A couple years ago, I wrote about some work from Kansas State University related to woody plant expansion in prairies. Many of us who work with prairies constantly wrestle with questions about trees in prairies. Why are they encroaching so quickly these days? What prevented them from doing that in the past? During our recent trip to Konza Prairie, we got to discuss this topic more in-depth with Jesse Nippert and other researchers at Kansas State.
Clearly, a combination of factors influences how quickly trees and shrubs enter and spread in grasslands. One big reason is the increase in “seed rain” in some of today’s prairies. Prairies in fragmented landscapes with numerous trees and shrubs in nearby woodlots, road ditches, shelterbelts, etc., are deluged with seeds from those woody plants. The vast majority of those seeds fail to establish, but the high number of seeds coming in means that some will find opportunities to grow.
Other factors may include the higher rates of carbon dioxide in today’s atmosphere and higher amounts of nitrogen deposition (from industry and agricultural facilities, for example), both of which tend to favor woody plant establishment. In addition, we are in a relatively wet climatic period if you look at the geologic record. While there have been droughts, including severe ones, in recent years, those droughts are nothing like the multi-decade severe droughts that can be seen in the relatively recent geologic records for the central United States. Long and/or frequent droughts favor herbaceous plants (such as grasses and wildflowers) over trees.
However, Jesse Nippert’s research into the way trees, shrubs, grasses, and forbs (wildflowers) compete for water belowground provides some additional insight into the march of woody plants into prairies. As we started talking about roots, Jesse confirmed something I’d heard from Dave Wedin at the University of Nebraska; even though grasses can have very deep roots, most of their water use is actually very shallow – within the top 25 cm of soil. Jesse says the reason those grasses persist during very dry periods is not because of their deep root systems, but because they can continue to grow and function when available soil moisture is very low. Forbs also pull a lot of their moisture from shallow roots, but utilize slightly deeper roots (50-75 cm deep) during droughts because they can’t compete well with the ultra-efficient fine-rooted grasses at the upper levels.
It turns out that understanding root competition might help us better understand woody plant encroachment as well. In many parts of Konza prairie, clonal shrubs such as rough-leaved dogwood and smooth sumac have expanded rapidly over the last several decades. As Jesse and his students have studied this phenomenon, they have concluded that an important factor behind this expansion is the strategy those shrub clones use to acquire water. While grasses and forbs are mostly using water from the top 1/2m of the soil, shrubs pull much of their water from deeper in the soil profile, allowing them critical access to water not being utilized by their competition – especially in years when the upper soil layers are dry.
The clonal form of dogwood and sumac gives them another advantage. As clones expand, the tillers (aboveground stems) on the outer edge of the clones have very small roots. However, by studying the isotopic signatures of the water in those shallow-rooted tillers, Jesse can tell that they are also accessing water from deep in the soil profile. He says this is almost surely because the older, deep-rooted plants in the center of the clone are sharing the water they acquire with the younger stems on the outside. Not a bad strategy.
Of course, as these clones of dogwood and sumac use their water acquisition and sharing strategy to advantage and spread into the prairie, they also shade out their competition – especially beneath the tall/dense tillers toward the centers of clones. Suppressing the growth of grassy undergrowth not only removes that competition for resources, it also helps make the clones fireproof. Since dried grasses are the primary fuel for prairie fires, the absence of grasses beneath shrub clones means that fires can’t burn through them. It’s not hard to see how the processes of deep water acquisition/sharing and fire-proofing can create a positive feedback loop that helps drive an inexorable expansion of shrubs into the surrounding prairie.
We didn’t talk about this in Kansas, but my experience is that fire-proof shrub clones are an important avenue for the establishment of trees as well. Many tree seeds are deposited into those shrub patches by birds that see those shrubs as convenient and prominent perching sites. If those seeds are able to germinate and establish within those clones – and they often can – the resulting trees can grow without fear of the fires that would otherwise threaten them. Hiding in the middle of big shrub clones also gives those trees a chance to grow in relative safety from marauding prairie land managers…
Because much of Konza prairie has been managed under a variety of long-term fire regimes (1,2,4,10, and 20 year frequencies), Kansas State Researchers have some pretty good data on how fire frequency affects shrub expansion as well. Essentially, prairies burned every year or every other year do not have encroachment by dogwood or sumac, but prairies burned less often are being gradually overtaken by shrubs. Interestingly, the fastest expansion appears to be in prairie watersheds managed with a fire frequency of every four years (which is also about what the estimated average fire frequency was for that landscape during pre-European settlement). While it might seem counterintuitive that a four year fire frequency allows for faster woody encroachment than a 10 or 20 year frequency, the explanation appears to lie in the way shrubs respond to fire. Fire seems to stimulate radial growth in dogwood and sumac, meaning that the plants put an emphasis in growing horizontally rather than just vertically after they are burned. Under very frequent fire, this is apparently immaterial, probably because the shrubs never get enough rest between fires to take advantage of that radial growth. However, when they are given 3 years to recover between fires, that radial growth response after each fire means that burning actually stimulates faster expansion of shrub clones. Under a 10 year fire frequency, that extra radial growth only occurs once every 10 years, so the overall expansion is actually slower than in under a four year fire regime.
Before you jump to the conclusion that burning every year or two seems the obvious best strategy for shrub control, remember that woody plant suppression is only one of many objectives for prairie management. I’ll address some of the other, less positive, effects of frequent fires at Konza in an upcoming post.
As I said earlier, there are multiple factors that affect the rate of tree and shrub encroachment on prairies. Seed rain might be as important as anything, and climatic conditions, increases in nitrogen and carbon dioxide levels, and fire suppression are all likely contributors as well. However, the way plants compete belowground, particularly the deep water use strategy of clonal shrubs such as dogwood and sumac, also seems to play an important role. Frequent fire application can be one way to prevent encroachment, though it comes with other baggage (see upcoming post…) and may not help remove shrub patches once they’re established. At Konza, they took some of the every-20-year-fire-freuency watersheds and started burning them annually to see if they could get rid of the shrubs and trees. Thirteen years later, those patches are still there, though the individual stems are much smaller. It seems that while frequent fire might help prevent woody plant establishment, frequent fire alone might not be able to reverse it – at least not on a very fast timeline.
Woody plant encroachment is one of the biggest challenges we face in prairie management today. A solid understanding of the mechanisms behind that encroachment should help us design more effective strategies to combat it. Shredding, burning and herbicide application are all useful tactics, but figuring out the timing, frequency, and intensity of those applications will be critical. We need to use the various competitive strategies of grasses, forbs, and shrubs to our advantage. As an example, some recent work by Dirac Twidwell (University of Nebraska-Lincoln) seems to indicate that burning under more extreme heat and drought conditions than we typically feel comfortable with might be one way to really tip the scales away from woody plants. The feasibility of that will be limited in some landscapes, but surely there are other innovative tactics that can help. If we work together and aren’t afraid to try some new ideas, we can figure this out.
This article was very interesting — and fully comports with our experience here in Ohio (yes, Ohio has and had tallgrass prairie — at the eastern edge of the prairie peninsula).
I manage and oversee a 3000-acre native tallgrass prairie restoration project at NASA Plum Brook Station in Erie County, Ohio, in north central Ohio. The site in WWII was a giant TNT manufacturing facility, and in the late 1950s became a major (but little-known) NASA test site. Presently, NASA owns and manages 6,400 acres (10 sq mi) of land, of which about 3000 acres was on the presettlement Firelands Prairie. We are in the long-term process of restoring those acres to the tallgrass prairie there in pre-settlement times (before 1820).
And yes, just as with the sites mentioned in the article, rough-leaved dogwood is a major invader; a species we are attempting to suppress, primarily by frequent fires, and where sites have already been entirely captured by the shrub, by mechanical chopping (followed by re-seeding of local ecotypes).
And, yes, we have found exactly the same invasion sequence. Annual or biennial spring fires adequately suppress dogwood brush. Prescribed fires on three-yr rotations, or longer, are ineffective.
Here, in humid Ohio, soil moisture is not a factor. The entire soil column is moist throughout the entire year in most normal precipitation years. Infrequent late summer droughts will exhaust surface layer moisture, but the deep roots of both the prairie grasses and the ample roots of established dogwood shrubs do not suppress growth or survival in such years. New biomass may be reduced, but neither grasses, forbs, or woodies are lost.
We wonderfully have numerous settler accounts of the perennial fall and spring fires local Native Americans set.
There is no doubt, either from the historical accounts of settlers, or from our prairie management efforts at Plum Brook Station, that frequent — annual or biennial — landscape-scale fires are absolutely required to keep our moist, humid tallgrass prairies from quickly succeeding to shrub/scrub. Fires on frequencies less then annual or biennial sequences have proven here to be a waste of time and effort. Infrequent fires simply do not suppress woody invasion.
Many Ohio prairie managers still hold to the fallacy that prairie fires in Ohio were set primarily by lightning; that aboriginals played no part in landscape plant ecology and ecosystem dominance. Both the historical record and our prairie restoration and management experiences at NASA Plum Brook Station do not support that notion.
Plainly, tallgrass prairies in moist Ohio since the Xerothermic Interval were maintained solely by anthropogenic fire, nothing else. From the information in the article, it appears that this, too, might have been the case in the Konza prairies.
(Ohio prairie information here: http://www.OhioPrairie.org)
John, I’m glad you enjoyed the post, and I appreciate the information you shared – very interesting. I agree that frequent fires can play an important role in suppressing woody encroachment, and I agree that the majority of North American prairie fires prior to European settlement were likely set by people. However, I have some grave concerns about relying completely on annual or biennial fire regimes in today’s prairies. Some of my concerns have to do with invertebrate and other taxa that are vulnerable to those frequent fires, but I also have concerns about the homogenized habitat structure resulting from using fire as the only management tool. Finally, I think I don’t like the idea that we set today’s management regimes based on what we think historic regimes were (I am not putting words in your mouth – you didn’t say that) because today’s world is so different, and the challenges to today’s prairies – especially those in fragmented landscapes – require more creative approaches than just replicating what we think were historic disturbance regimes. I’m not saying frequent fire shouldn’t be used in some prairies if it meets management objectives. But I think there are some reasons to look outside that box as well. I’ll be discussing all this in more depth in an upcoming post. I hope you’ll weigh in on that discussion as well. thanks again!
Annual fire is definitely homogenizing at Konza. Would it be several hundred miles to the east? I am not so sure. Most of our mesic prairies in SE Wisconsin, for examble, are dominated by grasses that are much different–cespitose grasses like little bluestem and prairie dropseed. It is hard to know what would happen with annual burning, but many of the prairies here are burned every 3-4 years, and fire seems to lead to much more of a presence of forbs, particularly annuals, than a flush of grass (unlike the big bluestem, switchgrass, and indiangrass annually burned watersheds at Konza). I think there is a difference in fire response between the Konza dominants and the cespitose, mid-height grasses…for one, their below ground buds are held in different locations with different degrees of vulnerability to fire). Oddly here,we have Poweshiek skipperlings not showing up until fire is brought back to prairies, but once they are found, there great hesitance to burn those prairies again. Historically, square miles or more burned. Clearly, we live in a different world, but there are parts of the historical tallgrass prairie region that are so fire-dependent that one might as well just plant a diverse stand of mixed hardwoods if burning at least reasonably frequently is not an option. There is a point, and I’m not sure where/when it is, but in a lot of places we’re close to it, where it just isn’t feasible to conserve or restore prairie in the long-term if management with fire is difficult or too infrequent. In many such areas, I would argue that a more frequent than historical fire frequency is the only way to get prairie communities back to a point where there is the luxury of more balanced (or creative) management.
I think the missing piece of the puzzle is browsers. A hot fire will burn through a shrub clone. I know this because we made the mistake of thinking the almost bare soil under a dogwood clone would be a suitable fire break. If the hot gases from fire are blown through certain woody species then they will be knocked back to the ground. Certain ignition techniques can be utilized to draw hot gases through a clone. When a woody species has to resprout from the base then browsers can reach the buds. In my area the browsers are deer and they consume most of the tender new growth and buds during winter. I am sure elk would be important too if they were still present. The consumption of the buds delays leaf out of the shrubs. This delay puts these shrubs at a considerable disadvantage. It seems every small advantage or disadvantage adds up and if the sum is not positive then the shrub declines and eventually dies.
James, please keep saying “elk.” Hopefully more people will listen. It would at least be nice to have research on elk, but alas…
How about using a mobile infantry of grazing goats to attack woody brush clones at peak growing times?
Patrick, I think it could work as long as you were persistent and hit them every year. You’d also want to be sure to watch the goat forage selection closely to be sure they’re not also eating forbs… I still think it would probably take many years of repeated use for the goats to be successful. That might be a lot more work than it’s worth – careful application of herbicide might be slower, but a more sure answer… depending upon the scale of the problem, of course. AND, I think goats combined with fire or other treatments could be helpful.
When they use goats to clear power lines they found the best way to kill saplings is to allow the goats to defoliate them and then have the goats return right after the leaves regenerated. This effective killed hard wood species. However, our invading shrubs seem much more resistant and I agree that it would take many years to kill them with defoliation. Personally, I am currently on year three of repeatedly spraying a hedge of tartarian honeysuckle resprouts. I think after three years I might have finally killed a few. Conversely, they all might just resprout again next spring.
Note that the Konza fire treatments are largely during a fairly short spring window. Fires are assigned to watersheds for research purposes and not prescribed to impact shrub encroachment, so burns are not timed to make maximal use of dry fall leaf litter (or generally when fuels might maximize top kill) or to coincide with spring bud burst (though this happens at fortuitously some times during the March-April burn schedule). I find it interesting that management burns in other areas seem to keep the same or similar species at bay (or even make progress) at 3-4 year intervals (e.g. SE Wisconsin where I am now), and it isn’t as if seed rain is less. So there is a lot of data, but I am skeptical that it says a lot about how effective fire at a particular interval can be for any given management purpose, because that’s not what the watershed-level studies were designed for, nor is it how they were/are implemented.
Dan (PrairieBotanist) – it’s an excellent point, and thanks for making it. Burn timing is certainly critical.
I think one of the results of late spring burns is that it reduces or eliminates the growing season for the cool season species. It seems like years of repeated late-spring burns can lead to a monoculture of warm-season grasses. When I look at photos of Konza, I always ask myself: “where are the forbs?”. I don’t know if the tallgrass prairie in that area originally had a lower forb abundance/diversity than the eastern tallgrass prairie, or if the forb diversity was reduced by a century of grazing or by recent annual late-spring burns, but the difference I see is striking.
Hey Chris – good to hear from you! I don’t think most of the burns at Konza would be characterized as late spring, necessarily. They burn in March and April – which is a wide window, of course. However, I do agree that while repeated late spring burns can sure help decrease brome abundance, they can also have a homogenizing effect on the plant community that might not be positive overall. You’re not the first to ask “where are the forbs” with regard to the Flint Hills, but what’s funny is that I think their prairies are very forby! It depends upon your point of reference, I guess. It’s a drier and less productive prairie than Illinois, for sure, but they’ve got a very strong and diverse plant community – definitely more forby than many of the upland prairies I see in central Nebraska, for example. There may be some historical issues (broadcast spraying, esp) that have decreased forb abundance in some places, but overall, I think the Flint Hills are just a different prairie type.
Very interesting and good information, but I didn’t see any information about the effect of grazing animals on the curtailment trees and shrubs
russell studebabker, tulsa, ok
Russell – an excellent question. I was going to talk about it in the post but decided I had already been too wordy and skipped it. Konza researchers have seen very little impact of either bison or cattle grazing on woody encroachment. Neither positive or negative. If anything, grazing might slow encroachment down slightly only because grazing removes fuel for fire and can change how often shrub clones actually are affected by fire. If fire stimulates radial growth and grazing reduces how often fire/radial growth occurs in a particular clone, the clone might grow more slowly. Maybe. A little. But overall, it sounds like they’re just not seeing much impact at all.
I also find Russel’s question a good one. To bad we live in a future time where the millions of Bison, Antelope and Elk no longer exist in the masses they once did and the impact they played in the environment and/or role in their effects on vegetation. I’ve written about this as well with regards the possible impacts of what some estimate to be 500,000+ Tule Elk in California’s Central Valley which are a mere few hundred today, with one small preserve containing only a few northwest of Bakersfield. I’m often at odds with the ongoing over use of fire as the answer for everything. Although I believe fire has always been natural and is an important tool in management, I find over the decades so much over use of it and the justifications for it’s use in seed germination for many shrubs and trees to be incorrect. The over use of fire has actually hurt ecosystems rather than help and coupled with the ongoing continued human stupidity and criminal behavior which has created numerous unnatural fires, the health of systems out there is the reverse of what you are experiencing on your prairie environment. Grasslands and non-native weeds are taking over many once pristine shrublands and forests. Again, something else I’ve observed in the bush over three decades where these same plants promoted as needing fire to regenerate have other strategies for spreading themselves around wildlands. I would imagine that massive Bison herds in the physical act of stampeding could have also had a major effect, but again I’ll never know for sure.
The herds of bison we have today act very differently than they did at European settlement. The bison herds used to move like a river of ice across the land scouring everything in their path. In today’s landscape Bison are treated like cattle and as a result it is unsurprising they act much like cattle.
This is exactly what inspired me to title my own blog, “Earth’s Internet”. I’m obsessed with the subject of underground networks and all the mechanized components and the associated phenomena which comes with it. I haven’t read all of your blog posts and only recently added you to my list of interesting blogs to follow. You might look up phenomena call hydraulic lift & redistribution, and also hydraulic descent which is less talked about or discussed, but very important none the less. I am fascinated with techniques for establishment and/or re-establishment of forests. I love the science practices of biomimicry or biomimetics and wish more science research was pursued along the lines of replicating nature. I historically use specific deeply rooted chaparral plants to establish both pine and oak seedlings, even in areas where expert foresters told me a forest would grow. Nature proved them wrong.
The other interesting thing is that term “invasive”. Plants don’t plan or scheme maliciously to invade an area or ruin some farmer’s, rancher’s or timber company’s livelihood, But often times when reading articles it comes across that way. Of course the answer is always, “let’s acquire a chemical and kill it”. Often researching the reasons for the increase in presence or maybe the ecological imbalance which created the scenario in the first place is never addressed. You made reference to climate change and I believe that has more to do with in more than anything else, but I don’t believe the world’s present leadership has the ability nor will to do anything about that. It’s just the nature of human leadership, even if some leaders are well meaning and conscientious. The trees and shrubs are simply responding to environmental cues which I’m glad you addressed.
Thanks for your articles, as I have always enjoyed them.
Just one more point. I’m not sure how the shrub seed spreads there, but generally where I am from, animals and birds disperse the seeds which they eat for food. For example, there are many towns and cities which pocka-dot the prairies now and this provides launching points for birds to further disperse seed in areas which normally wouldn’t receive anything but light wind blown feathery seed as from grasses and other annuals.Many aggressive competitive non-native birds do better around humans than others and they seem to follow humans where ever they go.. I always look at fence lines to see what the birds are eating since they make for perfect perches and rest stops and the fact that so many trees and shrubs get their footholds they first. Fences are everywhere in the prairie belt now, maybe that is another contribution. Sorry for the multiple posts, just find the subject interesting and I have a bit of time before work. Cheers, Kevin
Thank you for your views on multiple subjects. I used to feel the same way about many of the topics you discussed. Please realize that the goal of these hard working people is not to preserve one ecosystem, but all of them with specific attention to those that are disappearing. This requires difficult decisions be made with the goal of decreasing one set of species, in favor of another set of species.
There are probably many factors involved. Grazing and how the area is grazed, many questions as to the animal interaction with the woody areas. But what I have noticed is the type of fire and timing.
I like to burn when it is somewhat windy. A stiff breeze has a dramatic effect on tall thin stalks. Since wind pushes fire faster and hotter it burns cottonwood saplings and stands of Indian Hemp stalks. Without the wind fire just creeps along at ground level.
Another interesting post and some equally interesting responses. Another feedback mechanism for woody encroachment appears to be microbes. There are a number of published articles that discuss how the microbial community changes as woody vegetation invades prairies. Simply put, grassland-loving microbes give way to shrub and tree-loving microbes as woody vegetation invades grasslands. In our area (southern WI) we often use the term “woody or brush memory” to refer to stubborn woody vegetation that resists repeated cutting and treating (herbicide application) in degraded prairie remnants. It can take a decade or more before nice prairie sod returns. It would have been very interesting if soil microbes were monitored during one of these restoration periods.
As to fire frequency, I think folks will argue about it forever. It is not unusual in our area for a high-quality savanna to be completely canopied in by oak grubs in just two years of fire absence. Conversely, a dry bluff prairie may stay relatively woody free and healthy for a decade without fire. It just all depends on a lot of different variables. Managers my take too much credit for how their varying management techniques aid in promoting great diversity. Certainly varied management practices can be important, but I also see example after example of how only one simple management technique, say dormant season burns for example, repeated year after year on the same parcel results in spectacular different displays of flora and fauna from one year to the next. I think it is important to remember we can only control a few things in the grand scheme of things.
Again, thanks Chris for maintaining this blog!
Here is some before bed reading for you all.
Click to access econatres.napc17.vmckinley.pdf
I also wanted to point out that our “dry bluff” prairies in Illinois are being over taken by woody encroachment even with regular fire. There was a nice write up about this in the Illinois Steward magazine. The article was titled “The Alarming Loss of Our Hill Prairies”. The address below lists the article. Unfortunately, it seems to not be available through the link.
However, you can read another article at the following address titled “50 Years of Change in Illinois Hill Prairies.”
I do hope they find a way to save the remnants studied in the article. They listed a lot of nice species!
Good Post Chris,
This topic is something we have been considering on our grassland in SE Nebraska (dogwood, sumac, buckbrush, honey locust). David’s post above is similar to what we have learned in recent USDA/NRCS Soil Health training. Simplified: Grassland soils are dominated by bacteria and fungi dominate soils are found under forest. This year we implemented “concentration zone” treatment of our shrub patches with the cattle herd (walking bacteria vats). When we approach a sumac patch, we tighten the grazing paddock with polywire and toward evening crowd the cattle right on a portion of the shrub patch we want to impact. All night long the shrubs are bombarded with bacteria (80% of what goes in the cow goes out the back, ~30 lbs a day plus urine). Next morning the herd moves on to their new paddock. The concentration zone is a soupy bacteria mess. Since this is a new technique we do not have long term results to report, but appears promising.
For those without cattle, how about bacteria dominate compost tea application along with mechanical disturbance? Sure worth a try in place of toxic options.
Thanks Doug – I’ll be very curious to hear your results…especially on a 3-5 year timeframe. I worry a little that we know so little (almost nothing) about soil microbes that it’s hard to predict results. It seems similar to saying we want more birds in our yard. What kind of birds? If we ended up with lots more goldfinches, cardinals, and other pretty birds, we’d be happy. But if we ended up with thousands of starlings, we might not be. Not knowing what kind of bacteria are produced by cattle and how they might or might not affect the soil ecology, I’m not sure how to even start thinking about management planning. Don’t get me wrong – I’m not saying what you’re doing is a bad idea; in fact, I’m honestly very interested to hear what you find. I’m just saying I don’t feel like I have the background to even start asking the right questions, let alone getting answers that I can use! Good luck!
Also, Doug, I wonder how the information you heard in your training jives with what Sarah Hargreaves said when I interviewed her for my blog back in March… Here’s a portion of her answer to my question about how to think about soil microbes in prairies… “Microorganisms, and microbial communities, are not all equal. For example, fungal-to-bacterial ratios are critical to soil health and sustainability. This is because soils with more fungi relative to bacteria (higher fungal to bacterial ratios) regain structure faster, retain more nitrogen and are more resilient to drought and floods. In addition, all bacterial and fungi aren’t equal. Ideally, a prairie soil has a mix of fast and slow growing bacteria and a diversity of symbiotic fungi so that prairie plants can find an ideal match.”
Again, I just wonder if we know enough yet about how changing soil biota will affect things to make smart decisions. Hopefully, experiments like yours will help us move forward.
Yes our training is along the same lines. I read your interview posts back in March. Good stuff as usual, keep up the good work Chris!
Thanks Doug for your explanation of the concentrated grazing mobbing technique. That seems to mirror what Joel Salatin does on his Polyface Farms in Virginia. He also mobs up his hogs within his forests and then moves them on. His rule in the forest management is one month of disturbance and 11 months of regeneration. Joels use of this technique actually rehabilitated his families farmland which was mere dirt and rocks as a result of mismanagement from the 1960s and back. Now his has some of the richest pastureland without adding any seed other than the natives around there and no industrial chemical fertilizers either. He calls his method Salad Bar Beef because he wants his cattle to eat more than just grasses, but other plants like Plantain, Burdock, Sourdock, etc.He also pastures chickens right behind them in concentrated fencing a week later to mimic Prairie Chickens scratching through and spreading cattle manure further in the process of looking for fly maggots and other insects aside from also grazing on the grasses. Anyway here is a short video:
You are correct about the grasslands and environments that favour ruderals as being more of a bacterial one and shrubs/Trees being more of a mycorrhizal one. We have this exact reverse problem where the mycorrhizal environment will be replaced by ruderals which were always restricted to valley floors and meadows, but now climbing slopes where trees and shrubs dominated. This has also created worse fire scenarios out in California. Anyway I’m glad you are using a more holistic approach of Biomimetics.
Thanks for the feedback. When we began our journey with cattle, Joel’s book was one of the first ones we read. I believe he has since changed or modified his position about trying to keep forage in the “teenage stage” of growth. He has a more recent Acres USA article on “Grazing Tall” but I no longer see this article as a free download from the Acres site? Of course his classic Acres USA article (my opinion) is the April 2002 article “Balance”.
Some favorite quotes:
“Nature never appreciates too much concentration.”
“Population buildups and crashes are common phenomena in nature”.
Paraphrasing here… when humans tries to exceed ecological constraints, “the balancers known as E. coli and salmonella will bring balance back as surely as day follows night. Cycles have a way of restoring balance.”
And my favorite quote from 2002: “While it may be hard to imagine a world without the space shuttle, it is even harder to imagine a world without the earthworm. I’m betting on the earthworms.” Let’s see, 2011…
Yet he also demonstrates that ecological constraints can be exceeded without pathogen problems, i.e. multi-species interactions within an ecosystem.
Trying to imagine the source of mycorrhizal decline you describe? We should be careful here as Chris points out above that there is so much diversity and unknowns when it comes to the microbe world under our feet. Generally speaking, three dominate factors that reduce or eliminate mycorrhizae populations:
1) Tillage, destroys the fungi’s hyphae
2) Bare soil, lack of a living root to feed the fungi
3) Highly soluble sources of nutrients (N, but mainly P), plants don’t need to invest in providing a food source to the fungi. See Jerry Brunetti, “The Farm as Ecosystem”.
Dr. Lee Manske, ND has some interesting insights concerning specific mycorrhizae in the grasslands of his area worth researching and considering.
As a Kansan who grew up near the Flint Hills and regularly observed what I perceived (without actually knowing for sure) as annual burning practices by the ranchers there, I found this article deeply interesting. Some of my notions about grassland development and maintenance have been put on the “maybe not after all” list. I had long thought that the presence of woody plants mostly on steep slopes was because the slopes were in some way protected from burning, like maybe by upward air currents over the flames. And I’d also thought the annual burning was a very effective technique for preventing the establishment of shrubs and trees on the higher open pasture areas. As with so much, this appears to be a lot more complicated than I had believed. I’m looking forward to future posts.
I’m late to the party, but I thought I’d through this out there too. And maybe someone’s already mentioned it, but when Elmer Fink was at Emporia State he had a few grad students working on the population of pronghorn in the flint hills. One of them was working on pronghorn diet, and found Rhus species to be a large component of their diet. I always find this disjunct population and this study particularly interesting, and wonder how browsers may have influenced the historic plant communities. Here’s a link to the thesis: https://esirc.emporia.edu/handle/123456789/1395
Pingback: Konza Prairie Trip Part 3 – Questions About Frequent Prairie Burning | The Prairie Ecologist
Pingback: Save the Date – Grassland Restoration Network July 11-12, 2017 | The Prairie Ecologist
Pingback: Register for the 2017 Grassland Restoration Network Now! | The Prairie Ecologist
Pingback: A Closer Look at Prairie Roots | The Prairie Ecologist