ECOSYSTEMS
Ecosystems
•Ecosystem = all organisms and nonliving entities thatoccur and interact in a particular area at the sametime
–Includes abiotic and biotic components
–Energy flows and matter cycles among these components
•Biological entities are highly intertwined withchemical and physical entities
–Interactions and feedback loops
Systems of interacting entities inecosystems
•Energy from the sun flows in one direction
–Energy entering the system is processed and transformed
•Matter is recycled within ecosystem, resulting inoutputs such as heat, water flow, and waste products
Energy is converted to biomass
•Primary production = conversion of solar energy tochemical energy by autotrophs
•Gross primary production (GPP) = assimilation ofenergy by autotrophs through photosynthesis
•Net primary production (NPP) = energy remainingafter respiration, and used to generate biomass
–Available for heterotrophs
•Productivity = rate at which ecosystems generatebiomass
Net primary productivity of variousecosystems
High net primary productivity = ecosystems whose plantsrapidly convert solar energy to biomass
NPP variation shows global patterns
NPP increases with temperature and precipitation on land, andwith light and nutrients in aquatic ecosystems
Nutrients can limit productivity
•Nutrients = elements andcompounds required for survivalthat are consume by organisms
–Macronutrients = nutrientsrequired in relative large amounts
•nitrogen, carbon, phosphorus
–Micronutrients = nutrients neededin smaller amounts
• iron, cobalt, chromium, copper, iodine,manganese, selenium, zinc andmolybdenum
•Stimulate plant production
•Nitrogen and phosphorusare important for plant andalgal growth
Growth of algae in watercontaminated with phosphate
Nutrient runoff is devastating aquaticsystems
•Dead zones of water result from nutrient pollution fromfarms, cities, and industry
•Pollution and human impact have devastated fisheries andaltered aquatic ecosystems
•Scientists are investigating innovative and economical ways toreduce nutrient runoff
Phytoplankton blooms off theLouisiana coast
Ecosystems integrate spatially
•Ecosystems vary greatly in size
•The term “ecosystem” is most often applied to self-contained systems of moderate geographic extent
•Adjacent ecosystems may share components and interact
•Ecotones = transitional zones between two ecosystems inwhich elements of different ecosystems mix
•Landscape ecology = the study of landscape structure and how itaffects the abundance, distribution, and interaction of organisms
–Helpful for sustainable regional development
•Patches = form the landscape, and are distributed spatially incomplex patterns (a mosaic)
•Landscape = larger than an ecosystem and smaller than a biome
Landscape ecology
