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45 Cards in this Set
- Front
- Back
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Vital attributes of California Annual Grassland |
1. Reproduction, germination, and seedling growth is high 2. Avoid summer drought by growing during winter and die off as rains stop 3. Effective dispersal mechanisms |
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California Annual Grassland tenure |
80-85% private |
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What cultivated the transition of California annual grasslands into a 70-90% introduced grass species composition? |
Increased livestock, drought, Cultivation (prep and abandonment), vital attributes of introduced annuals |
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What method was use to date the transition to a primarily introduced grass species composition |
Dating of plants used in Mission infrastructure |
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Methods of management in California Annual Grassland |
Base grazing off of timing of first germianting rain and frequency of the rains (determines species) Manage mulch amount (RDM) - to much not enough light - to little not enough water retention in soil Manage intensity of grazing |
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Physiognomy of a California Chaparral |
Dense Shrub, Few trees, Low herbaceous abundance unless after a fire |
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Seasonal regime of the California Chaparral |
Hot Dry summer Fire in october Wet mild winter |
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California chaparral herb response to fire |
Scarification of seed coat allowing water permeability Kills neighboring allelopathic species
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Is Adenostoma fasciculatum and obligate seeder or sprouter and how does this effect Herbaceous growth |
Chamise is a sprouter and can recover 1/2 its original size after the first year. This introduces cover but limits further herbaceous germination due to the return of allelopathic chemicals |
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Differences in temperature intensity can be used to select for specific species in a California Chaparral. What stimulates Chamise |
Low temperature fires stimulate the best regrowth from Adenstoma Fasciculatum and High intensity fires support growth of Ceanothus greggi |
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How can fire intensity be managed? |
Weather Addition or removal of fuels |
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How are Seedlings and obligate seeders effected by a high frequency fire regime |
Seedling germination is dependent the existing seed bank. As fire occur more readily this bank is depleted and adult plants wont exist to replenish the seed bank. - also seen in perennial herbaceous growth |
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What would the expected density be for an introduced annual if fires were a frequent occurrence? |
Density would be at its highest as the introduced annuals begin to out compete natives by taking advantage of and supporting a high fire regime. |
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Plant response to fire occurs as a response to? |
1. Frequency 2. Time since last fire |
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Place these communities in order as they would appear as elevation increases - Pinyon-juniper woodland, sagebrush-grass, Ponderosa Pine-grass, and Salt desert shrub |
1. Salt Desert Shrub 2. Sagebrush - grass 3. Pinyon-juniper woodlands 4. Ponderosa Pine-grass |
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What is the relationship between fire and age structure in California Oak Woodland |
Fire stimulates recruitment by removing cover and allowing increased sunlight and precipitation on seedlings |
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When would grazing provide the greatest support for Blue Oak survival and why? |
Winter gazing would provide the greatest survival of blue oak because annual grass growth occurs mostly in the winter and is most edible during this time. grazing would have the greatest impact and reduce the potential for fire. |
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What is the tenure of Sal-desert shrub (cold desert) |
90% public |
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Attributes of Salt-desert shrub community |
6-10 Inches of precipitation 100-150 days without frost Soil high in salt content |
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Where is the bulk standing crop found for plants in a Salt desert shrub community? |
4000-8000 Kg/ha underground compared to 500-2000kg/ha above |
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What the greatest limiting factor to a species living in a Salt desert shrub community? |
Water |
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What factors contribute to species survival in a Sal-desert shrub community? |
precipitation and following root growth |
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When was the Taylor grazing act implemented and what effect did it have on canopy cover over time in a salt-desert shrub community? |
1934, which caused a reduction in grazing to favor a more sustainable approach. This caused a double in canopy cover in the next 30 years. |
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Why would winter grazing cause less impact on salt-desert shrub? |
Majority of growth occurs in spring. |
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Environmental attributes of a sagebrush-grass community? |
80-90% public land Soils have a lower concentration of salt physiognomy: Big condense shrub land (not as dense as Chaparral), More grass under story Precipitation: 8-20 inches a year Elevation: 4-7000ft |
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What 2 factors determine the species appearance in a sagebrush-grass community? |
Moisture elevation |
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What are the 4 soil surface morphologies and which would be most favorable for seedling establishment in a Sagebrush-grass community? |
Coppice Coppice bench Intercoppice microplain playette |
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High fire frequency in Sagebrush-grass communities caused an increase and decrease in what species and what was the cause? |
Reduction in seed bank reduced Artemisia tridentata as well as chrysothamnus species that also suffered from energy expenditure from sprouting. |
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Attributes of Pinyon-juniper Woodland |
Elevation: 4,500 - 7000ft Late April growth and Second growth with Summer rain |
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Summer dominated precipitation leads to what time of physiognomy in Pinyon-juniper woodlands? |
Savannah |
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Absence of fire in pinyon-juniper Savannah would lead to what transition in physiognomy |
Transition into woodland shrub land and persistent woodland |
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Grass productivity is contingent on what factor in a Pinyon-juniper woodland |
Nonlinear association based on tree cover which depends on how much tree cover already exists |
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Spreading low-intensity ground fires were important in what types of pinyon-juniper woodland |
Wooded Shrubland and Savannah *not Persistent Woodlands because stands are 300+ years old (High intensity are stand replacing) |
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Fire intervals and rotations were long in what type of pinyon-juniper woodland |
Persistent Woodland |
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High intensity Stand-replacing fires are similar to historic fires in what type of pinyon-juniper woodland |
None, but there is moderate evidence in Persistent woodlands |
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Stand dynamics were driven more by other disturbances other than fire such as climate, insects, or disease in what type of pinyon woodland? |
Persistent Woodlands |
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Are mechanisms for expansion and infill not well known in pinyon-juniper woodland types? |
Yes |
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What are possible mechanisms for expansion and infill in pinyon-juniper woodlands? |
Recovery from past severe disturbances Natural range expansion direct effect of livestock grazing Fire exclusion Climate variability including CO2 increase - Favoring C3 plants |
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In the early 1900s what additional successional pressure was added to pinyon-juniper woodlands that resulted in a decline in diversity, sustainability, and aesthetics and how? |
Grazing removed majority of surface grasses allowing accelerated erosion. This invited shrub invasions which die, add to present fuels, and spurred new fire regimes with the introduction of annuals that perpetuate this new regime. |
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Physiognomy and Species composition of California Chaparral |
Dense Chamise (Adenostoma fasciculatum) or desert Ceanothus (Ceanothus greggi) shrub dominance, with few trees and little understory unless after a fire |
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Physiognomy and species composition of California Oak Woodland |
Blue oak trees at 10-60% cover, with herbaceous understory, and common shrubbery |
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California Oak woodlands and Pinyon-juniper Woodlands have different historical fire regimes and pressures. Due these differences how do you expect age structure to vary and why? |
Pinyon-juniper woodlands would have an array of multiple aged individuals ranging back hundreds of years, whereas the California Oak Woodland would have large areas with similar age structure. This is due to the increase in fire following the gold rush in 1848 clearing canopies and the blue oaks ability to resprout following these fire, which consistently restarted the cohort to the same ages. |
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Physiognomy and species composition of Pinyon-Juniper woodland. |
30-60% cover from short trees with shrub and grass - Pinyon pine - Pinus edulis |
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Physiognomy and species composition of Ponderosa pine-grass |
Tall trees with grass understory and and few shrubs |
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What changes led to a releases from the historical fire regime disturbance to a regime of high fire intensity in Ponderosa pine-grass communities? |
- Second Growth (intense regrowth) due to significant timber harvesting in 1880s-1890s - Reduced Herbaceous due to open access grazing - Fire suppression due to less fuels - Wet years led in the early 1910s led to high seed production and growth - |
