DR. DAVID WALKERDR. WILLIAM MATTER

Stream Ecology SWES/WFSC/ECOL 471/571

Definitions

…a given discipline cannot readily develop without precise categorization of language.

…one of the fundamental aims of science must be the isolation of semantic categories so that these defined units can serve as a basis for empirical permutation.

Balgooyen, 1973

The Art of Meaningless…ness

Peripathetic adj  Moping about or from place to place; whining while walking. Having failed to convince us that the loss of her mall privileges was a terrible

crisis, my peripathetic sister moved on to try and convince another group of friends in the cafeteria.

Sarcastrophe noun The embarrassing and catastrophic results of a failed attempt at sarcasm. "Oh yeah, like blowing up Afghanistan is going to end terrorism. We might as well just invade Iraq!" - U.S. National Security Advisor, 2003.

Melancholera noun A form of the disease cholera characterized by extreme depression and sadness. I hate life, I hate my parents, I have everything, but I'm too sick to put on my black lipstick.

Spatulence noun The abrupt expulsion of cooking utensils from one's body cavity.  My spatulence produced several nice melon ballers today.

From Decombust.com

So…what is “ecology”?

German Ökologie, from öko- eco- + -logie -logy

Eco-, Gr. oiko-, oikos, house

History

Ernst Haeckel coined the term ecology in the mid-19th century.

The Haeckelian definition emphasized biotic and abiotic components of the natural world and that organisms are the relevant manifestation of the biotic realm.

Largely neglected inconspicuous organisms, such as microbes, and ecological systems at higher hierarchical levels than organisms.

H.G. Andrewartha and L.C. Birch

Emphasized both abiotic and biotic factors influencing distribution and abundance of species.

Still had a predominately biotic focus.

Introduced the concept of “metapopulations”.

Several distinct populations together within areas of “currently unoccupied suitable habitat”.

Systems Ecology: “Ecosystems”

Provided several statements on the scope of ecology.

Major emphasis on structure and function of ecosystems.

Both believed in the idea of a “superorganism” and went to great lengths to try and quantify as many different energy pathways and interactions as possible.

For our purposes…

An ecosystem is a conceptual unit comprised of an assemblage of organisms, their interactions with each other and their environment, and having the major attributes of: Structure and function Complexity Inter-action and inter-dependency Temporal change No inherent definition of spatial dimension

What is ecosystem structure and function?

Two distinct camps in ecosystem scientists: those concerned with measuring inputs and outputs and those concerned with specific populations.

Usually, ecosystems are defined first by the biota and second by the environment.

In any ecosystem, patterns of organization at almost any spatial or temporal scale are common.

But are these organizational patterns considered “structure”?

Structural pattern should (must?) be tied to those functions that are critical for the evolutionarily-derived operation of the ecosystem.

Structure derives from function.Structure is the minimal or parsimonious

pattern of organization necessary for a function to operate.

Ecosystem Function

Possible Structures

Productivity Nutrient availability/algal biomass/herbivory and grazing/photoperiod

Decomposition Bacterial biomass/temperature/oxygen demand

Energy transfer/trophic interactions

Food web length/complexity/connectivity

Nutrient cycling/spiraling

Water chemistry/watershed inputs/flow/bio-availability

The Big Picture

Evolutionary Theory• Ecology

Systems Ecology• Ecosystems

The Stream Environment: Categorical Units

Watersheds

Hydrologically-bound units based upon topography.

Larger watersheds composed of several “sub-watersheds” or smaller drainages.

Since whatever happens up-stream affects everything downstream, watershed management is increasingly used by resource agencies as a more integrated approach to solving water quality problems.

A watershed is… "that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of a community." John Wesley Powell

Stream Order

A hierarchical classification system of stream segments (R.E. Horton, 1945).

Segments are ordered numerically from headwaters to reach so that individual tributaries at the headwaters were given the order of “1”.

The joining of two 1st order streams were given the order of “2” and the joining of two 2nd order streams the 3rd order and so on.

1) Stream length increases with stream order. 2) There are 3-4 times as many streams of the order n-1 as

there are of n

Problems with Stream Order Classification

Difficult to identify first order streams. Leopold et al (1964) suggest that first order

streams should be considered the smallest ones marked on a 1:24,000 scale map.• Does this have any ecological significance?

Stream order classifications ignore the entry of streams n into n + 1.

Streams systems exhibit a large degree of spatial variability from headwater to reach to mouth.

Classification schemes work well for communicative purposes.