate for greater vertical, viney growth. In a greenhouse experiment I plan to grow both ASDI and ROMU alone and with LOJA to see if there is a competitive growth pattern similar to that seen in the data analysis.
    • Mitchell Vaughn (Fall 2014 – Spring 2015)
      
      Modern suburban forests have become an amalgamation of native and non-native plant and animal species, so when analyzing species interactions, it is essential to consider whether the species are native or non-native and their region of origin. Plant species typically posess defensive chemistry and other  defenses, and only species that have been exposed to another species’ defenses can have evolved ways to overcome them. I aim to look at how  non-native, invasive species’ origins may affect their interaction with species of the same origins and different origins. I am analyzing the spatial distribution of plants from Europe and Asia in the field. I am also performing feeding trials with invasive, European slugs to determine if they have a preference for plants with the same geographic origin.
      
    • Jennifer Wells (Fall 2014 – Spring 2016)
             
      Forest ecology is a complex web of interactions, so the successful invasion of certain plant species can depend on many aspects. One thing a successful plant invasion can depend on is the already-established plant community. This is called a priority effect, in which one species can have a positive or negative impact on future species that arrive at the same site. Priority effects are important because they can impact the succession or diversity of a forest. For my project, I am focusing on the priority effects between two local invasive species, Japanese stiltgrass and garlic mustard. My goal is to determine if prior establishment of each plant will help or hinder the establishment of the other species. This experiment will further knowledge of invasive plant interactions as well as have implications for invasive plant control and removal.
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  • Nicole Mallotides (Fall 2012 – Spring 2014)
    
    Undergraduate work: My project focused on temperate, deciduous, metropolitan forests that increasingly face threats due to fragmentation; the alarming lack of juvenile trees indicates such threats. We wanted to investigate if this lack of juvenile trees was related to overabundant white-tailed deer since the abundance of white-tailed deer greatly reduces natural flora because of excessive herbivory. Tree seedlings represent the future of the forest, thus forest regeneration is critical to maintain the forest; young trees must successfully establish and grow to renew the tree cover. Deer are a keystone herbivore and have negative direct and indirect effects on tree seedlings. Deer-resistant tree species can persist in forests with overabundant white-tailed deer, however, thus my objective was to determine how the tree seedling community is influenced by the extent of deer pressure within metropolitan forests.  By using a measure of chronic deer pressure, a measure of current deer pressure, canopy importance values, and an herb layer census, we found the forest with the most severe chronic deer browsing was not the forest with the most severe current deer browse as expected. We hypothesized that deer cease general feeding in forest fragments that are nearly empty below the browse line. There is little food or shelter for the deer, so they may avoid the forest. Further, we found what little browse happens in these fragments is targeted to species with low deer-resistance.
    Current Work: Currently I am a manufacturing technologist at a clinical-stage company. We develop monoclonal antibody-based products for the targeted treatment of cancer. We create humanized antibodies that can be used either alone in unlabeled or “naked” form, or conjugated with radioactive isotopes, chemotherapeutics, cytokines or toxins. My team is responsible for the manufacturing of the antibodies, antibody fragments, and conjugates. We purify antibodies using ion-exchange and affinity column chromatography and virus removal filtration.
  • Giovanna Tomat-Kelly (Fall 2013 – Fall 2015)
    
    Undergraduate work: While in Janet’s lab, Giovanna studied plant-soil interactions. Her independent project aimed to test whether M. vimineum was a driver of change in Nitrogen (N)-cycling processes and whether there was relationship between the level of M. vimineum invasion and the potential for N-cycling. A greenhouse experiment was established with either no plant treatment (only soil), M. vimineum plants, or Arisaema triphyllum (Jack-in-the-pulpit) plants which were left to condition potting soils for two months.  Soil samples were then collected from the center of each pot. A field study was also conducted by collecting soil samples from forest plots with varying levels of M. vimineum invasion which were previously established as part of the lab’s larger field study. All soil samples collected were analyzed for N-cycling potentials (denitrification, nitrification, mineralization etc) and abiotic soil properties (soil moisture, organic carbon and other variables that influence N-cycling). No differences in N-cycling or soil properties were observed across plant treatments in the greenhouse experiment, however positive correlations were observed in the field between M. vimineum cover and both soil moisture, potential mineralization and potential net N nitrification. Using structural equation modeling a best-fit model was determined that suggests M. vimineum invasions are drives of nitrification rates. Insignificant trends in the greenhouse experiment match this model. This research helps shed light on the process of M. vimineum invasions and its implications for the structure and functioning of surrounding plant and soil communities.
    Current work:
    After graduating in December 2016, Giovanna took an internship position with the department of energy working at the Battelle Marine Science Lab in Sequim, WA. There she is researching the use of the protein metallothionein (MT) as a biomarker for metal contamination within near-shore waters. After the completion of her internship in WA, Giovanna will be moving back to the east coast to work as an intern for the Conservation Land Management Fund’s “Seeds of Success” program in Staten Island, NY. She says she is really enjoying lab work, but is eager to get back in the field where she can put the plant identification skills she acquired in Janet’s lab to good use. From there she hopes to work as a field technician until she (tentatively) begins grad school in the fall of 2017.
  • Cynthia Timko (Fall 2013 – Summer 2015)
    
    Undergraduate work:
    My research spanned two summers of MUSE (2014 & 2015) and focused on the effects of earthworm populations on forest ecosystems. It is known that earthworms modify soil microenvironments and affect bottom-up change by shifting nutrient cycling and interacting with native and non-native invasive plants. I studied the relationship between earthworm abundance and the invasion success of the two plant species that our multi-year study focuses on—Japanese stilt grass and garlic mustard. We extracted earthworm samples in our forest plots by electrochocking the ground, and then identified the worms by species to determine localized and forest-wide abundance. The findings were presented at the Mid-Atlantic Ecological Society of America conference in Elizabethtown, PA in spring 2015 and at the Ecological Society of America annual conference in Baltimore, MD in summer 2015. In my first summer of MUSE, I attended the BOTANY conference in Boise, Idaho.
    Current work:
    Proper land management and conservation are key takeaways of Dr. Morrison’s lab’s research. I am able to see these principles carried out daily, as I currently work for the United States Department of Agriculture (USDA) in the Farm Service Agency (New Jersey’s State Office). My hands-on research experience in this lab has given me a distinct understanding of ecological principles, which makes working for USDA even more enriching. When I graduate in May, I will begin working as a financial analyst for Lockheed Martin in their Space Systems division in Philadelphia.
  • Brian Corbett (Summer 2007 – Spring 2009)
    
    Undergraduate work:
    My research focused on the allelopathy of Japanese stilt grass (microstegium vimineum), an invasive species in the local forests around TCNJ. We found that extracts of microstegium vimineum decreased growth of lettuce and radish seedlings, supporting our hypothesis that the invasive success of Japanese stilt grass may be due to allelopathy.
    Current work:
    After graduating from TCNJ, I attended Thomas Jefferson University and earned a PhD in neuroscience. I am currently a postdoctoral fellow at The Children’s Hospital of Philadelphia where I study the neurobiology of stress.
  •  Paul Fourunijan (Fall 2009 Spring 2010)
    
    Undergraduate research:
    My role in the current project was to help set up
    the foundation for the experimental plots. Working with Professor Morrison
    and Joanna Sblendorio, we marked out the experimental plots. Before the
    deer enclosure experiment we began, we needed to take a census of all
    understory plants present before hand, and measure deer abundance of each
    forest through deer pellet plots. While our work was largely preliminary,
    we were able to present our results on deer browse, plant species
    abundance, and pellet counts at the April 2010. Mid-Atlantic Chapter of the
    Ecological Society of America Annual Conference.
    Current work:
    After ecology research I transitioned into the bioenergy
    and sustainable agriculture fields. I’m currently working on a PhD in
    Microbiology & Molecular Genetics at Rutgers University. There I research
    the genome of Spirodela polyrhiza and the other duckweed family members,
    along with their applications to the waste water treatment, human
    nutrition, animal feed, and bio-energy industries.
  • Megan Fertitta (Fall 2009 – Spring 2012)
    
    Undergraduate research:
    While working in Dr. Morrison’s lab, I studied the interactions of invasive plant species and white-tailed deer and their combined effects on suburban/exurban forests.  I measured the abundance of garlic mustard and Japanese stilt grass in forests with varying levels of deer browse.  Additionally, I quantified deer browsing on invasive species by conducting visual inspections of plants and by examining what plant species grew out of collected deer pellets.
    Current work:
    After graduation, I spent two field seasons in Montana.  I studied grasshopper populations on the National Bison Range.  I also assisted with U.S. Forest Service research identifying and classifying Lynx habitat throughout Montana’s national forests.  Currently, I am working as a Commercial Lines Underwriter with the Cincinnati Insurance Company.  I still love spending time in the forest and I plan to visit all the National Parks within my lifetime!
  • Kerry Mauck (Spring 2004 – Spring 2005)
    
    Undergraduate research:
    The goal of my project was to test the hypothesis that introduced species become invasive largely due to release from natural enemies present in their native ranges. To test this hypothesis, I used a system consisting of seedlings of two co-occurring, congeneric maples growing in the understory of eastern deciduous forests: the invasive, non-native Acer platanoides and native Acer saccharum. For these two species, I examined damage from herbivores and pathogens, growth, survival, and ecophysiological traits such as photosynthetic rate and time to bud burst in the spring. I found that while the two species experienced similar attack rates from natural enemies, the invasive A. platanoides had greater survival and earlier spring bud burst. This research suggests that for A. platanoides, ecophysiological traits contribute more to its invasive tendencies than escape from natural enemies. With Janet’s help, I turned this project into an honors thesis, presented my work at the Northeast Ecology and Evolution Conference, and published a paper in the Journal of Ecology.
    Current work:
    After graduation in May 2005 I went to work for the Phillip Alampi Beneficial Insect Laboratory in West Trenton, NJ, where I assisted with monitoring populations of insect natural enemies released to control non-native insect pests and invasive plants. Through this experience I became more interested in studying insect-plant interactions, and so I left my position to attend graduate school at Penn State University in the Department of Entomology. For my graduate work I studied the ways that insect-vectored plant pathogens can change plant appearance and chemistry in ways that encourage insect vectors to visit those plants, which results in a greater likelihood of the pathogen being picked up and transmitted to a new host. My work also focused on the many ways that plant pathogens can change plant chemistry and how this affects the broader insect community, including natural enemies that attack insect vectors. Currently, I am a post-doctoral researcher at the ETH Zürich in Switzerland, but I will soon move to start as an assistant professor in the Entomology Department at the University of California at Riverside. I plan to continue researching how plant phenotype mediates interactions among plants, pathogens and insect vectors and I am looking forward to mentoring students from a wide range of backgrounds and experiences. Along my journey to becoming a scientist, I have also become a wife and mother to a happy, healthy baby girl.
  • Danielle Leng (Fall 2011 – Summer 2014)
    
    Undergraduate research:
    My research project investigated the possibility that invasive Rosa multiflora may protect seedlings of the native tree Liriodendron tulipifera from deer herbivory. We set up a forest experiment in high and low deer density forests with both R. multiflora and L. tulipfera present as well as a greenhouse experiment.
    Current work:
    Currently, I’m working at Memorial Sloan Kettering Cancer Center as a Pathologist Office Assistant in New York City. I’m trying to take advantage of the opportunities my job and city has to offer. In the future, I hope to attend graduate school for Masters in Public Health with a concentration in Biostatistics.

• Undergraduate Researchers	Start Date	End Date
  Dave Nancaniano	Fall 2013	Fall 2014
  Alison Ball	Fall 2012	Spring 2014
  John Speigel	Fall 2012	Spring 2014
  Nicole Mallotides	Fall 2012	Spring 2014
  Priya Dalal	Fall 2011	Summer 2015
  Shane Wilkins	Fall 2011	Summer 2014
  Chika Akparantha	Fall 2010	Spring 2011
  Catherine Zymaris	Fall 2009	Spring 2012
  Joanana Sblendorio	Fall 2008	Spring 2010
  Amanda diBartolo	Fall 2008	Spring 2009
  Jason Wong	Fall 2008	Spring 2009
  Brian Dunn	Spring 2004	Spring 2005
  Kelly-Marie McCartney	Spring 2004	Spring 2005
  Heather McMahon	Fall 2001	Spring 2003
  Leone Brown	Fall 1998	Spring 1999
  Undergraduate Research Shadows	Start Date	End Date
  Kiara Proano	Fall 2015	Present
  Shanile Bautista	Fall 2015	Fall 2015
  Mari Angel Rodriguez	Fall 2015	Fall 2015
  Jessica Ayres	Fall 2015	Fall 2015
  Adriana Mendizabal	Fall 2015	Fall 2015
  Amanda St. George	Fall 2014	Fall 2014
  Elena Aversa	Fall 2014	Fall 2014
  Shreya Patel	Fall 2014	Fall 2014
  Ben Reason	Fall 2013	Fall 2013
  MaryJo Lambino	Fall 2011	Spring 2012
  Nupur Patel	Summer 2007	Spring 2008