No leaves. No photosynthesis. No food. How do trees survive in winters?

They find their strength in fasting. Water fasting to be exact, as their roots continue to suck in water. 

Just like us, trees need water and food to live. Food in this case is carbohydrates generated by photosynthesis in leaves. These carbohydrates are utilized for:

1. Living: Performing essential biological functions (e.g. respiration and generation of chlorophyll). You see, this chlorophyll is a tricky substance. It breaks down easily. So the tree has to work to manufacture it continuously to keep the leaves green. 
2. Growing: Producing new cells for tree growth.
3. Reproducing: Making flowers and fruit.

In summer, there's no problem. There's plenty of sunlight to fuel photosynthesis, which produces tons of carbohydrate to grow and give fruit. In winters, there's not much sunlight. So the output of photosynthesis drops dramatically. Hence it's not worth the effort to keep making chlorophyll. So, evolution came up with this neat idea: 

Every winter, the tree sucks in all nutrients from its leaves causing them to fall off, cuts down its energy needs, shuts down growth, and, enters a period of rest called "dormancy."

During dormancy, trees also break down their stored carbohydrates. This increases the concentration of sugars in the cell sap throughout the tree. The elevated sugar level acts as an antifreeze, helping protect the tree from freezing damage. 

Here are some latest pics from the orchards. Click on them for larger view.

Carpenter Ranch:

Whitmore ranch: