Earth is the third planet from the Sun and the only object in the Universe known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.
Although forests are dynamic systems, the speed of change to which they are subjected is now at an unprecedented level. This is due to factors such as climate change, nitrogen deposition, the introduction of invasive species, and the loss of biodiversity and habitat.
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