Prof. Dr. Yingzhi Gao

Northeast Normal University

Phone:13664319768

Email:gaoyz108@nenu.edu.cn

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

Decomposition

Animals

Excreta (Urine)

Degistation

Excreta

(Dung)

Mineralization

Dead belowground phytomass

Decompo-

sition

internal internal nutrient cyclingnutrient cycling

System input:

- wet and dry deposition- N2-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

TO

0.05T79

0.6

T79

5 - 9TO

3 - 5

Living roots

Dead roots

Living shoot

Standing dead and litter

N-uptake

TO

0.23 - 0.26 T79

2.8 - 2.9

TO

1.4 - 2.3T79

2.2 - 3.1

TO

16.7T79

25.4

TO

4.5T79

8.3

TO

1.4 - 2.3T79

2.2 - 3.1

TO

0.6

TO

0.1

TO

0.4TO

1,0

TO

5T79

7

TO

330T79

400

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, man

y bacteria, phytoplankton),• Primary consumers: heterotrophs that feed on auto

trophs (herbivores, zooplankton);• Secondary consumers heterotrophs that feed on pri

mary consumers;• Tertiary consumers (quatenary consumers);• Detritivores (organisms that feed on decaying orga

nic matter, bacteria, fungi, and soil fauna)• Omnivores (feed on everything), frugivore, fungiv

ore…….

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: 284-307

• 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

www.magim.net