Unit 6 lecture 1 - Wetlands Unit 6 Vegetation Ecology...

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Unformatted text preview: Wetlands Unit 6: Vegetation Ecology Reproductive Plant Strategies and Wetland Succession Reproductive Adaptations Reproduce both by Seed and Vegetatively Dispersal Wind- Anemochory WindWater Hydrochory Animal Zoochory Timing of dispersal Synchronized with appropriate flooding regime for germination Long lived in seedbank Timing of germination Seed germinates only under drawdown Seeds can germinate only under flooded conditions Rapid stem elongation during seedling development 1 Hydropattern and Seed Timing Cottonwood recruitment box Sandbar Willow recruitment box Seedbanks Seeds that are often small and easily dispersed Survive for long periods in soil Germinate upon soil exposure and increased variation in temperature and availability of oxygen. 2 Prairie Potholes "Environmental Sieve Model 3 Life History Establishment Model (Van der Valk 1981) Life Span A - Annual P - Perennial V - Perennial with vegetative growth Propagule longevity S Long-lived propagule, persist and accumulate in the seed bank and Longbecome established when ever suitable conditions occur. D Short-lived propagule, seed remains viable for less than one year, Shortseed is dependent upon dispersal to a site to provide suitable conditions conditions for establishment. Propagule establishment requirements I Establishment only under drawdown (drained) conditions II Species can establish under flooded conditions A-Annual P-Perennial V-Vegetatively propagated S Seed Bank Species long-lived seeds D Dispersal dependant short-lived seeds I Species established only in absence of standing water II Species can establish in standing water Community Forcing Functions (P. White, in Davis and Ogden, 1994) 4 Change over Time Hydrarch Succession Shoreline Hydrarch Succession 5 6 7 Water levels are not always stable 8 Orange Lake 5,300 hectares 58 NGVD 0 1 2 Kilometers Sampling Sites and Lake Zone Designation I II III 0 1 2 Kilometers 9 Map of lake with study communities 11 sites 65 sampling sites Samplin site locations Sediment Coring Device turning handle, inner head stabilizer and piston rod coring platform > "A" frame and corer closure shoot cutting head Field Deployment 10 11 January 22, 1994 June 13, 1996 PG Run Sector July 23, 1996 September 24, 1996 0 100 MC MC 10 110 MC MC 20 water 120 30 130 503 + 60 503 + 60 depth, cm 140 200 C 784 + 60 784 + 60 D ? Panicum sp. P. cordata < Charcoal M. cerifera 210 ? E N. luteum odorata orN. Polygonum sp. Panicum sp. 220 F ? P. virginica, Panicum sp. N. luteum or N. odorata 230 S. lancifolia G 300 K Open Water S. lancifolia N. luteum or N. orodata310 or Q R ? Polygonum sp. E. capillifolium 320 Open Water Eupatorium sp. L < Scattered charcoal fragments 330 174 + 60 174 + 60 depth, cm H 150 S. lancifolia depth, cm 40 240 Composite M D. verticillata, E. capillifolium N. luteum or N N. luteum or or N. odorata O ? N. luteum or N. odorata Open Water S Clay 50 542 + 60 542 + 60 I S. lancifolia N. luteum or N. odorata 250 60 352 + 50 352 + 50 A P 160 260 Core SSa-3A SSaSSa-3A Q Open Water 70 Salix caroliniana 170 P. virginica J 270 ? S. lancifolia N. luteum odorata 280 orN. 80 B 90 180 Composite S. caroliniana P. virginica S. latifolia, D. verticillata Polygonum sp. Hydrocotyle sp. T. thelypteroides 190 K Shrub Swamp Southeast, Orange Lake 552 + 40 552 + 40 290 Open Water S. lancifolia N. luteum odorata orN. 300 100 Composite C Panicum sp. Polygonum sp S. caroliniana, P. cordata 200 12 Classical View of Hydrarch Succession (organic sedimentation) forested climax submerged aquatic floating leafed marsh stage sedge grass stage shrub stage Chronosequence organic depositional sediment original bottom Reality View of Hydrarch Succession (Orange Lake, Loxahatchee, Okefenokee Swamp) forested climax marsh stage floating leafed marsh shrub stage submerged stage aquatic marsh stage shrub stage sedge grass stage organic depositional sediment original bottom 13 Spatial and Temporal scales of Forcing Functions Temporal Scale (years) <1-3 Fast (1-10) Herbaceous vegetation regrowth to steady state biomass Residual impact of alligator activity (holes and nest mounds Woody vegetation regrowth to steady-stat biomass Soil Accretion to stable depth Microbedrock topography Spatial Scale (meters2) <100-300 Non severe fires >100-300 Hydropattern Water quality Intermediate (10-100) Sever fires Hurricanes Freezes Drought/Flood cycle Slow (>100) State of Sea level Macrobedrock topography (L. Gunderson, in Davis and Ogden, 1994) Summary Biological adaptations provide potential establishment and persistence of species Establishment Reproductive strategies Persistence Morphological (inundation, draught, fire etc.) Environmental conditions (Forcing Functions) select among species Hydrarch Succession Change in community structure over time in response to biological adaptations and Forcing Functions 14 ...
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