Creating a Video of Vegetative Cover Sampling

As part of my graduate obligations for a course in methods of measuring and monitoring plant populations, I had to do some type of course project. Though our instructor offered several options of varying difficulty, it was clear that he really wanted someone to attempt to produce a video outlining how to do a method.

As I had done a couple of videos for other projects in the past, I was fairly certain that this would be the most difficult of the graduate project options, but after exploring my other project options, I decided to attempt the video.

So over the last few days I’ve been writing a script, planning shots, doing on-site filming, editing, and voiceover work. Then more on-site filming, more editing and more voiceover work. After several hours of dedicated editing time, I’ve finished the video.

I think it’s pretty good. It’s not great, but it’s got potential. The main challenges were equipment related. It was windy on both filming days and I don’t have fancy microphones, so we had wind noise in some of the live action clips. Despite that I was using an HD video camera that I won at a conference, the video quality wasn’t as good as I’d expected, but it was the best method of filming the video with what we had available.

Anyway, the end-result is an 8 minute video that demonstrates how to sample vegetative cover using the point-intercept method. I briefly walk viewers through what cover is, why it’s commonly measured, and how to establish random sampling locations. Then I illustrate how to lay out a transect and how to sample points using a drop rod. I discuss how to record the data and finish with a demonstration of how the recorded data can be summarized in Excel. (There’s a mistake in that section, that I caught very late in my editing and didn’t want to tackle fixing as it would have required a new voiceover that took me four takes to do the first time. See if you can spot it).

If you’re curious you can find the video on You Tube at: http://youtu.be/NhcNjikpApg

Feel free to provide comments – as long as they’re positive 😉

Night Blooming Cerus, Peniocereus greggii

The Night Blooming Cerus, or Queen of the Night, (Peniocereus greggii) is a Sonoran Desert cactus that most of the year would be virtually impossible to find. It’s main stem is a thin, dull-green to brown stalk that resembles the branch of shrubs like the palo verde, Ironwood, or creosote bushes that it normally grows beneath.

What makes this cactus special is that on certain summer nights the plants in each population produce large blooms synchronously – with some plants producing numerous flowers, some producing one and some none at all. The flowers open at sunset and last for one night, withering in the morning sun.

The flowers are produced only at night, are mostly white, about 3 inches wide and are strongly scented (though some people apparently cannot smell them). The flowers have long floral tubes and are pollinated by hawk moths (Sphingidae) which fly hundreds of yards between different plants in search of nectar. In return they exchange pollen between individuals.

The Night Blooming Cerus is actually not a cerus at all. When cacti were first collected and categorized they were lumped into one genus named ‘Cactus’. Later, taxonomists determined that there were several groups of cacti and split the plants into groups like Opuntia (beaver tail cacti), mammillaria (fish-hook cacti), Cerus (columnar cacti) and others. In the newer classification many columnar cacti were lumped into the Cerus genus, the Night Blooming Cerus being one of them – hence it’s name. However later work further subdivided plants in the Cerus genus into more groups. Columnar cacti like the Giant Saguaro remained in the genus Cerus, but vine-like cacti like the Night Blooming Cerus were moved into a new genus named ‘Peniocerus’, where the species is currently classified.

In Arizona and New Mexico, the Night Blooming Cerus is a protected or endangered species that has seen much of its habitat lost to agricultural and urban development. In addition, its future is dependent upon hawk moths which themselves are vulnerable to impacts from nearby development. For example, where pesticides are heavily used in agricultural areas adjacent to desert habitat, the hawk moth populations can be greatly reduced, such that few remain to pollinate the Night Blooming Cerus to help maintain the cactus’ population size.

Photos from the 2012 Night Bloom at Tohono Chul Park:


All images on this page copyright 2012 by John Donoghue II. All rights reserved.

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