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Index of Subjects
Index of Subjects --001a113a7976bf30bc056658c808 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Pardon my ignorance, but, briefly, what was the red spruce saga? Thanks, Dave in Halifax On 28 Feb 2018 08:10, "John and Nhung" <nhungjohn@eastlink.ca> wrote: > There=E2=80=99s another point worth discussing: if and possibly how less= ons from > the red spruce saga could/ should be applied (or not!). > > > > *From:* naturens-owner@chebucto.ns.ca [mailto:naturens-owner@ > chebucto.ns.ca] *On Behalf Of *Nick Hill > *Sent:* February 27, 2018 3:14 PM > *To:* naturens@chebucto.ns.ca > *Subject:* RE: [NatureNS] Notice of Meeting on Hemlock Woolly Adelgid > > > > I agree, John. > > I too am leery about introducing yet another exotic to combat an exotic. > > The sanitary approach is also worrisome as that approach leaves no organi= c > no food for woodpeckers and doesn't let the tree determine its fate. I ju= st > got back from a walk where I showed my sister from UK healthy beech and > then we found a large slightly chancred beech that had overgrown a > miserable chancred individual that had died. I had to think about the > possibility of differential susceptibility and evolution of resistance. W= e > need to give the hemlock that chance. > > And then there was the American Chestnut and its loss and replacement by > chestnut oak. > > > > Yes. We can do more than one thing and that's good. But I may be averse t= o > any agency that has the authority because of its name to come and cut out > my hemlock. They did this with the red spruce with not much ecological > understanding. > > Nick > > > > On Feb 27, 2018 2:26 PM, "John and Nhung" <nhungjohn@eastlink.ca> wrote: > > Good points, and I=E2=80=99d be uncomfortable with some proposed interven= tions. > Introduction of any exotic, for instance, has unpredictable consequences. > > > > I don=E2=80=99t think there=E2=80=99s any necessary conflict between atte= mpts to preserve > hemlock and other sustainable forest management initiatives. For instanc= e, > I keep wondering about seed banks, which may or not be a good idea =E2=80= =A6 > > > > Hope you=E2=80=99re gonna catch some of the sessions, Nick. The MTRI-org= anized > ones are probably more geographically conveniently-located. You could > contribute substantively to the discussions! > > > > *From:* naturens-owner@chebucto.ns.ca [mailto:naturens-owner@ > chebucto.ns.ca] *On Behalf Of *Nick Hill > *Sent:* February 27, 2018 12:17 PM > *To:* naturens@chebucto.ns.ca > *Subject:* Re: [NatureNS] Notice of Meeting on Hemlock Woolly Adelgid > > > > Hi John and John > > I don't doubt that the woolly adelgid will kill hemlock trees and that is > change and unwelcome. > > Let us first put it in a North American context with climate change and > atmospheric N deposition. > > We can research the impact that has occurred where the pest has moved > through from Virginia through New England. > > And then we can look at stand vulnerability factors. We stand to lose > trees and some stands. The outbreaks will be heterogenous: stands receivi= ng > more N in SW Nova could be more affected. Cool ravines should be less > affected. Stands near the coast may be less affected because there has be= en > less temperature change over the past 30 y. > > > > From what I have read, things were not wholly disastrous. The trees in > some infected stands were mainly killed whereas hemlocks in other stands > were less affected and in some, most trees survived. The carbon stays in > the ecosystem. This is habitat. A new forest takes shape and this normall= y > includes in the US where hemlock trees have been killed, *Betula lenta* > that we dont get here and *Betula alleghaniensis* (yellow birch) that we > do. > > > > We should fight the things we can fight and influence such as > clearcutting, unnecessary roads, poor land use and wetland loss. > > We can do all measure of things: fighting invasives broadly, spraying the > budworm with bacteria and sprays, introducing organisms to fight adelgid > or the sanitary removal of diseased hemlock. Or we can protect forest > processes by reducing cutting frequency and intensity (this will mean les= s > nutrient and organic matter, structure and carbon removal), using > shelterwood management (maintains shade and moisture and structure), > protecting by buffers ravines (shade and moisture) and wetland corridors= , > and setting up mature forest corridors (birds, mammals, herbs...and...?) > throughout the forest. We cant stop this climate change but we can make o= ur > forests as healthy as we can. The forests will be dynamic and we can > protect mature forest processes but not determine what the eventual fores= t > will look like. > > > > Losing some hemlock stands does suck but any reactive response to adelgid > can be seen in a larger perspective of processes. > > Let's fix unsound forestry practices and let the forest take care of > itself. We would be pleasantly surprised on balance. Less hemlock, more > yellow birch,white pine, red spruce and in 50 years, our forest may have > changed again. > > > > Nick > > > > > > https://etd.ohiolink.edu/ap/10?0::NO:10:P10_ETD_SUBID:76019 > > a PhD thesis on hemlock riparian forest in Va and WV (K Martin 2012 Ohio > State) > > Hemlock forests exhibit low species richness, and thus have low > resiliency. In uninvaded forests of Ohio, hemlock dominates the vegetatio= n, > although other species are structured by environmental gradients. > Structural equation modeling indicates hemlock has a negative influence o= n > vegetation species richness, light availability and productivity. Thus, a > likely future HWA arrival will result in a complete reorganization of the= se > ecosystems, but impacts will differ across environmental gradients. Data > from sites impacted by HWA 9-32 years in West Virginia and Virginia > indicate all hemlock forests will likely be impacted. Although mortality = is > initially slowed at higher elevations and on steeper slopes with northerl= y > aspects, eventually, the duration of HWA invasion is the most important > driver of mortality and ecosystem change. As decline progress, hemlock > remains dominant in sites impacted for decades, although compositions are > shifting and diverging across overstory hemlock decline classes. Some > species, including the native evergreen shrub rhododendron (Rhododendron > maximum) and other evergreen species including red spruce (Picea rubens), > may be particularly influential during community reorganization. > Environmental gra