Prof. Dr. Yingzhi Gao Northeast Normal University Phone: Introduction to Ecosystem Ecology

Textbook: Principles of Terrestrial Ecosystem Ecology by F. Stuart Chapin III Pamela A. Matson Harold A. Mooney

Course Goals Understand basic principles Interaction, scale, process, pools and fluxes, trophic, Integration ， regulation and management Get you involved –Participate!!!

Why should we care about ecosystem ecology? Ecosystem ecology provides a mechanistic basis for understanding the Earth System Ecosystems provide goods and services to society Human activities are changing ecosystems (and therefore the Earth System)

Complex: human activity influence

Study of interactions among organisms and their physical environment as an integrated system What is Ecosystem Ecology?

What is an ecosystem? bounded ecological system consisting of all the organisms in an area and the physical environment with which they interact –Biotic and abiotic processes –Pools and fluxes

Living aboveground phytomass Living belowground phytomass Mineral nutrients in soil solution Uptake ExudationWashout Uptake for shoot production Retranslocation Humus Humification Immobilization Standing dead Litter Mineralization Decompos ition Animals Excreta (Urine) Degistatio n Excr eta (Du ng) Mineralization Dead belowground phytomass Decomp o- sition internal nutrient cycling System input: - wet and dry deposition - N 2 -fixation - fertilization - water inflow System definition nutrient cycling System output: - water outflow - wind erosion - losses to air (denitrification) - fire (burning dung) - haymaking - animal products (meat, wool,...)

Nitrogen fluxes and pools 2004 and 2005 (g/m²) Living roots Dead roots Living shoot Plant available N Soil Humus N (0-20 cm) Decomposition Standing dead and litter Export N-uptake Sheep uptake Root N-uptake T O 0.05 T T T O Living roots Dead roots Living shoot Standing dead and litter N-uptake T O T T O T T O 16.7 T T O 4.5 T T O T T O 0.6 T O 0.1 T O 0.4 T O 1,0 TO5TO5 T 79 7 T O 330 T Sheep Decomposition

Ecosystem Structure: Trophic relations Trophic relationships determine an ecosystem’s routes of energy flow and chemical cycling Trophic structure refers to the feeding relations among organisms in an ecosystem Trophic level refers to how organisms fit in based on their main source of nutrition, including

Trophic levels Primary producers: autotrophs (plants, algae, many bacteria, phytoplankton), Primary consumers: heterotrophs that feed on autotrophs (herbivores, zooplankton); Secondary consumers heterotrophs that feed on primary consumers; Tertiary consumers (quatenary consumers); Detritivores (organisms that feed on decaying organic matter, bacteria, fungi, and soil fauna) Omnivores (feed on everything), frugivore, fungivore…….

Other Definitions An ecosystem is a bounded ecological system that includes all the organisms and abiotic pools with which they interact. An ecosystems is the sum of all of the biological and nonbiological parts that interact to cause plants grow and decay, soil or sediments to form, and the chemistry of water to change.

Ecosystem Ecology The study of the movement of energy and materials, including water, chemicals, nutrients, and pollutants, into, out of, and within ecosystems. The study of the interactions among organisms and their environment as an integrated systems.

Example 1 Small scale: e.g., soil core, appropriate for studying microbial interactions with the soil environment, microbial nutrient transformations, trace gas fluxes,…

Example 2 Stand: an area of sufficient homogeneity with regard to vegetation, soils, topography, microclimate, and past disturbance history to be treated as a single unit. Appropriate for studying whole-ecosystem gas exchange, net primary productivity, plant-soil-microbial nutrient and carbon fluxes

Example 3 Natural boundaries: sometimes, ecosystems are bounded by naturally-delineated borders (lawn, crop field, lake). Appropriate questions include whole-lake trophic dynamics and energy fluxes (e.g. Lindeman)

Example 4 Watershed: a stream and all the terrestrial surface that drains into it. Watershed studies use stream as “sample device”, recording surface exports of water, nutrients, carbon, pollutants, etc., from the watershed.

Temporal Scale Instantaneous

Temporal Scale Instantaneous Seasonal

Temporal Scale Instantaneous Seasonal Succession

Temporal Scale Instantaneous Seasonal Succession Species migration

Temporal Scale Instantaneous Seasonal Succession Species migration Evolutionary history

Temporal Scale Instantaneous Seasonal Succession Species migration Evolutionary history Geologic history

General approaches Systems approach –Top-down approach

General approaches Systems approach –Top-down approach Comparative approach –Bottom-up approach –Based on processes

Historical roots Community ecology –Elton –Clements Geography –Warming, Schimper, Walter Soils –Jenny

Systems Approach Lindeman: Trophic dynamics Odum: Energy and nutrient flows Margalef: Information transfer O’Neill: Hierarchy theory Holling: Resistance and resilience

Process Approach Jenny: State factors Billings, Mooney: Ecophysiology

Tansley, British plant ecoslogist The use and abuse of vegetational concepts and terms. Ecology 16: First to coin term, “ecosystem” Emphasized interactions between biotic and abiotic factors Argued against exclusive focus on organisms

Hans Jenny, Soil scientist Factors of soil formation, 5 state factors that constrain soil and ecosystem development Soil = function of Climate, organisms, parent material, relief (topography) and time, or s=f(clorpt) Many patterns of soil and ecosystem properties correlate with state factors (climate and vegetation structure and function)

Ramond Lindeman Qualified pools and fluxes of energy in a lake ecosystem emphasizing biotic and abiotic components and exchange Fluxes of energy, critical “currency” in ecosystem ecology, basis for comparison among ecosystems Synthesized with mathematical model Coupling of energy flow with nutrient cycling

J. D. Ovington, English forester Central question, how much water and nutrients are needed to produce a given amount of wood? Constructed ecosystem budgets for nutrients, water, and biomass Also included inputs and outputs: exports of logs involves exports of nutrients (thus inputs of nutrients required to maintain productivity One of the first to state the need for more basic understanding of ecosystem function for managing natural resources

H. T. Odum and E. P. Odum Used radioactive tracers to study movement of energy and materials through a coral reef, documenting patterns of whole system metabolism System analysis- ecosystem as a life- support system concept

Earth System and Global Change Making history in ecosystem ecology Impact of human activities on Earth has led to the need to understand how ecosystem processes affect the atmosphere and oceans Large spatial scale, requiring new tools in ecosystem ecology (fluxes tower measurements of gas exchange over large regions, remote sensing from satellites,global networks of atmospheric sampling, global models of ecosystem metabolism).

Frontiers in ecosystem ecology Integrating systems analysis, process understanding, and global analysis How do changes in the environment alter the controls over ecosystem processes? What are the integrated consequences of these changes? How do these changes in ecosystem properties influence the Earth system? Rapid human-induced changes occurring in ecosystems have blurred any previous distinction between basic research and management application