LANDFIRE Biophysical Setting Model Biophysical Setting 6717150 Alaska Arctic Floodplain

This BPS is lumped with: This BPS is split into multiple models:

General Information Contributors (also see the Comments field Date 10/8/2008 Modeler 1 Kori Blankenship [email protected] Reviewer Janet Jorgenson Janet_Jorgenson@fws .gov Modeler 2 Keith Boggs [email protected] Reviewer Modeler 3 Reviewer

Vegetation Type Map Zone Model Zone Wetlands/Riparian 67 Alaska N-Cent.Rockies California Pacific Northwest Dominant Species* General Model Sources Great Basin South Central Literature SAAL DRIN4 Great Lakes Southeast Local Data SARI4 CHLA13 Northeast S. Appalachians SAGL LUPIN Expert Estimate Northern Plains Southwest SAPU15 POBA2

Geographic Range This BpS is found on floodplains throughout the Arctic region of AK. It includes all floodplains except those associated with the Yukon and Kuskokwim rivers. Biophysical Site Description This system includes active and inactive glacially- and non-glacially-fed floodplains. It is mosaiced with various wetland systems but these are modeled separately. The rivers are typically braided, and the floodplain terraces may be short-lived (<100yrs) or last for more than a 1,000yrs (Boggs et al. 2008). Soils develop on alluvium and are typically shallow and well-drained; barren alluvium is common (Boggs et al. 2008). Permafrost is usually present on the North Slope but may be absent elsewhere. Vegetation Description The following information was taken from the draft Arctic Ecological Systems description (Boggs et al. 2008): Common existing vegetation types include: mesic herbaceous, low-tall willow, Dryas, dwarf shrub, and patches of Populus balsamifera or Betula papyrifera. Herbaceous species include Chamerion latifolium and Lupinus spp. Common willows include Salix alaxensis, Salix richardsonii (= Salix lanata), Salix glauca and Salix pulchra. Dryas integrifolia dominates the Dryas existing vegetation type, but other species may also be common such as Lupinus spp., Cassiope tetragona, Vaccinium uliginosum, Salix spp. and Arctostaphylos rubra. The tall-low willow class may be absent at higher elevations. Disturbance Description Floodplain succession begins with herbaceous or shrub species colonizing bare ground after a flood. Dryas or poplar and paper birch patches can eventually develop. Experts at the arctic meeting disagreed about how to treat dryas for BpS modeling. Some felt that dryas may take hundreds of years to develop and

*Dominant Species are from the NRCS PLANTS database. To check a species code, please visit http://plants.usda.gov. **Fire Regime Groups are: I: 0-35 year frequency, surface severity; II: 0-35 year frequency, replacement severity; III: 35-100+ year frequency, mixed severity; IV: 35-100+ year frequency, replacement severity; V: 200+ year frequency, replacement severity.

Tuesday, December 29, 2009 Page 99 of 102 would therefore be treated as a separate system outside of the floodplain. Others felt that dryas could develop more quickly and could be modeled as part of floodplain succession. This model takes the later approach.

Frequent river channel migration and associated flooding are the major disturbances affecting this type. Adjacency or Identification Concerns Wetlands systems are mosaiced with this system but modeled separately. Floodplains occur adjacent to most other systems that occur in the arctic. Native Uncharacteristic Conditions

Scale Description Linear.

Issues/Problems This model should also contain a separate early seral bare ground phase but this is not included because LANDFIRE does not map barren seral stages.

Input from experts at the Arctic Modeling Meeting (April 08) indicated that on the North Slope the low- tall willow stage can persist for 300 years and then might succeed to dryas/dwarf shrub. A separate model would be required to capture this dynamic. This model contains two later seral endpoints: forest (Populus balsamifera or Betula papyrifera) or dryas. In reality some areas will likely succeed to dryas whereas other sites will succeed to the forested stage. This could be accounted for by creating separate models but a clear geographic distinction would have to be made for where each model would apply. It is recommended that this be evaluated for future modeling efforts.

Comments This model was based on input from the experts who attended the LANDFIRE Fairbanks Arctic (April 08) modeling meeting and refined by Kori Blankenship and Keith Boggs. Minor edits were made to the description as a result of review comments.

Vegetation Classes

Class A 20 % Structure Data (for upper layer lifeform) Min Max Early Development 1 All Structures Cover Herbaceous Herbaceous Upper Layer Lifeform Indicator Species* and Height Herbaceous Herbaceous Canopy Position Herbaceous Tree Size Class None Shrub CHLA13 Upper Tree LUPIN Upper Upper layer lifeform differs from dominant lifeform.

Description 0-5yrs

Herbaceous vegetation colonizes bare ground after a flood.

This class succeeds to class B. Flooding (probability = 0.05) resets the age of this class.

Tuesday, December 29, 2009 Page 100 of 102 Class B 65 % Structure Data (for upper layer lifeform) Min Max Mid Development 1 All Structures Cover Open Shrub (25-74% shrub cover) Closed Shrub (> 75% shrub cover) Upper Layer Lifeform Indicator Species* and Height Low Shrub (20cm to 1.5m) Tall Shrub (>1.5m) Herbaceous Canopy Position Tree Size Class None Shrub SAAL Upper Tree SARI4 Upper Upper layer lifeform differs from dominant lifeform. SAGL Upper SAPU15 Upper

Description 1-99yrs

Low and tall shrubs gain dominance (succession from class A) or colonize bare ground after a flood. This stage should start at age zero but LANDFIRE rules only allow one seral stage to start at age zero; therefore, for modeling purposes it starts at age one year. On colder sites, this class is more likely to succeed to the dryas stage (class D). This class may be absent at higher elevations (Boggs et al. 2008).

This class can succeed to class D or follows an alternate succession pathway (probability = 0.001) to class C. Flooding (probability = 0.05) causes a transition to class A.

Class C 10 % Structure Data (for upper layer lifeform) Min Max Late Development 1 Closed Cover Open (25-59% tree cover) Closed (60-100% tree cover) Upper Layer Lifeform Indicator Species* and Height Tree (> 3m) Tree (> 3m) Herbaceous Canopy Position Tree Size Class Pole 5–9" (swd)/5–11" (hwd) Shrub POBA2 Upper Tree BEPA Upper Upper layer lifeform differs from dominant lifeform.

Description 20yrs+

Closed patches of Populus balsamifera or Betula papyrifera may occur in some areas as a later seral stage within the floodplain but their presence will diminish closer to the coast.

This class may persist in the absence of disturbance. Flooding (probability = 0.01) causes a transition to class A.

Class D 5 % Structure Data (for upper layer lifeform) Late Development 2 All Structures Min Max Cover Open Shrub (25-74% shrub cover) Open Shrub (25-74% shrub cover) Upper Layer Lifeform Indicator Species* and Height Dwarf Shrub (< 20 cm) Dwarf Shrub (< 20 cm) Canopy Position Herbaceous Tree Size Class None Shrub DRIN4 Upper Tree SALIX Upper Upper layer lifeform differs from dominant lifeform. CATE11 Upper VAUL Upper

Tuesday, December 29, 2009 Page 101 of 102 Description 100yrs+

Dryas dwarf shrubs are a likely late seral stage within the floodplain, especially on sites that are too cold to support trees. Dryas will take longer to develop than the poplar or birch patches (class C) but the age range on this class is uncertain and probably highly variable.

This class persists in the absence of disturbance. Flooding (probability = 0.01) causes a transition to class A.

Class E 0 % Structure Data (for upper layer lifeform) Min Max [Not Used] [Not Used] Cover Upper Layer Lifeform Indicator Species* and Height Canopy Position Herbaceous Tree Size Class Shrub Tree Upper layer lifeform differs from dominant lifeform.

Description Disturbances Fire Intervals Fire Regime Group**: NA Avg FI Min FI Max FI Probability Percent of All Fires Replacement Historical Fire Size (acres) Mixed Avg 0 Surface Min 0 All Fires Max 0 Fire Intervals (FI): Fire interval is expressed in years for each fire severity class and for all types of fire Sources of Fire Regime Data combined (All Fires). Average FI is central tendency modeled. Minimum and Literature maximum show the relative range of fire intervals, if known. Probability is the inverse of fire interval in years and is used in reference condition modeling. Percent of all Local Data fires is the percent of all fires in that severity class. Expert Estimate Additional Disturbances Modeled Insects/Disease Native Grazing Other (optional 1) Flooding Wind/Weather/Stress Competition Other (optional 2) References Boggs et al. 2008. International Ecological Classification Standard: Terrestrial Ecological Classifications. Draft Ecological Systems Description for the Alaska Arctic Region.

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