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Ecosystem (生態系)






Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily

[ community | environmnt | ecosystem ]
[ plant community ecology | problems | criteria | ecotone ]

Plant community ecology (植物群集生態学)


Objectives: analyses of pattern and process on plant community

Pattern: spatial, temporal, niche patterns, species along gradients, community in landscape
Process: succession → site index, competition, biotic reaction、disturbance

The nature of plant community (vegetation)

Uniquity of change in time - patchy dynamics
Vegetation in space: vegetation is never separated from the ground surface

Plant community structure: structure of plant communities: species richness, species abundance, and spatial and temporal distribution patterns and changes (life forms, vertical structure, allelopathy, etc.)

(Ecological) niche (ニッチ)

all of the interactions of a species with the other members of its community, including competition, predation, parasitism, and mutualism
Niche breadth and overlap
Niche breadth (ニッチ幅) = niche width (van Valen & Grant 1970), niche size (Klopfer & MacArthur 1961), versatility (Maguire 1973)

the breadth is the "distance through" a niche along some particular line in niche space)

Niche overlap (ニッチ重複)

niche
Resource or environmental gradient

索引
Guild (ギルド): any group of species that exploit the same resources, or that exploit different resources in related ways
The prerequisites for coexistence: = resource limitation, niche and guilds

50 species in New Guinea
Group 1. Occupied in species-rich islands
Group 2. Species-rich islands + species-poor islands (trampers)
Group 3. Species-poor island (super trampers)

[ biome (バイオーム)| ecosystem ]

Community (群集/群落)


Term: proposed by (Humboldt 1805)
1) Organic concept: Profile, stratification, etc. - closed system
2) Individualistic concept: Habitat segregation(棲み分け, 同位社会) - open system

Plant community (association) is a very global term

  1. an example of vegetation within a habitat
  2. a unit in a classification of vegetation

The organisms which affect, directly or indirectly, the expected reprocutive success of a reference organism. By a "true" community is meant one whose member individuals interact, either directly or through a chain of other individuals, in a way that effects their individual life times and chances of reproduction and survival. (MacMahon et al. 1981)

A group of populations (個体群) of all organisms that coexist in a space and time. The species may interact to each other.

Plant community

A plant subset of community; viz. all plants coexist in a space and time.

Vegetation (and phytocoenosis)

I use as the synonym of 'plant community' in my lecture.

Reference: Phytosociological term
Association: a particular plant community type that can be determined by the characteristics of species composition, physiognomy and environments

Coevolution and competition

Coevolution called to tight associations or not ⇔ Competition called to swamp associations or more overlaps
community concept

Problems

Are plant communities real or artifact?

Real: sample, stand, plot, quadrat, etc. ⇔ Artifact: associations, community types - phytosociology

  1. How do we recognize plant communities?
    Clementsian paradim, Gleasonian apporach, and the synthesis
    Ecotone
  2. How do we draw the boundary of two communities?

Criteria for plant community analysis


  1. Flora
    Species composition
  2. Plant community physiognomy
    Abundance(percentage) cover, basal area, density, frequency
  3. Distribution correlated with environment

Physiognomy (相観)

is 'the form and structure of vegetation in natural communities'.

Examples: Forest, shrubland (bushland), grassland, desert
forest zones of the Cascades

Physiognomy is one of the keys to determine the types of communities, ecosystems and biomes.

A few examples of physiognomy

forest1 bushland2
[1] A forest canopy on Tomakomai Experimental Forest (October 1995). The physiognomy is categorized into "Forest"! [2] A bushland in Western Australia (October 3 2003). In this case, there are no trees.

[vertical distribution of vegetation]

Zonation (ゾーネイション)


Mosaic Distribution (モザイク分布)

Mosaic vegetation diagram
mosaic
Mosaic vegetation change
Association = overstory/understory

Crown(overstory) - slow/gradual → Understory - fast/quick
→ Braun-Blanquet: characteristic species + absolute/relative cover → phytosociological taxonomy key

Ecotone (エコトーン)

A transitional area between two adjacent (plant) communitites
Transition zone between two major ecological communities where one does not merge gradually into the other, for example that between grassland and woodland. Such steep gradients between communities are often man-made (see 'skislope').

The development of ecotone is tightly connected with the environmental gradient.

ecotone in WA
In the case of western Washington

Environment (環境)


  1. general concept → urban environment, desert environment, etc. (Billings 1974)
  2. specific (biological) concept → interaction(s) between environment-organism (individual, population, or community) → biologial meaning
Ecology (生態学)
  1. The complex of climatic, edaphic and biotic factors that act upon an organism or an ecological community and ultimately determine its form and survival.
  2. the physical conditions which exist within the area which will be affected by a proposed project, including land, air, water, mineral, flora, fauna, noise, and objects of historic or aesthetic significance.
Environmental science
  1. everything except me (most general)
  2. everything except human
    Declaration of the United Nations Conference on the Human Environment (Stockholm Declaration on 5-16 June 1976) follows this.
    The protection and improvement of the human environment is a major issue which affects the well-being of peoples and economic development throughout the world.
  3. everything except earth

Action, reaction and coaction

Action: environments → organisms
Reaction: organisms → environments
Coaction: organisms ↔ organisms
action
succession (遷移) explaiend by spatio-temporal changes in environments

[ system | ecosystem | environment | ecosystem services ]

Ecosystem (生態系)


= ecosystem, biosystem, or ecological system

System

regularly interacting and interdependent components forming a unified whole. The individual organism cannot survive for long without its population any more than the organ would be able to survive for long as a self-perpetuating unit without its organism.

Ecosystem

An ecological system that incluedes all the organisms and their environment within which they occur naturally.

+ Plant community
+ Animal community
+ Environment

or,
+ Biotic components
+ Abiotic components

Ecological system
Used for environmental problems → general systems containing ecological characteristics

Characteristics
1) resilience (弾力性)
2) adaptation (適応性)
3) dynamics (動的)

(Theodore 1976)

Characteristics of ecosystems
  1. A living system exits only within the context of its physical and chemical environment. This environment establishes the "ground ruler (基本的役目)" for a system’s continuing existence.
  2. An especially important part of item (a) is the requirement of that a living system captures all resources (materials and energy) needed for its continuing existence. These requirements, especially energy, impose further restrictions upon the mature of ecological systems.
  3. A system will develop a characteristic structure in response to these and other influences.
  4. In nearly every case the structure of a system will not be static, but rather will be dynamic and responsive to changing conditions. To promote continuing survival, these must be appropriate mechanisms that allow ecological system to cope with change. Otherwise, potential competitions would replace them.

If you think protecting species is hard, just wait until we try to protect whole ecosystems. (Noss 1996)

  1. Geoecosystems: segments of the Earth’s living space, functional units of nature on the face of the Earth. Any single perceptible ecosystem is a topographic unit, a volume of land and air plus organic contents extended a really over a particular part of the Earth’s surface for a certain time (Rowe 1961)
  2. Bioecosystems: Community (organisms) + environment. The danger in simple definition is: a) inconstant nature of vegetation, and b) the wandering habits of all animals.

Quiz
  1. List several distinctly different non-seral shrub-dominated community types and several herb-dominated community types. For each, state the environmental factor or factors that permit these growth forms to dominate and to persist.
  2. Distinguish between subalpine and alpine meadows. For each, describe three major associations.

Metacommunity (メタ群集)

a set of interacting communities which are linked by the dispersal of multiple, potentially interacting species → patch dynamics, species sorting, source–sink dynamics (or mass effect) and neutral model

Ecological model (生態系モデル)


Unchangeable model

This model can be applied with some restrictions, e.g., no consideration of temporal changes

Ex. population unit: age structure (structure survyed at a given time = disequilibriumo of age structure

Changeable model

= dynamic midel (system dynamics)
Dynamics: the ways in which characteristic structural elements are first developed and subsequently maintained in the various levels of ecological organization.

an ecological system that includes all the organisms and their environment within which they occur

Steady-state open system (定常開放系)

Ex. Structure of capitalism (都市化の構造)
    ┌──────────────┐
    │  Capitalism                │   ↑
    │┌────────────┐│   ↑
    ││Advanced nations        ││ Exploitation
    ││(eg, Europe, Japan, USA)││   ↑
    ││     [Capitalist]       ││   ↑
    ││     [Laborer]          ││   ↑
    │└────────────┘│   ↑
    │┌────────────┐│   ↑
    ││The third world         ││   ↑
    │└────────────┘│   ↑
    └──────────────┘

Landscapee model (景観モデル)

Landscapee simulation model (森林景観シュミレーションモデル)
LANDIS-II: landscape change model (景観変化モデル), forecasting landscape change due to natural and human causes
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