The natural world exhibits substantial variation in climate, which influences the distribution, reproductive success, and survival of plants and animals. Although students are aware of weather, their understanding of climate is typically less clear, especially the concept of microclimate--the climate of a specific place within an area as contrasted with the climate of the entire area. Microclimate can influence where birds place their nests (Lloyd and Martin 2004), where insects reside (Lorenzo and Lazzari 1999), and where plants successfully germinate (Tomimatsu and Ohara 2004). Therefore, microclimate can have a profound effect on local community structure and biodiversity, particularly on plants, which are unable to move and thus often limited by local environmental conditions.
Students can gain an appreciation for the structure and function of local environments by studying the potential impacts of small changes in local microclimate on plant distribution. The concept of microclimate is easy for students to comprehend, simple to measure, exists in all schoolyards, and has important and tangible ecological implications. This article discusses an inquiry in which students learn the differences between weather and climate as well as the degree of natural variation in climate that exists across spatial scales. In this activity, students are introduced to the concept of climate and how climate varies. Students also observe and measure variation in microclimate and plant distribution throughout the schoolyard and learn to make associations between the microclimate and plant life.
Preparing for a microclimate investigation
This investigation is designed to address National Science Education Standards A (Science as Inquiry) and C (Life Sciences) by examining how variation in abiotic factors can lead to variation in the distribution of plants (NRC 1996, pp. 30, 37). Successful completion of this inquiry requires roughly two one-hour class periods: the first to establish the ecological foundation of this exercise, introduce students to the vocabulary, and gather measurements; the second to compile data, make maps, and discuss findings.
The activity requires a few basic materials (Figure 1), a map of the schoolyard (Figure 2a, p. 40), and a datasheet (Figure 3, p. 40). If students are interested in looking at the influence of microclimate on specific plant species, a book of local flora is also useful. A simple hand-drawn map of the schoolyard is sufficient, but all students should work with the same map to make combining and comparing data among groups easier.
The datasheet (Figure 3) should include columns for the sample number, plant type, and microclimate variables such as temperature, relative humidity, wind speed, and light availability. To measure microclimate conditions, students can use any of the following instruments: a thermometer (temperature), hygrometer (relative humidity), anemometer (wind speed), or photometer (light intensity). The exact variables measured depend on the equipment available and the interest of the class. Instruments that give instantaneous digital readings are ideal. Any instrument that measures relative humidity also measures temperature and is therefore well suited for this activity.
Introducing basic concepts
Before heading out to the schoolyard, introduce students to the basic concepts needed to successfully understand and measure microclimate. Open discussion is a good method for introducing the related vocabulary (Figure 4, p. 41), which includes terms that may be new to students. For example, have students describe simple concepts such as current weather conditions, the components of weather (e.g., temperature, rain, wind, or snow), and trends in weather at different locations around the world (e.g., tropics versus polar). Students should discuss the important distinction between weather (the state of the atmosphere at a given time) and climate (the average or prevailing weather conditions). …