developing ecological site keys
TRANSCRIPT
Developing Ecological Site Keys
Kirt Walstad NRCS Rangeland Management
SpecialistBozeman, Montana
Helping People Help the Land
Topics of Discussion• Ecological Site System
– Where Montana NRCS is currently at• Development of Montana’s Key
– Structure– Process
• Other Tools for Development and Site Concept Validation
An Ecological Site is defined as a distinctive kind of land, with specific physical characteristics which differs from other kinds of land in its ability to produce a distinctive kind and amount of vegetation and in its ability to respond to management actions and natural disturbances.
What characteristics cause sites to be different?
Soil Depth
Soil Chemistry (salts, sodium, pH)
Calcium Carbonate %
Parent Material
Texture
Available Water Holding Capacity
Coarse Fragments (Skeletal Material)
Soil Development
Nutrient Cycling
Human Influences
Position on Landform
Time
Living Organisms
AspectSlope
ElevationLandscape
Effective PrecipitationClimate
Wetting and Drying Cycles
Freeze Thaw Cycles
TemperatureGrowing Season
Question?How do we organize these
chemical and physical influences, in a way so that we can describe what is expressed out on the landscape throughout Montana?
• Create a System where the framework is flexible enough to adapt to the different parameters of each MLRA in the state.
• Needed a system where ecological sites could consistently be identified by a variety of individuals in the field.
When Identifying an ecological site in MLRA’s that Montana NRCS is responsible for, we partitioned the landscape at three different scales of a nested hierarchy.
• MLRA – Regional split• LRU – Matrix of Moisture and Temperature
regimes with a geographical component.• Ecological Site - Soil and/or Landscape
Land Resource Units• LRUs are partitions within a MLRA
that are typically characterized by growing season and effective moisture.
• Some geographical partitions are used to maintain integrity of KAP.
What do we use to classify the growing season and effective moisture?
•REAP•FFD
Relative Effective Annual Precipitation
• REAP is derived from actual rain gauge precipitation with debits or credits given based upon slope and aspect and is calibrated to vegetation.
http://www.nris.mt.gov/nrcs/reap/
• 16.1”• 14.2”• 12.6”
• Growing Season – consecutive days >32 degrees F
• Use Frost Free DaysFFD are sourced from the soil survey
Frost Free Days
58A Sedimentary Plains
• Fairly consistent # of growing degree days• Fairly similar growing season precipitation
amount across MLRA• Difference in precipitation timing within the
growing season
58A - Percent of annual precipitation that that occurs from April – June.
58A - Percent of annual precipitation that occurs from July – September.
Draft
Development of LRU Charts
• 3 Meetings (MT Responsible MLRAs)
• Local Expert Knowledge Soil Scientists, Range Cons, and other Ecologists
• State and Regional Support
Ecological Site Key
The Key is a tool to collect effective documentation.
Process of Development• Meetings / Controversy
– Differences in clay• % thresholds may vary based on mineralogy
• Versions of the Key 07-3 08-3 09-2• Active Soil Surveys Contributions• Area Range/Soil and Field Input and
Comment• Regional and State Support• Range Soil Relationship
Structure of Key Development• An ecological site only exists in the
context of MLRA / LRU• Descriptive dichotomous key• Hierarchy to the key• 53 ecological sites in the key
• Complex Ecological Sites– Ecosite Application ToolBadlands, Thin Hilly, Panspots, Thin Breaks, Shale
• Site concepts and Definitions– Additional information and explanation
Part of Montana’s Ecosite Key
ESD Key Terminology
• Texture - %Clay• Shallow to very shallow• Saline or saline-sodic• Strongly or violently effervescent• Argillic horizon• Soil Skeletal• Mollic epipedon present
Soil Skeletal averages > 35% rock fragments by
volume in the 10”-20” layer
Definitions
Determining if a Mollic epipedon is present?
Moist – The Value AND Chroma are both 3 or less.
Issues• All site concepts need to be consistent
throughout the MLRA• Only one key per MLRA• Multiple MLRAs can be encompassed in
one key • Montana has chosen to develop and
maintain one ecosite key
Correlation Table 43BA
Data?
• Planning• Development
Other Database Tools That Support The System
• NASIS (Site Concept Validation)
• Soils Vegetation Database (interface)
• Rangeland Database• NRI Database
National Soil Information System (NASIS)
• The NASIS data system consists of multiple interrelated soil applications and databases.
• This data system aids in the collection, storage, manipulation and dissemination of soil information.
Value of Soil Based Ecosite Key
FFD RVAWC 40”ponding frequencyponding depthdrainageflooding frequencyflooding durationtemp regimelandformparent material kindparent material originpermeability class
MLRAsurvey IDMU symbolcomponent namecomponent %component acresES keyedsurface textureslope RVelevation lowelevation highprecipitation RV
Develop a report in NASISrestrictive layer depth% stones/bouldersEC at 4”SAR 10”pH at 4”% Lime 4”% Lime 10”particle sizetaxonomic subgrouporiginal range siteforest habitat typeproduction
NRI Database
MT NRCS Homepage Under Technical Resources http://www.mt.nrcs.usda.gov/technical/ecs/range/ecolsites/
Rangeland Ecological Site KeyESD – LRU Matrix By MLRAMontana Ecological Site Development Policy
Relative Effective Annual Precipitation http://www.nris.mt.gov/nrcs/reap/index.asp
http://www.mt.nrcs.usda.gov/soils/mtsoils/guides/otherl ocal/NASISprecipitation.html
Summary• An ESD is an ecological site within a
MLRA/LRU.• Each MLRA has its own LRU’s based on the
moisture and temperature regimes that occur within the MLRA.
• The Ecological Site Key is an integral part of the system.
• Development concept used is easily adapted to other areas.
• Upper level management and technical support crucial.
Thank You