1 . The world is getting greener, according to a new study published in Nature this week.

Chi Chen, lead author of the study, and his colleagues have been mining data collected by an orbiting NASA camera that monitors green vegetation on Earth’s surface, day by day. Even more interesting: They are able to show the exact causes of increasing or decreasing leaf cover in particular areas.

In some cold places, increase in leaf cover apparently resulted from global warming. Since the climate is becoming more and more temperate and the growing season is getting longer and longer, the plants are growing bigger and leafier there.

2 . A wildfire kills most things in its path, but despite the flames and intense temperatures, rarely is everything reduced to ashes -and that plays a key role in a forest's regeneration. Just one year after the fire, the survivors dominate the forest, and grasses replace the burnt ground. Wildflowers are abundant bushes and small trees have started to grow, and Jack Pine returned. So, it's an amazing ecological system of creating new forest life when it appears that all is lost, one that has evolved throughout the ages, where fire has always played a vital role.

3 . The number of trees larger than two feet across has declined by 50 percent on more than 46, 000 square miles of California forests, the new study finds. No area was spared or unaffected, from the foggy northern coast to the Sierra Nevada Mountains to the San Gabriels above Los Angeles. In the Sierra high country, the number of big trees has fallen by more than 55 percent; in parts of southern California the decline was nearly 75 percent.

4 . The connection between people and plants has long been the subject of scientific research. Recent studies have found positive effects. A study conducted in Youngstown，Ohio，for example, discovered that greener areas of the city experienced less crime. In another, employees were shown to be 15% more productive when their workplaces were decorated with houseplants.