|No, I Mean Nutrients|
A few days ago the Science News Wires were a buzz with the latest on the extinction of Megafaunas from an ancient past ice age. Adults, like little kids, are intrigued with all manner of ancient mythical beasts, who while once very real in their past existence, are often times the subject of exaggerated storytelling which sensationalizes and creates a creature with more of ferocious reputation than what probably existed. But I tend to like a more realistic viewpoint in what those ancient animals were truly like. In many ways, I don't find them to be much different in their ecosystem roles than the modern wild animals we have today. They just did things on a grander scale. For example, I've always like Paleontologist, Jack Horner's take on T-Rex perhaps actually being a scavenger as opposed to that ferocious Hollywood Killer. Doesn't it make sense that even in such an ancient ecosystem, such large scavengers would be necessary to clean up the mess of a dead Brachiosaurus carcass which died for whatever reason ? Otherwise such dead carcasses would hang around for days, maybe even weeks stinking up the place, flies everywhere [& who knows how big those things were ?] and perhaps spreading disease. Problem is, most people really want their long held traditional centuries old stories, perhaps for no other reason than for it's entertainment value. You can compare this behavioral fascination with the violence angle to many of the modern Nature TV shows of countless "Crocodile Hunter Wannabes". Have you ever actually paid attention to the subject matter they are they're focusing attention on and the seemingly viciousness of these things when a creature strike out at the Show's Host ? It's all for show of course. It's not like the old days of Mutual Omaha's Wild Kingdom where Marlin Perkins simply showed everyone how the animals lived and what their little niche in Nature actually was. How many film takes do you suppose they had to do in order to get that incredibly vicious response they were looking for from the poor animal ? How much prodding, poking and torment did the poor thing have to endure before it lashed out in defense ? To the film editor though, it was well worth the effort. Well, the Ice Age Megafauna creatures are often depicted the same way as well, and yet as the article brought out in so many of it's important points, they had so many amazing plant ecosystem maintenance effects back in that very healthy ancient world. Often when a documentary leans to much towards the entertainment angle, they often loose the more important learning features. Sadly, even today's Forested ecosystems are often times barely hanging on as a result of the removal of modern day wild animals through human influence. Reintroduce them and we may see amazing remarkable changes for the better. But it's that human stain that is so hard to rub out. Human's by their very historical imperfect nature are just lousy custodians of Earth. And yes, I'm also including those indigenous folks who are often depicting as being more animal, than ecosystem disrupting humans. Seriously folks, they were human. This has been this way apparently from the beginning according to the research. Where ever humans go and colonize, the natural world collapses locally in that area and degenerates into something less productive.
|Chip Clark, Smithsonian's Natural History Museum|
Giant Ground Sloth dung found at Rampart Cave
around the Lake Mead Recreational Area (1938)
Rampart Cave den of Giant Ground Sloth
This video is about 15 minutes in length:
So in that video, this Holistic Land Management guy, Bill Burrows, demonstrates just exactly how a very large herd of Goats can with very little effort, brutalize and reshape an otherwise tough rangy vegetative environment we all know as Chaparral. Not many animals left today can accomplish this necessary task. But although I found their program to be a bit of overkill in the damage department, nevertheless, we can through imaginative pondering, picture just how Megafauna could have possibly shaped the Earth's environment and all the while spreading vital recycled nutrients and other microbiological organisms throughout the ancient landscape which kept the ecosystem under continual productive enrichment. And of course, such efficient biological chaparral mastication machines would have also been kept in check by the the mega-predators of the day. But back to that August 12th, 2013 article from the University of Oxford, they demonstrated how large animals acted as carriers of key important nutrients to other plants and animals over thousands of years on large continental scales. Here are some important quotes from that source:
"Up until 12,000 years ago, much of the world looked like an African savannah." [side point here: I'm not sure I buy into their 'most of world Africa Savanna' imagination here. I believe there were also heavily forested systems like the present Tropical and Boreal Forests we have now, but more open than presently found as a result of rich biodiverse animal presence] "For instance, South America was teeming with large animals, described by scientists as ‘megafauna’ – a term for animals with a body mass of more than 44kg (the size of a large dog). These megafauna in South America, which overlapped with the earliest humans, included several species of elephant-like creatures, giant ground sloths, and armadillo-like creatures the size of a small car. In South America, most nutrients originate in the Andes mountain range and are washed into the forests through the river system. However, on dry land, these nutrients are in short supply unless they are transported through animal dung and bodies. While small animals distribute nutrients over small distances, large animals have a much greater range. According to the study, the extinctions of large animals 12,000 years ago wiped out one of the main means of transporting nutrients far from the rivers creating a nutrient deficiency which continues to affect plant and animal life in parts of the region today."
|Nutrient rich flood plains with their lush plant life|
are understandable, but how did all those important
nutrients move further inland in drier regions ?
"The study finds that the effect of the mass extinction of megafauna 12,000 years ago was to switch off a nutrient pump – vital nutrients, such as phosphorus, were no longer spread around the region but became concentrated in those areas bordering the floodplains and other fertile areas. It concludes that even thousands of years after the extinctions, the Amazon basin has not yet recovered from this step change. Nutrients may continue to decline in the Amazon and other global regions for thousands of years to come, says the paper."
Okay, so far very interesting. Sounds logical that large megafauna had major impact on Earth's vegetative systems. But this article like many are talking about ancient times, especially with regard to the use of the word/term 'prehistoric'. That word/term for me (and this is for me personally), makes me think of a time prior to human writing and documenting things for which we today have access to. If we could fast-forward a bit by several thousand years to say, just a thousand years ago in North America, then we also have a human population not necessarily documenting through hand written text of what life was back then and the animals which were in much greater abundance that we actually have today. So what impact did the modern animals we know of, have on plant life ecosystems just in the past several hundred years ? I would say plenty. I believe part of the problem we have today are the consequences of irresponsible human behavior which has contributed to modern day extinctions in many areas of Earth's wildlife which no longer impact much of the vegetation. Could this also be another reason for vegetation decline in many areas today ? I'm reminded of this very subject from a post a few days back by Chaparral Biologist, Richard Halsey who made this commentary about loss of animal richness and it's impact on vegetation in which he referenced a comment by a Chaparral Institute member, Kurt Schasker who also referenced a 2009 study which I also remember reading a while back:
"I have never bought into the notion of a "fire cycle" since I started learning about chaparral. It doesn't make sense that nature would evolve to turn perfectly good calories into smoke and heat, instead of life. I ran across this article recently that indicates what I'm talking about: Ecological consequences of Late Quaternary extinctions of megafauna "
"In my mind the giant megafauna, specifically the browsers, had a huge impact on American ecology."
"Consider the shrub ox, close relative to the musk ox, as a shaper of chaparral ecology. These creatures tend to stand and fight as a herd when threatened, and make easy targets to human hunting techniques."
"From the point of view of Wildfire Science, I suggest that fire itself is unnatural. A biorich environment full of both browsers and grazers would never provide a landscape that would burn."
I also have to say I have the same sentiments as Richard Halsey and Kurt Schasker. I don't believe that the megafires which presently bring repeated destruction year after year were a normal ecological component of the past, though there was some fire no doubt prior to human presence as plant systems do have an element of fire recovery strategy encoded within their DNA. But getting back to the past 100+ years, other studies have shown that as recently as a few hundred years ago, though there was fire, not the megafire or forest canopy Fires the globe is experiencing today. (SMU Research: Ancient tree-ring records from southwest U.S. suggest today’s megafires are truly unusual) . The study relied on more than 1,500 years of tree-ring data and hundreds of years of fire-scar records gathered from Ponderosa Pine forests. Once again, what role did millions of then existing large animals play across North America even with the presence of Native Americans ? I previously alluded to this with my post Dances With Myths: Indigenous Native Peoples and Fire Ecology where I attempted to provide a more realistic picture of the average Native American as more of a real human, instead of being who has been romanticized as the ultimate land management Ecologist. Yes, who better than a Native to have a vast amount of knowledge about surviving off the land. But they still clearly had some impact on nature. I just don't believe it was always a positive effect. Take for example a couple of illustrations I used in that post of what the potential for massive animal numbers could have been on an earlier ecosystem even prior to European arrival.
Ponder this for a moment. What impact on California vegetation would 500,000+ Tule Elk grazing and pooping everywhere have had in the San Joaquin Central Valley along with a few thousand Beaver in a lush well watered Paradise ? Do you think that historical animal rich environment had a huge health impact on the region's vegetation ? As that article brought out from the Chaparral Institute's Richard Halsey referenced, there was far more of an impact than just nutrient recycling. There was also vegetation shaping and influencing which would have also had more of a phenotypic plasticity impact with regards fire ecology. Megafires which also include the present ongoing Canopy or Crown Fires, would have not been helped along by the then prevailing forest or other vegetation design. Here are some helpful quotes from the other article:
"Most of the extinct megafauna were herbivores. I focus specifically on changes in the structure, composition and dynamics of plant communities that can be attributed to the loss of those large herbivores that were present in terrestrial ecosystems at the beginning of the Last Glacial cycle ca 130 ka (i.e. thousands of years ago), but which went extinct before the historical period."
"Big herbivores have big effects on plants." [side point, as has been illustrated, so can large herds of much smaller animals] "Beyond the direct impacts of herbivory on the physiology, form and growth of individual plants, herbivores shape plant communities in many ways: by reducing vegetation density and creating gaps; facilitating species coexistence; dispersing seeds; suppressing sensitive species; reducing fire potential by preventing accumulation of dry plant tissue; and accelerating nutrient recycling via urine and faeces"
Dropping much further down the paper, we come to the subheading section labeled: Flammable New Worlds
"The prediction that fire should have increased after megafaunal extinction holds true in most cases where it can be tested, but with much variation in the way in which fire subsequently affected vegetation dynamics. In the northeastern USA, Robinson et al.'s (2005) data are consistent with a pure form of the ‘herbivore replacement’ hypothesis. Burning increased several hundred years after megafaunal extinction, suggesting that plant biomass that had been consumed by herbivores before the extinctions was consumed by fire afterwards, after an interval of increased accumulation of fuel. This did not induce a change in the dominant vegetation type, as would have been the case had fire consumed more biomass than herbivores had formerly done, or selected for plants with very different forms or life strategies."
"Many of these plants were originally most successful in ecological zones that were heavily used by large herbivores, which maintained dry and open conditions and suppressed fire. If these conditions changed as a result of herbivore extinction, and especially if fire became a more significant control of vegetation, ‘megafauna plants’ might have declined as a result."
"Plants species that had depended wholly or partly on large herbivores for seed dispersal should have suffered declines in distribution and genetic variance following megafauna extinction, potentially leading to extinction."
|Credit: Jasper - InciWeb|
Understory fire in 2009 Aspen Fire
Grand Canyon North Rim
So how do we know all of this and how can we be sure ? As I've previously stated above, the scientific method opportunity for studying Megafauna's presence & effect on ancient ecosystems is gone, and it's almost impossible to gauge the large impact of modern wildlife on vegetation given that most of their once vast numbers have been eliminated. So in many ways the scientific method is still tough to put into practice. Replacing it with a Lab or imaginary computer model is out of the question also. However, we today have animals which humans have selected in vast quantity because of their great economic value for consumerism which do allow us to see an impact either for a positive or a negative effect on vegetation. I've already mentioned goats, but we also have sheep and especially cattle which European Enterprises in the late 1800s provided in such greater numbers than the land could accommodate, that they became the beginning of the end for many ecosystems around the globe. I actually took a few pictures around Lake Henshaw in San Diego County to show a positive impact on shaping vegetation. Unfortunately, most domestic livestock animals have had many of the wild instincts for moving and roaming bred out of them. They are more docile and easier to handle as a result. Unlike the wild animals who keep on the move from predators, these animals tend to stay put and grind vegetation down the the soil. Look at most late 1800s and early 1900s photos and you will see what I mean. This is where humans have to do actual management of them by prodding the livestock along. In the two photos below there are examples of the pruning services for which animals will provide under the proper management.
Mataguay Creek looking west towards
Lake Hensahw from the State Hwy79
In both photos we have a clear illustration of what large animals can do for a landscapes understory by pruning is up from the ground. Like wild grazing animals, they prefer far more than just grassland diets. Something the early pioneers and some modern day ranching interests just don't get. Although, allowing permanent pasturage in and around riparian ecosystems can have some long term negative effects which could last decades. In historic times past, predators laying in wait near watering hole sources would have kept the situation in check as prey animals would not have lingered for very long after drinking.
Historic grove of Fremont Cottonwoods
south of Cal-Trans Maintenance Yard on
California State Hwy 79
|(Credit: Victoria Sánchez)|
Palaeontologists in Argentina
have discovered that dung balls
reveal much about the ecology of
a lost world of giant mammals
University of Helsinki had a great article Aug 22, 2013 on the benefits of Dung Beetles dining on 'Meadow Muffins' or otherwise known as 'Prairie Pizzas'.
Beetles Modify Emissions of Greenhouse Gases from Cow Pats
More Illustrations Which Teach
|Wild Thyme FarmNatural Forest Succession Pig Meadow over 21 years|
"Just to the west of Ridgecrest Boulevard is Pig Meadow. It was the site of the most recent clearcut, around 1985, just a few years before the property was acquired. It was not replanted after harvesting, and continuous grazing since then kept the area open, leaving only stumps, ferns and grasses. In early 1988, a neighbor's lone 300-pound pig held court in the clearcut, and so it was named "Pig Meadow". By the end of that year, all the livestock was removed, new seedlings rapidly appeared and the transition back into forest had begun."
1988 Liza. Up to this time, goats grazed the high meadow, a wide open grassy field.
1999 John. No goat grazing over the past 10 years. Young fir trees up to 20 feet high and many bushes have grown up alongside the road and in the meadow.
2001 Robert and Nesta. Firs have been thinned and limbed up. New firs have been planted in the spaces to complete the promenade.
2009 John and Nesta. Before the firs have been limbed or trimmed.
"When the property was acquired in 1987, the high meadow was being grazed by the neighbor's free-ranging sheep and goats. With no fences to contain the livestock, the animals foraged deep into the surrounding forest, creating an attractive pastoral landscape. Grazing livestock in a woodland is known as "Silvo-pasturing", as it achieves the dual purpose of growing trees while providing continuous forage for animals. Trees that make it above browsing height can achieve maturity, but relentless grazing prevents any tree regeneration and eliminates most brushy understory species. When the neighbor passed away in 1988, the animals were removed and the fringes of the high meadow started on the path to natural forest succession."
I'm going to finish up here for the moment, but I also have a second part on this. The information on this subject has far too much practical application to allow this to be mere passing interest story. Stay tuned for Part II.