Investigating canopy diversity in the Clemson Experimental Forest. K. Briana Cairco ... pooling data from traps in each treatment group (Fig. 2). The proportion of ...
Investigating canopy diversity in the Clemson Experimental Forest K. Briana Cairco, Robert Bennett, Langston Jones, Charles Matthews, John C. Morse and Michael Caterino Clemson University, Clemson, SC
Introduction The Clemson Experimental Forest (CEF) is a 17,500acre (7,082-hectare) forest maintained by Clemson University, a land grant university in South Carolina (USA). As part of an ongoing project cataloguing the insect biodiversity of the CEF, insects were sampled to determine whether the canopy of the temperate deciduous forest contributes as much to the arthropod diversity of the forest as the understory.
In the well-studied tropical rainforests, as much as 50% of the insect diversity exists only in the canopy of the forests (Stork and Grimbacher 2006). This may hold true for the less well studied temperate forest canopies of the world, but few studies have investigated the topic (Ulyshen 2011). The Clemson University Creative Inquiry on insects of the Experimental Forest provided an opportunity for us to test this trend in a temperate setting.
Objectives Design a trapping method to collect insects from both the canopy and understory. Collect and identify specimens to family level. Compare relative diversity between collections from canopy and understory traps. Determine if families show preference to canopy/understory based on proportional distribution.
Over 1400 individual insects were collected, curated and sorted to family. Collection information was recorded in a spreadsheet that is available in the electronic appendices. A family accumulation curve was created by pooling data from traps in each treatment group (Fig. 2). The proportion of individuals in each family that were found in traps belonging to either treatment group is summarized in Table1. Those families that showed greater than or equal to 70% specificity to a treatment group were tentatively considered specialists to that environment, pending further investigation. Figure 3(Left): Unrooted dendrogram based on corrected BrayCurtis Dissimilarity(after Clarke et al. 2006). Distance represents differences in fauna collections between traps. Canopy traps are boxed in green, and understory traps are boxed in purple.
Materials & Methods To maximize spatial difference between the canopy and understory samples, we chose to conduct our study in the Aull Natural Area which is one of the longest standing undisturbed sections of the forest. We then devised combination flight intercept/malaise traps adapted from a design by Bar-Ness et al. (2012). A diagram of our adaptation is show in Figure 1. We constructed 8 traps, 4 for use in the understory, and 4 to be suspended in the canopy. Trapping areas were scouted and 8 trees were chosen to suspend our traps on. Understory traps were simply hung from a branch at about 3 meters above ground, and canopy traps were suspended from a branch about 25 meters above ground.
Figure 1 a) 11kg fishing line tied to holes drilled in water bottle and secured over tree branch b) Mason jar with propylene glycol secured to water bottle using aquarium sealant. c) Top of 5 gallon water bottle used to funnel insects into jar. d) Two perpendicular plastic screens secured between top and bottom bottle segments via wooden dowel rods.
Results & Discussion
The fishing line anchor was launched to a suitable tree branch in the canopy using a bow and arrow, then mounted to the ground for future access.
Samples were collected weekly for 7 weeks and specimens were identified to family and preserved in 90% EtOH. As the most abundant taxa, only dipterans and coleopterans were used in data processing. Data for individual traps and canopy and understory levels collectively was processed using Excel, Program R, and Paup4.
Family
Table 1 (Right) Shows the Coleopteran and Dipteran families identified and the proportion of individuals found in canopy/understory traps. Families were labeled “specialist” if more than 70% of the specimens were found in the canopy/understory.
Observed Specificity by Family (Proportional) Canopy Understory Group
Empididae Tachinidae Sarcophagidae Heleomyzidae Faniidae Anthomyiidae Drosophilidae Chironomidae Ephydridae Muscidae Scathophagidae Calliphoridae Tipulidae Culicidae Cecidomyiidae Sciaridae Mycetophilidae Phoridae Anisopodidae Psychodidae Aulacigastridae Latridiidae Laemophloeidae Curculionidae Cryptophagidae Staphylinidae Curculionidae (scolytinae) Nitidulidae
1.00 1.00 0.86 0.83 0.66 0.56 0.56 0.55 0.50 0.50 0.47 0.47 0.44 0.38 0.36 0.29 0.28 0.24 0.17 0.15 0.11 1.00 0.75 0.64 0.52 0.33 0.17 0.00
0.00 0.00 0.14 0.17 0.34 0.44 0.44 0.45 0.50 0.50 0.53 0.53 0.56 0.63 0.64 0.71 0.72 0.76 0.83 0.85 0.89 0.00 0.25 0.36 0.48 0.67 0.83 1.00
Canopy specialist Canopy specialist Canopy specialist Canopy specialist Habitat Generalist Habitat Generalist Habitat Generalist Habitat Generalist Habitat Generalist Habitat Generalist Habitat Generalist Habitat Generalist Habitat Generalist Habitat Generalist Habitat Generalist Understory specialist Understory specialist Understory specialist Understory specialist Understory specialist Understory specialist Canopy specialist Canopy specialist Habitat Generalist Habitat Generalist Habitat Generalist Understory specialist Understory specialist
The canopy traps, as a whole, are extremely variable, with dissimilarities between traps as Figure 2 (Above): Graph depicting high as 96% (Fig. 3). While the numbers of families documented in the understory traps seemed to two sample groups over the 7 sample periods. share similar family composition, the canopy traps were highly variable in comparison. With more sample periods in different seasons we hope to continue adding to our data and expanding on the sparse research regarding temperate canopy diversity.
References
Bar-Ness, Y.D., McQuillan, P.B., Whitman, M., Junker, R.R., Cracknell, M. & Barrows, A.. 2012. Sampling forest canopy arthropod biodiversity with three novel minimal-cost trap designs. Australian Journal of Entomology 51: 12–21. Stork, Nigel E., Grimbacher, Peter S. 2006 Beetle assemblages from an Australian tropical rainforest show that the canopy and the ground strata contribute equally to biodiversity. Proceedings of the Royal Society. 273: 1969–1975.
Ulyshen, Michael D. 2011. Arthropod vertical stratification in temperate deciduous forests: Implications for conservation-oriented management. Forest Ecology and Management. 261 (9): 1479–1489.
Acknowledgements
We like to thank the Clemson Experimental Forest and the Clemson University Creative Inquiry program for providing the opportunity to complete this project.
