Exercise+2_Climate+and+Microhabitat

Exercise 2: Climate and Microhabitat ( Adapted and edited from Brewer & McCann 1982; Brower, Zar, & von Ende 1998) This Killdeer was observed on a ‘nest’ it made in the parking area between the Science II building and Barstow Ave. Why would it choose this odd ‘microhabitat’ for such an important life-history activity? Introduction As we discussed in lecture and as is covered in SimUText, climate, season, and weather affect the distribution and activity of both terrestrial and aquatic organisms. Climate refers to the general prevailing atmospheric conditions over the years in a given region. Climates are usually characterized by seasonal temperature, humidity, and precipitation. Weather refers to the momentary conditions of the atmosphere. Four major physical factors compose the atmospheric component of a habitat such as air moisture, temperature, wind, and solar radiation. Extremes, rather than averages, of these variables usually affect the distribution and abundance of organisms. In this lab exercise, we will focus on variation in simple climatic factors across small scales of space and time (microclimate). Climatic variables largely determine the type of biotic community in an area and the distribution of individual species. We will pay similar attention to the analysis of weather conditions that largely affect the daily and seasonal behavior and abundance of species. Background: Climate Climates are often broadly categorized by latitude as polar (or arctic), cold temperature (or boreal), temperate, and tropical, with terms such as subtropical or subarctic

denoting intermediate climates. Temperature and precipitation are characteristic variables. Recall that biomes distinguish both climate and predominant vegetation in large geographical areas. For a more detailed picture of the climate for a given region, ecologists use two types of climate diagrams (aka climatographs). In Figure 2B.1, the mean monthly temperature and the mean monthly precipitation are plotted for each month of the year, and the plotted points are connected sequentially to form an irregular polygon. Data for this type of graph are available from local weather stations or from government documents prepared by the National Oceanic and Atmospheric Administration (NOAA), Washington, DC (http://www.ncdc.noaa.gov); and regional climate centers (http://met.www.cit.cornell.edu/other_rcc.html). A second method of presenting the climate of a given region is to graph the mean monthly precipitation and mean monthly evapotranspiration as functions of time of year. Figure 2B.2 is an alternative presentation that helps to diagram water availability based on readily obtained temperature and precipitation data. As evapotranspiration is directly related to temperature, a plot of seasonal changes in temperature will be similar to a plot of evapotranspiration. A temperature of 10 ° C is considered roughly equivalent to 20 mm of monthly precipitation in terms of evapotranspiration (Walter, 1985). Consequently, points on Figure 2B.2 where temperature and precipitation curves intersect represent a condition where the amount of water lost through evapotranspiration is about equal to the amount gained through precipitation. Thus, in Figure 2B.2, July and August would have a water deficit in the Pacific Northwest but would experience a water surplus for the mid-Atlantic coast of the United States. Microclimate Variation in the local climate due to such factors as elevation, slope, vegetation, and shade can result in temperatures, humidities, and light intensities quite different from those of surrounding areas. For example, the atmospheric conditions in a forest on a north-facing slope are quite different from those on a south-facing slope ( Is this statement true in both the North

important to note that rates of evaporation are not directly related to relative humidity, but are a function of the vapor pressure deficit and the air temperature. 4. Wind Speed Wind speed can affect the distribution of heat and the removal of moisture from a habitat, affecting the relative humidity of the surrounding air. 5. Temperature a) Air temperature : Measure air temperature approximately 0.5m above aground (~ knee high). Take care to shield the temperature measurement device from direct sunlight. You can use either the onboard temperature measurement or the thermocouple probes to measure air temperature. b) Surface temperature : Touch the tip of the thermocouple probe to the ground surface, or place just below the water surface of the pond. Again, take care to shield the measurement device from direct sunlight. c) Instantaneous temperature : Temperature measured at a specific point in time. d) Diel (24hr temperature) temperature : Temperature measured across the 24-h day cycle. Would we expect the same amount of temperature variation across microhabitats over a day, regardless of their instantaneous temperatures at a specific time? Part of this lab will be to propose a simple measurement experiment using very small temperature probes to take temperature readings in various microhabitats every 15 minutes over a 24 hr period. Propose a study that will examine what variables affect the stability (or variation) of temperature over a given 24-hour period. Sources: Brewer, R., and M.T. McCann. 1982. Laboratory and field manual of ecology. Saunders College Publishing, Philadelphia. Brower, J.E., J.H. Zar, and C.N. von Ende. 1998. Field and laboratory methods for general ecology, 4 th Ed. WCB/McGraw-Hill, Boston. __________________________________________________________________________

Lab 3: Climate and Microhabitat Data Sheet Name: Mario Hernandez Lab Day/Time: Thursday/ 2-5 pm PART 1: Measure Instantaneous microclimates Form small groups of 2-3 people. You will work with this group throughout today’s lab. Your TA will instruct you on the use of the hand-held weather stations, and you can consult the instruction manual (should be in the case). Using the hand-held weather stations, measure light intensity, humidity, windspeed, air temperature and surface temperature at each location denoted in the table below. Write the measurements in the table below and INCLUDE UNITS. General Atmospheric Conditions: Cloud cover (%): 50% Recent precipitation?: Little rain Measurement Open ground (over gravel) Mini Greenhouse Tree Stand Pond Edge Pond Dock Light Intensity (units) 13580 lux 1519 lux 3430 lux 7940 lux 6410 lux Humidity 41.6 % R/H 56.0 % R/H 47.1 % R/H 56.2 % R/H 47.9 % R/H Wind Speed 4 km/hr 0 km/hr 0 km/hr 0 km/hr 0 km/hr Air Temperature (~0.5 m above ground) 22.5 °C 23.1 °C 22.4 °C 22 °C 22.5 °C Surface Temperature 1.6 °C 26.3 °C 15.2 °C 16.8 °C 27.2 °C 1. Compare the measurements from the different microhabitats. For any measurements that vary by ~10% or more among sites, suggest reasons why those measurements are so different in the space below. Please provide physical reasons rather than suggesting “measurement error.” The first measurement that varies by more than 10% is light intensity(Lux). The Lux is much higher in the open ground compared to the other areas and I believe this is due to more sunlight hitting the open ground as the other locations had trees covering the sunlight and also structures. The second measurement that varies by more than 10% is humidity in the mini greenhouse and the pond edge from the rest of areas. This is most likely due to these two locations having more water present. The pond edge could be more humid because it was next to a body of water and the mini greenhouse is very warm and humid. The last

PART 2: Influence of color on heat gain/loss (light vs. dark colored bottles) Each group will be assigned a single location. Use bottles wrapped in white & black to monitor changes in temperature over a short (10 min) time span. Track temperature by placing the end of the thermocouple within the water in the bottles. Calculate the change in temperature ( Δ T ) as the last temperature measured minus the first temperature measured. Location:Open ground(over gravel) Min. White Temp Black Temp Min. White Temp Black Temp 0 18.4 °C 20.5 °C 6 18.4 °C 16.6 °C 1 16.8 °C 17.9 °C 7 18.4 °C 17.2 °C 2 16.5 °C 17.4 °C 8 22.5 °C 24.7 °C 3 18.2 °C 18.5 °C 9 16.6 °C 16.3 °C 4 18.7 °C 17.5 °C 10 17.2 °C 17.6 °C 5 20.5 °C 20.6 °C White Δ T: -1.2 °C Black Δ T: -2.9 °C Using information from the other groups, complete the following table: White final T White Δ T Black final T Black Δ T Open ground (over gravel) 17.2 °C -1.2 °C 17.6 °C -2.9 °C Mini Greenhouse 19.3 °C -1.2 °C 22.11 °C 2.6 °C Tree Stand 25.3 °C -0.2 °C 26.3 °C -0.9 °C Pond Edge 23.3 °C 0 °C 21.7 °C -0.5 °C Pond Dock 23.4 °C 1.7 °C 23.2 °C 1.0 °C 2. Which location and bottle color was hottest after 10 min? The hottest was the black bottle in the tree stand. 3. Which location and bottle color was coolest after 10 min? The coldest was the white bottle in the open ground. 4. Briefly explain why these locations and bottle colors differed in temperature? These locations and bottle colors differed in temperatures because the black bottle in the tree stand was able to attract the sunlight since it was black and the color black attracts

sunlight. While the white bottle in the open ground was obviously the coldest since it was exposed to all the elements like wind and air and it wasn’t black so it didn’t attract as much sunlight as the black bottle would have. PART 3: Find the most extreme thermal environments Your challenge is to predict the locations that will have the most extreme temperatures near the greenhouses, using your knowledge from parts 1 and 2. First predict the hottest and coldest locations and explain your reasoning. Next, test your predictions by measuring the temperature at those locations. Finally compare your results to those of the other groups to see if you actually picked the most extreme thermal microenvironments. 5. Predicted HOTTEST location: Mini greenhouse . Reasoning: Greenhouses are usually very warm and humid inside which is why I believe it would be the most hot location. Recorded temperature: 23.1 6. Predicted COLDEST location: Open ground. Reasoning: The open ground would be the coldest because it is the most exposed to the elements like the wind and cold weather. Recorded temperature: 22.5 7. Confer with the other groups. Write the hottest and coldest locations discovered, and their temperatures below. The coldest location was the open ground and the temperature was 17.2 °C. The hottest location was the tree stand and the temperature was 26.3 °C. 8. If the locations with the most extreme temperatures differ from what you predicted, suggest physical properties that caused these locations to be even hotter and colder than your predicted sites. I predicted the coldest location correctly but no the hottest location. The tree stand was the hottest probably because it was in a more covered and concealed area allowing the heat to not escape. The coldest was the open ground and again this is due to the location being the most open and exposed to the cold.