Photo of the Week – February 1, 2019

It’s till pretty drab and brown outside, so today’s photos are again selected from last summer’s shots. I’m sure I’m not the only one who is glad to look at some color.

We missed out on most of the polar vortex here in Aurora; we only dropped as low as -5 degrees one night, and we’re back up close to 50 degrees today. The misplaced jokes I’ve heard (“heh heh, global warming, am I right?”) reminded me that I’d written a post several years ago about how global warming does, in fact, influence longer and colder temperatures at times during the winter. I looked up the post and was dismayed to see it was almost SIX YEARS OLD. And we’re still arguing (and joking) instead of acting.

Moving on, though, here is some color from last August. I photographed bees and a few other insects on tall thistle (Cirsium altissimum) several different times during that month. (Which reminds me of another previous post, this one on native thistles and their importance to pollinators). Here are some highlights from those August thistle photos.

A crab spider waits for the next pollinator to stop by…
A skipper butterfly on tall thistle at our family prairie.
I think this might be a fruit fly (Tephrellia?) that lays eggs in thistle flowers. Anyone know for sure?

16 thoughts on “Photo of the Week – February 1, 2019

  1. Speaking about acting on climate change … you mentioned before that you graze, but don’t burn your family prairie. This is not an option for those managing larger prairies. However, I am curious if your family prairie has more soil organic matter stored in the soil than prairies which are managed with periodic burning?

    • Actually, I would say that grazing without fire is the dominant way most prairies in Nebraska are managed – especially by private landowners. It’s been a pretty successful way to maintain very high biodiversity on many sites, though it does have some disadvantages (such as requiring other methods to control eastern red cedar trees). And of course, there are plenty of sites where grazing (and other management practices) has been implemented in ways that decreases biodiversity and ecological resilience. It all depends on the landowner/manager and their approach.

      On the question of soil organic matter and fire, that’s a complicated issue. In general, prescribed fire can reduce nitrogen in prairies (if no grazing is present) but soil carbon losses from fire are mainly right at the surface – litter and maybe the very upper layers of soil. Most soil carbon, and that which is arguably most important for plant productivity, is produced by plant roots (decomposition of roots and root exudates) and isn’t affected by fire. In fact, fire can increase soil carbon production by stimulating stronger root growth, depending upon fire frequency, presence/absence of grazing, rainfall, and other factors. So, at least in our part of the country, burning probably doesn’t have much impact on soil carbon overall. I’ve been meaning to write a blog post on soil carbon in prairies, but we know so little, the post would mostly be about what we don’t know. I might still write that (and maybe soon) but the major message will be – we don’t know much about this yet. With fire, though, Konza Prairie researchers have done enough long-term work that I think we can confidently say what I said above about fire and soil carbon. Here’s a link to their education site that summarizes their findings: https://keep.konza.k-state.edu/prairieecology/fire.html

      • It seems logical that prairies which are grazed and not burned would have higher soil organic matter because of the manure being returned to the soil. Just looking at the color of the soil in my garden that has been amended with composted manure versus the soil in other areas seems to validate this thinking. In prairies that are burned, manure probably gets burned up too preventing it from becoming incorporated in the soil. However, things don’t also work the way logic might lead someone to think they would work.

        The point about fire reducing nitrogen in prairies is interesting. In western forests they have found that fire decreases overall nitrogen in the ecosystem, but the rapid mineralization that occurs can increase the available nitrogen (and other nutrients) in the soil after a fire. One would think the increase in root growth observed in prairies after a fire would be from nitrogen being more available. However, the observed root growth in prairies could simply be due to more light and warmth rather than nutrient changes. It is a complicated world.

        Below are a few paragraphs, and the original link, that explains what has been found in western forests.

        https://forest.moscowfsl.wsu.edu/smp/solo/documents/GTRs/INT_280/DeBano_INT-280.php

        Nutrient Availability—Most changes in nutrient availability result from two different processes: (1) in situ changes, and (2) translocation of organic substances downward into the soil.

        Heating the underlying mineral soil directly affects nutrients contained in the soil OM (in situ changes). However, the responses of the different nutrients to heating indicate little change is likely to occur more than 4 to 5 cm below the soil surface, unless a very intense, long-duration fire occurs (for example, in piles of logs).

        More important, nutrient availability (particularly N) in the soil can be increased by the translocation of nutrients downward into the soil during a fire. This occurs because steep temperature gradients are produced in the upper soil layers during the combustion of the litter and humus on the soil surface. During combustion, surface soil temperatures may exceed 1,000°C. Poor heat conduction by the soil results in temperatures of 200°C or less within 5 cm of the soil surface. As a result, some of the vaporized OM and ammonium-rich nitrogenous compounds released during combustion are transferred downward where they condense in the cooler underlying soil (DeBano and others 1976).

        Although large amounts of total N are lost during the combustion of plants and litter, available NH4-N is usually higher in the underlying soil following a fire because of the transfer mechanism (DeBano and others 1979). The increase in N availability (as NH4-N) observed immediately following a fire appears related to the soil temperatures reached. For example, under an extremely hot fire most of the soil N is probably volatilized, particularly on or near the soil surface, and only small amounts are transferred downward in the soil. In contrast, under cooler soil-heating regimes, substantial amounts of NH4-N can be found in the ash and underlying soil. Therefore, depending on the severity and duration of the fire, concentrations of NH4-N may increase, decrease, or remain unchanged.

  2. Global warming yes, BUT
    1. How much is due to surface changes like farming, defrestation and simply paving and roofs on buildings?
    2. How much to Atmosphere changes?

    Thoughts Chris?

      • We heat the air above us with radiant heat from plowed fields, paved streets, roofs, etc and that heat rises. Forested or grass lands absorb heat. That is what I mean by ‘radiant heat’ vs absorbed heat. How much of our climate is heated by ‘radiant heat’ vs chemical changes in the atmosphere trapping heat???? These large radiant metropolitan areas even change the weather patterns and local temperatures near them. We talk about our ‘Carbon Footprint’ but what about our ‘radiant footprint’ (my word choice)?

        • I think Mark’s question is basically, how much are human caused changes to the albedo effect responsible for global warming versus greenhouse gas emissions. My understanding, from looking at a few articles, is human caused changes to the albedo effect causes changes locally, but are not of global concern like greenhouse gas emissions.

          • Yes. thanks Was curious and had not read or heard this discussed particularly in the past

  3. Learned today about the Jack and Laura Dangermond Preserve brought about with The Nature Conservancy landmark deal from the 165M gift investment. Truly visionary! The winter issue of TNC included photographer David Liitschwager work documenting the Coastal Oaks Woodlands.
    The critters and fauna brought to mind Hey this guy is doing stuff just like Helzer! Thank you for all of the great photography and naturalist remarks.

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