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Ecology

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					CHAPTER 1




INTRODUCTION
               1
Ecology: Study of relationships
between organisms and the
environment.

Ecosystem: all organisms that live in
an area and the physical environment
with which those organisms interact.

Nutrients: the raw materials that an
organisms must acquire from the
environment to live.

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                           Ecology
   Understand the relationships between organisms
    and the environment.
   We are not fully understand the relationships and
    the changes that we do in earth.
   Broad scientific discipline under ecology (study
    individuals, entire lake, or even whole earth)
   Ecologist could study:
           organisms
          Non-biological
          Theoretical models of ecological systems
          Ecological research in the laboratory



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    Using Field Studies to test theory
                  Warbler study case 1
   Robert MacArthur 1955, bird-watcher test for
    theory of warbler feeding on insects of spruce
    trees. Fig. 1.1




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Fig. 1.1
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                       Warbler study case 2

   Douglass Morse 1980, 1989. address questions on feeding
    zones and whether warblers use the same feeding zones in
    the absence of others.
    – Compared warbler on mainland to small islands inhabited by
      one to three species.
           Feeding zones are partially maintained by aggressive interactions
           Aggressiveness help maintain different feeding zones.


    – Figure 1.2




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Fig. 1.2

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Contributions of field and laboratory
              studies
                  Bumblebees study case
   Bernd Heinrich (1979, 1993)
   Combination of laboratory & field study.
    –   Measure Energy budget.
    –   Oxidation
    –   Time of flying
    –   Types of flowers visited
    –



    Figure 1.3, 1.4




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          Forest Nutrient Budgets
      Inventories and large-scale experiments 1
   Nalini Nadkarni (1981, 1984a, 1984b).
   Studied budget of nutrients in rain forest of C R.
    Correlation of epiphytes with nutrient budget.
   Epiphytes store nutrients estimated to be half of
    nutrients content of the foliage of the canopy
    trees.
    The research showed that ;
    – Both temperate & tropical rain forest, trees access to
      nutrient stored by epiphytes by sending out roots from
      their trunks and branches above the ground.
    – The roots grow into the epiphyte mats and extract
      nutrients from them.


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Fig. 1.5   13
                large-scale experiments 2

   Gene Likens and Robert Bormann (1994, 1995)
   Hubbard brook experimental forest of New Hampshire.
   Their hypothesis suggest that organisms, specially plants
    will regulate the rate of nutrient loss from forest.
   Measuring nutrients before and after deforestation.
   They estimated the rate at which some organisms fix
    atmospheric nitrogen and rates at which weathering release
    nutrient from granite bed-rock of the stream basins.
   They found that over 90% of the nutrients are tied up in
    soil organic matter. While the rest 9.5% was in vegetation.
   Following cutting the trees they found that 40-50 of Nitrate
    where lost.
   Major elements in stream draining increased by 177% to
    1,558%.
   Show clearly influence of vegetation on nutrient
    movements.

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Fig. 1.6
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                 Vegetation change
     Information from pollen record and modeling
   Margaret Davis (1983,1989).
   Theoretical models provide long-term ecological changes.
   Study of different lake sediments provide historical changes of
    vegetations (spatial & temporal).
   Ecotones : transitions from one type of ecosystem to another
    (e.g. woodland to grassland or vise versa)
   Phase transition model include change in the state of matter such
    as water from liquid to solid state as temperature decrease.
   Phase transition take place abruptly under some critical condition,
    water shifts to solid at 0 ° C.
   Critical densities regulate the transition from one vegetation to
    another.
   The research indicated there are a relationships between ecotones
    and their sensitivities to environmental changes .
   Also distance between edges are defined by different plant
    densities.
   Edges defined by different densities of vegetation are more widely
    spaced, the environmental gradients is likely to be more gradual.

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Fig. 1.8   17
Fig. 1.9
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