Here are some possible answers for the Plants and Climate Change student sheet questions.
EurekAlert Article, Part A
It is always important to run an experiment more than once. Sometimes random fluctuations can occur that may skew your data, and by repeating an experiment more than once, you basically get a better picture of what’s happening. Also, for this experiment, climate change is a gradual process. By doing a long-term study, it is easier to simulate the effects of global climate change since the effects usually occur slowly over time.
The scientists manipulated the climate for the area by adding water as predicted by the climate change models. In adding water to certain plots, those plots had to adapt to the new climatic conditions. The scientists found changes in the experimental plots over time that they could measure.
Controls are important for making comparisons. If the scientists changed how much water the plots received but had no control plots for comparisons, then how would they know how much the grassy plots had changed?
Climate Change Research in California, Part A:
The area is expected to become wetter—global climate change models predict that as time goes on, this specific area will receive more rain.
With the addition of more rain, the plants in the area may grow more rapidly and in greater abundance. The animals that feed on the plants may have more food at first, causing their populations to grow. As the populations grow and there are more mouths to feed, food may become scarce and the animals may die off. Other animals that feed on the herbivores may die off as well, as their food sources will decrease. Over years, the quantity and distribution of specific species of plants may change with a corresponding change in animal diversity.
One of the most famous graphs in science is the Keeling Curve (see http://scrippsco2.ucsd.edu/ ). Part of the atmospheric increase in carbon dioxide is attributable to human inputs. Carbon dioxide emissions from cars, industry, and other known greenhouse gas emitters can be discussed to see if students’ opinions change about human impacts.
EurekAlert Article/Climate Change Research in California, Part B:
With the additional rain, nitrogen-fixing plants thrived. As those plants grew in greater abundance, they essentially fertilized the annual grasses and caused the annual grasses to grow in greater abundance. The insects in the area thrived as well in response to the extra water. In time, the large amount of grasses began to die and created a litter layer. This dense litter layer decreased species richness, and as plants died, so did the food source for many insects. As a result, many insects died. Species diversity changed over time as predicted. However, what was most interesting was that the longer the experiment in the CA grassland meadow went on, the more simplified the food web became rather than increasing in complexity as had been predicted.
This answer will vary based on your students’ research.This teacher sheet is a part of the Simulating Climate Change Research in Grasslands lesson.