Sardinian Dunes (IMAGE) Brown University Caption Under all kinds of circumstances and in places all over the world a wide variety of plant communities follow a pattern of stress response predicted by the Stress Gradient Hypothesis. Credit Mark Bertness/Brown University Usage Restrictions With credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.