Disturbance Interactions in Subalpine Forests: Compound Effects and Adaptive Resilience
Başlık:
Disturbance Interactions in Subalpine Forests: Compound Effects and Adaptive Resilience
Yazar:
Gill, Nathan S., author.
ISBN:
9780438024465
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (135 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Advisors: Dominik Kulakowski Committee members: Steward T.A. Pickett; John Rogan; Florencia Sangermano.
Özet:
Disturbances such as droughts, fires, beetle outbreaks, and wind storms are recognized as a natural part of terrestrial ecosystem dynamics. However, recent climatic warming has altered the frequency, severity, and spatial extent of these processes, which in turn has created increased interaction among disturbance agents. One disturbance may interact with another to alter the severity, extent, and other attributes of the subsequent disturbances. Compound effects of disturbance interactions modulate regeneration at three phases: source (e.g., production of seed bank), function (regeneration strategy), or context (biotic and abiotic). The quantities at which regenerating individuals are produced, mechanisms by which they disperse, and conditions under which they establish are all sensitive to disturbances and disturbance interactions. Using in situ data from permanent plots, linear regression, an ensemble spatial distribution model and numerous mixed-effect models, I evaluated the effect of disturbance interactions on four major tree species that dominate Rocky Mountain subalpine forests (Abies lasiocarpa, Picea engelmannii, Pinus contorta, and Populus tremuloides ). I organized these analyses into three themes: 1) the temporal stochasticity in regeneration composition and density after wind blowdown and subsequent fire, 2) the relationships between ground cover and post-fire conifer seedling establishment after multiple, interacting disturbances, and 3) the potential for forest type conversion as a form of adaptive resilience against compounded disturbances. Highly stochastic patterns of regeneration composition and density within a relatively short (< 15-yr) timeframe revealed that forest regeneration patterns exhibit more temporal variability than is often assumed, particularly following severe and compounded disturbances. Mixed-effect models revealed a novel mechanism by which multiple disturbances exhibit a compound effect on forest regeneration via altered relationships between post-fire conifer establishment and ground cover. Ground cover patterns strongly influenced conifer regeneration and were sensitive to compounded disturbances. The post-fire roles of certain ground cover categories were fundamentally different when fire was preceded by other disturbances. Finally, ensemble modeling of P. tremuloides seedling distributions shed light on constraints to the species' ability to sexually regenerate and highlighted an underappreciated but significant pathway to adaptive forest resilience against fire and compounded disturbances. Together, these findings emphasize that with warming climate, disturbances are interacting in ways that are quantifiably changing the spatial patterns and ecological processes of forests and the services they provide, with important implications for management and ecological forecasting.
Notlar:
School code: 0048
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(680239.1) | 680239-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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