Let me wade in to specifically address the issue of old-growth: its definition, its value, its stability and its replaceability [go ahead, "sic" me if you like!] On Thu, 2 Mar 1995 era@islandnet.com [a.k.a. David White] wrote [to the knforestry@cyberstore.ca discussion group]: > The term "old growth" has not been adequately defined, but I think that the > essense of the idea is that it is undisturbed by humans. As such, these > places are complex ecosystems and are become rarer. With increased > awareness of the importance of protecting biodiversity and because of the > almost universally poor forest practices of the past, these areas have > become the focus of the debate in forestry. > A concensus on the meaning of "old-growth" has been developing over the last 5 years or so. It is the ultimate or final stage in forest stand development, where processes and structures associated with gap dynamics (single-tree replacement) prevail over those associated with stand initiation from an earlier "catastrophic" disturbance. It need not be undistrubed by humans: that would be "virgin" forest, or "primieval" forest, and we _can_ grow more old-growth, merely by waiting long enough for gap dynamics to assert themselves, or even accelerate the process by changing the stand to an uneven-aged structure. It is now becoming widely accepted that most forest types can have "great cycles" of stand initiation and development after major disturbance (such as wildfire or clear cutting) and "lesser cycles" of tree replacement and stand maintenance (associated with senescence of individual trees, insect attacks, or selection logging). Many of the forests we like were initiated from catastrophic disturbance, and hence cannot be maintained (without intervention) to approximate their present form indefinitely; but the take-home message is that both forms of forests are natural, and can be found around the world (even in the boreal), though their relative abundances vary greatly. Note that old-growth need not be a climax forest; composition may keep changing (e.g., Douglas-fir giving way to hemlock). Conversely, however, all climax forest (defined as being compositionally stable and self-replacing) _is_ old-growth. Old-growth need not have big trees. As Chris mentioned, most old-growth in the boreal is black spruce, pretty scruffy stuff that has escaped fire because of swampy terrain. It is ironic that Cathedral Grove on Vancouver Island, with its 400 to 500 year old Douglas-fir starting to die off, is only now achieving true old-growth status, one that will be dominated by more cedar and hemlock. What happens "after" old-growth, following canopy break-up, remains one of the most controversial issues in forestry and (now or soon) in park management. I have seen evidence for both schools of thought: (1) the site becomes "a degraded forest" dominated by shrubs or herbs; or (2) the stand keeps regenerating itself as a climax forest. On much of the outer coast and northern half of Vancouver Island, a long history without fire or stand-replacing windstorms has resulted in an increasing abundance of salal. Similar patterns can be found in some high-elevation and sub-boreal spruce-fir forests, and in muskeg where Labrador tea and sphagnum can outcompete black spruce regen. On the other hand, even stands of presumably early-successional or fire-dependent tree species _can_ regenerate themselves by gap dynamics: we find evidence of this (especially on drier sites where densities are low to begin with) in lodgepole pine and aspen stands which are out of the range of spruce or fir seed sources. In the lowland continental tropics, with >100 spp./ha, there is always some other tree species with the right set of attributes to fill the void, and so "the forest" is maintained; but in more species-depauperate montaine rain forests, the tree population often gives way to one dominated by treeferns or bamboos. Is that good or bad? Bad if you are managing for trees, fiber, timber, carbon sinks, etc.; neither good nor bad if you are managing a natural area ... unless over-zealous fire protection means you start running out of earlier successional and stand-development stages. Biodiversity at the stand or local site level may be higher than in the industrially preferred mature or juvenile stages, but at a landscape level (which is what really counts for most conservation purposes) indigenous biodiversity is greatest over a mosaic of all stand ages and stand types. So what does all this mean? IMHO, i think: (1) we can probably manage many more forests by the "small cycle" of single-tree, small group, small patch selection (i.e., gap level management) than is currently thought practical; and (2) most environmentalists (self included) aren't primarily concerned about old-growth per se. Be careful, because if you say you just want old-growth, traditionally trained (UBC and other) foresters can engineer it quite readily! But if we say we are concerned about other elements and values of wild forests, then more care is needed in the identification and management of protected areas, and of multiple use lands. For example, i would suggest that we need to be concerned about: (a) old-growth dependent species of plants, animals, fungi, etc., and the dispersion (spatial arrangement) of habitats available to them; (b) having representative examples of all types of old-growth stands and climax forests on all site types within a biogeoclimatic region, to serve as benchmarks for research, understanding, and curiosity ... if not out of respect for their uniqueness; (c) protecting large and small wilderness areas of virgin forest, where natural processes of stand development, succession, disturbance and evolution are allowed to run their course; and (d) protecting "sacred groves" of big trees to inspire us (no "scientific" reason needed!). So, if stakeholders, land-owners, tenure-holders, and the public can be encouraged to articulate exactly what they want, rather than the much abused terms of simply "old-growth" or "biodiversity" or "sustainability", i think we will find that we share many more objectives than a confrontation-searching media would suggest. That's my $0.02 worth. Phil Burton. p.s. These ideas are developed further on the basis of some real data in a forthcoming paper, soon to be submitted to "Ecologial Applications" (right, Dan?) p.p.s. Please cc: me any responses to this posting, as i do not subscribe to all the lists i am posting to. ======================================================================== burton@unixg.ubc.ca Philip J. Burton, Ph.D. Assistant Professor University of British Columbia Department of Forest Sciences #270 -2357 Main Mall Vancouver, B.C. V6T 1Z4 Canada
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