Create a nature inspired, out of bound photo effect in Photoshop

Final Result Preview:

Step 1:

Open two desert stocks. Cut a part from desert 1 (I resize it to 900x675 px) and move into desert 2 (resized to 900x804 px). You can use any your favorite tool (I used Polygonal Lasso Tool) to do it:

To edit the new part moved, create a new layer with Clipping Mask option:

Use soft brush with color #292a27 to paint over its top, then set this layer to Multipy 20%:

Create a new Curves Layer with Clipping Mask option:

After this step we see a part on desert with color that is not fit background. So we will fix it by adding a new layer above background layer:

Use soft brush with color #797c98 to paint on this part then set this layer to Color 100%:

Step 2:

Now we will change color and light to create dry and burning effect for desert.

Create 3 new adjustment layers:

Gradient Map:

Set this Gradient Map layer to Soft Light 100%.

Selective color:

Yellows: 41, 11, -27, 30

Blacks: -6, 0, 5, 0

Levels:

Then use soft black brush on layer mask of Level layer with Opacity 50% to reduce light on clouds as shown below:

Stamp all visible layers.

Step 3:

Create a new document (950x850 px) and fill it with white. Move desert (the result from two steps above) into it, reposition to make the stroke of desert picture:

Stamp all visible layers.

Step 4:

Open waterfall stock. I resize it to 600x900 px. Create a new layer with 642x939 px. Move waterfall picture into middle of the pic. Then stamp all visible layers.

Step 5:

Create a new document (1200x1000 px) and fill it with white. Create a new layer and fill it with Gradient.:

Drag a line from top to bottom:

Step 6:

Open hand stock. Cut it out and place it as shown below:

Create a new layer above hand layer with Clipping Mask option. Choose Spot Healing brush to remove blemishes hand. Make sure that Sample All Layers is checked on property bar. Then lower Opacity to 60%:

Step 7:

Create a new layer above hand layer with Clipping Mask option. Use soft brush, color #9f8079, Opacity 20%, flow 40% to paint over the hand. This step is to soften the skin appearance: