SEE-U 2000: Biosphere 2 - Module 13:Exercise 13

General Methadology for Instructors and TAs
## Exercise 13: Do Roads Affect Biodiversity? Module 13: Habitat Fragmentation and Deforestation Printer format ### Background Lecture Instructor gives biological background on the forms of habitat fragmentation, some of their effects on biodiversity, and results that others have found. Roads have several impacts on biodiversity The impact of roads on biodiversity tends to be greatest immediately at roadside and then decrease rapidly, although roads do have an effect several hundred meters into the forest At road sides the habitat is drier, hotter, brighter (more sun), more open, windier, and there is a different plant community there than deeper into forests ### Student Pre-field Preparation After lecture, before the start of field time, the students will be asked to confer with their lab mates and will be required to draw up a plan outlining how their group will collect the data Instructor and TAs need to remind students of desert field safety ### Activities in the experiment Students should be allowed to brainstorm on their own, but be directed towards something close to the following experimental layout. The activity will occur in Tucson Mountain Park (TMP), on and around the Sonoran Arthropod Studies Institute (SASI) property. Steve Prchal is SASI’s director. Experimental Plan: Lay out transects perpendicular to roads of different traffic intensity, different road surface, and/or different road widths Given small class size, only two replicates from no more than two road types should be used — total of four transects Could assign three students to each transect Because road effects tend to be greatest immediately at roadside and then to decrease rapidly, the transects should follow something close to the following layout: 0m (roadside), 6m, 12m, 24m, 48m, 84m, and 120m An overall distance of 120m from the road should be maintained to ensure that the deeper patch dynamics will be sampled Students should sample for each of four tree/woody species (see b.i. below for list) If there is not an individual of a desired species at the transect line, then the students should move laterally until the first one of the desired species that they find, and then that one should be sampled. The sampled tree/woody plant should be the same number of meters from the road as the desired sample location. Slope, drainage, surrounding topography, and surrounding vegetation should be standardized among all transects Best transect locations would be to have two off Gates Pass Road (a two-lane paved high intensity road) and two off the immediately adjacent single-lane unpaved dirt road that leads up to SASI Dirt road sampling would have to be located approx. 200m from Gates Pass Road Permission to sample on TMP will have to be obtained, Steve Prchal has said that there will be no difficulty in doing so. Students should sample from four different woody species for all arthropods on the plant. Preferred woody species: Ironwood (Olneya tesota) Mesquite (Prosopis sp) [Need to check which sp. — P. julifolia is not listed in Flora for the Tucson Mtns (Rondeau et al., Desert Plants 12(2) Dec 1996) ] Palo Verde (Cercidium floridum) Burbush (? Franseria/Ambrosia sp) First three species can be sampled using beating sheets, the last would be done using a sweep net One student should beat and the other should aspirate the insects, but not the spiders Priority in collecting: those that are quick to escape (homopterans and orthopterans), then ants All arthropods that are on the beating sheet should be collected Beating and sweeping efforts should be standardized Beating: Working quickly, the students should place the 1m X 1m beating sheet under a branch on the tree and quickly beat the branches immediately above the sheet for 10 seconds The beater should then hold the sheet while the aspirator collects the insects One beating per tree Sweeping: with sturdy sweep net, students should quickly sweep entire Burbush (?) plant and collect all insects that are in the sweep net. All insects that have been collected in the aspirators are then transferred to 70% ethanol vials for later sorting Sorting will occur at SASI, in the conference and educational facilities The facilities are comfortable and ample for a class of 12-15 size, with air conditioning, bathrooms, computer projector, etc. Students should sort the taxa to morphospecies these specimens should be used to create a reference collection for next year ### Hypotheses to test (two sets) Roads negatively effect overall insect biodiversity (richness and abundance) in desert ecosystems (biodiversity should be lowest in sampling points closest to the road) Ha: Overall insect biodiversity is either not affected or is increased as a consequence of roads being present Road surface, traffic intensity, and road width mediate the influences of roads (as all three increase in human development, biodiversity should decrease) Ha: Road surface, intensity, and width either do not have an effect on biodiversity, or insects are more diverse in the transects nearest the high intensity roads ### Independent variables in the experiment Road condition Distance from road Plants from which the insects are collected ### Dependent variables in the experiment Species richness Average per species abundance Overall insect abundance Taxon specific richness Taxon specific abundance Simpson diversity index Shannon-Wiener diversity index Jaccard similarity diversity index Morisita-Horn similarity diversity index ### Student Evaluation Oral report will be no more than 15 minutes long — depending on how the students organize themselves, there may be as few as a single presentation Students should submit in their journals answers to the following questions, referring to the experimental results for justification of their answers How could the effects of roads be mitigated in these ecosystems? Would it be possible to retain roads, but manage the surrounding habitat differently and thereby reduce the road effects? What were some of the possible reasons why you observed what you did? How do you think that roads effect biodiversity? What are the proximate mechanisms?