1 Create a triangle by using the Polygon tool. Draw the polygon and while drawing, hold the down arrow to reduce the number of sides. Fill it with a lighter green and add a heavy stroke of a darker green. Use the Stroke panel to round the corners of the stroke.
2 Duplicate the first triangle, then increase the size and place it below the first triangle. Do not scale the stroke and effects while sizing; open the Transform panel and make sure Scale Stroke and Effects is off before you scale.
3 Choose Object > Blend > Blend Options. Set the spacing to Specified Steps and choose 3 steps. Click OK.
4 Choose Object > Blend > Make to blend the shapes together.
Expand
5 Select the blended shapes and choose Object > Expand.
6 This creates shapes for each step of the blend. Select all the shapes.
7 Choose the Pathfinder Unite mode to make all the shapes into one shape.
8 Duplicate the shape and set the stroke weight to zero. Duplicate the tree and position it up and to the right slightly.
Draw Inside
9 Choose the Pathfinder Minus Front mode to leave a small section. Fill the small section with a darker shade of the fill color. Cut the shape using Edit > Cut.
10 Select the tree shape and choose the Draw Inside mode at the bottom of the toolbar.
11 Paste the darker section in and move it to the left, making a slip shadow. Click on the Draw Normal mode.
12 Add lines in the same color and weight as the stroke of the tree. Add a circle at the end of the rounded lines for visual texture. Select all the objects and group them.