January 25, 2018
by Liz Clift
“What we contemplate here is more than ecological restoration; it is the restoration of relationship between plants and people. Scientists have made a dent in understanding how to put ecosystems back together, but our experiments focus on soil pH and hydrology—matter, to the exclusion of spirit.” — Robin Wall Kimmerer, a scientist and writer
Pinus flexilis, the limber pine, has gained some level of notoriety in recent years—in part because these trees have the ability to live for a relatively long time and in part because they are competing with bristlecone pines (Pinus longaeva, Pinus aristate, and Pinus balfouriana) in movement upslope, in response to climate change. The oldest limber pine is estimated to be roughly 3,000 years old, and is located in Alberta, Canada (the oldest living bristlecone pine is estimated to be approximately 4,765 years old, for the record, and it lives in an undisclosed location in eastern California—in fact, it’s the oldest known living tree).
Many of us are, perhaps, particularly fascinated with long-lived trees now that we know that they might not always be around. Take, for instance, the news that’s been trickling in over the past few years about the decline of the redwoods in California or the logging of old-growth forests. These old trees provide habitat for a variety of animals and plants and can also tell us a lot about ourselves, if we take the time to study the rings and the forest around them.
At the Denver Botanic Gardens, there are several examples of limber pine I like to visit. They are small and look sturdy against the landscape, and I have to remind myself that although small, these trees are not all that young—some are older than I am. They’re set in an area that represents Colorado’s more extreme soil conditions: dry and rocky, and yet they’ve found purchase. There’s a lesson in that for all of us, and this is part of what makes the limber pine one of our more resilient trees in montane and subalpine ecosystems.
Limber pine is a keystone species in these montane and subalpine ecosystems. It provides food for a variety of animals, including bears, small mammals, and birds—and its needles are the sole food of a small ermine moth. Nutcrackers, a type of bird in the jay family, rely heavily on limber pine, particularly in certain areas—including Craters of the Moon National Park—where few other coniferous trees exist. This relationship is mutually beneficial, as nutcrackers create caches of seeds for the winter, but don’t return to all the caches, which allows these newly planted seeds the opportunity to take root.
Limber pine is also an effective pioneer in colonizing disturbed areas, and is able to stabilize soils in places where few other vegetative species thrive. Despite this, limber pine is rarely used in restoration projects because it is so slow growing—which makes achieving results within standard monitoring time frames a challenge, and as a result, the average landowner does not easily recognize the ecological value of using limber pine for restoration.
There’s something to be said for developing more patience with these, and other, slower-growing trees. It might not be us—or our children, or theirs—that see slow-growing trees reach maturity, but in this way we can be stewards of the environment for future generations. We can also learn, again, how to build a relationship with plants, to understand the role they play not only in the ecosystem, but in our lives.Leave a comment
January 18, 2018
By Kay Wiseman and Liz Clift
Fires in the west have become larger, more frequent, and more severe in recent decades. This upward trend is likely to continue, making it vital to understand the implications these massive fires have on our landscapes.
For nearly 100 years, fire management policy has established a best practice of suppression to control potential fires and sources of fire. However, suppression can lead to the disruption of natural fire regimes essential for fuel load reduction, seed germination, and soil nutrient cycling. Despite best efforts for prevention, fires continue to ignite and spread and with nearly a century worth of fuel accumulation, a wildfire can quickly turn into a devastating threat.
While there is room for debate as to what defines a “severe wildfire” in differing ecosystems, it is well documented that for the United States’ dry western landscapes fuel accumulation has been a major component for increased fire intensity. Heavy fuel loads can have multiple negative impacts:
There’s a balance though between removing fuel and allowing some of the vegetative fuel to stay because of the role it plays in a biotic community. Vegetative material that could easily become (excess) fuel provides beneficial soil stabilization and habitat areas. Fuels, such as senesced grasses, may allow soil to hold moisture more effectively or provide bedding or nesting materials for a variety of animals, as well as providing cover to small prey animals. Larger fuel, such as tree snags or “standing dead” trees provide nesting habitat for a variety of birds as well as a rich environment for a diversity of beneficial insects and fungi that provide decomposition—thus enriching the overall nutrients within the soil (and which may also be forage for a variety of animals, including some songbirds). Trees, even dead ones, may also provide soil stabilization for many years.
Additionally, if these fuels are fully cleared soil is exposed to sunlight and wind creating dry conditions more conducive to increased fire intensity or increased erosion. The presence of fuels is also essential for topsoil production and nutrient cycling—nutrients from vegetative fuels cycle back into the soil as they decompose—which is another reason that it should be considered undesirable to completely remove fuel sources from the landscape. Therefore, fuel management can be a delicate balance between leaving too little or accumulating too much. Other than the human safety aspect, why should we concern ourselves with fire intensity? Let’s dive more deeply into the points made in the bullets above.
Fires that burn underground—especially those burning peat—can release inordinate amounts of stored carbon. That’s because peat, which makes up only 3% of the world’s surface contains 25% of the world’s carbon soil. What does that mean? It means that there’s currently about as much carbon in the air as there is in all the peatlands in the world.
That’s not all. According to Guillermo Rein, an expert on smoldering fires, “Once ignited, these fires are particularly difficult to extinguish despite extensive rains, weather changes or firefighting attempts, and can persist for long periods of time (months, years), spreading deep (5 meters) and over extensive areas of forest subsurface” (as summarized by Andrew C. Revkin, for the New York Times). These fires occur in tropical, temperate, and boreal forests around the world—because peat exists on all seven continents, including places you might not expect if you don’t know much about the landscape.
Although it’s often easy for anyone who isn’t a soil scientist to see the soil as dirt, it is, in fact, alive with microorganisms and invertebrates which are integral to overall soil health. Additionally, a complex mycorrhizal (fungi!) system exists beneath the soil, which is integral to soil health (in particular helping different plants receive nutrients). Hot fires can kill this mycorrhizal system, which can take years or decades to restore. These intense fires can leave soils not only hydrophobic (which has implications for loss of soil function and may increase risk of erosion or downstream flooding and sedimentation), but effectively sterilizes the soil, leaving it a “moonscape.” This isn’t a reference to the moon that controls the tides—it refers to a post-fire devoid of all vegetation, potentially for years after the initial devastating fire. Moonscapes burned so hot below ground that seeds, soil microbes, and even the compounding properties of inorganic materials in the soil have been expunged.
Without protective vegetation and woody debris, the soil is left exposed to the elements. Exposure and water repellency increase the erosive potential of soil and the subsequent runoff after fires cause stream sedimentation and low water quality, because plants that may have normally acted as “filters” to rainwater or other precipitation were removed from the ecosystem as a result of the fire. In addition to increased repellency, the absence of plants in the landscape means that there is little to slow down precipitation—which can further decrease water percolation into the water table.
Crown fires—especially in the absence of intense ground fires—can provide new opportunities for younger trees and understory growth to flourish. However, the loss of the tree canopy can result in greater vulnerability for some canopy dwelling organisms, can increase damage to lower forest strata during precipitation events (canopies can effectively slow down rain, hail, for instance), and increase surface soil temperatures, due to the absence of the shading properties a full canopy provides during the hottest months of the year.
Restoring areas hit by severe wildfire is resource intensive and expensive but is also necessary to immediately stabilize soil and prevent future erosion, along with reviving ecosystem function. There are a variety of options for short term soil stabilization, and remediation, which can help limit some of the impacts of a fire on an ecosystem (and the human community that depends on that ecosystem as well). Long-term solutions must take into account the current soil quality, options for soil remediation (if appropriate), appropriate (native) plant communities, planting plans, and land management to support revegetation. Other abiotic factors, as well as the pre-fire history of the landscape, may also provide important clues about what restoration techniques will work best for the landscape.
But, these are reactions. We should also be having proactive conversations about how fire management plans can be effectively and appropriately incorporated into a variety of landscapes. These conversations—and the implementation of plans—will likely help fire managers effectively and safely reduce the fuel load that’s resulted from decades of fire suppression.
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October 26, 2017
By: Liz Clift
Not too long ago, sand cat kittens were filmed for the first time, and the internet went gaga over the brief video—especially the portion of the internet that’s convinced the internet is for cats.
So, I pose this question to you: what could be better than cats wearing snowshoes?
Yes, these exist.
Well, sort of.
Canada lynx (Lynx canadensis) are a member of the cat family that lives primarily in boreal forests that receive high levels of snowfall—and so in the US are generally found in Alaska and in montane forested areas along the Canadian border; although, they can also be found in high elevations further south in the contiguous US. They have giant paws that help distribute their weight over the surface of the snowy areas in which they live—which allows them to more effectively pursue their prey.
Lynx populations—like many other predators—fluctuate in response to their food supply. Lynx primarily eat snowshoe hare (Lepus americanus), so when populations of snowshoe hare decrease, so do populations of lynx. Lynx typically have litters of up to five kittens, but particularly food-rich years and a fertile mother can lead to litters of up to seven. In years of scarcity, these litters are smaller, which helps keep populations in check (there’s no evidence of significantly higher adult mortality when prey populations are smaller).
Lynx populations are dependent on areas with stands of conifer (also a preferred habitat of snowshoe hares)—which are areas that can be disturbed by forest fire or landslides, but also human-caused disturbances such as mining, logging, and infrastructure or housing development, all of which can cause habitat fragmentation and loss. Additionally, with lynx, there’s evidence that competition from other predators can also impact lynx populations—and that this competition can be increased as other resources, including habitat, become scarcer.
This has implications for how we think about restoration—and how we think about development projects. Do we include wildlife corridors as a part of our planning process (even while development or logging or mining is happening)? Do we try to replicate natural patchiness upon restoration, and provide phased restoration work that will provide a mix of older and younger conifer forest? How do we best pay attention to all the factors that make up critical habitat for species of concern?
These questions are important for considering how this species can be de-listed (it was listed by US Fish and Wildlife Service as threatened in 2000). For this to happen, its population will need to continue to increase, which means we must work to negate habitat loss and fragmentation.
And we should do this because lynx provide economic benefits by controlling snowshoe hares and its other prey animals, which are considered agricultural and silvicultural pests, because these animals have evolved to be part of our boreal forest ecosystems, and because most of us want more cat videos on the internet.
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October 12, 2017
By Kay Wiseman
When was the last time you observed a healthy fox in Colorado?
I moved from the mid-west to Fort Collins, CO in 2011. I work and play in the outdoors so I tend to take notice when nature seems a bit “off.” No sooner had I settled into my new city that I began seeing foxes (Vulpes vulpes) scamper about neighborhoods and green spaces. But something about them just wasn’t right.
They were out in the open in the middle of the day.
They didn’t shy away at the first sign of people.
They looked absolutely dreadful; scrawny, dirty, scabby, tailless.
They were not the foxes I remember from back east. What I soon learned from my colleagues was that I had apparently moved to the Front Range during a major sarcoptic mange outbreak.
Natural systems have a process of checks and balances for populations. Populations generally fluctuate in regular cycles over periods of time. In some instances, a species population can seemingly grow exponentially until it reaches a certain carrying capacity1 and then rapidly decline. If you paid attention in middle or high school science, you’ll remember this as a “J-curve” pattern.
While there are many causal factors that must be taken into account for these declines, one factor that contributes significantly is disease. A species approaching carrying capacity is competing with itself for resources. As resources become scarce, the health of individuals may decline, which increases their susceptibility to disease. For the Front Range foxes, disease came in the form of sarcoptic mange, and to a lesser extent, rabies and West Nile.
Sarcoptic mange is caused by burrowing mites in the Sarcoptidae family. The mites dig through the skin causing intense itching and inflammation. Foxes that have contracted these mites scratch and bite furiously causing skin damage and opening themselves up—very literally—to severe infection. Mange is highly contagious in mammals and can even be transmitted to humans through direct contact. In humans, sarcoptic mite infection is referred to as scabies…gross. Luckily, for humans and our domestic animal friends, there is treatment. Unfortunately for wildlife, nature must take its course.
As much as we complain about the sly fox breaking into our hen houses, these adorable little predators have an important role to play and sadly we never seem to appreciate that role until they’re gone. During the outbreak, the Front Range reported increased rodent populations such as rats (Rattus spp.) and rabbits (Sylvialgus spp.; Lepus spp.), as well as outbreaks of disease carried by rodents. Health departments across the state were reporting human cases of tularemia (rabbit fever), hantavirus, and plague. Without predators, like the fox, the rodent population was not controlled and their numbers skyrocketed exposing people to an elevated risk of disease transmission.
After this 2 to 3 year mange outbreak ended, I no longer observed foxes anywhere along the Front Range. In fact, it was the summer of 2016 before I saw my first healthy fox in Colorado. The fox was beautiful with a sleek red coat and fluffy white tipped tail. Over the next year, I observed multiple frolicking foxes and my face lit up with excitement each and every time. The once devastated fox population is rebounding! Watch your hens everyone!
Photo: Red fox observed in Fourmile Canyon, Boulder County. Photo courtesy of Michael Duran
1 The carrying capacity of a population represents the absolute maximum number of individuals in the population, based on the amount of the limiting resource available. An Introduction to Population Ecology – The Logistic Growth Equation. Brandon M. Hale and Maeve L. McCarthyLeave a comment
September 28, 2017
By Liz Clift
Sea Otter Awareness Week is September 24-30, 2017
This summer, I had the opportunity to watch an otter hunt in the surf off the coast of Olympic National Park, in Washington state. The otter rode the waves in, close to the shoreline, and then swam back out, repeating this routine a couple of times before settling on a rock to watch us humans.
Sea otters (Enhydra lutris) are the heaviest members of the weasel family (male otters weigh up to 100 pounds), and unlike other marine mammals, lack a layer of blubber to help keep them warm. Instead, they have the densest fur in the animal kingdom (as many as a million hairs per square inch). This means that though they may look wet, the water isn’t actually penetrating all the way to their skin.
In fact, sea otter pups have such dense fur, they can’t dive under water until they get their adult fur. This is likely a survival adaptation: this dense fur will help keep them warm and also allows the mother to safely leave their pups floating on the surface of the water while they hunt for food.
Like other members of the weasel family, sea otters are carnivores. They eat urchins, shellfish (including mussels and clams), a variety of snails, squid, and a few dozen other marine species. Sea otters may store food they’ve gathered—or a favorite rock—in the large sections of extra skin near their armpits. This extra skin acts as a pocket (and who doesn’t want more pockets??).
A male might eat approximately 20 to 25 pounds of food a day! Much of this eating occurs on the surface of the water, and an observer might see an otter floating on its back and smashing a shellfish against a rock the otter has balanced on its chest in order to get at the meat.
Of course, if you’re lucky enough to see sea otters regularly, you’ll notice that they float on their back for more than just eating. They’ll also casually float in groups, called rafts (and these rafts may include hundreds of individuals!) to rest. When they’re resting, they often wrap themselves in kelp to keep themselves tethered to a single area, and mothers will also do this to their pups.
Otters play a valuable role in kelp forest ecosystems by helping control the sea creatures (including sea urchins) that would otherwise eat (and devastate) these kelp forests. Unfortunately, due to fur trading, their historic numbers have plummeted, which means these ecosystems have changed. To give you an idea of the scale of devastation around the sea otter fur trade here are some numbers:
Although they have made a fairly remarkable recovery, sea otters aren’t in the clear yet. They remain on the IUCN Red List (endangered) and now face threats of infectious disease. As recently as 2015, hundreds of sea otters showed up sick or dead along Alaska’s southern coast as the result of toxins from harmful algal blooms and bacteria. There’s also the possibility that orcas (aka, killer whales, Orcinus orca) have started to eat otters as their other food resources have disappeared, although even if this is true, it does not account for the large otter die-offs.
As sea otter populations to continue to fluctuate, we should consider how this impacts our coastal ecosystems in the areas where they live—and how this, in turn, impacts our local economies since the kelp forests that rely, at least partially, on otters (at least on the west coast) also provide shoreline protection against waves, and foster greater biodiversity of fish, crustaceans, bivalves, and other animals.Leave a comment
September 26, 2017
By Liz Clift (with thanks to Joseph Ehrenberger!)
If you grew up in one part of the US (many of the eastern states extending into the Great Plains), the calling of the American bullfrog (Lithobates catesbeianus) was probably a staple of your childhood evenings. If you grew up in other places, perhaps not so much.
However, this might be changing. The American bullfrog can show up as an aggressive—and invasive—species in parts of the US where it isn’t native, and is able to outcompete native frog species. It doesn’t just impact frogs though. The American bullfrog will eat anything it thinks it can get in its mouth, including small rodents, birds, and other frogs—which means it can have a detrimental impact on some threatened and endangered species or state-listed species of concern.
Of course, in the eastern US, bullfrogs will still prey upon native frogs and anything else they can fit in their mouth. But, there is a greater amount of water and more diverse aquatic habitats. This means that bullfrogs and other frog species are better able to co-exist. In general, bullfrogs are especially fond of slow-moving open bodies of water, while other frogs can happily exist where there are more aquatic plants or within damp forests.
In the western US, where for the most part, water is scarcer and where modifications (like dams) have altered natural watercourses, bullfrogs have a prime opportunity to outcompete other frogs. And, like other invasive species, once bullfrogs have invaded a place, they can be difficult to remove. This is due in part to the large number of eggs that they lay (females may lay a clutch of 20,000 eggs!) and the fact that removing adults can actually improve the survival of tadpoles, since the adult bullfrogs are cannibalistic.
In addition, they have lived for decades in many of the places where they are invasive, which means well-established populations must be dealt with (this is all the more reason to take steps to remove bullfrogs as soon as you notice them, if you live a place where they are not native). Bullfrogs can also travel nearly a mile in search of a new place to colonize, if something happens to their initial home—which could include draining a pond or other water resource, which is one of the methods of dealing with a bullfrog invasion.
Traditionally, practices for managing bullfrogs have included hunting/eating them, temporarily—and repeatedly—draining the ponds or other areas they have taken up residence, and potentially introducing (if necessary) predatory insects or other animals like largemouth bass into ponds where tadpoles are found. (Unfortunately, bullfrogs and their tadpoles don’t taste that great to many fish—so the fish may suck in a tadpole only to spit it back out.)
However, these practices can only do so much on their own. Additional, and more creative, management options should be considered. If bullfrog populations are managed, then native frogs tend to move back in fairly readily (or will re-establish once re-introduced). This is promising in terms of increasing biodiversity in areas impacted by bullfrogs.
Great Ecology is working with Adaptation Environmental Services to develop and implement some innovative approaches to bullfrog management in Colorado—and citizen-science may be one of the ways to monitor populations of bullfrogs compared to native frogs, such as the northern leopard frog (a species of special concern in Colorado) before and after such measures are taken. Citizen-science can also help detect a problem early on, if frog monitoring is incorporated into a management plan.
Not sure you can tell the difference between a bullfrog and other frogs? One way is to listen to their calls. Here is your moment of bullfrog-sound zen (so that you’ll know when you’re listening to a bullfrog and when you’re listening to some other frog, say a northern leopard frog).
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September 7, 2017
By Liz Clift
Visual note-taking, sometimes also called sketchnoting or graphic recording, allows you to represent ideas non-linguistically. And considering that the written word is a relatively modern invention (in particular, it wasn’t until very recently in the history of human beings that the written word was something most of us in the Western world, at least, have access to), it shouldn’t come as a surprise that an estimated two-thirds of people are visual learners.
As a perpetual doodler, who has always been drawn to less traditional forms of note-taking, learning about visual note-taking was eye-opening for me.
At last, I had a name for the thing I used to do—and the thing that “being a professional” had nearly stolen from me.
“Content-driven doodling” on the other hand, has the potential to spark creativity and improve comprehension, and to help people (like me) who learn better visually and kinesthetically, rather than aurally, retain information in a meeting or presentation—or a site visit or reading.
Visual note-taking can be as linear or as creative as you need (or as the presentation dictates), but visual note-taking usually utilizes some combination of the following:
What, you might be wondering, does this have to do with ecology or restoration or actual design of places?
I may be biased (I am a writer), but so much of the work we do as environmental professionals is about telling a story—and then helping it come to fruition, perhaps as a restoration project, a management or strategic plan, or an educational tool (like interpretive signage). For instance, depending on the project, you might be helping to tell:
Visual notes might spark exactly what you need to help you write a memo, report, interpretative signage, or your next presentation. Why? Because you’re already thinking outside the box. Something might be the beginning of a conceptual design or a presentation to the community or a sketch that eventually gets transformed into a publicly consumable good on a brochure.
Or, less immediately relevant but just as important, visual notes really can help you remember what you and others at a meeting or training discussed. Doodling does help people retain information (29% more than non-doodling counterparts) and improves overall problem-solving.
Plus, in many ways, visual note-taking is an extension of the type of field notes that our predecessors have used extensively—ranging from more detailed botanical drawings to a quick sketch of what the site looks like—and that we may even use ourselves.
Will you get it right the first time? Probably not. I’m certainly still practicing. But “not being able to draw” isn’t an excuse (google: “Star People: How to Storyboard”). Is it for you? Maybe. Maybe not. You’ll have to try it to figure that out.
But if it means that you retain more information, it’s more visually appealing, and it might help you make more creative connections that could improve your problem-solving ability, maybe it’s worth a shot.Leave a comment
August 30, 2017
by Liz Clift
Have you seen the photos—and worse, the video!—of the giant mats of floating fire ants (Solenopsis invicta) in the wake of the flooding in southeast Texas? Yeah, us too, and we’ll admit they’re a bit horrifying.
And look, guys. The ants are now just feet from house. pic.twitter.com/rt2aU7Uvm3
— Mike Hixenbaugh (@Mike_Hixenbaugh) August 28, 2017
But, they’re also fascinating.
Fire ants are invasive to the US and they love floods. Or, at least, they evolved to survive floods on river banks in South America, which means they happily use flood waters to relocate, which perfectly explains why my grandparents who lived in southeast Texas never actually removed them from their yards by spraying them with the water hose. When the waters rise, fire ants form “rafts” of thousands or millions of fire ants using their mandibles and their sticky feet and can do this in under two minutes. From there, they switch out the submerged ants with those that are drier, which helps keep the colony afloat.
In this configuration, they’re able to drift around on the flood waters until they reach a tree, land, or other suitable dry area (aka, literally anything solid) that they can scramble up.
Sure, you might be thinking, but they can probably be disturbed the swirling a stick through them, right?
If their configuration is disturbed, they will reconfigure to fill the hole (and I don’t know about you, but I wouldn’t want any of those little biters to come at me via a stick I was just using to torment them, especially because during flood times they are apparently more aggressive and more venomous. (More on that fun fact in a bit).
So what works?
Apparently dish soap, which will cause the configurations to break up and the ants to drown because they aren’t able to trap air near their bodies.
These fire ant rafts, fortunately, can’t last forever.
Post-Katrina, fire ant populations in New Orleans and other impacted areas decreased because it took weeks to pump all of the flood waters out. Those populations have never rebounded.
Which, many SE Texans might see as a good thing, especially if they’ve stepped in a fire ant pile before. Unlike regular ants, which will bite and then spray an acid (isn’t nature fun?) fire ants like to bite, hold on, and inject a poison into you that has 46 different proteins. Some people (somewhere slightly above 1:100 people) are pretty susceptible to this and can experience an allergic reaction or hallucinations. The rest of us just get welts (after Katrina, people were apparently entering field hospitals with welts upon welts from fire ants, after wading through the waters). But remember how I mentioned that right now they are more venomous? It averages 87% more venom per bite per ant. Yeah, that’s just making everything about this more of a nightmare.
How the floods from Harvey will affect fire ant populations in SE Texas remains to be seen, and will be largely determined by how long it takes the flood waters to recede (or, you know, a bunch of folks going out with bottles of Dawn to combat the terror mats the ants have formed).
A reduced population could be a good thing for more than just humans though. Ground nesting birds (like quail and meadowlarks) as well as some reptiles are also impacted by fire ants (whatever you’re imagining, that’s probably right) as well as native ant species, which are usually out-competed in areas cohabited with fire ants.
Who else wouldn’t be sad to see fewer fire ants? Ticks. Fire ants love to eat ticks.
So, if you’re searching for a bright side, wherever these fire ants wind up will likely be very free of ticks for the foreseeable future.Leave a comment
July 18, 2017
By Liz Clift
One of the easiest ways to get water from one place to the next is to let gravity do the work. While on the extreme end, this creates waterfalls, if the change in elevation is more gradual, it can create a meandering waterway. This is also the principle behind high line canals. The canals are constructed on the high line of elevation, and often meander to simultaneously follow the higher points of elevation while incurring only a small change in elevation over the course of a mile.
Construction on Denver’s High Line Canal (HLC) was originally completed in 1883, a mere 24 years after the gold rush that sparked white settlement in the Cherry Creek and South Platte River area. The original canal covered 71 miles, in what is now Douglas, Arapahoe, Denver, and Adams counties, and irrigated 20,000 acres. The canal loses about two feet of elevation for every mile it covers. Denver Water took over the canal in 1924, and maintains management of the canal.
Now, the canal covers 66 miles. Alongside most of the canal is a popular recreation trail. Although some areas of the canal are currently inaccessible to the public, the High Line Canal Conservancy is working with Denver Water and others to improve connectivity along the entire trail while preserving the natural character of the trail. Part of the vision planning, according to the High Line Canal Conservancy website, includes development work that is aimed toward increasing the amount of water the canal can hold and convey. The canal was designed to convey 750,000 million gallons of water a day, but currently only moves about 71 million gallons. There are multiple factors weighing into this lower-than-planned conveyance, loss to seepage and evaporation.
In fact, the canal is often dry. This is because Denver Water operates the canal only intermittently, to deliver water to the last remaining HLC customer, and to nourish trees that thrive on more water than is typical for this arid region.
There are plans to further develop and manage the HLC, including developing continuous trail connectivity* and temporarily detaining higher flows a bit longer through segmenting berms, which will provide some water quality improvements. This change may also alter the ecology of the canal slightly by shifting which soils are wet longer, although these higher flows are not expected to be a regular event. Vegetation that could be supported includes cottonwood (Populus deltoides), which provide broad and dappled shade to the canal, the adjacent recreational trail, and human and non-human (such as deer and foxes, as well as aquatic animals like crayfish!) users of the trail and the canal, as well as native shrubs like snowberry (Symphoricarpos albus) and willow (Salix spp.) which provide shelter and forage for many species of bird.
The canal also provides a nesting spot for turtles. A friend of mine was recently walking along the HLC, and came across a young painted turtle (Chrysemys picta). This is where I fully disclose that I love turtles, and seeing her picture on Facebook of the baby painted turtle made me want to immediately hop on my bike and start cruising along the trail in hopes of finding one also.
Painted turtles thrive in habitats with slow moving waters and soft bottoms with ample basking spots (such as partially submerged branches), which pretty much describes the HLC, when it has water, perfectly. They consume aquatic vegetation, small fish, insects, and crustaceans. As a child, I caught baby painted turtles with a net. They would often be basking on top of pockets of algae, their hind legs stuck straight out behind them, as though they were flying. I loved noticing the differences in their plastrons which range from pale yellow to red with dark markings in the middle. I loved that if the baby turtle was especially young and its shell hadn’t begun to harden, that I could feel its heart beating on my palm.
The increased connectivity proposed for HLC could provide more access for those who live along, or near, HLC—or have access to it from other Denver-area trails that intersect it—the chance to experience more of the biodiversity along the canal. Although in this post, I only talk about a couple of plant species, and turtles, the canal is an important migration corridor for a variety of animals, and also hosts many different plant species.
In addition, increased connectivity of the trail could increase beneficial health outcomes for those who access the trail. Daily physical activity, including biking, walking, and horseback riding (all of which are activities people engage in on portions of the trail) is linked to physical health benefits, as is general contact with green space, which more studies are indicating benefit our overall well-being. In The Nature Principle, Richard Louv writes, “In wilderness, and in natural cases or even natural urban parks, we find our senses….” He puts forward the idea that being in nature, and being present in nature (rather than still engaging in technology) helps nourish our deeper senses, and the very essence of our human intelligence.
Updates on the progress of the HLC can be found through the City & County of Denver and the High Line Canal Conservancy websites.
*The City & County of Denver has made conceptual designs of some of this increased connectivity available through public meetings and its website.
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July 10, 2017
By Liz Clift
One of the definitions of ecology is the study of how organisms relate to one another and their environment. Think back to your childhood classrooms when you considered food chains. For the most part, they were structurally pretty simple.
Slightly more complex are food webs, which showed interrelated dietary preferences. Animals with diversified sources of food are generally seen as better able to tolerate disruptions to the food web. For instance, a grizzly bear (Ursus arctos ssp.) eats salmon (Oncorhynchus sp.) in the food chain above. But as this is expanded into a food web, we also see that grizzlies eat berries, roots and tubers, small rodents, and even carrion or human food when it’s available.
If diet alone determines a grizzly bear’s survival, and say, chinook salmon (Oncorhynchus tshawytscha), are eliminated from the food web due to changes in how a river flows (perhaps because of a dam), the grizzly would, theoretically, simply rely more on other sources of food. Case closed, right?
An ecologist—by training or by curiosity about the world—knows it isn’t this simple.
If that same river is dammed, the grizzly might be able to find other sources of food, and do well enough, but the health of the river is impacted, as is the health of other apex predators, like orcas (Orcinus orca). Some orcas have diversified diets and will also prey on seals and other marine mammals or fish and so would feel less impact from the extinction of salmon species.
However, according to an article from American Rivers, published in June of this year, a distinct population of fish-eating orcas, called the Southern Resident Killer Whales (SRKW) waits for a salmon feast at the mouth of the Columbia River each spring. Although SRKW mostly eats chinook (Oncorhynchus tshawytscha, which make up 80% of their diet), they will also eat other salmon—and each whale eats 18-25 of these 30+ pound salmon every day. For that population to remain at its current level, they need at least a half million salmon a year—and if we want them to reach their recovery level (140 individuals), they would need a million salmon a year. It should be noted that since this group of orcas was first counted in 1974, the population has not been higher than 98 individuals (1995). This population lives in the Salish Sea, and Granny (J2), the oldest living whale until her presumed death in 2016, used to be part of their population.
SRKWs rely on salmon populations, and although they will travel through the Salish Sea, and down through the Haro Strait and Strait of Juan de Fuca, and are often spotted near the San Juan Islands, salmon populations in these areas are decreasing—and have been for a long time.
Unfortunately, structures we use for hydroelectric power or river control (like dams) can impede fish passage, and by extension, fish reproduction. Overfishing, algal blooms, non-point source pollution, and the disconnection of floodplains can all also impact river health, and by extension the ability to reproduce and the health of fish who use these rivers. (See our blog on healthy and connected floodplains!)
To give you an understanding of how these things have impacted salmon populations, more than 800,000 salmon used to return to the Yakima River every year to spawn. However, increases in agriculture and large reservoirs that were built without fish passage systems have impeded this population. In 1990, only 3,000 to 4,000 salmon returned to this river system each year. A variety of groups, including government agencies, tribal entities, recreation groups, non-governmental organizations, and others have been working to restore salmon populations. This includes reconnecting floodplains, and restoring instream habitat, as well the establishment of local hatcheries where supplemental stock is raised.
These are important steps to restoring salmon populations, as are dam removal projects, like the Elwha River Restoration Project. This is the largest dam removal in US history, and now the river is thriving—tons of sediment have been pushed out, salmon and steelhead are running the river, small squid are making their homes within the estuaries, and other animals including elk and shorebirds, appear to be thriving in the regenerating ecosystems (including young forests) that are moving into former reservoir areas.
The role of salmon in riverine ecosystems isn’t just limited to their benefits to bears and orcas though. They play an important cultural role for many Native peoples, a large economic role for people in the Northwest, and act as “pumps” that move ocean nutrients into lower productivity rivers. In fact, salmon can support the growth of forests as their remains are dispersed by predators, which in turn, provides more shading of the rivers, increased bank stabilization, and improved water quality before it ever hits the river (among other ecosystem services). In fact, salmon populations in Alaska contribute up to 25% of nitrogen in foliage!
Restoring and protecting salmon habitat—and salmon themselves—is critical because so much evidence points to wild pacific salmon as a keystone species for the northern Pacific. So, as you think about those food webs you once worked on, think about all the lines you might need to erase if salmon were to disappear.Leave a comment