SEE-U 2000: Black Rock Forest - Module 8:Exercise 8

Exercise Contents:

• | Your Questions
• | Background
• | Objectives
• | Key Skills
• | Timetable
• | Procedural Notes
• | Materials Needed

Exercise Contents:
Return to Module 8

# Black Rock Forest ## Exercise 8: Recycler Communities and Internal Forest Fragmentation Module 8: Decomposers: The End and The Beginning
Printer format ### Your Question What effects do linear disturbances such as hiking trails or power-line cuts have on carrion recycler communities? ### Background Internal fragmentation by power-line cuts, hiking trails, low-intensity dirt roads and other types of clearings cause a branching network of linear clearings in forest areas. These clearings can reduce the movement of many species from fragment to fragment. When it completely isolates populations from each other, this separation could potentially isolate gene pools and increase the risk of local extinction (Module 4). However, even when incomplete, a partial barrier effect may still alter the interactions between species, decreasing the ability of less vagile species (those that do not disperse far or quickly) to compete for patchily distributed resources and producing a reduced local community diversity. Linear clearings and their edge effects reduce total habitat area. Edge effects (Module 13) include abiotic changes in micro-environment such as increased light penetrance, heat, and increased wind and the consequent biotic changes. These edge-related changes in the forest often penetrate 100 m. Many species of forest birds and insects completely avoid forest edges. If edge effects are assumed to penetrate at least 50 m into the forest (a conservative estimate) a 10 m wide road may actually be equal to a 110 m wide reduction in habitat for forest species. These types of disturbance combine to suggest that areas that are more fragmented by roads may contain a community that is distinct from that found in less disturbed forests. More internally fragmented areas may support a less diverse endemic forest community and a higher percentage of the species present may be invasive exotic species (Module 14). Similarly, because smaller areas have proportionately more edge than interior and provide smaller targets for colonization, smaller fragments should contain a lower diversity of forest endemic species than larger fragments. These hypotheses are inadequately explored at present. A recent related study at the BRF using the diverse, abundant, and easily sampled carrion feeding burying beetles (Family Silphidae see http://www.eeb.uconn.edu:591/nicroweb/nicrophorus.htm) supports the prediction that communities are negatively affected by internal forest fragmentation. Burying beetles were shown to significantly avoid crossing roads. The aversion to this type of road crossing was determined to be primarily due to an aversion to exposed areas without leaf litter present. We will broaden these preliminary data to examine the effects of internal fragmentation on the composition and species richness of carrion feeding beetle communities. We will use species diversity and abundance of burying beetles, other species of carrion feeding beetles (Staphylinidae [http://www.ifas.ufl.edu/~insect/misc/beetles/rove_beetles.htm], Histeridae, Leiodidae, and Scarabaeidae [http://www.museum.unl.edu/research/entomology/guide/Scarabaeidae.htm]), in the areas surrounding internal fragmentation events within and around the BRF. Insect decomposers such as these are particularly appropriate for this study as they are susceptible to forest fragmentation. Burying beetles have very few young, both sexes often cooperate in brood care, and their natural brood failure rate can be high. As such, their already variable fecundity may be made even more so if the population movement is further restricted by internal forest fragmentation. A page that has excellent photos of the larger species that we will find in the traps is at http://collaboratory.acns.nwu.edu/fmnh/urbanwatch/hifi/fieldguide/beetles. We will revisit this question when we get to habitat fragmentation during Module 13 next week. However, during that time we will replicate this experiment along road sides ### Objectives Comprehension of the effects of linear human disturbances, such as roads, on decomposer communities. Conceptualization of the edge effect and how its influence changes with distance from the disturbance. Knowledge of the basic biology of arthropod communities that decompose carrion. Increasing understanding of the scientific method. ### Key Skills Capacity at designing a set of testable hypotheses around a question of their own design. Ability to use a predetermined experimental methodology and sampling regimen as basis for determining appropriate analysis and data configuration method. Improved familiarity with appropriate settings to use simple statistical tests (Chi-square, t-test, ANOVA) for data analysis. Ability to identify the key invertebrate species important in carrion decomposition. Improved fieldwork experimental design skills and GPS/eBiome dexterity ### Timetable Total elapsed time to perform the experiment : One day Traps will be set out on Thursday, five days before harvesting Sorting will occur on Tuesday Total elapsed hands-on time : approximately Eight hours Set up and preparation time = 1-2 hours Trap harvesting = 2 hours Specimen sorting = 2 hours Data analyses = 1 hour Web page creation = 1 hour ### Procedural Notes Sites could be laid out ahead of time by TA The students can just harvest and sort the beetles in the same day. Best location would be to do it nearby a power-line cut, but I don’t think that there are any that run through BRF—may have to do it outside the forest, which may be preferable to provide a change of pace. Alternative could be near a heavily trafficked walking trail—like near the main trail leaving from the parking lot near the gate. Should choose sites to allow greatest analytical flexibility, in accordance with the possible independent variables listed in General Methodology point #3 Sampling methodology Hang baited 2-liter bottles cut as at http://collaboratory.acns.nwu.edu/fmnh/urbanwatch/hifi/fieldguide/beetles/trap-diagram.html — except the flap should be cut so that it opens from the bottom (rather than the top as in the illustration, and the traps on the ground are not necessary, only the hanging bottle. TA will set traps out five days ahead of when they will be harvested in the late morning or early afternoon. Take GPS readings of the sites, to use to georeference the data after the beetles have been sorted at a later time. Collect the beetles from the traps using the methodology included here. Sort and identify all beetles to morphospecies that were collected in the traps. Enter raw data into eBiome. Do appropriate statistical analyses on richness, abundance, and diversity values. Think about how to go about doing the analyses—what would be the appropriate types of data analyses, given what we did during Modules 5 - 7? Presentation Mode Today we will present the information that we collect not in a traditional form, but rather by creating a class web page for the activity. Microsoft Word has a feature wherein you can type out the information that you want, create the charts and tables you wish to include, and imbed illustrations. This is done just using the regular program. Instructions: Go under View on the main menu bar, select Online Layout. Create the document using all the line drawing and background selection capability that you have available. When you have finished creating it, save the document as an HTML document (by selecting Save as HTMl... under the File menu option). ### Materials Needed One 2-Liter soda bottle per trap that has had a 5 x 5 cm flap cut into it, with the flap opening from the bottom One 15 gram piece of meat bait per trap One funnel per group(a cut-off top of a 2-liter bottle) Knife 50ml Falcon Tubes (at least one per trap for all sites) Soft forceps (for handling things you don’t want to touch!) Latex gloves (optional) Pure Ethanol Field notebook and pencils to write in rain, if needed GPS units and eBiome input sheets Sampling pan or bucket Sorting well trays