Effects of Wildfire Burn Severity on Soil Microbial Communities and Invasive Plant Species in the Cascade Range of Oregon PDF Download
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Author: Cassie Lenae Hebel Publisher: ISBN: Category : Endemic plants Languages : en Pages : 126
Book Description
Fire suppression in the last several decades has resulted in unprecedented accumulations of organic matter on the landscape, leading to an increase in large, intense wildfires. This study investigated the soil microbial community (using phospholipid fatty acid analysis) across recently burned forests on the eastern slope of the Cascade Range in Oregon to examine the effects this belowground community has on the growth of native and non-native plant species in severely burned "red" soil and in less severely burned "black" soil. Long duration, smoldering conditions creating red soils drastically altered both soil nutrients and microbial community structure. Changes in soil properties and biota affected plant growth in a controlled growth chamber, as well as vegetative colonization on red soil plots in natural field conditions. Differential growth was observed between native and non-native plant species when grown in soil from the two burn severities. Native plant growth did not differ between black and red soil, while non-native plants showed reduced growth in red soil. Although it previously had been reported that fire increased the likelihood of invasion by non-native plant species in a burn area, these results do not support the notion that red soil conditions are more susceptible than moderately burned soil to non-native, invasive plant species colonization. While many factors in addition to mycorrhizal colonization and burn severity influence plant growth, such as soil nutrient availability, our results suggest that a variety of strategies allow plants to grow in disturbed environments. Continued monitoring of microbial communities and re-vegetation in red soil sites could further our understanding of the length of post-fire recovery time of severely burned red soil.
Author: Cassie Lenae Hebel Publisher: ISBN: Category : Endemic plants Languages : en Pages : 126
Book Description
Fire suppression in the last several decades has resulted in unprecedented accumulations of organic matter on the landscape, leading to an increase in large, intense wildfires. This study investigated the soil microbial community (using phospholipid fatty acid analysis) across recently burned forests on the eastern slope of the Cascade Range in Oregon to examine the effects this belowground community has on the growth of native and non-native plant species in severely burned "red" soil and in less severely burned "black" soil. Long duration, smoldering conditions creating red soils drastically altered both soil nutrients and microbial community structure. Changes in soil properties and biota affected plant growth in a controlled growth chamber, as well as vegetative colonization on red soil plots in natural field conditions. Differential growth was observed between native and non-native plant species when grown in soil from the two burn severities. Native plant growth did not differ between black and red soil, while non-native plants showed reduced growth in red soil. Although it previously had been reported that fire increased the likelihood of invasion by non-native plant species in a burn area, these results do not support the notion that red soil conditions are more susceptible than moderately burned soil to non-native, invasive plant species colonization. While many factors in addition to mycorrhizal colonization and burn severity influence plant growth, such as soil nutrient availability, our results suggest that a variety of strategies allow plants to grow in disturbed environments. Continued monitoring of microbial communities and re-vegetation in red soil sites could further our understanding of the length of post-fire recovery time of severely burned red soil.
Author: Richard V. Pouyat Publisher: Springer Nature ISBN: 3030452166 Category : Science Languages : en Pages : 306
Book Description
This open access book synthesizes leading-edge science and management information about forest and rangeland soils of the United States. It offers ways to better understand changing conditions and their impacts on soils, and explores directions that positively affect the future of forest and rangeland soil health. This book outlines soil processes and identifies the research needed to manage forest and rangeland soils in the United States. Chapters give an overview of the state of forest and rangeland soils research in the Nation, including multi-decadal programs (chapter 1), then summarizes various human-caused and natural impacts and their effects on soil carbon, hydrology, biogeochemistry, and biological diversity (chapters 2–5). Other chapters look at the effects of changing conditions on forest soils in wetland and urban settings (chapters 6–7). Impacts include: climate change, severe wildfires, invasive species, pests and diseases, pollution, and land use change. Chapter 8 considers approaches to maintaining or regaining forest and rangeland soil health in the face of these varied impacts. Mapping, monitoring, and data sharing are discussed in chapter 9 as ways to leverage scientific and human resources to address soil health at scales from the landscape to the individual parcel (monitoring networks, data sharing Web sites, and educational soils-centered programs are tabulated in appendix B). Chapter 10 highlights opportunities for deepening our understanding of soils and for sustaining long-term ecosystem health and appendix C summarizes research needs. Nine regional summaries (appendix A) offer a more detailed look at forest and rangeland soils in the United States and its Affiliates.
Author: Sam Fox Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Fires, both wild and prescribed, have lasting impacts on the landscape and environment. Factors such as fire return interval, timing, and fire intensity and severity all play a role in the direct and indirect impacts fires have on the soil microbial communities (bacteria and fungi). Soil microbes play vital roles in soil stability, nutrient exchange, and many other ecosystem functions. Understanding how fires impact these communities is important for future land management decisions, especially in areas predicted to have more frequent and severe fires. In my dissertation, I first provide a synthetic review of what is currently known about the subject of fire impacts on fungi. This includes ecological frameworks, fungal fire traits, key fire-responsive fungal species, and community dynamics and trajectories. While this review is detailed and explores many facets of fungal responses to fire, I also address areas that still need to be explored, such as functional gene analysis following a fire, and having more controlled fire experiments. Second, I explored how fire frequency impacts the microbial communities residing in different soil horizons- A (topmost), E, and B (bottommost) as well as abiotic attributes that may be indirect drivers of community dynamics such as; Total N, Total C, SOM, inorganic N, P, and pH. For this project, we utilized an experimental infrastructure that had sixty years of continuously maintained, controlled fire regimes. This experiment included replicated experimental units that had been burned annually, every two years, and every four years, as well as a fire exclusion treatment that had not been burned in over sixty years. We observed that fire frequency impacts the microbial communities, but does so mainly in the topmost soil profile. The fire exclusion treatment differed from others when we compared the topmost soil horizons (where most microbial activity occurs). In almost all of our community and abiotic parameters, the fire interval manipulation treatments differed in the topmost A horizon, whereas the two deeper horizons E and B, had only a few parameters that differed between the fire interval treatments. Lastly, I investigate effects of low and high severity fires in a mid- to long-term experiment. This experiment manipulated fire severity and compared high and low severity fires to determine how the microbial communities change over a six-year time span. We also collected samples before the fire samples to enable comparisons to samples after fire to assess community recovery. My results suggested that the high-severity fires had a greater impact on the microbial communities compared to the low severity fires for both bacteria and fungi. Within the high severity fire sites, the communities remained distinct six years post-fire. In the low severity treatments, the communities started to resemble those before the fire, especially richness and diversity of the bacterial communities. This project allowed us to gain valuable understanding in microbial community trajectories following fire, and could aid in planning future restoration projects. Taken together, my dissertation research has allowed us to answer whether and how fire severity and frequency impact the soil microbial community. Indicator taxon analyses that I employed in both studies, identified taxa that seem to drive the community distinctions amongst the treatments, such as fungal taxa, Anthrocobia, Morchella, Pholiolata, and Pyronema which are described as pyrophilous taxa in my synthetic review. My dissertation research strongly indicates that microbial communities change with fire events and that these responses depend on fire interval and severity contexts. Whilst my studies provide considerable insight into the microbial responses to fire, the underlying reasons why they respond still remain complex and poorly understood. In all, fire changes soil chemistry, plant physiology and community composition, soil fauna, and many other system attributes that interact with microbial communities in soil. Exploring which of the many potential drivers are most important for microbial community fire responses and recovery remain a lingering area of research that needs to be explored.
Author: Therese M. Poland Publisher: Springer Nature ISBN: 3030453677 Category : Science Languages : en Pages : 455
Book Description
This open access book describes the serious threat of invasive species to native ecosystems. Invasive species have caused and will continue to cause enormous ecological and economic damage with ever increasing world trade. This multi-disciplinary book, written by over 100 national experts, presents the latest research on a wide range of natural science and social science fields that explore the ecology, impacts, and practical tools for management of invasive species. It covers species of all taxonomic groups from insects and pathogens, to plants, vertebrates, and aquatic organisms that impact a diversity of habitats in forests, rangelands and grasslands of the United States. It is well-illustrated, provides summaries of the most important invasive species and issues impacting all regions of the country, and includes a comprehensive primary reference list for each topic. This scientific synthesis provides the cultural, economic, scientific and social context for addressing environmental challenges posed by invasive species and will be a valuable resource for scholars, policy makers, natural resource managers and practitioners.
Author: Christopher J. Dunn Publisher: ISBN: Category : Conifers Languages : en Pages : 126
Book Description
Mixed-severity fire occurrence is increasingly recognized in Pseudotsuga forests of the Pacific Northwest, but questions remain about how tree mortality varies, and forest structure is altered, across the disturbance gradient observed in these fires. Therefore, we sampled live and dead biological legacies at 45 one ha plots, with four 0.10 ha nested plots, stratified across an unburned, low, moderate and high-severity fire gradient. We used severity estimates based on differenced Normalized Burn Ratio (dNBR), and captured a disturbance gradient, but plots in our low-severity class underestimated fire effects because of misclassification or delayed mortality. We estimated probability of mortality for shade-intolerant (Douglas-fir, incense-cedar, sugar pine) and shade-tolerant (western hemlock, western redcedar, true fir) trees from 5,079 sampled trees and snags. The probability of mortality was higher for shade-tolerant species across all fire-severity classes, and decreased with increasing DBH except for western hemlock. Only large, shade-intolerant trees survived high-severity fire. Post-fire snag fall and fragmentation were estimated from 2,746 sampled snags and logs. The probability of snag fall decreased with increasing DBH for all species, and was positively correlated with fire severity, except for Douglas-fir that had a higher probability following low-severity fire. Snag fragmentation was positively correlated with DBH and fire severity for all species. We also estimated the coefficient of variation within- and among-plots by fire severity class, as well as across all sampled conditions. Structural attributes varied more within- than among-plots, likely a result of increasing sub-hectare patchy mortality as fire intensity increased. Although vertical and horizontal structural diversity increased at sub-hectare scales, the coefficient of variation was highest for all structural attributes when compared across all fire severity classes. Therefore, the range of fire effects observed in mixed-severity fires may be functionally important in creating structural complexity across landscapes, which is an important attribute of old-growth forests in the Pacific Northwest. Understory vegetation response to mixed-severity fires has not been characterized for these forests even though the majority of vegetation diversity is found in these vegetation layers. Therefore, we sampled forest structure (1000 m2 circular plots) and understory vegetation (100 m2 plots) at 168 collocated plots stratified across unburned, low, moderate and high-severity conditions 10 years (Tiller Complex) and 22 years (Warner Fire) post-fire. We focused on shrub species, but sampled forbs, graminoids, ferns and moss as functional groups. Offsite colonization and fire stimulated soil seedbanks increased the total species richness from 23 to 46. The life-history strategies of residual and colonizing species resulted in three dominant species response-curves to the magnitude of disturbance: 1) 'disturbance-sensitive', when relative abundance was highest in unburned plots and continued to decline with increasing fire severity, 2) 'disturbance-stimulated', when relative abundance was highest following low or moderate-severity fire and 3) 'disturbance-amplified', when relative abundance increased with increasing fire severity. Residual and colonizing species assemblages promoted five or six distinct understory communities, dominantly driven by legacy tree basal area rather than the proportion of basal area killed. Understory communities were rarely associated with one disturbance severity class as fire refugia, variation in overstory and understory fire severity, and compensatory conditions offset fire effects. Early-seral habitats were the most different from unburned forests, but were not the only post-fire conditions important across these burned landscapes. Interactions among live and dead forest structures following low or moderate-severity fire, and the vegetation response to these conditions, are also unique to the post-fire landscape and likely important for various wildlife species. Therefore, if ecological forestry paradigms focus dominantly on creating old-growth structure or early-seral habitats, they might exclude important conditions that contribute to the landscape structural complexity created by mixed-severity fires. Additionally, tree regeneration response to mixed-severity fires has not been characterized for these forests even though they offer insight into one aspect of the resilience of these ecosystems to disturbance. Therefore, we sampled forest structure (1000 m2 circular plots) and regeneration dynamics (100 m2 plots) at 168 collocated plots stratified across unburned, low, moderate and high-severity conditions 10 years (Tiller Complex) and 22 years (Warner Fire) post-fire. The largest marginal increase in tree mortality (stems ha−1) occurred between unburned and low-severity fires, given preferential mortality of small trees and shade-tolerant species, but basal area mortality had the largest marginal increase moving from moderate to high-severity. Pairwise comparisons of legacy tree basal area between low and moderate-severity weren't as significant as other comparisons, but did capture a gradient of increasing fire effects. Quadratic mean diameter and canopy base height were positively correlated with fire severity as incrementally larger trees were killed and canopy ascension followed. Regeneration density increased regardless of severity, relative to unburned forests (median density of 1,384 trees ha−1), but the highest median density (16,220 trees ha−1) followed low-severity fire at the Tiller Complex and moderate-severity fire (14,472 trees ha−1) at Warner Fire. Plot-level average species richness was highest following these same fire severity classes, supporting the Intermediate Disturbance Hypothesis. Statistically distinct regeneration communities occurred across the fire severity gradient at both fire sites. The relative abundance of shade-tolerant tree species decreased as fire severity increased, except for a divergent response following stand-initiation at the Warner Fire. While divergent successional pathways were evident within a couple decades following stand-initiation, low or moderate-severity fires also modified successional trajectories and may be the most functionally important disturbance magnitude because it has the greatest potential to increase compositional and structural diversity. Incorporating mixed-severity fire effects into landscape management of Pseudotsuga forests could increase structural complexity at stand and landscape-scales.
Author: C. T. Dyrness Publisher: Forgotten Books ISBN: 9780331399387 Category : Technology & Engineering Languages : en Pages : 34
Book Description
Excerpt from Effect of Wildfire on Soil Wettability in the High Cascades of Oregon The study was conducted in the 7, 700 acre (3 116 ha) Airstrip Burn on the crest of the Cascade Range near Santiam Pass, Willamette National Forest. The fire occurred during the period of August 28 until September 8, 1967. The pattern of burning included several areas of very severe burn, some light burn with only partially killed tree crowns, and some completely unburned islands. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.
Author: Cassie Lenae Hebel
Author: Cassie Lenae Hebel
Author: Richard V. Pouyat
Author: 
Author: C. T. Dyrness
Author: 
Author: Sam Fox
Author: Therese M. Poland
Author: 
Author: Christopher J. Dunn
Author: C. T. Dyrness