Transcript Slide 1
Production Photos from Wikimedia Commons & http://www.deere.com/en_US/products/equipment/frontier_implements/ livestock_and_equine_equipment/manure_spreaders/manure_spreaders.page Ecosystem Ecology Ecosystem – all the organisms and the physical environment of a given place, including energy flow and nutrient cycling (coined by Sir Arthur G. Tansley) Photo of Tansley from http://wiley-vch.e-bookshelf.de/products/reading-epub/product-id/595067/title/ Shaping%2BEcology.html?autr=%22Peter+G.+Ayres%22 Primary Production Gross Primary Production (GPP) Total amount of C fixation by autotrophs into energy-rich molecules Photoautotrophic (i.e., use photosynthesis) Marine microalgae Photos from Wikimedia Commons Marine macroalgae Terrestrial angiosperms Primary Production Gross Primary Production (GPP) Total amount of C fixation by autotrophs into energy-rich molecules Chemoautotrophic (i.e., use chemosynthesis) Marine hydrothermal vent archaea & bacteria Photos from Wikimedia Commons Primary Production Net Primary Production Amount of energy captured by autotrophs that contributes to biomass All living plant (or other autotroph) tissues respire (autotrophic respiration = AR); so some captured energy is unavailable to produce biomass NPP = GPP – AR Aboveground NPP & Belowground NPP Photo from Wikimedia Commons Net Ecosystem Production or Net Ecosystem Exchange (NEE) NEE = GPP – AR – HR If NEE > 0, then C sink If NEE < 0, then C source Cain, Bowman & Hacker (2014), Fig. 20.8 Aboveground NPP Varies as a function of Leaf Area Index (LAI) and position within leaf layers Cain, Bowman & Hacker (2014), Fig. 20.4, after Larcher (1980) Physiological Plant Ecology Limitation of Primary Production Water & Temperature Key variables controlling global variation in terrestrial NPP Cain, Bowman & Hacker (2014), Fig. 20.11, after Schuur (2003) Ecology Limitation of Primary Production CO2 & Nutrients (e.g., N, P, K, micronutrients) Alpine nutrient-addition experiment Dry meadow N & N+P increased biomass Subordinate plants increased Wet meadow P, N & N+P increased biomass Dominant plants increased Cain, Bowman & Hacker (2014), Fig. 20.13, after Bowman et al. (1993) Ecology Limitation of Primary Production CO2 & Nutrients (e.g., N, P, K, micronutrients) Lake nutrient-addition experiment P, N & C addition (far section of lake) caused a massive cyanobacteria bloom Whereas N & C addition alone (near section of lake) did not Cain, Bowman & Hacker (2014), Fig. 20.16, after Schindler (1974) Science Limitation of Primary Production Salt marsh nutrient-addition experiment “Nutrient levels commonly associated with coastal eutrophication increased above-ground leaf biomass...” TIDE experiment photos from Deegan et al. (2012) Nature Limitation of Primary Production “In nutrient-enriched marshes, smooth cordgrass allocated less photosynthate to nutrient-gathering roots and storage rhizomes, resulting in a third less total belowground biomass and a lower root:shoot ratio...” TIDE experiment photos from Deegan et al. (2012) Nature Limitation of Primary Production “Plants tend to allocate the most NPP to those tissues that acquire the resources that most limit their growth” i.e., nutrient addition shifts nutrient limitation to light limitation TIDE experiment photos from Deegan et al. (2012) Nature; quote from Cain, Bowman & Hacker (2014), pg. 453 Limitation of Primary Production “Alterations in these key ecosystem properties reduced geomorphic stability, resulting in creek-bank collapse…” TIDE experiment photos from Deegan et al. (2012) Nature Limitation of Primary Production “Current nutrient loading rates to many coastal ecosystems have overwhelmed the capacity of marshes to remove nitrogen without deleterious effects…” TIDE experiment photos from Deegan et al. (2012) Nature Global Pattern of Terrestrial Chlorophyll Normalized Difference Vegetation Index (NDVI) – calculated from satellite measurements of reflectance in red and infrared wavelengths Image from Wikimedia Commons Global Pattern of Terrestrial NPP Cain, Bowman & Hacker (2014), Fig. 20.7 Global Pattern of Marine NPP Cain, Bowman & Hacker (2014), Fig. 20.10 Global Pattern of NPP NPP patterns coincide with patterns of climate and upwelling High terrestrial NPP in warm, wet tropics Lower terrestrial NPP in dry (30) latitudes & cold, high (>60) latitudes Highest marine NPP in mid-latitude zones of nutrient-rich upwelling Cain, Bowman & Hacker (2014), Fig. 20.18, after Field et al. (1998) Science Net Secondary Production NSP = ingestion – respiration – egestion (losses via urine & feces) NSP becomes heterotrophic biomass Most NSP in most ecosystems occurs in detritivores (especially bacteria & fungi) Video from Wikimedia Commons – “A decaying peach over a period of six days. Each frame is approximately 12 hours apart, as the fruit shrivels and becomes covered with mold.”