scholarly journals Simulation and statistical modelling approaches to investigate hydrologic regime transformations following Eastern hemlock decline

2020 ◽  
Vol 34 (5) ◽  
pp. 1198-1212 ◽  
Author(s):  
Kanishka Singh ◽  
James Knighton ◽  
Mark Whitmore ◽  
M. Todd Walter ◽  
James P. Lassoie
Keyword(s):  
Statistical Modelling ◽  
Eastern Hemlock ◽  
Hydrologic Regime ◽  
Hemlock Decline ◽  
Modelling Approaches

Characterization of the Soil Hydromorphic Conditions in a Paludified Dunefield during the Mid-Holocene Hemlock Decline near Québec City, Québec

1996 ◽  
Vol 46 (3) ◽  
pp. 281-297 ◽  
Author(s):  
Najat Bhiry ◽  
Louise Filion
Keyword(s):  
Soil Fauna ◽  
Tsuga Canadensis ◽  
Eastern Hemlock ◽  
Plant Colonization ◽  
Quebec City ◽  
Hemlock Decline ◽  
Short Period ◽  
Time Required ◽  
Hemlock Looper

The mid-Holocene eastern hemlock [Tsuga canadensis L. (Carr.)] decline has been recently attributed to the activity of insect defoliators. N. Bihiry and L. Filion, Quaternary Research 45,312–320 (1996). In this study, soil hydromorphic conditions were investigated for the period 6800–3200 yr B.P. using micromorphological data from a peat section from a swale in a paludified dunefield in southern Québec. After a short period of plant colonization in shallow pools between 6800 and 6400 yr B.P., mesic conditions predominated in the interdune before the decline (6400–4900 yr B.P.), as evidenced by strong bioturbation and abundance of excrements from the soil fauna. During the decline, a shift from mesic to wet conditions occurred (4900–4100 yr B.P.), although xeric to mesic conditions persisted on dune ridges until at least 4200 yr B.P. Wetness culminated when beaver occupied the site (4100–3750 yr B.P.). Hemlock needles with chewing damage typical of hemlock looper (Lambdina fiscellaria) feeding were identified at levels dated 4900, 4600, and 4200 yr B.P., respectively, implying that the hemlock decline was associated with at least three defoliation events. The ca. 400-yr interval between these events likely represents the time required for this late-sucessional tree species to recover.

Bryophyte response to eastern hemlock decline caused by hemlock woolly adelgid infestation1

2008 ◽  
Vol 135 (1) ◽  
pp. 12-25 ◽  
Author(s):  
Natalie L. Cleavitt ◽  
Anne K. Eschtruth ◽  
John J. Battles ◽  
Timothy J. Fahey
Keyword(s):  
Hemlock Woolly Adelgid ◽  
Eastern Hemlock ◽  
Hemlock Decline

scholarly journals When a foundation crumbles: forecasting forest community dynamics following the decline of the foundation speciesTsuga canadensis

2017 ◽  
Author(s):  
Bradley S. Case ◽  
Hannah L. Buckley ◽  
Audrey A. Barker-Plotkin ◽  
David A. Orwig ◽  
Aaron M. Ellison
Keyword(s):  
Tree Species ◽  
Community Dynamics ◽  
Initial Conditions ◽  
Basal Area ◽  
Adelges Tsugae ◽  
Eastern Hemlock ◽  
Forest Community ◽  
Forest Communities ◽  
Salvage Logging ◽  
Hemlock Decline

AbstractIn the forests of northeastern North America, invasive insects and pathogens are causing major declines in some tree species and a subsequent reorganization of associated forest communities. Using observations and experiments to investigate the consequences of such declines are hampered because trees are long-lived. Simulation models can provide a means to forecast possible futures based on different scenarios of tree species decline, death, and removal. Such modeling is particularly urgent for species such as eastern hemlock (Tsuga canadensis), a foundation species in many northeast forest regions that is declining due to the hemlock woolly adelgid (Adelges tsugae). Here, we used an individual-based forest simulator, SORTIE-ND, to forecast changes in forest communities in central Massachusetts over the next 200 years under a range of scenarios: a no-adelgid, status-quo scenario; partial resistance of hemlock to the adelgid; adelgid irruption and total hemlock decline over 25 years, adelgid irruption and salvage logging of hemlock trees; and two scenarios of preemptive logging of hemlock and hemlock/white pine.We applied the model to six study plots comprising a range of initial species mixtures, abundances, and levels of hemlock dominance. Simulations indicated that eastern white pine, and to a lesser extent black birch and American beech, would gain most in relative abundance and basal area following hemlock decline. The relative dominance of these species depended on initial conditions and the amount of hemlock mortality, and their combined effect on neighborhood-scale community dynamics. Simulated outcomes were little different whether hemlock died out gradually due to the adelgid or disappeared rapidly following logging. However, if eastern hemlock were to become partially resistant to the adelgid, hemlock would be able to retain its dominance despite substantial losses of basal area. Our modeling highlights the complexities associated with secondary forest succession due to ongoing hemlock decline and loss. We emphasize the need both for a precautionary approach in deciding between management intervention or simply doing nothing in these declining hemlock forests, and for clear aims and understanding regarding desired community- and ecosystem-level outcomes.

scholarly journals Statistical tyre/road noise modelling based on continuous 3D texture data

Acta Acustica ◽  
2021 ◽  
Vol 5 ◽  
pp. 52
Author(s):  
Reinhard Wehr ◽  
Andreas Fuchs ◽  
Simon Breuss
Keyword(s):  
High Frequency ◽  
Measurement Data ◽  
Principal Component ◽  
Statistical Modelling ◽  
Frequency Range ◽  
Road Noise ◽  
3D Texture ◽  
Texture Parameters ◽  
Highly Correlated ◽  
Modelling Approaches

In this article, statistical modelling approaches for tyre/road noise levels (according to the CPX method) based on continuous 3D texture measurements are presented. The main focus is to estimate if viable correlations of interpretable 3D texture parameters with frequency-dependent CPX levels can be found. Therefore, a set of descriptive 3D texture parameters is introduced. Two different modelling approaches, focussing on linearity in order to gain interpretability, are shown. First, a linear model is calculated based on the first principal components of the texture parameters, and second, a random forest regression approach is performed on the direct texture parameters. As a principal component analysis of the CPX measurement data reveals three highly correlated frequency ranges, both approaches are calculated independently for low, mid and high frequency bands. Both models show good performance in the low and mid frequency range, whereas the accuracy in the high frequency range declines. Due to the focus on linearity, both approaches result in comparable statistical benchmark parameters.

Effects of Eastern Hemlock Decline on Large Wood Loads in Streams of the Appalachian Mountains

2011 ◽  
Vol 48 (2) ◽  
pp. 266-276 ◽  
Author(s):  
Daniel M. Evans ◽  
C. Andrew Dolloff ◽  
W. Michael Aust ◽  
Amy M. Villamagna
Keyword(s):  
Appalachian Mountains ◽  
Eastern Hemlock ◽  
Large Wood ◽  
Hemlock Decline

scholarly journals Eastern Hemlock Decline in Riparian Areas from Maine to Alabama

2011 ◽  
Vol 28 (2) ◽  
pp. 97-104 ◽  
Author(s):  
Daniel M. Evans ◽  
W. Michael Aust ◽  
C. Andrew Dolloff ◽  
Ben S. Templeton ◽  
John A. Peterson
Keyword(s):  
New England ◽  
Hemlock Woolly Adelgid ◽  
Adelges Tsugae ◽  
Ecosystem Dynamics ◽  
Eastern Hemlock ◽  
Forest Composition ◽  
Mountain Range ◽  
Riparian Areas ◽  
Conifer Species ◽  
Hemlock Decline

Abstract Eastern hemlock (Tsuga canadensis) in the Appalachian mountain range is threatened by the introduced hemlock woolly adelgid (Adelges tsugae). Potential impacts on riparian systems are great because of eastern hemlock's role as a foundation species that influences site soil, vegetation, and stream characteristics. We installed permanent research sites at 49 locations in riparian areas, from Maine to Alabama, to survey eastern hemlock health, measure stand dynamics, and predict near-term forest composition without eastern hemlock. This report summarizes the initial stand measurements from summer of 2008. We found hemlock woolly adelgid present at 25 of 49 stands from Massachusetts to Georgia, and all of these stands had some degree of hemlock decline. New England states, Ohio, western Pennsylvania, Kentucky, and Alabama had good hemlock health and no sign of hemlock woolly adelgid. Eighteen of the 49 sites had no nonhemlock conifer species in the overstory, and 30 of 49 sites had less than 5 m2 ha−1 of nonhemlock conifers. Without eastern hemlock, 25 of the stands would have more than 90% hardwood in the overstory, many of which are in the mid-Atlantic and southern states at sites dominated by shrubs in the understory such as Rhododendron maximum. Competition from shrubs may hinder stand regeneration after disturbance by hemlock woolly adelgid. On the basis of the abundance of hardwood species and lack of conifer species present in the overstory at many infested hemlock-dominated stands, these sites may convert to hardwood-dominated stands, which will affect terrestrial and aquatic ecosystem dynamics.

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