Pacific Spirit Regional Park

One of the things we don’t emphasize enough at the Garden is the fact that we neighbour Pacific Spirit Regional Park. The cliffside forest to the west of the David C. Lam Asian Garden, the Garden’s entrance and our parking lot provides biodiverse frames for our views of Georgia Strait and the distant Gulf Islands. This photograph, from our parking lot, shows what can happen (oh so very rarely) when one encounters a combination of late afternoon autumn light and a retreating (or advancing) fogbank directly above where the open water meets the cliff.

Ecological processes are difficult (for me) to photograph, but I do think this image at least partially illustrates the effect of vegetation on light attentuation–where the foliage is thickest, most of the light is absorbed or reflected. Thin or no foliage, of course, permits light to pass through. Figure 1 in Schäfer, K. V.R. & Dirk, V. W. (2011) The Physical Environment Within Forests. Nature Education Knowledge 2(12):5 shows how the intensity of light reaching the forest floor and lower levels of the forest declines with canopy height in an oak forest in the summertime.

The variable amount of light reaching the forest floor in different seasons can prompt niche differentiation, defined on Wikipedia as “the process by which natural selection drives competing species into different patterns of resource use or different niches”. As an example, the floor of eastern North American hardwood forests, where one finds species such as Trillium grandiflorum flowering in the early spring, has a number of early spring-adapted plant species that complete growth and flowering before the leaves fully emerge on the canopy trees. The forest floor species that occupy the same physical space but instead grow and develop during the summer have to deal with the low intensity of light and generally drier soil conditions (but, conversely, do not have to be adapted for potential early spring conditions such as harsh frosts or snow). Occupying (potentially competing for) the same space but adapted to conditions associated with different times, spring- and summer- flowering species can be considered to niche differentiated.

Evergreen forests, like the second-growth forest of Pacific Spirit Regional Park, do not have the same springtime phenomenon. However, one can still observe the effects of light attenuation by paying close attention to the changes in species composition as one transits from the edge of the forest to the core (as one might also observe in forests bordering clearcuts, or riverbanks in the tropics). High light levels at the forest edge generally promote an elevated diversity of shrubs and herbaceous plants, whereas the forest core tends to have fewer of these types. Do note that it is not necessarily an elevated diversity of native species, as invasives tend to be better competitors in these edge sites (at least early on).

I had promised to share photograph details from time to time. This image is actually 3 photographs composited together, using a technique known as tone mapping, which “addresses the problem of strong contrast reduction from the scene radiance to the displayable range while preserving the image details and color appearance important to appreciate the original scene content”. In other words, it is a high dynamic range, or HDR, image. The three photographs were exposure bracketed, so one underexposed, one was overexposed, and one was somewhere in the middle. These were then combined in software that algorithmically composites the three into a single image, essentially drawing from the highlights of the underexposed image (so that the photo is not entirely blown out), the shadows of the overexposed image (to preserve detail in the shadows) and pulling both of these closer to the middle exposure of the photo. I’m oversimplifying, but that’s the gist of it.

HDR images have a poor reputation among many in the digital image world, with the critique that most applications of the technique exceed the boundaries of believability. If done subtly, though, the tool is useful for overcoming the limitations of a single exposure on a camera while still preserving what was seen by the photographer. I hope that today’s photograph falls into the believable group, but feel free to disagree.

Pacific Spirit Regional Park

17 responses to “Pacific Spirit Regional Park”

  1. Ginny

    An amazing photograph and fascinating write up (though I confess to not understanding every single bit). Thanks, Daniel!

  2. Wendy Cutler

    I believed it, but that’s because you took it. I didn’t believe for one minute that I could have taken that photo.

  3. Raakel

    Beautiful photograph Daniel.

  4. Cyndy Henderson

    Awesome tone mapping … just perfect. Makes me want to be there.

  5. Merrill Jensen

    Congratulations on making an HDR look believable!

  6. Michael Fox

    Have you ever noticed the pattern of light and shade on bare level ground (such as a groomed trail) under medium or large sized deciduous trees (e.g. big leaf maple) on a sunny day with the sun overhead?
    You will see a deeply shaded surface with many bright circles whose consistent diameter depends on the mean height of the foliage. I have some photos if you would like to see them.
    The tree ‘arranges’ its leaves to intercept as much light as possible with the result that the few spaces for light to reach the ground act as small apertures as in a camera.

  7. Daniel Mosquin

    Michael, I can’t say that I have, but I would be very interested to see the photos.

  8. Michael fox

    Well, I can’t find my photos right now but I might later. This reference gives the general idea but the circles are not as sharp as we have seen them. I suspect that there is an optimum canopy density for perfect circles; too little and the circles overlap and are not well defined, too much and we see total shade.

  9. Cindy

    Beautiful and fascinating. Good job. Well done!

  10. Jeanne Larson

    My kids and I once watched a solar eclipse on the floor of our patio under a large Mulberry tree. It looked like hundreds of pinhole projectors. Each circle of light Michael refers to, was a little eclipse at our feet. Quite spectacular!

  11. Paul Schmitt

    The last paragraph’s comment:
    “…the technique exceed the boundaries of believability.”
    I must note that the dynamic range (of tones) perceived by the human eye also exceeds the range recorded by all film and digital sensors. So, a single camera image never fills the boundaries of human perception. That is why, done sensitively, HDR is so terrific. The image above is a terrific expression of what is believable.

  12. Hallie Anderson

    This image perfectly represents the name of the Park…Pacific Spirit. So beautiful! Thank you for this morning gift!

  13. Kwilly

    Spectacular and uplifting photo, Daniel! Thank you, so much, for the info as well. This made my day!!

  14. Dana D

    Oh Daniel, this was BEAUTIFUL! I must confess I glanced at the picture before diving in to the description (and like other commentators, I didn’t follow every word, but I got the idea). Once I got to your description about how you took the picture in layers, I went back for a close look. That is when I realized I see a 3D quality to the photo, very detailed and not fake or unbelievable in any way. It actually looks more real than an ordinary picture to me.

  15. Lynn Wohlers

    This is a great entry – and such a striking, unusual photograph. To jump to the end, your description of the HDR process is clear and concise. Maybe the software is getting better. I have used HDR applications that don’t have that unpleasant exaggeration of edges and tones. Then you review what happens on the forest floor as light declines, again very clearly – including the note that edge species are often non-natives. It’s a feast, this entry – and the photo is beautiful. I’m even more eager to visit UBC after that first paragraph. Thank you for taking the extra time on this and including so much good information.

  16. Val Walsh

    Absolutley beautiful photo; you certainly captured exactly what you wanted to illustrate.

  17. Paul

    Beautiful photo, your use of HDR is perfect and very well applied. Thank you for sharing this!

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