Peter, you said:
"I remain a vegetarian, still convinced that grazers are causing much distress for Gaia at present."
===I agree, and, I am a vegetarian also. The issue is that we can do much better, and in many situations I have found no better tool for developing a healthy ecosystem than PROPER management of livestock. Other cases, wild animals will serve well, but are a bit more "bother" to manage.===
"You make a strong point, that the prairies have been grazed forever, mostly without human management.
I have two questions:
1) You assert that it's hard to build up the soil without the pruning/mulching/fertilizing actions of the grazers. What they use for fertilizer is just ground-up plants, no? Why doesn't it work just to have the plant matter recycle without animal intervention? Seems to work in forests, doesn't it? Of course there is microbial action in forests, but I don't think there's any important grazing-type link in the recycling chain."
===The plant matter alone remains on the surface, where it is valuable. But, in drier places in particular, and in places where rainfall comes in torrents and then is gone, the uptake of water is different than in forests (speaking generically -- always dangerous). The uptake must be fast and the water holding capacity must be high to absorb, say, a 3-4 inch rain falling in 1 or 2 hours. This requires a lot of organic matter, say 3% or more, for maybe 1-1.5ft deep. Plant matter on the surface won't get the job done. However, when we have dung beetles burying the dung up to maybe 3 feet, leaving holes the size of a China marker (wax pencil) with many branches above leading down to a dozen or more dung balls, that puts the organic matter where it can do some good. The earthworms and other earth-critters do a lot of the mixing, and make the soil into a tremendous sponge. The plants, particularly the deep rooted bunch grasses fill in and make a thick mat that can extend 10-20 feet deep. This is a HEALTHY prairie! Basically, water just doesn't run off! But, springs flow and seeps appear on hillsides. We get a much greater diversity of plants, woody in some spots, mostly herbaceous though, as a result of the seeps, and higher water table. Along with the diversity we get soil organism diversity, since the organic matter is basically their food.===
Peter, you continue,
"2) You say too few animals are as bad as too many. This seems so counter-intuitive that I'm having a hard time with it. True, once upon a time there were wall-to-wall buffalo (was that the long or shortgrass prairie?). And this question obviously relates to (1)."
===Yes, it's been counter intuitive for years. The problem is we don't think like a grass plant. Grass grows from the base of the leaf, not the tip of a stem like a woody plant or a herbaceous dicot. Grasses growing in prairies, plains, and "deserts" are not shade tolerant -- not many trees for shade! So, without a regular "pruning"/mulching/eating the annual growth of a perennial will accumulate, and shade the new growing points in the following year. With mostly dry air, the microbial action doesn't weaken the blades and stems near the ground, so they remain standing for literally years. As they accumulate, they shade more and more. As they create more growth around the periphery of a bunch of grass, the oldest stems and leaves accumulate in the center, and slowly begin to decay. This creates a place for the fungi and bacteria to begin causing damage to any tender growth points, and the plants begins to die in the center.
If you live where there has been no grazing for a few years, and there are bunch grasses, pull out some of the dead grass, and you'll find the roots and healthy tissue are in a "donut" around the edges, and the center is dead. To make matters worse, eventually the plants themselves will begin to die because there is no replacement of cover between them, and runoff increases and they begin to suffer more drouth effects. As the bunches die, the spaces between them gets larger, and erosion sets in, and you see the bunches looking like they were pushed up out of the soil. Actually, the topsoil has washed away from between them. You will also see pebbles sitting on a pedistle also. There will be NO seedlings, and the bare ground becomes sparsely vegetated with woody plants. Then we call it a desert.
If you have good management, the vegetation will remain mostly grasses, and the seedlings will appear if a grass bunch dies. The animals will create an environment with litter on the surface and dung/organic matter below. A hoof print will be the site of new seedlings, where the capillary connections between the seed on or near the surface are compacted somewhat on/in the soil. When the seedling sprouts, it can get roots into the moist soil quickly, and grow. If the surface has become covered with algae, this changes the oxygen/carbon dioxide balance just below the surface, and the nitrogen that is fixed is used by microbes, not grasses. The real nitrogen fixation is by legumes (often seasonal) and microbes feeding in the rizosphere of the roots, where the grasses "leak" sugar to them for energy.
I describe this like I really knew what I was talking about. This is a partial story, and there is moderate evidence for it. However, the soil community of microbes is so complex that I describe it to my students as more diverse than a rainforest that is mostly above the ground. If we consider this species diversity on a microscale, and the organic matter matter in the top several feet of soil in a prairie, and the relatively slow turnover of the carbon compared to a rainforest, we have a "carbon sink" approximately as great as the rainforests. The greenhouse effect is as much a matter of loss of grassland to sparse shrubland as it is clearing rainforests. BUT, please note that this is where rainfall is not of the type to support a rainforest. Clearing forest for livestock is a disaster, not justified, and ignorance at it's worst. Grasslands have their place, and that is where livestock are vital, since we don't have the other herbivors available, and, if they are, they don't have the predators that create the needed behavior, and they can't roam widely to avoid overgrazing (eating and re-eating tender regrowth).
So, if we look at the world from a grasses' perspective, we see that removal of old growth is important. Getting new seedlings established is important when there is exposed soil. Getting the organic matter DEEPLY buried by the dung beetles and earthworms is important. This takes a lot of animals close together for a short stay in a particular place, AND a return not too quickly to avoid overgrazing. There also is a benefit or two from species multiplicity for the kinds of vegetation they eat (not just species, but when they eat it and how they eat it matters very much). If we don't have millions of bison, or elk, then we need cattle. If we don't have millions of pronghorn, or deer, then we need sheep. If we need to balance the herbaceous with the woody species, goats are great. I suspect we need just about every species we can muster, but haven't learned why yet.===
You quoted me:
" However, if I see lots of trails from animals moving in an area by
> following one another, several times down the trail, I need to increase the
> number in order to get more dung and urine and mulching activity. If I get
> too many, they eat too much of the food, and they begin to suffer from
This really befuddles me!"
===The trailing is a way we can see the effects of low density, which signals us to look for the more subtle effects on the plants. It's an "early warning" way to monitor our management.===
"> the more "critters" the better.
Sounds good. If we weren't concerned about making money off the land, what would be the optimum mix of ungulates in your area?"
===The mix depends on the particular pasture (and fences need to bound similar areas, not just be geometric). It also depends on the way we perceive the recovery route of the habitats. We can "make" an area more woody or more open many times, just by the way we manage. Sometimes, for example, if we're trying to create habitat for a species or group of species that is rare in an area, we can do so even if it might not have been what was there a century ago. Also, sometimes we need to pass through one kind of habitat to get to another. I'm really just beginning to see some of these options, and in only a few places. There's so much to learn, and so little time to learn it!===
> "Letting nature have her way" might develop a high diversity of healthy,
> interdependent species eventually, but it's another misperception that we
> have "stable" and "healthy" ecosystem function if we just leave.
Another good point. Humans have altered the ecosystem so gravely that it will certainly not be able to recover immediately. Unfortunately, all too often in the past we've thought we knew what was needed and only made things worse. You sound like you have the personal experience and observational knowlege to be closer to right. I hope so.
===SO DO I! But, the more I see, the more I see that I don't understand. Sure, I have ideas, but I'll bet that if I'm close one tenth of the time, I'm lucky. This is what makes me awed -- and I don't use that word lightly.===
> "> Why is it gone? Cattle? Good chance you'd be right. Overgrazing? Good > chance you'd be right again. Solution? This is were I disagree - in > general terms - with many of the opinions that have been expressed. I've > not heard anything new about cattle damage on this list, but some people > I've heard say the same things have now changed their minds, once they quit > believing they had the answers and began to take a look from a different > perspective.
It's not necessarily the _cattle, it's how _many_ cattle. Which is one reason I keep suggesting a return to the much lower-percentage animal protein diets of previous centuries. For starters."
===Well, I'd say not how MANY cattle, but how long they can rebite regrowth, and how well they can keep the carbon cycle going. I would hazard a guess that we need all the animals in the tropics out of there, and used properly in the proper areas! There were many more bison than we have cattle, and the system was fabuously productive. Now it's less so, mostly because the number of animals is too low -- in density -- and they are there too frequently and overgraze. This gets the worst of both worlds, and our grasslands continue to decline, in spite of reducing numbers. It seems that the decline is slow enough that casual observation can't tell the difference between "good management by numbers" and "bad management by numbers". Frankly, I think we lump the well intentioned managers in with the jerks because they both are doing the wrong thing. The good ones do it as they're told, and the bad ones do it their way. It took me a long time to realize that what I'd learned in school wasn't even close to correct! Dogma dies slowly, regardless where it comes from!
Hope this helps and I'd appreciate any questions. It's often the question that sparks something in mind that I'd overlooked.
peace R. H. (Dick) Richardson