Its three multiple exposures done in camera on one image. The Nikon D90 ( as well as a lot of the newer model digital camera) will allow you to make multiple exposures on one image. Step one, set the camera to Multiple Exposure. The first exposure was the leaves against a bright sky. Shutter speed is set to a very fast exposure, I used 1/2000 for this image which will make the leaves very dark (under exposed). The second image was a shot of waves on the river, which created the horizontal lines, for this shot I left my shutter speed at 1/2000. You can experiment with exposure to get different effects. The third image was also of the waves in the river except this time I rotated the camera to put the waves on a diagonal to create the texture pattern. Because the leaves were under-exposed the pattern was able to fill into the dark areas of the leaves. The background was not completely blown out because of the very fast shutter speed, which allows the pattern to still show in the background. I have found this Multiple Exposure feature to be a lot of fun for some interesting results; I opened image in PhotoShop and converted it to Black and White and adjusted the curves to add a little more contrast. This technique can also produce some very nice color images also; I just liked this image in Black and White to bring out the patterns. Below are samples of the three images shot as single exposures. Try this effect on flowers, for some very unique images.
So now you know how I did it, get out there and shot some multiple exposures.
Please feel free to comment on my post,
You can see more of my photography on my Flickr page at http://www.flickr.com/photos/baw26/ or if you are interested in purchasing one of my photos go to http://fineartamerica.com/art/all/Bruce+Wunderlich/all