How is the sampling design well suited to detect this phenomenon?

Elevation GradientsPage 2of 11Background InformationZonationZonation is the change in species composition ina community over a landscape. For example, the change in species composition as one climbs a mountainor the change in species composition along an ocean shoreline from the subtidal zone (always submerged) through the low, mid and high intertidal zones (experience times of emersion and immersion). Zonation can be caused by biotic factors, such as competition and food availability,and abiotic factors, such as moisture, salinity, and temperature, in a community. Often it is a combination of these factors that leads to the species composition that we observe in an area. Wewill look at zonation in an ocean shoreline community and in a mountain community. Measurements of Community Composition There are a number of different ways to measure and compare the diversity of organisms (biodiversity) in different communities. Species Richness The simplest method of examining community composition is to evaluate species richness, which refers to the total number of species in the community or species richness. So, if you go out and observe five different species in a community then your species richness is five. Species Evenness(or Abundance) Species abundance measurements calculate how many of each species is found in a community. ni= number of individuals of a particular species counted in ALL quadrats N = number of individuals from ALL species counted in ALL quadrats Species Abundance = n𝑖NSpecies DiversityRefined measures of species diversity account for both the number of species and the relative abundance of each species. Ecologists use diversity indices to generate quantitative estimates of species diversity that incorporate both species richness and evennessinto a single value. Simpson’s diversity index calculates diversity by estimating the probability of picking two organisms at random from the community that belong to two differentspecies. Simpson’s diversity index = 1 –DWhereD=∑ni(n−1)N(N−1)*Remember that the ‘∑’symbol means to sum the terms.Diversity values calculated using this index can range from 0 to 1 where 0= no diversity, all members of the community belong to the same species and 1= an infinite number ofspecies in the community, all with equal abundance
Elevation GradientsPage 3of 11In this study,we will compare species richness and species diversity vertically in the low and the high intertidal zone of the rocky shore. We will also examine how species composition changes along an elevation gradient in the IDF forest community. Methods/Set upI.Intertidal Habitat and Video Habitat SummaryEnvironmental stresses of the intertidalThe intertidal zone is the narrow region of the marine environment that lies between the areas covered by hightides but exposed bylow tides(typically a 2-4 m vertical height difference for coastal BC), and is therefore only sometimes submerged by water. Since it is regularly exposed to air, marine organisms that live in the intertidal zone must be adapted to severe fluctuations in physical conditions. The major physical factors that challenge intertidal organisms are temperature (heat and cold stress during exposure to air), desiccation (drying up), wave action, oxygen availability, and salinity fluctuation (important for tide-pool inhabitants).Since rocky intertidal organisms generally can’t burrow (exception: rock-boring clams can burrow into soft sandstone), they have adaptations for attaching to rock (e.g., muscular foot of a limpet, holdfast of a seaweed, etc.) to keep from being swept away by waves. Those that inhabit the higher regions of the intertidal zone have to spend more time out of water and must be better able to tolerate temperature extremes and desiccation. Some animal species hide in crevices or under seaweeds to keep from drying out during low tide. Bivalves remain tightly shut and limpets clamp their shell tightly to the rock to seal in moisture. Mobile species simply move further down in the intertidal and await the incoming tide. Seaweeds, on the other hand, just tolerate desiccation. Rockweeds (Fucusspp.) can withstand as much as 90% water loss from their bodies, becoming almost completely dried out and “crunchy,” but quickly rehydrate when the tide returns.Vertical Zonation in the IntertidalMost animals can feed only while under water, so sessile animals that live higher up in the intertidal have reduced feeding time than those that live lower in the intertidal. Yet their tolerance or adaptations to survive the harsh conditions may allow them to escape severe predation and competition, since somepredators and species that compete for space and food may not be able to tolerate the temperature fluctuations and desiccation. Mussels dominate the mid intertidal zone on many rocky shores, because they are good competitors for space. They cannot survivethe abiotic stresses of the high intertidal zone and they are prevented from occupying the low intertidal zone due to increased predation by sea stars. Sea stars tolerate desiccation even less than mussels, so they remain in the low intertidal zone, but access prey at the lower edge of the mussel bed. These are examples of how the distribution of organisms may be determined by their adaptations and their interactions with other organisms. The result is the presence of distinct bands of different organisms at different intertidal heights: this is called vertical zonation (Figure 1).
Elevation GradientsPage 4of 11Figure 1. Vertical zonation of seaweeds and of sea starsand mussels. Video Watch thevideo ‘Mayne Island Intertidal’(posted on Moodle). You will see that Lee (a KPU lab instructor) encounters different algal species (red, brown, and green seaweeds) and different sessile invertebrates (e.g., barnacles, mussels) and mobile invertebrates (e.g., limpets, snails, sea stars). Some of these animals, like the barnacles and mussels, are filter feeders, meaning they actively filter organic particles such as phytoplankton and zooplankton that are suspended in the water. Others have specialized feeding structures for scraping algae from rocks, e.g., limpets, and some snails are called grazers. Carnivores capture prey and include sea stars, crabs, and predatory snails that drill into mussels and barnacles. Other crab species and crustaceans, such as amphipods and isopods, are scavengers or detritivores. Scavengers feed on pieces of seaweed and other things that drift in from deeper water. FieldSampling Design and ProcedurePlease note that you will not be conducting field sampling. Rather, this portion is included in order to give perspective on you the data we will provide you with were gathered. Then with this data you will approximate community composition. Leesampled for you at two sites(thanks Lee!), one in the lowest intertidal zone (close to ocean) and one in the highest intertidal zone (farthest from ocean). A researcher would then record a brief description of the site, including measurements of physical factors, e.g., ifthe site wave-exposed or wave-sheltered, the air and water temperature (if any tide pools are present), and salinity (of tide pools); and describe the substrate (sand, gravel, boulders, rocky ledge, or mixture of gravel and boulders). In this lab the abiotic factor that we will focus on will be emersion/exposure time (with low intertidal organisms having less emersion timeand therefore less risk of dessication).In the high and low intertidal zones, Leeplaced a 20-m measuring tape parallel to the water line. Hethen used a random number generator to determine where to place theten, 30 x 30 cm quadrats along each transect line (Figure 2). The quadrats were placed out in order from the start to the end of the quadrat). Quadrats were randomly placed on each side of the transect line. Leecounted all of the individuals in each quadrat.
Elevation GradientsPage 5of 11Figure 2.Intertidal sampling location and sampling designin the intertidal zone of Mayne Island, BC.Leerecordedthe number of individuals of each animal species and each seaweed species found in each quadrat. Since seaweed blades tendedto overlap, hedeterminedindividuals by locating the holdfast. For smaller animals that live in large dense groups (e.g., barnacles), he estimated percentage cover, then counted asubset of the number of individuals in a smaller area (and notedthe size of the area), to convert the percent cover value to an estimatedtotal number of individuals (Figure 3).Figure 3. Example of 30x 30 cm quadrat deployed in the intertidal zone of Mayne Island, BC.II.Interior Douglas Fir Habitat and Video Habitat SummaryThe interior Douglas fir (IDF) forest is dominated by Douglas fir,Pseudotsuga menziesii, a common conifer species in BC;(Hope et al.1991). You can identify Douglas fir trees by the characteristic three-pronged bracts just below the scales of their cones (Figure4). Other tree species found in the IDF forest include ponderosa pine(Pinus ponderosa), white spruce(Picea glauca),Rocky Mountainjuniper(Juniperus scopulorum, western redcedar (Thuja plicata), western larch(Larix occidentalis), and white birch(Betula papyrifera). The IDF forest hosts multiple shrub species such as ocean spray, sagebrush, and soap berry. The map below indicates the extent of IDF forest in BCand the line depicts the approximate sampling location of this lab (Figure 5). This habitat is not completelycovered in trees, there are areas of open grassland with interspersed tree species as well.
Elevation GradientsPage 6of 11Figure 4. Douglas fir cones, Pseudotsuga menziesii. Figure 5. Distribution of interior Douglas firforest in British Columbia from Hope et al.(1991). The composition of the IDF community varies depending on the level of moisture. On south facing slopes where sunlight is most intense, soil moisture levels are reduced as elevation increases. The change in abiotic conditions,such as sunlight and moisture,createsvertical zonation in plant species as you climb the south facing slope of a mountain valley (Figure 6). You will look at this type of vertical zonation in your lab.
Elevation GradientsPage 7of 11Figure 6. From the top of the south facing slope in interior Douglas firforest field sitein the Okanagan Valley, BC.On the photograph the white transect line indicates the transect walked from the top of the slope to the valley bottom. The black line with quadrats is a schematicof the samplingthat was conducted.Field FootageCarefully watch/listen to the annotated PowerPoint slide show ‘IDF Presentation’ depicting field sampling on a south facing slope of a narrow mountain valley in the Okanagan region of BC. This slideshow was created and narrated by KPU instructor Carson. Thanks Carson! You will see that as Carsonmovesdown the sampling gradient from 600 m to the valley floor, the species composition as well as relative abundances change.Sampling Design Your goal will be to determine how plant species composition changes as you move from the top of the south facing slope to the river valley at the bottom. To collect data for you, Carson walked along asingle600m long line transect. Every 100 m, a single 10 x 10-m quadrat was sampled. The number of individuals of all tree and shrub species were recorded (Figure 6). This study focused on tree and shrubspecies, which means that, the abundance of grasses and other low growingspecies were not considered.At each site the researchers recorded information on soil type. The BC Ministry of the Environment Field Manual for Assessing Terrestrial Ecosystems (1998) includes a guide for identifying soil moisture regime classes. Xeric soils are soils that are extremely dry even directly after precipitation and hydricsoils are soils that are always inundated with water (Table 1).
Elevation GradientsPage 8of 11Table 1. Breakdown of soilmoisturetypes and their rankings. Adapted from B.C. Ministry of the Environment Land Management Handbook (2010). CodeClassDescription0Very Xeric Water removed extremely rapidly in relation to supply; soil is moist for a negligible time after precipitation1XericDry and drought resistant, little moisture retention, excessively drained. May have multiple assignments. Water removed very rapidly in relation to supply; soil is moist for brief periods following precipitation2Sub-XericMoist to dry, seasonally moist, periodically dry. Water removed rapidly in relation to supply; soil is moist for short periods following precipitation3Sub-MesicWater removed readily in relation to supply; water available for moderately short periods following precipitation4MesicMoist, adequate soil moisture retention year-round. Water removed somewhat slowly in relation to supply; soil may remain moist for a significant, but sometimes short period of the year. Available soil moisture reflects climatic inputs5Sub-HygricWater removed slowly enough to keep soil wet for a significant part of growing season; some temporary seepage and possibly mottling below 20 cm6HygricWater removed slowly enough to keep soil wet for most of growing season; permanent seepage and mottling; coloured (greenish/blue/grey) layerscommon 7Sub-HydricWater removed slowly enough to keep water table at or near surface for most of year; blue and/or graymineral or organic soils; permanent seepage < 30 cm below surface8HydricWet, plants periodically or often inundated by water. Water removed so slowly that water table is at or above soil surface all year; blue and/or graymineral or organic soils. III.AssignmentAll your completed work must be submitted on the Moodle page as a single PDF document, before the due date.Intertidal HabitatCalculationsAfter reading the lab exercise and watching the video of the intertidal community, open the Excel file entitled ‘IntertidalCommunity Data’. In this file you will see two tabs, a high and a low intertidal tab. Perform the following calculations to help you with your discussion questions.1.Calculate the total species richness for thelow and high intertidal sites.2.Calculate the relative abundance of each species two intertidal zones. You can do this by counting the mean abundance for all of your quadrats for each species and then calculating the relative abundance for each species.3.Calculate Simpson’s diversity index for each site.
Elevation GradientsPage 9of 11Intertidal HabitatFollow-up Questions As part of your assignment, answerthe following questions. Each correct answer is worth up to 5 marks. 1.At which site, low or high intertidal, was species richness highest or are the two measurements relatively similar? Propose an explanation for why richness is similar or different among the two sites. Feel free to use information from Lee’s video, the lab,and any other resources you feel are appropriate to help you answer this question, but cite the source if you do this. 2.At which site, low or high intertidal was diversity highest? Or are the two measurements relatively similar? Propose an explanation forwhy diversity is similar or different among the two sites. Again feel free to use resources here as long as you properly attribute them. 3.Where do organisms in the intertidal experience less desiccation stress? Where individuals in the intertidal experience more competition? Explain. Interior Douglas Fir HabitatCalculationsAfter reading the lab exercise and watching the slide show of the IDF community, open the Excel file entitled ‘IDF Data’. Performthe following calculations help you answer the discussion questions.1.Calculate total species richness along the transect lineand in each quadrat.2.Calculate relative abundance and Simpson’s diversity for each quadrat and the entire transect.3.Plot a line graph that shows how soil composition changes with elevation. You should plot elevation on the x-axis and soil composition on the y-axis.4.Finally, plot a line graph that shows how relative abundance for each species changes as a function of elevation. This graph should be similar to relative abundance graph in Figure 7. The x-axis should indicate elevation and the y-axis should indicate abundance. Note, your graph should have the same number of lines as the number of species found in the entire sample.
Elevation GradientsPage 10of 11Figure 7. Abundance of trees along a moisture gradient (Whittaker, 1956as cited byRelyea andRicklefs, 2018)IDF Follow-up QuestionsAs part of your assignment, complete the following questions. Each correct answer is worth up to 5 marks.1.Do you see a change in species composition from high elevation to low elevation? What abiotic factor(s) besides elevation may be associated with that change? How is the sampling design well suited to detect this phenomenon? How do the graphs that you made support your findings? 2.We calculated diversity and relative abundance in each quadrat in the IDF Forest study. Do you feel that these are accurate estimates of diversity? 3.Based on your analysis of the data, which tree and shrub species appear to be most drought tolerant? How do you know this? Which appear to be least drought tolerant?4.Finally, compare the sampling design in the intertidal survey to the sampling design in the IDF survey. How are they similar and how are they different? Describe some potential benefits and drawbacks to each kind of sampling.