Copyright 2011
CLIMATE-RELATED CLUES FROM PLANTS – MODERN & ANCIENT ATMOSPHERE STOMATA – special pores on leaves PHOTOSYNTHESIS water + carbon dioxide chlorophyll & sun sugar + oxygen CO 2 “Stomata” means “mouths”
Copyright 2011 If CO 2 levels in atmosphere are low, plants need more stomata to get enough CO 2 for photosynthesis If CO 2 levels in atmosphere are high, plants need fewer stomata to get enough CO 2 for photosynthesis SO numbers of stomata can be a clue to whether CO 2 levels were high or low at the time the plant was alive!
Copyright 2011 How do scientists count stomata? 400X
Copyright 2011 STOMATAL DENSITY Scientists can use stomatal density to determine whether past climates had high or low CO 2 and to compare past climates Stomatal density is the average number of stomata that can be counted in a microscope view.
Copyright 2011 STOMATAL DENSITY = average number of stomata area of the microscope view
Copyright cm In our activity, the circular area of the microscope field has been measured. And its area is 0.05 mm 2. Measure the diameter of the circular field of view, then calculate the area of the circle.
Copyright cm In our activity, the diameter of the microscope field is 0.25 mm. Find the area, to the nearest hundredth of a mm 2, and write it in the column in the worksheet table. Measure the diameter of the circular field of view, then calculate the area, using A = πr 2.
Copyright Looking through a microscope, count & record the # of stomata in 3 different areas on the slide – then find the average of the 3 counts.
Copyright 2011 Each team member will count stomata in one of the three areas of a slide The team will calculate the average of the three counts & divide the average by 0.05 mm 2 to find STOMATAL DENSITY (avg./0.05 mm 2 ) high value = lots of stomata = low CO 2 low value = fewer stomata = high CO 2
Copyright 2011 Each team member will count stomata in one of the three areas of a slide The team will calculate the average of the three counts & divide it by the area of the microscope field to find STOMATAL DENSITY (avg./area ) high value = lots of stomata = low CO 2 low value = fewer stomata = high CO 2
Copyright 2011 ACTIVITY 2 STOMATA SPECTACULAR This activity uses photomicrographs from an actual study of plant fossils
Copyright 2011 Stenochlaena Common Name: Thailand Climbing Fern You will find the Stomatal Density for 2 examples of different aged fossils of this fern and compare CO 2 levels for their time periods Photos copyright Japan International Research Center for Agricultural Sciences, used with permission.
Copyright 2011 Finding stomata in the photos