Ecosystem Ecology Lecture Notes PDF

Ecosystem Ecology Image: https://www.nationalgeographic.org/activity/sorting-gulf-ecosystem/ Announcements Assignment 3 will be posted tonight, due next Friday Midterm review: - Next Monday 2:30 PM – 3:15 PM, room to be announced - If you cannot make this, there will be a few additional slots nex...

Ecosystem Ecology Image: https://www.nationalgeographic.org/activity/sorting-gulf-ecosystem/ Announcements Assignment 3 will be posted tonight, due next Friday Midterm review: - Next Monday 2:30 PM – 3:15 PM, room to be announced - If you cannot make this, there will be a few additional slots next week available for review Guest lecture next Monday Learning goals Recognize what an ecosystem is, and give examples of the emergent properties that differentiate ecosystems from communities Distinguish between stocks, flows, and turnover, and be able to calculate one given the others Outline the main steps and key differences between nutrient cycling and energy flow Distinguish between gross and net primary production, and secondary production Understand the concept of a limiting nutrient, and recognize which nutrients are limiting given a scenario Understand the implications of the 2nd Law of Thermodynamics for production, and calculate production and trophic efficiency Continuing: Aquatic biomes  Aquatic Biomes Aquatic biomes show far less latitudinal variation than terrestrial, with all types found across the globe If not latitude, what is the primary characterization of aquatic biomes? Physical environment 1. Amount of salt (freshwater vs. salt water 2. Depth – determines access to light, temperature 3. Whether water is flowing or not  Freshwater biomes: 2 types Standing water: lakes Running water: streams - Vertical zonation - Longitudinal zonation Note: See textbook for “ocean” zonation diagram  Zones of a lake/ocean :Fig. 52.12 Littoral/Neritic zone Limnetic/oceanic zone Surface phytoplankton Photic zone Aquatic Pelagic zone macrophytes (Photosynthesis > Respiration) Aphotic zone (Photosynth. < Resp.) P=R Compensation line ~ 1% light remaining Think about: What is the most productive area of the lake per m2?  Marine Biomes Best predictor of global distribution? - Distance from land, depth Intertidal Coral Reef Ocean Pelagic Zone Marine Benthic Zone Copyright © 2018 Pearson Canada Inc  Energy and Nutrients in Marine Systems New energy is captured here (photosynthesis) Organisms or detritus (dead organisms) fall Nutrients are to the bottom returned to the surface via upwelling or from the land Only energy is from falling organisms (+ small amount of chemoautotrophs)  Intermediate biomes Estuaries: Intermediate between freshwater & saltwater Why are estuaries so productive? - Nutrients from land, mixing - Some of the world’s most fertile ecosystems, but also some of the most polluted  Intermediate biomes Wetlands: Intermediate between land & water Why are wetlands so valuable? - Provide many ecosystem services, e.g. - Water quality regulation, flood regulation Image © Ducks Unlimited Canada  Intermediate biomes Intertidal Zones intermediate between land and saltwater Distribution of organisms is limited by: - Vertical zonation - Duration of drying  Ecosystem ecology: the study of transformation of energy and movement of chemical elements between biotic and abiotic components of an ecosystem  What is an ecosystem? A biological community and its interactions with the abiotic environment Examples of the emergent properties? - Energy flow, nutrient cycling, etc…  Ecosystems can vary in size. Their boundaries are defined based on the question that you are asking. For example, a small tide pool and the entire Amazon rainforest can both be considered ecosystems Images: Brocken Inaglory, CC BY-SA 4.0; Neil Palmer/CIAT, Center for International Forestry Research, CC BY 2.0  Difference between ecosystem and biomes? Biomes are broad categories of ecosystems that correspond to particular geographic areas. Biomes occur at a much larger spatial scale, and can contain multiple ecosystems (ecosystem is more specific than biome) Image: OpenStax College, Biology, CC BY 4.0 Key idea in ecosystems: Stocks versus flows Inflow of Two key ideas to understand water ecosystems and energy transfer: (L/day) Stock (or pool, or reservoir): an amount of some resource. While measured at some point in time, has units of e.g. kg, J, etc. Stock of water in a Flow: A measure of inputs into, or cistern (L) outputs from, a stock. Measured in units of kg/hour, J/year, etc. Outflow of water (L/day)  Stocks, flows, and turnover 25 Stocks change due to liters/day inflows and outflows Stock size will only change if inflow ≠ outflow Turnover time: time it would take to replace the whole stock: 𝑆𝑡𝑜𝑐𝑘 𝑠𝑖𝑧𝑒 1000 liters 𝑖𝑛𝑓𝑙𝑜𝑤 (𝑜𝑟 𝑜𝑢𝑡𝑓𝑙𝑜𝑤) 𝑟𝑎𝑡𝑒 25 liters/day  Concept question: 25 What units will turnover time liters/day have here? A) Liters/day B) Liters C) Days/liter D) Days 1000 liters 25 liters/day  Concept question: 25 What is the turnover time for liters/day this example? A) 1000 Days B) 50 Days C) 20 Days D) 40 Days 1000 liters 25 liters/day  An example: Oxygen The atmosphere holds ≈ 1 × 1018 𝑘𝑔 of 𝑂2 Photosynthesis produces ≈ 3 × 1014 𝑘𝑔/𝑦𝑒𝑎𝑟 of 𝑂2 1×1018 𝑘𝑔 Turnover time = 𝑘𝑔 ≈ 3300 years 3×1014 𝑦𝑒𝑎𝑟 Result: if plants stopped producing oxygen today, it would take 3300 years to use it all up at present rates  An example: Carbon Dioxide The atmosphere holds ≈ 3.0 × 1015 𝑘𝑔 of C𝑂2 Photosynthesis fixes ≈ 2.6 × 1014 𝑘𝑔/𝑦𝑒𝑎𝑟 of 𝐶𝑂2 3×1015 𝑘𝑔 Turnover time = 𝑘𝑔 ≈ 12 years 2.6×1014 𝑦𝑒𝑎𝑟 Result: if plants stopped photosynthesizing today, the amount of 𝐶𝑂2 in the atmosphere could double in just 12 years!  Which of these will empty faster without rain? A B 100,000 L 1,500 L 5,000 L/Day 7.5 L/Day Which of these will empty faster without rain? 100,000 L 1,500 L = 20 Days = 200 Days 5,000 L/Day 7.5 L/Day  Stocks, flows, and turnover “Cycle” Ecosystem If there aren’t flows of some quantity (e.g. water, nutrients, etc.) into or out of an ecosystem, but there are flows within the “Flow” Ecosystem system we say that quantity cycles  Energy and nutrients flow from abiotic stocks to biotic stocks, and among other biotic stocks, via consumption, uptake, and decomposition by living organisms Decomposers Primary producers take energy from the sun (photoautotrophs) or abiotic chemicals to fix carbon and nutrients into new material Nutrients Energy Consumers get energy and nutrients by consuming other organisms All trophic levels are linked to decomposers Decomposers Decomposers (or detritivores) play an essential role in recycling nutrients back to primary producers (autotrophs).  A key ecosystem concept: Energy flows, nutrients cycle Fate of all energy? Lost as heat Fate of all material? Stays in the earth system (converted between forms) Campbell Biology 3rd Can. Ed. Fig. 55.4 Up next: Production and energy flows through the ecosystem Photo by Eric Pedersen, ©.2023  Primary production The source of all energy for ecosystems GPP (gross primary production) = light energy that is converted to chemical energy by photosynthesis NPP (net primary production) = GPP – Respiration by PP - Biomass available to consumers What are the most & least productive ecosystems on earth? Fig. 55.6 NPP of different ecosystems? % of earth’s area NPP per m2 % of earth’s NPP What limits NPP on land?  What limits primary productivity on land? - Intensity of sunlight - Water - Nutrients Best predictor: Latitude  What do we mean when we say something is a “limiting nutrient”? All organisms require energy, water, and carbon, but also need other basic elements to build proteins, DNA, fats, etc.  What do we mean when we say something is a “limiting nutrient”? For every 100 atoms of carbon fixed, ocean plankton need ~16 atoms of nitrogen and 1 atom of phosphorus to grow If we double the amount of carbon available without adding more nitrogen or phosphorus, plankton cannot grow more quickly  What do we mean when we say something is a “limiting nutrient”? Different nutrients (or other resources) are limiting in different places (e.g., light for algae in the deep ocean, water for desert plants, silica for diatoms…)  What limits primary productivity in oceans? nutrients Make connections: What characterizes marine biomes?  What is the main limiting nutrient in oceans? N Pollution from duck farms adds N and P to (NH4+) coastal water off Long Island. (PO4-3) To determine which nutrient limits phytoplankton growth, ecologists cultured phytoplankton with water from several sites. They added either ammonium (NH4+) or phosphate (PO4-3) to some of the cultures. Fig. 55.7  “From Iowa, the excess fertilizer heads downstream into the Mississippi, where it helps fuel an annual dead zone in the Gulf of Mexico” Read: https://www.motherjones.com/environment/2017/08/cover- crops-iowa-maryland-farmers-nitrogen/  But other nutrients can also be limiting in the ocean From abc.net.au/news/2019-11-16/blue-whale-worlds- largest-animal-caught-on-camera-having-a-poo/11708368 Read: https://www.theatlantic.com/science/archive/ 2021/11/whaling-whales-food-krill- iron/620604/ From: en.wikipedia.org/wiki/Iron_fertilization  What about in freshwater systems? In 1974, Dr. Dave Schindler did a “whole lake experiment” in Canada’s Experimental Lakes Area (ELA) area that showed phosphorus limitation in lakes P added Barrier Added P Did not add P Fig. 55.8 MODIS satellite image of Cyanobacteria bloom in Lake Erie in 2012 (credit: NASA)  What limits primary productivity in water? Nutrients - N, P, iron (sometimes silica) Best predictor - Distance from land No latitudinal effect in oceans - Littoral zone revisited  Production at higher trophic levels Secondary production: energy captured in the bodies of consumers after eating plant matter Image: aphids feeding on a plant stem, tended by ants. © Eric Pedersen, 2023  Think about: If a pack of wolves devour a 100 kg deer, does the pack increase in mass by: a) >100kg b) 100 kg c) < 100 kg d) 100kg b) 100 kg Energy transfers between trophic levels are c) < 100 kg inefficient d)