Your commentary is interesting. In North America, we do consider the prairies and their plants to be adapted to grazing, and that is true of grasses in general around the world. They have meristems distributed in the plant body so that they grow from the base, and regenerate if cut back almost to the soil level. Many other prairie plants have below ground reproductive structures in the form of tubers, bulbs, and roots.
Some excellent examples, though generally small in extant, of "native" prairie, have survived because they were grazed rather than converted to row crops. Some other examples have survived because they were hay meadows, mowed periodically. The Nature Conservancy (TNC) and some state and national entities are now using grazing as one tool in conservation of protected areas. For one example, see TNC Tall Grass Prairie Preserve just north of Tulsa, Oklahoma. This preserve was a ranch that preserved native prairie species not on purpose necessarily, but because its cattle grazing program sort of mimicked grazing by bison. Today TNC maintains a herd of bison on the preserve, and also sometimes moves bison from there onto smaller preserves temporarily to promote the prairies there. TNC practices "flash grazing," whereby a herd is moved onto a property and literally allowed to trample and chew so that the landscape begins to look pretty beaten up. But the prairie plants seem to thrive if then allowed to recover well before another flash grazing episode. I do not know what the interval used is, and that might vary from locale to locale depending on conditions. In the southern plains, under the grazing regime practiced by many ranches, and on smaller landholdings where fire is excluded, Eastern Red Cedar, a noxious native weed tree under those circumstances, soon crowds out the native prairie. David McNeely ---- David Burg <david.b...@gmail.com> wrote: > I find this discussion very interesting. I am not a scientist, but have > been looking for management studies that directly compare grazing, fire, > and combinations of the two. My friend, paleoecologist Guy Robinson, was > coauthor of a paper published in Science on changing conditions at the end > of the pleistocene in North American. A consistent find all around the > world seems to be that fire frequencies shoot up dramatically with the > die-off of megafauna and the arrival of humans. Which leads me to wonder > how many of the species we now consider fire dependent were also adapted to > impacts of large animals? I see so many management prescriptions for fire > in prairies and savannas, but fewer studies of impacts of various grazing > regimes. Based on historic and ongoing conservation conflicts with > agriculture one suspects a bias towards fire and against grazing. > > David Burg > > On Sun, Oct 7, 2012 at 3:28 PM, Thomas J. Givnish <givn...@facstaff.wisc.edu > > wrote: > > > The list goes on and on and on. Bulbostylis in Venezuelan savannas flowers > > within a few days after fires; several orchids in Australian woodlands > > obligately depend on fires to trigger flowering; many other plants in other > > systems flower profusely a year or two after fires (e.g., Xanthorrhoea, > > Xerophyllum, Lilium). Several species in Mediterranean scrub in sw > > Australia, sw South Africa, and s California germinate in response to > > compounds released in smoke. Hundreds of species in many genera (e.g., > > Pinus, Cupressus, Eucalyptus, Hakea, Banksia, Protea) release their seeds > > promptly from serotinous cones, follicles, etc. only in response to fire. > > Many carnivorous or nitrogen-fixing plants are facilitated by fire. A suite > > of ca. 17 federally endangered species endemic to the Lake Wales Ridge in > > south-central Florida are almost surely facilitated by the extraordinarily > > high frequency of lightning strikes there. Long-term studies at Konza > > Prairie and Cedar Creek show that different plant species are favored by > > different long-term fire frequencies. The Karner Blue Butterfly has no life > > stages resistant to fire, but depends on fire to renew its habitat and > > maintain an abundance of Lupinus perennis, the sole larval food plant. > > > > -- > > Thomas J. Givnish > > Henry Allan Gleason Professor of Botany > > University of Wisconsin > > > > givn...@wisc.edu > > http://botany.wisc.edu/givnish/Givnish/Welcome.html > > > > > > > > > > > > On 10/07/12, "David L. McNeely" wrote: > > > I apologize. I left off the list of references I compiled for this post. > > Here it is: > > > > > > > > http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1010&context=barkbeetles > > > > > > http://www.gffp.org/pine/ecology.htm > > > > > > http://www.esa.org/education_diversity/pdfDocs/fireecology.pdf > > > > > > http://www.fs.fed.us/database/feis/plants/tree/pinconl/all.html > > > > > > http://fireecology.org/docs/Journal/pdf/Volume08/Issue02/107.pdf > > > > > > http://www.na.fs.fed.us/pubs/silvics_manual/Volume_1/pinus/contorta.htm > > > > > > http://www.firescience.gov/projects/briefs/01B-3-1-01_FSBrief30.pdf > > > > > > http://www.fws.gov/southeastfire/what/ecology.html > > > > > > http://cee.unc.edu/people/graduate-students/theses/Kaplan_MA.pdf > > > > > > > > > ---- "David L. McNeely" <mcnee...@cox.net> wrote: > > > > Wayne, I have heard this "fire dependent" terminology in reference to > > both community types and specific plants. However, most often it has been > > in reference to community types that included dominant fire adapted > > species. I also have heard more convincingly that lodgepole pine, _Pinus > > contorta_, was fire dependent due to serotinous cones. I accepted this > > without judgement. However, one of these references suggests that though > > serotinous, under warm enough conditions 45 - 50 C soil surface > > temperature) the cones may open without fire. I wonder if soils in the > > northern portions and higher elevations of the range get that hot, but I > > don't know. > > > > > > > > I have also heard the term applied to Longleaf Pine, _Pinus palustris_ > > , and the communities that it dominated prior to extensive exploitation of > > the SE U.S. forests. My understanding has always been that in that case, > > more shade tolerant species that have seeds that can reach the soil surface > > despite dense grassy understory replace the longleaf pine when fire is > > absent from an area for extensive time. > > > > > > > > Here are some references, some of them secondary, that discuss these > > phenomena. > > > > > > > > I am definitely not a forest or fire ecologist. > > > > > > > > David McNeely > > > > > > > > ---- Wayne Tyson <landr...@cox.net> wrote: > > > > > Ecolog: > > > > > > > > > > I just caught a video production on TV done by a major governmental > > fire authority. It contained a mixture of truth and superstition, as well > > as some questionable assumptions that y'all can help me clear up. > > > > > > > > > > 1. A uniformed fire official claimed that some plants are DEPENDENT > > upon fire for their survival. He did not say that some plants are ADAPTED > > to fire, he said "dependent." > > > > > > > > > > Please share your knowledge and references, please. > > > > > > > > > > Thanks, > > > > > > > > > > WT > > > > > > > > -- > > > > David McNeely > > > > > > -- > > > David McNeely > > -- David McNeely
