next message in archive
next message in thread
previous message in archive
previous message in thread
Index of Subjects
>rubens), may be particularly influential during communit Nick, what is a "chestnut oak"? The tree your referred to as replacing the Am Chestnut. Thanks, Nancy On 2018-02-27, at 3:14 PM, Nick Hill <fernhillns@gmail.com> wrote: > 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 organic no food for woodpeckers and doesn't let the tree determine its fate. I just 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. We 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 to 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’d be uncomfortable with some proposed interventions. Introduction of any exotic, for instance, has unpredictable consequences. > > > > I don’t think there’s any necessary conflict between attempts to preserve hemlock and other sustainable forest management initiatives. For instance, I keep wondering about seed banks, which may or not be a good idea … > > > > Hope you’re gonna catch some of the sessions, Nick. The MTRI-organized 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 receiving 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 been 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 normally 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 less 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 our forests as healthy as we can. The forests will be dynamic and we can protect mature forest processes but not determine what the eventual forest 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 vegetation, although other species are structured by environmental gradients. Structural equation modeling indicates hemlock has a negative influence on vegetation species richness, light availability and productivity. Thus, a likely future HWA arrival will result in a complete reorganization of these 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 northerly 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 gradients, including elevation and soil characteristics, are also important ecologial drivers. Among overstory hemlock decline categories, resource availability and nutrient cycling are accelerating, but this varies with environmental context. > > > > On Tue, Feb 27, 2018 at 10:18 AM, John Kearney <john.kearney@ns.sympatico.ca> wrote: > > Our hemlock trees are in serious trouble. The culprit is an aphid relative, the hemlock woolly adelgid, and currently, southwest Nova Scotia is the most at threat. > > Find out more at 7:00 P.M. Tuesday, March 13. The Tusket River