UCSB EEMB 171 - Lecture 6-8 2015 (1) (77 pages)

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Lecture 6-8 2015 (1)



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Lecture 6-8 2015 (1)

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Pages:
77
School:
University of California, Santa Barbara
Course:
Eemb 171 - ECOSYSTEM PROCESSES
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Human Activity Direct The Jenny State Factor Model ClORPTH Soil Ecosystem f Cl O R P T The fundamental independent variables driving ecosystem development Human Activity Indirect ClORPTH Species introductions Climate Change Possum in New Zealand Human Activity Indirect Nitrogen deposition ClORPTH ClORPTH Disturbance Any physical force such as fire wind flood extremely cold temperature and epidemic that damages natural systems and results in the mortality of organisms or loss of biomass Smith 1996 Ecology Field Biology Relatively discrete event in time and space that alters the structure of populations communities and ecosystems and causes changes in resource availability or the physical environment Chapin et al pg 379 ClORPTH Climate variability extremes come from disturbance 1999 Boundary Waters Canoe Area 2008 Santa Barbara 2005 Santa Barbara 2007 Manitoba These are common and critical in structuring ecosystems Disturbance time ClORPTH frequency distribution of disturbance in Northern forests Small disturbances are common Large disturbances are rare Frelich and Lorimer 1991 Ecological Monographs 61 145 164 Disturbance and space ClORPTH Consider fire in a10 m patch of forest 2 a 1 000 Km2 of forest source http 3 bp blogspot com CjwpWolRwVI Sj61QPUCNBI AAAAAAAABL4 NgD6Z4dBoQw s400 P6217595 JPG http www dendronautics com USERIMAGES canopy img0086 jpg Disturbance climate Arctic drunken forests ClORPTH source http upload wikimedia org wikipedia commons 7 7f 20070801 forest jpg what is soil Soil A soil a complex material with natural structure the basis of all terrestrial processes soil processes control plant growth and ecology Water Nutrients net primary productivity NPP resource allocation Despite this many ecologists see soil as external to the system WHY 1 Ecologists have traditionally started as botanists biologists 2 Soil development is slow 100 s 1000 s of years key characteristics of soil Texture sand silt clay Organic matter content Chemical composition mineralogy pH etc Physical structure soil development Vermont California New York Wisconsin Delaware Iowa Georgia Puerto Rico generic soil profile Why care about soil Regulating water Controls where rain snowmelt and irrigation water dissolved solutes goes Sustaining plant and animal life The diversity and productivity of living things depends on soil Filtering potential pollutants Soil minerals microbes filter buffer degrade immobilize detoxify organic inorganic materials e g industrial byproducts atmospheric pollution Cycling nutrients Carbon nitrogen phosphorus and many other nutrients are stored transformed and cycled through soil Supporting structures Societies depend upon stable soils for buildings development agriculture Key things to know about soil Texture How much clay sand silt Mineralogy What type of clay Structure How is the soil put together soil texture sand 2 mm 50 m silt 50 m 2 m clay 2 m source http school discovery com schooladventures soil teacher tips html soil texture sand 2 mm 50 m silt 50 m 2 m clay 2 m soil structure how individual soil granules clump or bind together and aggregate therefore the arrangement of soil pores between them Has a major influence on water air movement biological activity root growth seedling emergence source http ohiodnr com H Nav2 Soils OhiosSoils IntroductiontoSoils tabid 17818 Default aspx soil structure Granular Blocky Columnar Platy electron micrograph of grassland soil soils are complex CLAY STRUCTURE tetrahedral octahedral A 1 1 clay one tetrahedral sheet and one octahedral sheet 1 1 clay minerals A 2 1 clay an octahedral sheet sandwiched between two tetrahedral sheets 2 1 ratio silica Al3 Mg2 Fe3 O opposite each other REPEL 2 1 clay minerals 2 1 clay minerals allow H2O ions surface area clays have a large surface area 1 1 s 10 20 m2 g 2 1 s 800 m2 g chemically active organic matter ions and microbes stick to clays bacterium Cation NH 4 Clay negatively charged SOLUTION Mg 2 K etc Exchange Capacity CEC clay minerals major CEC source in most soils ions concentrate at clay surfaces 2 1 minerals have more CEC than 1 1 minerals 1 1 s 20 80 M of electric charge g 2 1 s 1 000 2 000 M g SOM also high CEC Water Holding Capacity WHC Fine pores and surfaces hold water Clays promote structure with lots of small pores 2 1 s hold water in interlayers soil organic matter SOM What is SOM Complex mix of stuff dead plant material microbial products humified material functions soil structure OM acts as glue H2O movement and retention high cation exchange capacity CEC nutrient supply Soil Organic Matter The bulk of carbon in the terrestrial world This stuf It is no longer plant litter it has been processed and reprocessed soil organic matter SOM Soil Organic Matter Why is it important Global pools of C Atmosphere 750 Tg 1015 g Plants 560 Tg Soils 1500 Tg underestimate Tropical Rainforest Plants 400 t ha SOM 300 t ha Boreal Forest Plants 120 t ha SOM 310 t ha sources of SOM Inputs into soil Transformation of plant detritus into SOM Inputs Leaf aboveground litter 20 60 Root death 30 60 Root exudates 5 10 Soil organic matter is complex Plant detritus Microbial biomass and products Humic materials Fulvic acid Humic acid Humin well decomposed organic matter highly stable organic material How do we characterize SOM Historical Fulvic Humic Humin Extracted with 0 1 M NaOH Extracted with 0 1 M HCl Insoluble How do we characterize SOM How do you go from plant inputs to SOM Some goes straight into microbial biomass and then into various microbial product pools Lignin Polymer Phenolic Monomer Humics New Polymer Microbial Biomass Conceptual Pools Soil taxonomy Why is it important It tells you a huge amount of information about the ecosystem Soil Taxonomy The 12 Soil Orders Young soils Entisol Very young Essentially no development Inceptisol Slight development Soil Taxonomy The 12 Soil Orders Young soils Entisol Very young Essentially no development Inceptisol Slight development Temperate soils Mollisol OM rich Grassland Alifisol Clays accumulate in B horizon hardwood forest Soil Taxonomy The 12 Soil Orders Young soils Entisol Very young Essentially no development Inceptisol Slight development Temperate soils Mollisol OM rich Grassland Alifisol Clays accumulate in B horizon hardwood forest Old weathered soils Ultisol Old Fe Al rich soil Warm forest Oxisol Extremely weathered Tropical forest Soil Taxonomy The 12 Soil Orders Young soils Entisol Very young Essentially no development Inceptisol Slight


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