Still said that the authors believe this study is unique in linking clouds to soil microbial activity. "While most previous research on fog and ecosystems has focused on its role in plant-water relations such as the well-known linkages between fog and coast Redwoods we show that soil microbial activity and metabolism in these coastal ecosystems may be very dependent on the light but frequent fog drip that occurs during the rainless summer months," said Still. The study is also unique in linking fog and low clouds to the carbon cycle of a coastal ecosystem, including its impact on tree growth and soil respiration.
"What we found was that there are two major effects of the clouds," said Carbone. "One is shading, which keeps the temperatures cooler and the soil moisture higher. The other is fog drip, which is a water input into the soil."
The soil moisture content was not depleted as rapidly where the trees were under more cloud cover, and thus they were able to grow longer into the dry season. Water pulses from fog drip immediately stimulated microbes in the litter and soil below, but did not directly enhance pine tree activity. The microbial activity releases carbon dioxide into the atmosphere.
"This study provides us with a greater understanding of how fog and the low coastal clouds which Californians commonly call 'the marine layer' affect plant growth and the activities of microorganisms in the soil," said John Randall, scientist with The Nature Conservancy, which owns and operates Santa Cruz Island in cooperation with the National Park Service and the University of California. "Their findings of the importance of fog and low
|Contact: Gail Gallessich|
University of California - Santa Barbara