Forest dynamics and agents that initiate and expand canopy gaps in Picea–Abies forests of Crawford Notch, New Hampshire, USA

By J. Worrall, Thomas D. Lee, T. Harrington. 2005

157 citations recorded by the source corpus.

1 Data from elevations ranging from mixed hardwood‐conifer forest at 600 m to subalpine Abies balsamea forest at 1120 m indicate that canopy gaps are not static but expand over time due to mortality of trees at the gap margin and coalescence of gaps. Gap expansion is more frequent than gap initiation. Ultimately such disturbance patches may become more extensive than is normally considered as typical of gap‐phase disturbance, but the processes of development are the same. 2 Disturbance agents involved in gap initiation tend to differ from those involved in gap expansion. Spruce beetle, dwarf mistletoe and most root diseases predominate as agents of gap initiation, while windthrow/windsnap, chronic wind stress and Armillaria root disease are important agents of gap expansion. 3 Concepts of equilibrium gap‐phase dynamics and a shifting‐mosaic steady state do not fully account for the dynamics of these spruce‐fir forests. A spruce beetle outbreak in the late 1970s/early 1980s killed most of a cohort of dominant, emergent Picea rubens. This epidemic initiated a long‐term cycle of disturbance and release that is likely to be repeated in many years when a new cohort of P. rubens becomes sufficiently large to sustain another major bark beetle outbreak. 4 Episodic disturbance agents affect long‐lived, dominant species at infrequent but regular intervals (up to hundreds of years) and operate at the landscape level. Gap‐phase cycles appear to be nested within the long‐term cycle. Over the long term, episodic disturbance drives such ‘nested bicycle’ dynamics. 5 Spatial and temporal distribution of disturbance results not only from stochastic events such as storms, but also from host specificity of agents of disturbance, their tendency to attack certain age classes of trees, local and regional contagion, and susceptibility of trees at the edge of disturbance patches.

Subfields: Ecology, Global and Planetary Change, Nature and Landscape Conservation

View Paper: https://www.semanticscholar.org/paper/20885a996707e59fe52a7acb0d1dbc4f091a5c32

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Citations in the corpus

Disturbance and diversity of wood-inhabiting fungi: effects of canopy gaps and downed woody debris (2014, background): “Previous research focused on natural disturbances and wood-inhabiting fungi has targeted the role of wood-decaying pathogens in creating and expanding canopy gaps (Hennon 1995; Worrall et al. 2005).”
Disturbance dynamics of old-growth Picea rubens forests of northern Maine (2005, background): “…consisted of singletree events, an estimate similar to that found in Picea jezoensis forests by Yamamoto (1993) and Picea-Abies forests of New Hampshire, USA (Worrall et al. 2005), yet approximately half that found in Picea-Abies forests of the southern Appalachian Mountains (White et al. 1985).”
The tree mortality regime in temperate old-growth coniferous forests: the role of physical damage (2010, background): “In a New England old-growth Picea–Abies forest, physical agents were responsible, proximately, for approximately 29% of tree mortality events (n = 312) leading to canopy gap formation or expansion (Worrall et al. 2005).”
Responses of insect pests, pathogens, and invasive plant species to climate change in the forests of northeastern North America: what can we predict? (2009, background): “As a forager of weakened trees, Armillaria serves an important ecological role in forests by aiding in structural diversification, creating habitat for wildlife and microbes, and recycling nutrients (Hansen and Goheen 2000; Worrall et al. 2005).”