Vegetation Changes in Sequoia National Park, California

Vankat, John L.; Major, Jack

doi:10.2307/3038030

Cited by 141 publications

(154 citation statements)

References 21 publications

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“…Kilgore and Taylor (1979) relate the increase of white fir understory in the sequoia-mixed conifer forest type to the absence of fire. Vankat and Major (1978) relate increased tree density at lower elevations in the upper montane to fire suppression, but at higher elevations increased tree density appears to be the result of reduced grazing pressure. For example, mixed, white fir and giant sequoia stands showed increases in white fir density and cover since the initiation of fire suppression.…”

Section: Influence Of European Settlement On Fire Patternsmentioning

confidence: 95%

“…In 1861, for example, cattle were first introduced to the current SequoiaKings Canyon National Park (Vankat and Major 1978), and the droughts of 1862-63 and 1876-77 added impetus to summer grazing in the mountains (Ratliff 1985). Grazing increased dramatically, and while cattle use was widespread, sheep soon became dominant (Ratliff 1985, Vankat andMajor 1978). Often great circuits were made with sheep from the south being moved up the eastside of the range early in the year, across the many passes during the summer, and down the westside to the central valley in the fall.…”

Section: Grazingmentioning

confidence: 99%

“…During the drought of 1897-99 the North Fork of the Tule River area was grazed intensively by about 200,000 sheep, and as late as 1900 this number of sheep were still grazing in the Sequoia-Kings Canyon region (Vankat 1970).…”

Section: Grazingmentioning

confidence: 99%

“…During drought years high mountain forage was used intensively by a wide range of stock including cattle, sheep, milk cows, horses, goats, and pigs. Early accounts of Sequoia-Kings Canyon National Park document that most of the park was used to at least some extent, and most use was, in fact, intensive (Vankat and Major 1978). Entry onto the range too early caused as many problems as excessive stocking, and often several herds used the same routes into the mountains over a period of time.…”

Section: Grazingmentioning

confidence: 99%

“…Changes to the landscape between the 1850's and early 1900's must have been particularly dramatic. Many studies show that, from the time of Spanish settlement until formation of the Forest Reserves, grazing completely changed the herbaceous layer of the grasslands and foothill woodlands (Burcham 1957, Vankat andMajor 1978). Most detailed accounts and analysis, however, are from lower elevations in the central valley and foothills.…”

Section: Grazingmentioning

confidence: 99%

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Forested Communities of the Upper Montane in the Central and Southern Sierra Nevada

Potter¹

1998

112

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Potter, Donald A. 1998 Upper montane forests in the central and southern Sierra Nevada of California were classified into 26 plant associations by using information collected from 0.1-acre circular plots. Within this region, the forested environment including the physiographic setting, geology, soils, and vegetation is described in detail. A simulation model is presented for this portion of the Sierra Nevada that refines discussions of climate, and disturbance regimes are described to illustrate the interaction between these features of the environment and vegetation in the study area. In the classification, plant associations are differentiated by floristic composition, environmental setting, and measurements of productivity. Differences in elevation, aspect, topographic setting, and soil properties generally distinguish each plant association described. A detailed description is presented for each plant association, including a discussion of the distribution, environment, vegetation, soils, productivity, coarse woody debris, range, wildlife, and management recommendations. A complete species list and tables for cross referencing specific characteristics of each association are provided.

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Section: Influence Of European Settlement On Fire Patternsmentioning

confidence: 95%

Section: Grazingmentioning

confidence: 99%

Section: Grazingmentioning

confidence: 99%

Section: Grazingmentioning

confidence: 99%

Section: Grazingmentioning

confidence: 99%

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Forested Communities of the Upper Montane in the Central and Southern Sierra Nevada

Potter¹

1998

112

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Can low‐severity fire reverse compositional change in montane forests of the Sierra Nevada, California, USA?

Becker

Lutz

2016

Ecosphere

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Citation: Becker, K. M. L., and J. A. Lutz. 2016. Can low-severity fire reverse compositional change in montane forests of the Sierra Nevada, California, USA? Ecosphere 7(12):e01484. 10. 1002/ecs2.1484 Abstract. Throughout the Sierra Nevada, nearly a century of fire suppression has altered the tree species composition, forest structure, and fire regimes that were previously characteristic of montane forests. Species composition is fundamentally important because species differ in their tolerances to fire and environmental stressors, and these differences dictate future forest structure and influence fire regime attributes. In some lower montane stands, shade-tolerant, fire-sensitive species have driven a threefold increase in tree density that may intensify the risk of high-severity fire. In upper montane forests, which were historically characterized by longer fire return intervals, the effects of fire exclusion are both less apparent and less studied. Although land managers have been reintroducing fire to lower and upper montane forests for >4 decades, the potentially restorative effects of these actions on species composition remain largely unassessed. We used tree diameter and species data from 51 recently burned and 46 unburned plots located throughout lower and upper montane forests in Yosemite National Park and Sequoia & Kings Canyon National Parks to examine the effects of low-to moderate-severity (hereafter, lower-severity) fire on the demography of seven prevalent tree species. The density of Abies concolor <30 cm diameter at breast height (dbh) was significantly lower in burned plots than unburned plots; densities of A. concolor 30-45 cm dbh, A. magnifica <30 cm dbh, and Calocedrus decurrens <15 cm dbh were lower in burned plots than unburned plots at a marginal level of significance. These diameter thresholds represent the maximum size at which each species is likely to experience significant mortality from lower-severity fire. We overlaid these thresholds on historical and contemporary diameter distributions to show that: (1) lower-severity fire has reduced mean tree density to historical levels for A. concolor but not for C. decurrens, and (2) variability in tree density among plots that burned at lower severity exceeded the range of tree densities reported in historical data sets. High proportions of shade-tolerant species in some postfire stands may increase the prevalence of shade-tolerant species in the future, a potential concern for managers who seek to minimize ladder fuels and promote forest structure that is less prone to high-severity fire.

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Shrinking windows of opportunity for oak seedling establishment in southern California mountains

et al. 2016

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Abstract. Seedling establishment is a critical step that may ultimately govern tree species' distribution shifts under environmental change. Annual variation in the location of seed rain and microclimates results in transient "windows of opportunity" for tree seedling establishment across the landscape. These establishment windows vary at fine spatiotemporal scales that are not considered in most assessments of climate change impacts on tree species range dynamics and habitat displacement. We integrate field seedling establishment trials conducted in the southern Sierra Nevada and western Tehachapi Mountains of southern California with spatially downscaled grids of modeled water-year climatic water deficit (CWD wy ) and mean August maximum daily temperature (T max ) to map historical and projected future microclimates suitable for establishment windows of opportunity for Quercus douglasii, a dominant tree species of warm, dry foothill woodlands, and Q. kelloggii, a dominant of cooler, more mesic montane woodlands and forests. Based on quasi-binomial regression models, Q. douglasii seedling establishment is significantly associated with modeled CWD wy and to a lesser degree with modeled T max . Q. kelloggii seedling establishment is most strongly associated with T max and best predicted by a two-factor model including CWD wy and T max . Establishment niche models are applied to explore recruitment window dynamics in the western Tehachapi Mountains, where these species are currently widespread canopy dominants. Establishment windows are projected to decrease by 50-95%, shrinking locally to higher elevations and north-facing slopes by the end of this century depending on the species and climate scenario. These decreases in establishment windows suggest the potential for longer-term regional population declines of the species. While many additional processes regulate seedling establishment and growth, this study highlights the need to account for topoclimatic controls and interannual climatic variation when assessing how seedling establishment and colonization processes could be affected by climate change.

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Vegetation Changes in Sequoia National Park, California

Cited by 141 publications

References 21 publications

Forested Communities of the Upper Montane in the Central and Southern Sierra Nevada

Forested Communities of the Upper Montane in the Central and Southern Sierra Nevada

Can low‐severity fire reverse compositional change in montane forests of the Sierra Nevada, California, USA?

Shrinking windows of opportunity for oak seedling establishment in southern California mountains

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