Academic journal article The Science Teacher

Keeping a (Digital) Eye on Nature's Clock: Students Use Digital Cameras to Monitor Plant Phenology

Academic journal article The Science Teacher

Keeping a (Digital) Eye on Nature's Clock: Students Use Digital Cameras to Monitor Plant Phenology

Article excerpt

Many of your students probably take pictures daily. Whether snapshots of their friends at a Justin Bieber concert or of their latest skateboard trick, these images document changes in a student's life. Digital cameras can do more, however, than record memories to post on Facebook. They can also help students examine changes in their environment. This article shows how to use a digital camera as a "scientific visualization tool" to monitor plant phenology over the course of a year.

Phenology, or the study of periodic natural events, is a growing body of science that is important to understanding our changing climate. By visually analyzing changes in nature, students can learn about their environment and provide scientists with valuable data to aid in global climate change research.

The activities described here align with several of the Scientific and Engineering Practices of A Framework for K-12 Science Education (NRC 2012), as students plan and carry out their own investigations, analyze and interpret data, use mathematics and computational thinking, and construct evidence-based explanations.

Such widespread technology as digital photography has been recommended for use in science classrooms for nearly two decades [Benchmarks for Science Literacy (AAAS 1993, pp. 47-48, 56-57) and the National Science Education Standards (NSES) (NRC 1996, pp. 190-192)]. A 2004 article in this journal noted, "Digital cameras open up enormous possibilities in the science classroom, especially when used as data collectors" (Leonard et al. 2004, p. 34). Nowadays, digital photography is ubiquitous; even many cell phones have a built-in high-quality digital camera; accordingly, we should show students how their cameras and smart phones can become tools of scientific measurement.

Phenology, the study of our planet's clock

Spring 2012 was the warmest of recent record. This meant earlier flowering dates for many plant species across the country, but why should we care? Tracking the chronology of periodic phases of plant development can provide data that helps test such hypotheses as: (1) Across the Northern Hemisphere, spring is arriving earlier at a pace of approximately 1.2 days per decade (Haggerty and Mazer 2008), or (2) An increase in the mean annual air temperature by 1 degree Celsius leads to an extension of the growing season by 5 days (Chmielewski and Rotzer 2001).

Phenology is one of the most prominent bioindicators of biological systems affected by climate change. Significant correlations exist between winter and spring temperatures and spring phenological phases, such as bud burst, leaf unfolding or flowering in mid and higher latitudes (Estrella and Menzel 2006; Soudani et al. 2008). Similarly, leaf senescence ("brown-down") and leaf drop in the fall can relate closely to both temperature and water availability. Such bio-indicators can suggest that our planet's nutrient cycling processes are changing and that farmers and gardeners will have to adjust the timing of planting or harvesting their crops, that migrating insects will have to adjust to new peak pollination times, that students' backyards could provide habitat for plants that require a longer growing season, or that the annual family vacation to see fall colors will have to be postponed.


Figure 2

A simple spreadsheet can help your students record their data. This sheet of RGB data recorded by a senior biology student in Minnetonka, Minnesota, is accompanied by photos of the oak tree she examined on September 6 and October 4, 2011. Students can also consider other variables, such as day length, temperature, cloud cover, and dew point. Henson also recorded temperature data (not displayed).


Table of recorded color RGB data for Oak Tree

Date     Red  green  Blue

Sept 6    13   104     63
Sept 7    13   104     63
Sept 8    13   102     65
Sept 9    13   102     65
Sept 12   13   102     65
Sept 13   15   102     63
Sept 14   15   102     63
Sept 15   15   102     63
Sept 16   15   102     63
Sept 17   15   101     64
Sept 19   15   101     64
Sept 20   18    99     63
Sept 21   18    99     63
Sept 22   30    92     58
Sept 26   34    90     56
Sept 27   39    86     55
Sept 28   46    79     55
Sept 29   59    68     53
Sept 30   67    60     53
Oct 1     78    51     51
Oct 2     89    48     43
Oct 3     96    48     36
Oct 4    113    37     30

For now, predicting the annual timing of fall leaf coloring and spring green-up remains challenging for scientists due to a lack of ground observations (Delpierre et al. …

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