logo Calflora Map Layer  HELP
Updated May 3, 2022
  VIDEO: Overview

  VIDEO: Using the map cursor

  • Interface
  • Region Layers
  • Grid Layers
  • Climate Layers
  • Soil Layers
  • Ultramafic Areas
  • Release Notes

    One Polygon Layer at a Time
    Layers are available in several Calflora applications that use Google Maps, including Observation Search. The map applications can show one polygon background layer at a time. When a background polygon layer is selected, and you click on the map inside of a polygon, you will see the name of the polygon below the map.

    County Lines and Streams can be turned on at the same time as a polygon background layer. These two layers are lines, not polygons, and so can be superimposed on top of the selected polygon layer.

    Map Cursor
    See the Introduction to Calflora Map Applications, which explains how the map cursor works.

    Polygon Background Layers
    Polygon background layers are divided into four groups: Region, Grid, Climate, and Soil. Click on a group name -- for instance Region -- to see all of the layers within that group. Then click on the name of a layer -- for instance Protected Areas (CPAD) -- and the colored polygons of that layer will be superimposed on top of the Google Map. Note that not all layers are available at all zoom levels.

    The four checkboxes at the bottom control the appearance of colored polygons in the selected background layer. If the appearance of the polygons is too subtle, you can emphasize the outline of each polygon, or ask for a darker background color for each polygon.

    Here is an example of the Climate / Precipitation layer with darker background colors and a thick white outline (click to see it "live").

    Click on Streams to see rivers and creeks on the map. If you are zoomed way out, you will only see the longest rivers. As you zoom in, the shorter streams appear.

    When you check Stream names, a stream icon will appear at the end of each creek or river. When you click on the icon, you see the name of the creek or river, and the name of the stream that the creek or river flows into.

    For instance, in Monterey County, the icon for the creek called Arroyo Seco appears at the end of the Arroyo Seco, where it flows into the Salinas River. When you click on the icon an info window pops up describing the junction:
    Arroyo Seco / Salinas River
    The course of the stream itself -- the Arroyo Seco -- is highlighted in blue. The course of the downstream creek or river -- the Salinas River -- is highlighted in green.

    Uncheck Stream names to clear the map of all stream icons and all stream course highlighting.

    If you move to a different location on the map or change zoom level, and would like to see stream name icons at the new location, press the refresh button .

    The Streams dataset is from the May 27, 2019 version of the California Department of Fish and Wildlife California Streams dataset.

    National Hydrography Dataset (NHD) high resolution NHDFlowline features for California were originally dissolved on common GNIS_ID or StreamLevel attributes and routed from mouth to headwater in meters. The results are measured polyline features representing entire streams.

    The named streams from the California Streams dataset are shown in Calflora map applications. If a named stream flows into an unnamed stream, that unnamed stream is also shown, with a label like "uns123". Many of these unnamed streams are canals or other engineered hydrologic features.


    If this background polygon layer is selected, you will see county boundary lines (the same as County Lines above) for California counties. The county polygons themselves are not colored. However, when you click on the map inside of California, you will see the county name below the map.

    California Protected Areas Database (CPAD)

    Version 2018a (December, 2018) from Greeninfo Network

    The California Protected Areas Database (CPAD) is a GIS inventory of all protected park and open space lands in California. The database contains lands held in fee ownership by public agencies and non-profits.

    The units level of this database is shown in Calflora map applications. Click in an area to see its name.

    For areas with restricted access or no access to the public, the warning is included after the name. For instance

    San Francisco Watershed Lands - restricted access
      No Access
      Restricted Access
      Park or Open Space area; Public Access
      Federal Land (other than National Parks); Public Access

    From CalWater 2.2.1.

    Downloadable from San Jose State University Marine Pollution Studies Laboratory.

    Calflora map applications can show the four levels of this dataset listed on the right. Which level is shown depends on how far in the map is zoomed in.

    Level Example
    Planning Watershed 3309.811105 Little Burnett Creek
    Super Planning Watershed 3309.8111 McLaughlin Canyon
    Hydrologic Area 3309.8 Paso Robles
    Hydrologic Unit 3309. Salinas

    Major Land Resource Areas (NRCS)

      04B Coastal Redwood Belt
      05 Siskiyou - Trinity Area
      14 Central California Coastal Valleys
      15 Central California Coastal Range
      16 California Delta
      17 Sacramento and San Joaquin Valleys
      18 Sierra Nevada Foothills
      19 Southern California Coastal Plain
      20 Southern California Mountains
      21 Klamath and Shasta Valleys and Basins
      22A Sierra Nevada Mountains
      22B Southern Cascade Mountains
      23 Malheur High Plateau
      26 Carson Basin and Mountains
      29 Southern Nevada Basin and Range
      30 Mojave Desert
      31 Lower Colorado Desert

    4ETa Zones (description)
    indicating evaopotranspiration (NRCS California)

      b18 - 21inches
      c15 - 18inches
      d12 - 15inches
      e9 - 12inches
      f6 - 9inches
      g3 - 6inches
      h0 - 3inches

    EPA Ecoregions

    Level III Ecoregions (documentation)
    1. Coast Range
    78. Klamath Mountains/California High North Coast
    4. Cascades
    9. Eastern Cascades Slopes and Foothills
    80. Northern Basin and Range
    6. Central California Foothills and Coastal Mountains
    7. Central California Valley
    5. Sierra Nevada
    13. Central Basin and Range
    8. Southern California Mountains
    14. Mojave Basin and Range
    85. Southern California Coast
    81. Sonoran Basin and Range

    Level IV Ecoregions (documentation)
    1. Coast Range
    1a. Coastal Lowlands
    1i. Northern Franciscan Redwood Forest
    1j. King Range/Mattole Basin
    1k. Coastal Franciscan Redwood Forest
    1l. Fort Bragg/Fort Ross Terraces
    1m. Point Reyes/Farallon Islands
    1n. Santa Cruz Mountains
    1o. San Mateo Coastal Hills
    78. Klamath Mountains/California High North Coast
    78a. Rogue/Illinois/Scott Valleys
    78d. Serpentine Siskiyous
    78e. Inland Siskiyous
    78g. Klamath River Ridges
    78h. Border High-Siskiyous
    78i. Western Klamath Low Elevation Forests
    78j. Western Klamath Montane Forests
    78k. Eastern Klamath Low Elevation Forests
    78l. Eastern Klamath Montane Forests
    78m. Marble/Salmon Mountains-Trinity Alps
    78n. Scott Mountains
    78o. Klamath Subalpine
    78p. Duzel Rock
    78q. Outer North Coast Ranges
    78r. High North Coast Ranges
    4. Cascades
    4d. Cascade Subalpine/Alpine
    4e. High Southern Cascades Montane Forest
    4f. Low Southern Cascades Mixed Conifer Forest
    4g. California Cascades Eastside Conifer Forest
    4h. Southern Cascades Foothills
    9. Eastern Cascades Slopes and Foothills
    9g. Klamath/Goose Lake Basins
    9h. Fremont Pine/Fir Forest
    9i. Southern Cascades Slope
    9j. Klamath Juniper Woodland/Devils Garden
    9k. Shasta Valley
    9l. Pit River Valleys
    9m. Warner Mountains
    9n. High Elevation Warner Mountains
    9o. Likely Tableland
    9p. Modoc/Lassen Juniper-Shrub Hills and Mountains
    9q. Adin/Horsehead Mountains Forest and Woodland
    9r. Adin/Dixie Low Hills
    9s. Modoc Lava Flows and Buttes
    9t. Old Cascades
    80. Northern Basin and Range
    80d. Pluvial Lake Basins
    80g. High Lava Plains
    80j. Semiarid Uplands
    6. Central California Foothills and Coastal Mountains
    6a. Tuscan Flows
    6b. Northern Sierran Foothills
    6c. Southern Sierran Foothills
    6d. Camanche Terraces
    6e. Tehama Terraces
    6f. Foothill Ridges and Valleys
    6g. North Coast Range Eastern Slopes
    6h. Western Valley Foothills/Dunnigan Hills
    6i. Clear Lake Hills and Valleys
    6j. Mayacmas Mountains
    6k. Napa-Sonoma-Lake Volcanic Highlands
    6l. Napa-Sonoma-Russian River Valleys
    6m. Sonoma-Mendocino Mixed Forest
    6n. Bodega Coastal Hills
    6o. Marin Hills
    6p. Bay Flats
    6q. Suisun Terraces and Low Hills
    6r. East Bay Hills/Western Diablo Range
    6s. San Francisco Peninsula
    6t. Bay Terraces/Lower Santa Clara Valley
    6u. Livermore Hills and Valleys
    6v. Upper Santa Clara Valley
    6w. Monterey Bay Plains and Terraces
    6x. Leeward Hills/Western Diablo Range
    6y. Gabilan Range
    6z. Diablo Range
    6aa. Eastern Hills
    6ab. Pleasant Valley/Kettleman Plain
    6ac. Temblor Range/Elk Hills
    6ad. Grapevine Transition
    6ae. Tehachapi Foothills
    6af. Salinas Valley
    6ag. Northern Santa Lucia Range
    6ah. Santa Lucia Coastal Forest and Woodland
    6ai. Interior Santa Lucia Range
    6aj. Southern Santa Lucia Range
    6ak. Paso Robles Hills and Valleys
    6al. Salinas-Cholame Hills
    6am. Cuyama Valley
    6an. Carrizo Plain
    6ao. Caliente Range
    6ap. Solomon-Purisima-Santa Ynez Hills
    6aq. Santa Maria/Santa Ynez Valleys
    6ar. Upper Sacramento River Alluvium
    7. Central California Valley
    7a. Northern Terraces
    7b. North Valley Alluvium
    7c. Butte Sink/Sutter and Colusa Basins
    7d. Southern Hardpan Terraces
    7e. Sacramento/Feather Riverine Alluvium
    7f. Sutter Buttes
    7g. Yolo Alluvial Fans
    7h. Yolo/American Basin
    7j. Delta
    7k. Lodi Alluvium
    7l. Stockton Basin
    7m. San Joaquin Basin
    7n. Manteca/Merced Alluvium
    7o. Westside Alluvial Fans and Terraces
    7p. Granitic Alluvial Fans and Terraces
    7q. Panoche and Cantua Fans and Basins
    7r. Tulare Basin/Fresno Slough
    7s. Kern Terraces
    7t. South Valley Alluvium
    7u. Antelope Plain
    7v. Southern Clayey Basins
    5. Sierra Nevada
    5a. Sierran Alpine
    5b. Northern Sierra Subalpine Forests
    5c. Northern Sierra Upper Montane Forests
    5d. Northern Sierra Mid-Montane Forests
    5e. Northern Sierra Lower Montane Forests
    5f. Northeastern Sierra Mixed Conifer-Pine Forests
    5g. Central Sierra Mid-Montane Forests
    5h. Central Sierra Lower Montane Forests
    5i. Eastern Sierra Great Basin Slopes
    5j. Eastern Sierra Mojavean Slopes
    5k. Southern Sierra Subalpine Forests
    5l. Southern Sierra Upper Montane Forests
    5m. Southern Sierra Mid-Montane Forests
    5n. Southern Sierra Lower Montane Forest and Woodland
    5o. Tehachapi Mountains
    13. Central Basin and Range
    13h. Lahontan and Tonopah Playas
    13u. Tonopah Basin
    13v. Tonopah Sagebrush Foothills
    13x. Sierra Nevada-Influenced Ranges
    13y. Sierra Nevada-Influenced High Elevation Mountains
    13aa. Sierra Nevada-Influenced Semiarid Hills and Basins
    13ab. Sierra Valley
    13ac. Upper Owens Valley
    13ad. Mono-Adobe Valleys
    13ae. Bishop Volcanic Tableland
    8. Southern California Mountains
    8a. Western Transverse Range Lower Montane Shrub and Woodland
    8b. Western Transverse Range Montane Forest
    8c. Arid Montane Slopes
    8d. Southern California Subalpine/Alpine
    8e. Southern California Lower Montane Shrub and Woodland
    8f. Southern California Montane Conifer Forest
    8g. Northern Transverse Range
    14. Mojave Basin and Range
    14a. Eastern Mojave Basins
    14b. Eastern Mojave Low Ranges and Arid Footslopes
    14c. Eastern Mojave Mountain Woodland and Shrubland
    14e. Arid Valleys and Canyonlands
    14f. Mojave Playas
    14g. Amargosa Desert
    14h. Death Valley/Mojave Central Trough
    14i. Mesquite Flat/Badwater Basin
    14j. Western Mojave Basins
    14k. Western Mojave Low Ranges and Arid Footslopes
    14l. Western Mojave Mountain Woodland and Shrubland
    14m. Western Mojave High Elevation Mountains
    14n. Mojave Lava Fields
    14o. Mojave Sand Dunes
    85. Southern California Coast
    85a. Santa Barbara Coastal Plain and Terraces
    85b. Oxnard Plain and Valleys
    85c. Venturan-Angeleno Coastal Hills
    85d. Los Angeles Plain
    85e. Diegan Coastal Terraces
    85f. Diegan Coastal Hills and Valleys
    85g. Diegan Western Granitic Foothills
    85h. Morena/Boundary Mountain Chaparral
    85i. Northern Channel Islands
    85j. Southern Channel Islands
    85k. Inland Valleys
    85l. Inland Hills
    85m. Santa Ana Mountains
    81. Sonoran Basin and Range
    81a. Western Sonoran Mountains
    81b. Western Sonoran Mountain Woodland and Shrubland
    81c. Western Sonoran Basins
    81d. Sand Hills/Sand Dunes
    81e. Upper Coachella Valley and Hills
    81f. Imperial/Lower Coachella Valleys
    81g. Lower Colorado/Gila River Valleys
    81h. Sonoran Playas
    81i. Central Sonoran/Colorado Desert Mountains
    81j. Central Sonoran/Colorado Desert Basins
    81k. Arizona Upland/Eastern Sonoran Mountains

    Jepson Flora Project Geographic Subdivisions
    Please see Jepson eFlora: Geographic subdivisions.
    Polygons are © 1993 Regents of the University of California.

    Jepson Regions

    Northwestern California
    Cascade Ranges
    Modoc Plateau
    Central Western California
    Great Valley
    Sierra Nevada
    East of Sierra Nevada
    Southwestern California
    Mojave Desert
    Sonoran Desert

    Historic Native American Tribal Territories
    From Historic Native American Territories in California, a shapefile contributed to ArcGis Online by SaltonSea.

    Based on Handbook of North American Indians Vol. 8. Smithsonian Institution, 1978. (SYNOPSIS).

    For a more detailed view that includes languages, territories, and overlap, see the Native Land Digital map.


    Geographic Grids

    USGS quadrangle. In most of the continental United States, quadrangles are a geographic grid where the side of a grid cell is 1/8 of a degree: There are also irregular quads around islands and on the coast.

    Quadrangle / 4
    Quarter quadrangle. This is a geographic grid where the side of a grid cell is 1/16 of a degree. (When Calflora observations are obscured, they are displayed at the center of the containing quarter quadrangle.)

    30 arcseconds
    This is a geographic grid where the side of a grid cell is 1/120 of a degree.

    Interlaced Metric Grids

    The side of a grid cell is 5 kilometers; the area of a cell is 25 square kilometers.

    The side of a grid cell is 2 kilometers.

    The side of a grid cell is 1 kilometer.

    100 M
    The side of a grid cell is 100 meters.

    Each climate and soil layer described here is presented as a abstract factor contributing to the characterization of a location. The choice of which factors to show as layers on Calflora maps is informed by USDA PLANTS Conservation Plant Characteristics (particularly Growth Characteristics), but within the pragmatic bounds of what data is available. The goal is to be able to use these factors as predictors of where various plants are likely to grow.

    as prepared by the Prism Climate Group at Oregon State University, and available from the USDA Geospatial Data Gateway.

    PRISM data is typically available as a raster, where a cell is 30 arcseconds (~ 800 m) on a side.

    CITATION: U.S. Department of Agriculture, Natural Resources Conservation Service, National Geospatial Management Center

    Average Annual Precipitation
    Annual average precipitation during the period 1971 - 2000.

    For predicting where a plant may grow, it is important to know the minimum annual precipitation it requires (and for certain plants, the maximum annual precipitation it will tolerate).

    157 inches 399 cm
    133 inches 338 cm
    107 inches 272 cm
    81 inches 206 cm
    61 inches 155 cm
    37 inches 94 cm
    17 inches 43 cm
    3 inches 8 cm

    As presented in Calflora map applications, the colors indicating climate layers are continuous. Colors associated with selected values of Annual Precipitation are shown here.

    Wet Season
    The number of wet months, as derived from monthly average precipitation (1981 - 2010) cell data. For a particular month, an 30 arcsecond cell is considered wet if it receives at least 1.3 inches of precipitation.

    As a characterization of location, this is similar to annual precipitation, but indicates the duration of a season during which rain is likely.

    12 months

    July High Temperature
    based on average maximum monthly data during the period 1981-2010.

    56 °F 13 °C
    68 °F 20 °C
    80 °F 27 °C
    92 °F 33 °C
    104 °F 40 °C
    116 °F 47 °C

    December Low Temperature
    based on average minimum monthly data during the period 1981-2010.

    8 °F -13 °C
    16 °F -9 °C
    24 °F -4 °C
    32 °F 0 °C
    40 °F 4 °C
    48 °F 9 °C

    Accumulated Temperature
    based on average mean temperature and average minimum temperature monthly data during the period 1981-2010. This is a measure of accumulated heat during those months during which the minimum temperature is greater than 43 ° F (6 ° C). It is related to the concept of degree-days, but unlike degree-days calculated for a particular year, this number is based on average mean temperature. It is roughly equivalent to an annual sum of degree-days during the growing season.

    In the context of these climate factors, accumulated temperature can help determine which places are too hot for a plant. It is particularly useful for differentiating very hot places (Death Valley) from moderately hot places (Fresno).

    60 °F 16 °C
    82 °F 28 °C
    104 °F 40 °C
    130 °F 54 °C
    156 °F 69 °C
    180 °F 82 °C
    204 °F 96 °C
    230 °F 110 °C
    256 °F 124 °C
    282 °F 139 °C
    300 °F 149 °C
    See also
      Wikipedia: Degree day:
        Total degree days from an appropriate starting date are used to plan the planting of crops and management of pests and pest control timing.

      Accumulated Temperature, Oxford Reference / A Dictionary of Ecology

    A comparative study of different temperature accumulation methods for predicting the start of the Quercus pollen season in Cordoba (South West Spain), H. Garcia-Mozo, C. Galan, M. T. Gomez-Casero and E. Dominguez-Vilches, in Grama 39: 194-199, 2000

    Temperature Range
    Calculated as July High Temperature minus December Low Temperature per cell. In climate modelling, temperature range is akin to temperature seasonality.

    In the context of these climate factors, temperature range is useful for differentiating coastal areas from inland areas. Coastal areas typically have a narrower temperature range than inland areas.

    Two Coastal Vacciniums:
    These two plants share much of their geographic range, but parvifolium extends further inland than ovatum. The difference is reflected in the Temperature Range value for each plant. The image below is a screen shot from What Grows Here, showing occurrences of the two plants in Humboldt County with Temperature Range as the background layer.

    Note how the background color reveals temperature range differences between inland mountains (green ~ 48° F) and valleys (orange ~ 66° F).

    10 °F -12 °C
    24 °F -4 °C
    36 °F 2 °C
    48 °F 9 °C
    54 °F 12 °C
    60 °F 16 °C
    66 °F 19 °C
    76 °F 24 °C

    Growing Season
    The number of consecutive warm months, as derived from average minimum monthy temperature (1981 - 2010) cell data. For a particular month, a 30 arcsecond cell is considered warm if the average minimum temperature is at least 43 ° F (6 ° C).

    12 months
    ≤ 1month

    USDA Hardiness Zone
    The map is based on average annual minimum winter temperature, divided into zones by 5 ° F increments. See the USDA Plant Hardiness Zone Map.

    Hardiness Zone differs from December Low Temperature above, in that it reflects the lowest temperature that might ever be experienced at a location.

    Units: degrees Fahrenheit

    5a: -20 to -15
    5b: -15 to -10
    6a: -10 to -5
    6b: -5 to 0
    7a: 0 to 5
    7b: 5 to 10
    8a: 10 to 15
    8b: 15 to 20
    9a: 20 to 25
    9b: 25 to 30
    10a: 30 to 35
    10b: 35 to 40
    11a: 40 to 45

    DISCLAIMER: Shapefiles of the hardiness zones for California were purchased and downloaded from Climate Source in February, 2014. They were subsequently modified (chopped into smaller pieces) for display as a map background layer.
    USDA Agricultural Research Service Terms of Use: Data: Users may obtain enhanced (high resolution) official USDA Plant Hardiness GIS data in shapefile and raster grid formats from Climate Source, Inc. (www.climatesource.com/PHZM/gis_data.html), subject to Climate Source terms of use. The USDA-ARS and OSU logos must be prominently displayed on any maps derived from the GIS datasets. The data may not be altered in any way without an explicit and prominently displayed disclaimer that the map is not the official USDA Plant Hardiness Zone Map, and USDA-ARS and OSU logos must not be displayed in the modified version.
    (See also GIS Data Downloads.)

    Climate Source Inc. Notice: This product contains data from The Climate Source and is used herein by permission. Copyright (c) 2014 The Climate Source, www.climatesource.com. All Rights Reserved.
    (See also License Agreement.)


    from the Soil Survey Geographic (2.2) Database dated October 1, 2018. Updated on Calflora April 17, 2019 and again on September 20, 2019.
    See also

    SSURGO Table Struture
    California is described by 18,960 mapunit records, each of which corresponds to one or more polygons.

    Within each mapunit there are several soil component records. A component record has a percent (comppct_r) attribute, indicating its relative strength within the map unit.

    A component record may be associated with several chorizon records. Each chorizon record has top depth (hzdept_r) and bottom depth (hzdepb_r) attributes specified in centimeters.

    Click on the Derivation links below for more information about how the value displayed was derived from SSURGO data.

    CITATION: Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Soil Survey Geographic (SSURGO) Database for California. Available online at NRCS Geospatial Data Gateway Accessed 04/10/2019.

    Soil Depth
    Minimum depth to the first restrictive layer of the components of a soil map unit.

    Derivation: For 9,886 mapunit records, minimum depth was available from the brockdepmin (minimum depth to bedrock) attribute in the muaggatt table.

    For the other mapunit records, minimum depth was calculated by choosing the deepest non-rock horizon of each component, and then averaging these numbers weighted by the component percent.

    25 cm
    40 cm
    60 cm
    140 cm
    160 cm
    250 cm

    Soil pH
    pH of the components of a soil map unit.

    From Soil Properties and Qualities:

      "Soil reaction" is a numerical expression of the relative acidity or alkalinity of a soil. ... Soils that have a pH of approximately 6 or 7 generally have the most ready availability of plant nutrients.

    See also this Calflora analysis of
    how many plants tolerate each soil pH

    Derivation: Each component record has one topmost chorizon record (where hzdept_r = 0). pH for the mapunit was calculated by averaging the chorizon ph1to1h2o_r attribute of these topmost horizons, weighted by the component percent.
      Class pH
      Extremely acid 3.5 to 4.4
      Very strongly acid 4.5 to 5.0
      Strongly acid 5.1 to 5.5
      Moderately acid 5.6 to 6.0
      Slightly acid 6.1 to 6.5
      Neutral 6.6 to 7.3
      Slightly alkaline 7.4 to 7.8
      Moderately alkaline 7.9 to 8.4
      Strongly alkaline 8.5 to 9.0

    Soil CaCO3
    The maximum calcium carbonate equivalent in the components of a soil map unit.

    From Soil Properties and Qualities:

      “Calcium carbonate equivalent” is the quantity of carbonate (CO3) in the soil expressed as CaCO3 and as a weight percentage of the less than 2 mm size fraction.
      ... The availability of plant nutrients is influenced by the amount of carbonates in the soil. This is a result of the effect that carbonates have on soil pH and of the direct effect that carbonates have on nutrient availability.
    Derivation: Each component record has one topmost chorizon record (where hzdept_r = 0). CaCO3 for the mapunit was calculated by averaging the chorizon caco3_r attribute of these topmost horizons, weighted by the component percent.

    < 1 %
    2.5 %
    3.5 %
    5.5 %
    7.5 %
    > 10 %

    Available Water Storage

      The volume of water that the soil, to a depth of 100 centimeters, can store that is available to plants. It is reported as the weighted average of all components in the map unit, and is expressed as centimeters of water.
    Derivation: Copied from the muaggatt table aws0100wta attribute.

    AWS is calculated from AWC (available water capacity) which is commonly estimated as the difference between the water contents at 1/10 or 1/3 bar (field capacity) and 15 bars (permanent wilting point) tension, and adjusted for salinity and fragments.

    1 cm
    5 cm
    10 cm
    15 cm
    20 cm
    25 cm

    Soil Salinity
    as indicated by electrical conductivity. The maximum conductivity of the components of a soil map unit.

    From Soil Properties and Qualities:

      Electrical conductivity is a measure of the concentration of water-soluble salts in soils. It is used to indicate saline soils. High concentrations of neutral salts, such as sodium chloride and sodium sulfate, may interfere with the absorption of water by plants ... [and] may also interfere with the exchange capacity of nutrient ions...
    Derivation: Each component record has one topmost chorizon record (where hzdept_r = 0). Electrical conductivity for the mapunit was calculated by averaging the chorizon ec_r attribute of these topmost horizons, weighted by the component percent.

      Class Conductivity in mmhos / cm
      Non-saline0 to <2
      Very slightly saline2 to <4
      Slightly saline4 to <8
      Moderately saline8 to <16
      Strongly saline≥16

    Soil Texture
    Texture as used here is based on the texture description of the major component of a soil map unit. A typical categorization of textures is shown below (image from the NRCS Soil Texture Calculator).

    From Soil Properties and Qualities:

      "Particle size” is the effective diameter of a particle as measured by sedimentation, sieving, or micrometric methods.
    The broad classes are
    • clay  [<0.002 mm] (fine)
    • silt    [0.002 to 0.05 mm] (medium)
    • sand [0.05 to 2.0 mm] (coarse)
    Derivation: Copied from the chtexturegrp table texdesc attribute, for the topmost horizon in the major (largest percentage) component of the mapunit.
    Silty clay
    Sandy clay
    Silty clay loam
    Clay loam
    Sandy clay loam
    Silt loam
    Sandy loam
    Loamy sand

    Land Capability Class, Dryland (LCC)

    History: An indicator of erosion hazard


    Vegetative Soil Group (VSG)

    eVegGuide HELP

    Ultramafic Areas
    from the USGS showing

      Ultramafic rocks, mostly serpentine. Minor peridotite, gabbro, and diabase.

    Unit 1: Trinity Ophiolite
    Unit 2: Western Sierra Nevada and Klamath Mountains
    (Late Proterozoic to Early Jurassic)
    Unit 3: Coast Ranges and Western Klamath Mountains
    (Middle to Late Jurassic)
    More Information
    Introduction to Calflora Map Applications

    Calflora Plant Characteristics and Associations Help

    Las Pilitas Nursery (native plant ranges and tolerances)

    Release Notes

    June 12, 2020
    The SSURGO layers Texture and Available Water Storage were re-done with new colors.

    March 1, 2020
    Added ultramafic areas as a soil layer, courtesy of USGS.

    September 20, 2019
    The SSURGO polygons loaded last April were over optimized: when you zoomed very close, the boundaries between polygons did not meet smoothly. The SSURGO polygons were reloaded on September 20 without this over optimization problem.

    Soil background layers will now appear on maps all the way out to zoom level 9.