Influence of Exogenous Disturbance on Bryophyte Community Assemblage and Tree Regeneration Dynamics in Southern Appalachian Spruce-fir Forests PDF Download
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Author: Sarah E. Stehn
Publisher:
ISBN:
Category :
Languages : en
Pages : 204
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Author: Sarah E. Stehn
Publisher:
ISBN:
Category :
Languages : en
Pages : 204
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Author: Richard T. Busing
Publisher:
ISBN:
Category : Fir
Languages : en
Pages : 396
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Author: Paul Richard Saunders
Publisher:
ISBN:
Category : Forest ecology
Languages : en
Pages : 354
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Author: Adam R. Krustchinsky
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Red spruce is a shade-tolerant conifer whose distribution and abundance reflect Quaternary climate history as well as natural and anthropogenic disturbances. This species once extended further south than its present localities, because of natural and anthropogenic disturbances such as logging, windthrow, and fire. Little is known about the disturbance regime of this species, because long term stand dynamics are difficult to obtain. This-long lived species is hypothesized to be suffering a decline in radial growth, density and abundance at the present time. Recent research suggests pollution, biotic stresses, climate change and natural stand dynamics are the driving forces behind these decreases. The purpose of this study is to investigate the influence of fire in a mesic ecosystem, specifically a high-elevation red spruce (Picea rubens Sarg.) forest on Whitetop Mountain in the southern Appalachian Mountains. Six plots were established in a high elevation red spruce stand to characterize the stand composition. Tree ring data were collected to investigate radial growth relations to inter-annual climatic variability and cross-sections were used to investigate fire history. Red spruce continued to establish throughout the 19th century until a severe fire occurred in 1919 and caused a new cohort of yellow birch (Betula alleghaniensis Britt.) to establish within the stand. Logging and fire caused high mortality in the stand, yet many spruce remain that outdate the past disturbances. Red spruce saplings continue to persist in the stand, showing regeneration despite the abundant hardwoods. Moisture was the main contributing factor to red spruce growth in the dendroclimatic analysis. Red spruce radial growth was significantly correlated to high precipitation and low temperatures of the previous growing season, which is similar to recent research results. This study collaborates the current literature on red spruce growth along with the results found here in creating a model to represent the growth characteristics of red spruce when inter-mixed with hardwoods after a severe disturbance.
Author: Hsing-Yi Chang
Publisher:
ISBN:
Category : Fir
Languages : en
Pages : 372
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Author: Nicole Jean Fenton
Publisher:
ISBN:
Category : Biotic communities
Languages : en
Pages : 440
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Author: Aaron M. Ellison
Publisher: MDPI
ISBN: 3039213091
Category : Science
Languages : en
Pages : 274
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This book is a printed edition of the Special Issue Causes and Consequences of Species Diversity in Forest Ecosystems that was published in Forests
Author: Clarice Marie Esch
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 162
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Trees affect seedlings through many pathways, including via interactions with soil and surrounding vegetation, that can shape seedling recruitment. Plant-soil feedbacks (PSFs) occur when a plant modifies soil biota or abiotic factors in a way that influences the performance of subsequent or co-occurring plants. PSFs shape plant community dynamics by affecting species relative abundance. After a plant initiating PSFs dies, legacies of PSFs occurring as soil signatures that influence subsequent plants could persist for unknown duration. In this dissertation, I investigated PSFs and PSF legacies of two species, Prunus serotina and Acer rubrum, and the effectiveness of a Hawaiian tree for forest restoration. To examine PSF legacies, my approach was to plant seedlings in soils collected around live trees and stumps of varying ages in greenhouse experiments. PSFs were measured in live tree soils and PSF legacies as the difference between seedling performance in live tree and stump soils. For P. serotina, negative PSF legacies were short-lived, lasting up to 0.5 years after tree removal and occurred under 5% but not 30% full sun. Though restricted to low light, short-lived legacies of P. serotina PSFs could have lasting impacts on plant community dynamics during crucial post-disturbance regeneration by disfavoring P. serotina in small tree-fall gaps. To examine how long soil pathogens outlive tree hosts in gap soils, I studied the presence of oomycetes in soils near live Prunus serotina trees, and 0.5 and 1.5-year-old stumps. I isolated five species of oomycetes from soils, two of which were pathogenic (Pythium intermedium and Pythium irregulare) to P. serotina and present in soils of all stump ages. Continued presence of pathogens of P. serotina in gap soils demonstrates the potential for impacts on conspecific regeneration after tree death, though pairing this finding with improved seedling survival after the first growing season suggests that pathogen effects may weaken with time. For A. rubrum, I found positive PSFs and PSF legacies lasting > 8 years in conspecific soils. These results demonstrate that escaping soil enemies is not a mechanism contributing to the historical rise of A. rubrum abundance in many forests of eastern North America. Rather, positive PSFs and multi-year legacies will promote A. rubrum seedling recruitment near conspecific trees and reinforce the growing dominance of A. rubrum across many forests. In a restoration context, I examined mature tree effects on seedling regeneration through a study of mechanisms of grass suppression and facilitation by planted trees; grass suppression is a crucial condition needed to create opportunities for seedling recruitment. Using stands of a native N-fixer, Acacia koa (koa), on Hawaiʻi Island, I evaluated whether koa suppresses invasive grasses and if so, by which mechanisms. I found consistent effects of grass suppression by koa via shading and litter accumulation, but importantly, total grass suppression rarely occurred. Grass persistence under koa canopies may be driven by a shift in composition to more shade tolerant species. If complete grass suppression and/or more diverse forest are desired, then further management interventions, like diverse understory plantings, could amplify mechanisms of grass suppression and thereby create seedling recruitment opportunities.Taken together, these findings demonstrate the relevance of PSF legacies for forest community dynamics and how PSF legacies can vary in duration and direction depending upon the tree species involved. When planting trees to suppress invasive grasses, multiple mechanisms are involved with a net effect of suppressing grasses, but they may be insufficient to meet goals.
Author: Daniel Howard Norris
Publisher:
ISBN:
Category : Bryophytes
Languages : en
Pages : 350
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Book Description
![Factors Influencing Re-assembly of Forest Floor Bryophyte Communities After Forest Harvest [microform] : Disturbance Severity and Potential Refugia PDF](https://books.google.com/books/content/images/frontcover/8YvwPgAACAAJ?fife=w80-h100)
Author: Nicole Jean Fenton
Publisher: National Library of Canada = Bibliothèque nationale du Canada
ISBN:
Category : Biotic communities
Languages : en
Pages : 440
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Book Description
