Topic%201%20Soils%20slides

Topic%201%20Soils%20slides - Soils The Foundation of the...

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1 Office: Plant & Environmental Sciences Building - 3134 Monday 1:30 – 2:30 pm Wednesday 9:30 - 10:30 am & by arrangement Soils – The Foundation of the Forest Soil ecosystem Soil is a critical component of terrestrial ecosystems Forest sustainability: We cannot manage forest ecosystems sustainably unless we maintain those soil conditions and processes that help to determine forest ecosystem function and ability to recover from disturbance. Sustaining the functional role of forest soils does not imply no disturbance. Much of the negative environmental impact of forestry in the past has been related to effects on soils .” (Kimmins’ Forest Ecology, pp. 268-269, 1997). Soils are a slowly (1000’s of years) renewable resources! Atmosphere Hydrosphere Biosphere Geosphere Soil Zone Additions Translocation Losses Transformations Losses Additions Major Soil Forming Processes
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2 Transformations Physical weathering Chemical weathering Clay mineral formation Litter to humus Transformations Translocation Transport up or down in profile Transport agents within soil profile: Water Soil organisms (e.g., gophers, worms) Translocation Additions Organic matter (C & N) from vegetation and animals Dust Soluble components in precipitation Groundwater inputs Additions Additions Losses Leaching of soluble components Erosion (by wind or water) Losses Losses Export or loss Import or accumulation R O horizons (Oi, Oe Oa) Organic layers ranging from slightly to highly decomposed materials A horizon A mineral (inorganic) layer near the soil surface that is enriched in organic matter B horizon A layer that accumulates (imports) materials transported from above or formed in place by weathering E horizon A layer of intensive loss (export) as water carries clay, iron, etc. into lower layers C horizon An unconsolidated layer relatively unaffected by biological activity or weathering (parent material) R layer Consolidated rock that can not be dug with a shovel (parent material) Minimal alteration Fig. 11.2, text Recent volcanic ash C Parent material
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3 A B C Zone of loss Zone of accumulation Parent material O Bh (humus) C Bs (iron oxides) E Forest Soil Organic Horizons Oi (slightly decomposed) Oe (intermediate decomposition) Oa (highly decomposed) ~19,000 different soils identified in the USA Soil Forming Factors
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This note was uploaded on 04/22/2011 for the course PLS 144 taught by Professor Rice during the Fall '08 term at UC Davis.

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Topic%201%20Soils%20slides - Soils The Foundation of the...

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