Interesting links worthy of thought and further research. I do not necessarily endorse the conclusions.
Green roofs in Vancouver, BC and at Facebook.
Benefits of “green microbreaks” viewing nature images.
Results of Sustained Attention to Response Task (SART).
Starting in the 1960’s play time went down while school time went up.
During the same time mental disorders and suicide went up.
Do students need more time to learn, or do students need more time to play?
The Sudbury Valley School.
Standardized tests, creativity, and play.
Social skills and play.
This isn’t exactly nature, but many people worry about sweat and the resulting body odor that outdoor activities produce. This abstract of a study that compared two control groups finds “red meat consumption has a negative impact on perceived body odor.”