Ecopsychology research draws on a range of disciplines including geography, neuroscience and psychology. This is a sample of some accessible articles on the subject.

Ecopsychology: An Idea Whose Times Has Come Want to feel better about yourself—just walk outside.
by Steven Kotler

[A] study analyzed 1200 people involved in 10 separate studies done in the UK and found that a five-minute "dose" of nature was enough to improve self-esteem. The study also showed that this effect held across a variety of outdoor activities-from hiking through fishing through gardening (and even farming).

The Park Prescription: Take Five (Minutes) and Call Me In the Morning
By Deborah Fleischer

Just five minutes of exercise in nature can boost your mood and improve self-esteem. No surprise then that research shows that nature is better at treating moderate depression than antidepressant drugs - and it's cheaper!

Greening our minds: How nature nurtures the brain
By Larry Gabriel

We know spending time in natural settings is good for you, but research is now revealing the details: interacting with nature can improve self-confidence, enhance cognitive functioning and can even make us the less materialistic.

This Side of Paradise: Discovering Why the Human Mind Needs Nature
By Eric Jaffe

More evidence that nature can ease mild depression plus the news that it can also make us less aggressive.

If you'd like to go deeper into the subject, the Landscape and Human Health Laboratory has an extensive bibliography of research papers on the Human Health Benefits Of Natural Landscapes.