Drivers of Post-fire Conifer Regeneration in Lassen Volcanic National Park PDF Download
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Author: Dani Niziolek
Publisher:
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Category :
Languages : en
Pages : 0
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Contemporary fires in California are becoming larger, more frequent, and increasingly severe, and this trend is expected to continue in the coming decades. Increases in area burned and area burned at high severity generate larger high severity patches without a tree canopy, which can impede forest recovery by limiting seed dispersal from live trees and triggering vegetation type change. Although there is an emerging body of research on post-fire conifer regeneration, there is uncertainty in how landscape and local site conditions interact to influence regeneration. This thesis identifies dominant drivers of postfire conifer regeneration in Lassen Volcanic National Park in the southern Cascades. We studied post-fire conifer regeneration in the footprint of nine fires, between 7 and 26 years after the burn, quantifying pre- and post-fire forest condition, topography and topoclimate, and local terrain and ground cover at each plot. Random Forest models assessed the relationship between these environmental conditions and regeneration stocking or species occurrence. We found that post-fire conifer regeneration was relatively abundant in Lassen Volcanic National Park, and abundance was related toto topography, vegetation type, and characteristics of the pre- and post-fire forest. Regeneration was densest in cooler, wetter topographic positions, and although overall regeneration did not respond to post fire water balance, species showed different responses to moisture availability. Regeneration responded positively to proximity to forest edge and longer time since fire, with the strongest regeneration occurring within 200 m of forest edge and >10 years since fire. Though high levels of shrub cover inhibited regeneration, at lower levels shrub cover supported more dense tree regeneration. These findings support trends found in the literature, and highlight the importance of studying regeneration over longer periods after fire, and incorporating characteristics of the local environment in studies of post-fire conifer regeneration.
Author: Dani Niziolek
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Contemporary fires in California are becoming larger, more frequent, and increasingly severe, and this trend is expected to continue in the coming decades. Increases in area burned and area burned at high severity generate larger high severity patches without a tree canopy, which can impede forest recovery by limiting seed dispersal from live trees and triggering vegetation type change. Although there is an emerging body of research on post-fire conifer regeneration, there is uncertainty in how landscape and local site conditions interact to influence regeneration. This thesis identifies dominant drivers of postfire conifer regeneration in Lassen Volcanic National Park in the southern Cascades. We studied post-fire conifer regeneration in the footprint of nine fires, between 7 and 26 years after the burn, quantifying pre- and post-fire forest condition, topography and topoclimate, and local terrain and ground cover at each plot. Random Forest models assessed the relationship between these environmental conditions and regeneration stocking or species occurrence. We found that post-fire conifer regeneration was relatively abundant in Lassen Volcanic National Park, and abundance was related toto topography, vegetation type, and characteristics of the pre- and post-fire forest. Regeneration was densest in cooler, wetter topographic positions, and although overall regeneration did not respond to post fire water balance, species showed different responses to moisture availability. Regeneration responded positively to proximity to forest edge and longer time since fire, with the strongest regeneration occurring within 200 m of forest edge and >10 years since fire. Though high levels of shrub cover inhibited regeneration, at lower levels shrub cover supported more dense tree regeneration. These findings support trends found in the literature, and highlight the importance of studying regeneration over longer periods after fire, and incorporating characteristics of the local environment in studies of post-fire conifer regeneration.
Author: Zachary J. Wenderott
Publisher:
ISBN:
Category : Abies concolor
Languages : en
Pages : 54
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Forests throughout much of the western United States are experiencing increasing climatic variability, often resulting in decreased forest productivity and elevated likelihood of tree mortality. Severe drought, such California’s recent 2012-2015 drought, are projected to increase in intensity, frequency, and severity throughout much of this region in coming years. Forest management has long relied on prescribed fire and mechanical thinning to reduce fuel loads and ameliorate potential fire hazards. These treatments may also have the ability to reduce stand density, alleviate competitive pressures, and allow residual trees access to critical resources during periods of extreme stress. Utilizing a long-term National Park Service fire monitoring program allowed us to analyze the effects of prescribed fire treatments on radial growth response in a mixed-conifer forest of northern California. Tree core samples were collected and analyzed from 136 yellow pine (ponderosa pine (Pinus ponderosa) and Jeffrey pine (Pinus jeffreyi)) and 136 white fir (Abies concolor) trees within Lassen Volcanic National Park. Tree-ring data was used to describe factors that influenced tree growth during the locally identified low moisture period (2007 - 2015), as well the potential ability of treatments to improve tree drought resistance and subsequent recovery. Radial growth was positively associated with crown ratio and annual precipitation totals, and negatively associated with localized competitive pressures. Within treatment sites, where stand density was effectively reduced, trees showed improved annual radial growth rates. This appeared to be generally driven by overall treatment intensity and its ability to alter forest density. White fir exhibited a stronger growth response to competitive pressures compared to yellow pine; however, radial growth rates were generally driven by the same factors. Drought resistance did not appear to be strongly correlated with competitive pressures, though drought recovery was slightly associated with increased competitive levels. Findings suggests future forest management techniques, such as prescribed fire and thinning, may be beneficial in terms of reducing competitive pressures and improving radial tree growth among residual trees during future more severe drought.
Author: Justin S. Crotteau
Publisher:
ISBN:
Category : Conifers
Languages : en
Pages : 192
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Author: Pablo Gregorini
Publisher: Frontiers Media SA
ISBN: 288976463X
Category : Technology & Engineering
Languages : en
Pages : 649
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This Research Topic is hosted in partnership with the "Grazing in Future Multi-Scapes" international workshop. The workshop will be held online, 30th May - 5th June 2021. Throughout different landscapes of the world, “grazing” herbivores fulfill essential roles in ecology, agriculture, economies and cultures including: families, farms, and communities. Not only do livestock provide food and wealth, they also deliver ecosystem services through the roles they play in environmental composition, structure and dynamics. Grazing, as a descriptive adjective, locates herbivores within a spatial and temporal pastoral context where they naturally graze or are grazed by farmers, ranchers, shepherds etc. In many cases, however, pastoralism with the single objective of maximizing animal production and/or profit has transformed landscapes, diminishing biodiversity, reducing water and air quality, accelerating loss of soil and plant biomass, and displacing indigenous animals and people. These degenerative landscape transformations have jeopardized present and future ecosystem and societal services, breaking the natural integration of land, water, air, health, society and culture. Land-users, policy makers and societies are calling for alternative approaches to pastoral systems; a call for diversified-adaptive and integrative agro-ecological and food-pastoral-systems designs that operate across multiple scales and ‘scapes’ (e.g. thought-, social-, land-, food-, health-, wild-scapes), simultaneously. There needs to be a paradigm shift in pastoral production systems and how grazing herbivores are managed –grazed- within them, derived initially from a change in perception of how they provide wealth. The thoughtscapes will include paradigm shifts where grazers move away from the actual archetype of pastoralism, future landscapes are re-imagined, and regenerative and sustainable management paradigms are put in place to achieve these visions. From this will come a change in collective thinking of how communities and cultures (socialscapes) perceive their relationships with pastoral lands. The landscapes are the biotic and abiotic four-dimensional domains or environments in need of nurture. Landscapes are the tables where humans and herbivores gain their nourishment, i.e. foodscapes. Foodscapes and dietary perceptions, dictate actions and reactions that are changing as developed countries grapple with diseases related to obesity, and people starve in developing countries. Societies are demanding healthscapes and nutraceutical foodscapes, and paradoxically, some are moving away from animal products. While indigenous species of animals, including humans (wildscapes), have been displaced from many of their lands by monotonic pastoralism, multifunctional pastoral systems can be designed in view of dynamic multi-scapes of the future. The purpose of this Research Topic is to influence future mental and practical models of pastoralism in continually evolving multi-scapes. We seek a collection of papers that will cultivate such a shift in thinking towards future models of sustainable multipurpose pastoralism. The contributions will be synthesized to establish how multifunctional pastoral systems can be re-imagined and then designed in view of the integrative dynamics of sustainable future multi-scapes.
Author: Kevin Robert Welch
Publisher:
ISBN: 9781321807653
Category :
Languages : en
Pages :
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This study examines postfire regeneration patterns in low to mid-elevation forests of northern and central California where conifers co-exist and compete with hardwoods and shrubs in the postfire environment. Due to fire suppression policies, timber harvest, and other management practices over the last century, many low- to mid-elevation forests in California have accumulated high fuel loads and dense, multi-layered canopies that are dominated by shade-tolerant and fire-sensitive conifers. These conditions promote high-intensity fires, which have major effects on forest structure, function, and composition. We established 1,854 survey plots in nineteen wildfires on ten National Forests across a range of elevations, forest types, and fire severities in central and northern California to provide insight into factors that promote natural tree regeneration after wildfires and the differences in post-fire responses of the most common conifer species and hardwood species. We developed a zero-inflated negative binomial mixed model with random effects to understand the importance of ten environmental variables in predicting conifer regeneration. This model identified as important factors distance to potential seed tree, annual precipitation, presence of regenerating shrubs, litter cover, fire severity and pre-existing forest type. We documented widespread conifer regeneration failure with nearly 50% of all plots devoid of conifer regeneration. When regeneration did occur, it was dominated by shade-tolerant but fire-sensitive firs, Douglas-fir and incense cedar. Active forest restoration (planting, brush control, reduction of undesirable species, etc.) may be necessary in more severely burned areas farther from seed trees where natural regeneration is insufficient to restore forest composition and structure, increasing forest resiliency in the face of climate change and augmented levels of fire disturbance. However, conifers do not exist in isolation in these forests and the interaction with other functional woody plant types must be considered. This study adds a unique contribution to understanding postfire regeneration dynamics by comparing the relative success of hardwoods to conifers across a fire severity gradient and in the first decade after mixed-severity fires. By utilizing vegetative sprouting (and to a lesser extent sexual reproduction), hardwood trees and shrubs are able to quickly capitalize on available resources and this ability may confer a competitive advantage to hardwoods. The results of this study indicate that increased fire severity leads to greater relative density of hardwoods via a combined impact of resprouts and seedlings, creating alternative states where hardwoods and shrubs (that suppress the relatively few conifer seedlings that do establish) may dominate for many years after disturbance. To a great extent, the future status of California's forests will depend on tree species' responses to patterns and trends in fire activity and behavior and post-fire management decisions.
Author: Catherine T. Airey
Publisher:
ISBN:
Category :
Languages : en
Pages : 70
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Author: United States. National Park Service
Publisher:
ISBN:
Category : Fire management
Languages : en
Pages : 156
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Author:
Publisher:
ISBN:
Category : Conifers
Languages : en
Pages : 0
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Shifting wildfire patterns and climate conditions, magnified by anthropogenic climate change, are threatening the resilience of conifer forests in North America and more specifically, the western US. If native conifer species are functionally maladapted to novel fire patterns and post-fire climate conditions, large-scale shifts in conifer forest structure, composition, and extent may occur as warming intensifies. Forest resilience in the context of fire and climate can be understood and quantified by the survival of trees through fire events and success of trees to regenerate post-fire and maintain population levels. In this dissertation, I use field observations and remote sensing to examine patterns of fire-induced tree mortality and post-fire tree regeneration as proxies of conifer forest resilience in the western US, across a range of environments and forest types, and particularly within the context of expansive high-severity, stand-replacing wildfires. In Chapter 1, I evaluate the interactions between climate-environment conditions and the spatial, structural, and temporal characteristics of fire refugia as drivers of subalpine forest recovery in the cool and moist Cascade Range of Oregon and Washington. In Chapter 2, I quantify large-scale patterns of post-fire delayed conifer tree mortality across three ecoregions and two broad forest types in the western US using high-resolution satellite imagery, and I evaluate whether post-fire delayed conifer tree mortality is a ubiquitous process across broad geographies, and if so, I ask i) what drives it? and ii) can it meaningfully affect seed dispersal and thus forest regeneration processes? Finally, in Chapter 3, I use an aggregated database of post-fire conifer establishment responses, across over 1800 sites and four ecoregions in the western US, to challenge the generalized notion that conifer species' shade-tolerance dictates their regenerative capacity within exposed early seral post-fire environments.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 124
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Author:
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Languages : en
Pages :
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Repeated observations of forest recovery using permanent plots allow scientists to map pathways of primary succession at the community level. This study continued the documentation of changes in forest composition on the Devastated Area in Lassen Volcanic National Park (LVNP) by re-sampling 34 randomly selected, permanent, 100-m2 plots first established and measured in 1988 (Kroh et al., 2000) in the Devastated Area. GPS coordinates and canopy closure of each plot were recorded. All living trees ≥ 0.10m tall were identified to species, and measured for height and diameter at breast height (DBH) in July of 2008. Pinus contorta, Abies magnifica and Pinus monticola were the dominant species on the Devastated Area. From 1988 to 2008, the mean height of trees per plot increased 73%, total mean basal area per plot increased 147%, and the mean density per plot increased by 19.9%. Despite large increases in basal area and height, full canopy closure has not occurred for most of the forest (median = 67%), indicating primary succession is still driven by abiotic factors. Comparison of the 2008 data to a similar age P. contorta stand on richer soils suggested that an additional 56 years may be required to reach a similar canopy closure of 91% and the onset of self-thinning due to biotic interactions.
