landscapes & hydric soils - association of state … · landscapes vs. landforms . ... organic...
TRANSCRIPT
![Page 1: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/1.jpg)
Landscapes & Hydric Soils
Bruce Vasilas
University of Delaware
![Page 2: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/2.jpg)
Hydric soils are defined as soils that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part.
![Page 3: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/3.jpg)
Overview
• Landscape position & the movement of water within the landscape dictate the distribution of wetlands.
• The characteristics of each wetland type are determined to a great extent by landscape position.
• Landscape position & surface shape impacts hydrologic characteristics.
• Hydric soil morphology is strongly influenced by hydrologic characteristics of a given wetland.
• Specific hydric soil morphologies are associated with each wetland type.
![Page 4: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/4.jpg)
-40
-30
-20
-10
0
10
Hydroperiod: seasonal pattern of water table depth (inches) in a wetland
Wetland A Wetland B
![Page 5: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/5.jpg)
Short Duration Saturation-Redox Concentrations
![Page 6: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/6.jpg)
Long Duration Saturation Grey-Stripped mineral grains
Black & brown-Organic matter
![Page 7: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/7.jpg)
Landscapes & Landforms
• Landscape: a collection of spatially-related landforms.
• Landform: a naturally-occurring physical feature on the earth’s surface with a characteristic shape.
• Example: a prairie landscape is a relatively flat & grass dominated area with hills, rivers, & depressions.
• Wetland landscape position: location of a wetland relative to other landforms
![Page 8: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/8.jpg)
Photo by Ben Kimball, NHDFL
Landscapes vs. Landforms
![Page 9: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/9.jpg)
Divergent & Convergent Landscape Positions
![Page 10: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/10.jpg)
Divergent slopes (A) disperse surface water, whereas convergent slopes (B) concentrate surface water. Surface flow paths are indicated by arrows.
Landscape Position-Slope Shape
![Page 11: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/11.jpg)
Landscape Position-Surface Shape
Linear
![Page 12: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/12.jpg)
Hillslope Position Effects
• Erosional position: – Soil material moves downslope or downstream
– Shallow soil, coarser texture, low o.m.
• Depositional position: – Soil material moves in from another location
– Deep soil, finer texture, more o.m.
Toeslope
![Page 13: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/13.jpg)
Wetland Landscapes
• Tidal marshes
• Peat bogs
• Mineral soil flats
• Riverine wetlands
• Slope wetlands
• Depressions
![Page 14: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/14.jpg)
Wet Wetter Wettest
A horizons Organic coated mineral grains
O horizons Organic
A O
A
![Page 15: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/15.jpg)
Histosols, Organic Soils • High primary productivity • Low decomposition rates Long-term saturation/inundation Low temperatures
O O
![Page 16: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/16.jpg)
Tidal Marshes Surface water-tidal Peraquic moisture regime: always saturated High primary productivity Erosional & depositional surfaces Hydrogen sulfide-rotten egg smell
![Page 17: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/17.jpg)
Tidal Marsh Soils • Soil forming processes: sedimentation & organic
matter accretion • Subsiding landscape-relative sea level rise 1. organic soils, 2. mineral soils, 3. soils with upland characteristics
1 2 3
![Page 18: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/18.jpg)
Tidal Marsh Soils
![Page 19: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/19.jpg)
Acid Sulfate Soils
High levels of iron sulfide minerals (Pyrite, FeS2) Submerged: benign Disturbed: FeS2 + O2 = sulfuric acid + iron
![Page 20: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/20.jpg)
Organic Soil Flats-Northern Peat Bog Permanently saturated Low temperatures, acidic conditions Low decomposition rates-organic soils
![Page 21: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/21.jpg)
Riverine Wetlands Overbank flow, groundwater discharge Transient flooding to long-term ponding Floodplains may be both erosional & depositional depending on the energy in the moving water. • High energy: erosional-low o.m., sandy soils • Low energy: depositional-loamy soils
![Page 22: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/22.jpg)
Riverine Wetlands-Accretion Floodplains Overbank flooding Young soils: limited development
![Page 23: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/23.jpg)
Floodplain-Stratified Layers
• Multiple thin horizons representing different parent materials.
• Large variability in textures
• Buried ‘O’ & ‘A’ horizons
![Page 24: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/24.jpg)
Riverine Wetlands-Backswamps Groundwater discharge Infrequent overbank flooding Long-duration ponding Organic soils
![Page 25: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/25.jpg)
Backslope Wetlands Discharge systems release groundwater to the land surface (seeps, springs). Erosional surface: shallow soils
![Page 26: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/26.jpg)
Toeslope Wetlands Depositional surface: deep soils Seasonal to near-permanent inundation Floodplain characteristics
![Page 27: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/27.jpg)
Closed Depressions • Subject to ponding: seasonal or long term • Precipitation, surface flow, groundwater • Depositional surface: loamy soils
![Page 28: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/28.jpg)
Depressional Wetlands
Center: seasonal ponding Umbric surface-thick, dark ‘A’
Edge: transient ponding Thin ‘A’, redox concentrations
![Page 29: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/29.jpg)
Mineral Soil Flats Seasonally saturated Seasonal or no inundation Dynamic water table ‘O’ thin or absent Thin ‘A’ Redox concentrations
![Page 30: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/30.jpg)
Take Home Messages
1. Hydric soil morphology reflects ecosystem characteristics, especially landscape position & long-term hydrologic condition. 2. Landscape position & surface shape has a strong influence on hydrologic characteristics of each wetland.
![Page 31: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/31.jpg)
Take Home Messages
3. Since each wetland class has characteristic hydrologic conditions, each wetland class has characteristic hydric soils.
a. Long-term inundation &/or near-constant shallow saturation: organic soils (tidal marsh, peat bog) b. Seasonal inundation: well developed ‘O’; thick, dark ‘A’ (depressions) c. Seasonal saturation: ‘O’ is thin or absent (mineral soil flats) d. Flowing surface water: stratified layers (floodplains, toeslopes)
![Page 32: Landscapes & Hydric Soils - Association of State … · Landscapes vs. Landforms . ... Organic coated mineral grains O horizons Organic A O A . ... characteristic hydric soils. a](https://reader031.vdocument.in/reader031/viewer/2022022607/5b840f6d7f8b9a4a488b79a5/html5/thumbnails/32.jpg)