That piqued Knapp and Smith's interest and led them to search for other explanations.
"One of the important differences between grasslands and deserts is that grasslands have a higher density of plants, and these plants can grow faster than desert plants " Knapp said "If you think about a desert environment, there's lots of bare ground between plants.
Knapp said even though regions with tallgrass prairies have less rainfall variability, the ecosystem and its plants are well adapted to respond to that variability.
"They grow very rapidly in wet years, yet can survive drought years as well," Knapp said. "So we see the greatest variation in year-to-year production in grasslands as opposed to deserts, and we see very little year-to-year variation in production in forest sites. "
According to both Knapp and Smith, they were intrigued that their analysis didn't fit their initial prediction.
"We knew the plant growth and precipitation are strongly related as you move across North America," Knapp said. "We assumed that variability in precipitation and variability in production would also be strongly related across North America. It turns out they're not. One has to factor in the characteristics of the biome as well, the potential responses of the plants, how dense they are; how fast they can grow. You have to factor in these biological characteristics with rainfall patterns to explain these patterns of variation in production across North America."
Knapp said although Kansans already have a strong affinity for the state's tallgrass prairies, this research gives the prairies "added value" in terms of their potential role in detecting changes in future climates.