The effect of invasive plant species on the biodiversity of herpetofauna at the Cincinnati Nature Center

Size: px

Start display at page:

Download "The effect of invasive plant species on the biodiversity of herpetofauna at the Cincinnati Nature Center"

Marvin Morrison
5 years ago
Views:

1 The effect of invasive plant species on the biodiversity of herpetofauna at the Cincinnati Nature Center Nicholas L. McEvoy and Dr. Richard D. Durtsche Department of Biological Sciences Northern Kentucky University Highland Heights, KY 4199 Abstract Amur Honeysuckle, Lonicera maackii, is an Asian woody shrub that has recently spread throughout the eastern United States. Despite the existence of a documented life history of this exotic plant, no studies have been performed to determine its effect on the native herpetofauna. The Cincinnati Nature Center (CNC) has recently documented the invasion of its preserve by exotic plant species, predominantly L. maackii. However, its effect on much of the wildlife located at the CNC preserve, especially reptiles and amphibians, remains undocumented. We studied the biodiversity of amphibian and reptile populations at the CNC in areas dominated by L. maackii and in areas lacking exotics (old growth forests) to determine the effect of invasive plant species on herpetofauna abundance and distribution. Maps documenting vegetation abundance at the CNC were used to differentiate sampling plots within highly invaded (L. maackii) areas from those in non-invaded areas. Various collection techniques, primarily haphazard sampling, were used in measuring herpetofauna distribution and abundance. The data for each organism were taken in the field, and the organisms were released. The results suggest that the herpetofauna collectively use invaded and non-invaded habitat equally. Frogs (primarily Rana clamitans) were found to be larger, both in snout-vent length and body mass, in the non-invaded habitats compared with those found in the invaded habitats. Turtles (Terrapene carolina) were found only in non-invaded habitats, while snakes were found only in invaded habitats. It appears from this preliminary study that, if effects exist, Amur Honeysuckle may influence the distributions of amphibians and reptiles in different ways depending on the type of animal studied. Introduction Invasive species in many biological communities are having a devastating effect on the diversity and abundance of species within those communities. Lacking few if any population control mechanisms (e.g., predation), invasive species are rapidly able to populate an area and consume resources that might otherwise sustain native species. Plant species such as Asian Milfoil, Purple Loosestrife, and Kudzu are prime examples of run-away vegetation that were originally introduced as garden ornamentals or governmental solutions to erosion problems. The Cincinnati area and much of Ohio has experienced its own invasion by the Asian woody shrub Amur Honeysuckle (Lonicera maackii, Caprifoliaceae), which has recently spread throughout the eastern US (Luken and Thieret 1996). Despite the well-documented life history pattern of this plant (Luken 1988, Luken and Goessling 1995, Luken and Mattimiro 1991), no studies have been conducted to determine the effect of this exotic plant on native animal life. The Cincinnati Nature Center (CNC), founded in 1965, has a three-part mission statement: to provide the Greater Cincinnati community, especially young people, the opportunity to experience, study, and enjoy the natural world; to encourage understanding, appreciation, and responsible stewardship of the environment through education; and to preserve the heritage and integrity of CNC natural and agricultural lands. The CNC has three locations to the east of downtown Cincinnati. This research focused upon the main location of Rowe Woods, which is located at 4949 Tealtown Road in Milford, Ohio. This location is considered a sanctuary for nature and the people of Clermont County. It includes over 14 miles of trails that transect the 79 acres of natural habitat. Norse Scientist 51

2 Much of the wildlife within the area remains uncharted, especially the herpetofauna, or reptiles and amphibians. Moreover, portions of the CNC have been recently documented as invaded by exotic plant species, including Amur Honeysuckle. This research investigates the understanding of the effects of invasive plants (e.g., Amur Honeysuckle) on the reptile and amphibian biodiversity found at the Rowe Woods location. Additionally, this study will provide valuable survey and inventory information for contribution to the geographic information systems (GIS) analysis of the property. The focus of this investigation will be to compare the abundance and diversity of herpetofauna species that inhabit the old-growth forests to those of areas that have succumbed to invasive plant growth. The vegetative regions of the CNC identified by the Environmental Resources Management Center at Northern Kentucky University are of value in this study. This research is significant because it provides an accurate account of the species of reptiles and amphibians specifically found in the Rowe Woods habitat and the effects invasive plant species have on their distribution patterns. This kind of survey has not yet been explored in these wildlife areas, yet the amphibian and reptile population is important because herpetofauna is a major link in the food web. They can be predators to smaller vertebrates and invertebrates, and also serve as food resources for other vertebrates. An understanding of their biodiversity will help to explain their evolutionary standing within the community. To facilitate wildlife management practices, the reptiles and amphibians were surveyed to determine the habitat specificity and the range of diversity within each group found in the area. Materials and Methods This study took place at the Rowe Woods location of the Cincinnati Nature Center (CNC), near Milford, Clermont Co., Ohio (N W ). Twenty locations for both invaded and non-invaded habitat were identified using vegetation abundance maps provided by the Environmental Resource Management Center of Northern Kentucky University. Areas of the CNC with the exotic plant species L. maackii were termed highly invaded. Plots for collection of herpetofauna were organized within these areas throughout the CNC along with corresponding non-invaded plots of similar terrain and general surroundings. To ensure that biodiversity and abundance were analyzed accurately, we completed a census of herpetofauna. We incorporated a variety of collection techniques to determine, not only the species found, but also their patterns of habitat utilization and activity. Many of the trapping techniques were relatively inexpensive, requiring more manpower than equipment (Heyer et al 1994). Hide boards were deployed throughout the plots. These were simple mechanisms that provided animals with cover from predators and the drying effects of the sun. The hide boards were constructed from.25 OSB plywood and were placed flat on the ground, allowing for an entrance and exit crevice for the organisms. The boards were deployed in a transect fashion within each of the habitat types. Each board covered an area of.37 m 2, and 4 boards were placed in each of the 4 survey plots. The boards remained in the plots for about 7 days before they were lifted in search of herpetofauna. Manual searches for animals were conducted using hand and rake survey techniques over.5-hectare plots of each habitat type. Surveying took place regularly in the afternoon on alternate days from mid-august through mid-october, 21. Collection intensity and duration were rated to equal one man-hour of searching in plots termed invaded and non-invaded. The random manual searches yielded the largest number of organisms of interest. The data collected included the location (in GPS units), date, weather notes, general observations, and a systematic method for recording each individual collected. Additional information included digitally imaged pictures and video, species identification, position, microhabitat, and biological information (sex, SVL, mass, etc). T-tests were run to compare mean values of individuals, SVL mass, etc., between invaded and non-invaded areas. Alpha was set at.5. Results Located within the 2 pairs of plots were 13 different species of reptiles and amphibians (see Table 1). Considering the numbers of species and individuals among the 2 sites sampled, we found no significant difference found with respect to biodiversity or abundance between habitat types (Figure 1). 52 Norse Scientist, Northern Kentucky University

3 Table 1: Species found within the CNC Salamanders Snakes Frogs Turtles Desmognathus fuscus Eurecea cirrigera Notopthalamus viridescens Plethodon cinereus Plethodon glutinosus Plethodon richmondi Elaphe obsoleta Storaria dekai Thamnophis sirtalis Bufo americanus Rana catesbeiana Rana clamitans Terrapene carolina We also found no significant differences, in neither the frog nor the salamander populations, We also found no significant differences, in neither the frog nor the salamander populations, between the mean number of individuals inhabiting invaded and non-invaded habitats (Figure 2). Snakes were observed or collected only from the invaded habitats, and turtles were found only in the non-invaded habitats. Only one species of land turtle was found in the area: the box turtle (Terrapene carolina) snout vent length was used as a mea- 3.5 Mean Number per Site Invasive No n-invasive # Species # Individuals Figure 1. Biodiversity and abundance in invaded and non-invaded habitats. Mean values are given with +/-1 SEM bars. Mean Number of Individuals frogs salamanders snakes turtles Invaded Non-invaded Figure 2. Mean number of individuals by habitat. Mean values are given +/- 1 SEM. Norse Scientist 53

4 18 sure of amphibian and reptile body size; this factor did not vary for individuals found in both invaded and non-invaded locations (Figure 3). Frogs (Rana clamitans) and salamanders (Plethodon glutinosus) living in non-invaded and invaded habitats differed significantly in body mass, however, with the larger frogs found in non-invaded habitats (Figure 4). Discussion Interestingly, there are no significant differences in biodiversity and abundance between habitats. How- Mean SVL (mm) Invaded Non-invaded R. clamitans R. catesbeiana S. dekai T. sirtalis E. obsoleta B. americanus T. carolina E. cirrigera P. cinereus P. richmondi D. fuscus N. viridescens P. glutinosus 3 Figure 3. Mean body sizes of individual species found in different habitat types based on snout-vent length. Mean values are given +/- 1 SEM. 25 Mean mass (g) 2 15 Invaded Non-invaded 1 5 R. clamitans R. catesbeiana S. dekai T. sirtalis E. obsoleta B. americanus E. cirrigera P. cinereus P. richmondi D. fuscus Figure 4. Mean body sizes of individual species found in different habitat types based on body mass (g). Terrapene carolina was excluded because of its large mass scale. Mean values are given +/- 1 SEM. N. viridescens P. glutinosus 54 Norse Scientist, Northern Kentucky University

5 ever, a few species were found only in one type of habitat. Snakes were found only within the invaded areas, and the turtles were found only within the non-invaded areas. P. cinereus is found only in the non-invaded areas. Another interesting observation is that the frogs (R. clamitans) and salamanders (P. glutinosus) found in the non-invaded areas were heavier. This could result from increased predation by the more prevalent snake species in the invaded areas. If this is the case, the data could suggest that the frogs live long enough to become larger in the non-invaded areas. Another idea is that the frogs food source may be more abundant in the non-invaded area. Providing conclusive evidence for the validity of this idea would require additional study. The snakes may prefer the invaded areas because these areas provide a lower canopy and thicker shelter. The turtles may prefer the non-invaded areas because these are less dense and easier for turtles to traverse. Also, the Amur Honeysuckle does not allow many other plant species to grow within its surrounding area. The turtles may not find the food source needed within the invasive areas. In conclusion, although no significant differences were found of the invaded and non-invaded habitats, in the biodiversity and abundance, many other observations were made that were relatively unexpected. The short duration of this experiment may have contributed to the observations made. However, the time expended allowed for intriguing results that may spur new interests within the scientific community and the CNC. Acknowledgements This research was made possible by the Greaves Undergraduate Research Summer Fellowship fund at the Northern Kentucky University and by the cooperation of the Cincinnati Nature Center. We would like to thank the administration and staff of both groups involved, which contributed to the success of this research. I would personally like to thank Dr. Richard Durtsche for his professional guidance and patience. References Heyer WR, Donnelly MA, McDiarmid RW, Hayek LC, Foster MS Measuring and monitoring biological diversity: Standard methods for amphibians. Washington D.C.: Smithsonian Institute Press. 364 p. Luken JO Population structure and biomass allocation of the naturalized shrub Lonicera maackii (rupr.) maxim. in forest and open habitats. Am Midl Nat 119: Luken JO, Goessling N Seedling distribution and potential persistence of the exotic shrub Lonicera maackii in fragmented forests. Am Midl Nat 133: Luken JO, Mattimiro, D T Habitat-specific resilience of the invasive shrub amur honeysuckle (Lonicera maackii) during repeated clipping. Ecol Appl 1: Norse Scientist 55

6 Amanda Trout displays her research on algae dietary supplements 56 Norse Scientist, Northern Kentucky University

James Lowry*, Cheryl Nushardt Susan Reigler and Omar Attum** Dept. of Biology, Indiana University Southeast, 4201 Grant Line Rd, New Albany, IN 47150

James Lowry*, Cheryl Nushardt Susan Reigler and Omar Attum** Dept. of Biology, Indiana University Southeast, 4201 Grant Line Rd, New Albany, IN 47150 * jamlowry@ius.edu ** FACULTY ADVISOR Outline Introduction