Due to leaf senescence. In autumn the leaves stop being the sink for phloem transport so the nutrient supply dwindles so the leaves age and turn brown (since there are no nutrients to carry on producing more chlorophyll etc.).
Senescence occurs due to reduced levels of cytokinin (plant "hormone") production.
The Chloroplasts in the leaves die.
In the summer a trees leaves are green... they don't turn colors until autumn
autumn leaves
leaves turn colours in Autumn.
Most deciduous trees lose their leaves in Autumn . . . trees like maples, linden trees, elm trees; however, oddly enough, many oak trees do not lose their leaves in Autumn. The leaves turn colors, and then die and turn brown. The dead leaves take their time to drop off. In my area, some oaks still have their dead leaves as late as early Spring.
The leaves turn colors in the autumn. It was the autumn of her life.
Pine trees leaves do not change colour during autumn, as they are evergreen trees.
Brown gold yellow orange
In fall, the rugged brown leaves come out.
In the autumn or fall, leaves begin to lose their chlorophyll and turn different colors. After that, the leaves lose their cohesion and fall to the ground.
During the autumn season, fall leaves change color to shades of red, orange, yellow, and brown.
When a banana begins to ripen, the peel begins to change color. It changes from green to yellow to brown. The same occurs with autumn leaves. The green leaves change from green to red and yellow and orange and eventually brown.