AW

ecology: interaction organisms <-> environment: chapter 1

How are plants adapted to their surroundings?

%%Trample-resistant plants%%

→adjustment to %%frequent trampling%%

  • %%grow from the bottom%% (other plants grow from the top) → mowing → growpoint not damaged
  • %%leaf position = vertical%% → no direct sunlight on leaf →protection overheating + more leaf area per m² → more optimal photosynthesis →grasses grow faster
  • %%dense and shallow root systems%% → to store H2O + nutrients →if parts above ground are damaged →fast regrowth →reserve H2O + nutrients

%%Succulents%%

→adjustment to %%drought%%

  • %%stem succulent%% example: a cactus
    • %%stem%% → ability to store water
    • %%leaves = needles%% → smaller leave area →limiting evaporation
    • %%thick wax layer%% → limiting evaporation
    • %%deep and well-branched roots%% →absorb more water from a bigger area
    • %%white hairs%%
    • reflecting sunlight → preventing overheating
    • retains air layer → isolation → limiting evaporation
    • retains dew and raindrops → water goes into the ground → roots can absorb it
  • %%leaf succulent%% example: Aloe Vera
    • %%thick wax layer%% → limiting evaporation
    • %%less stomata%% → limiting evaporation
    • %%stomata is deeper in the leaf%%→ preventing dehydration

%%Halophytes%%

→ adjustment to %%high salinity%%

without any adjustment → osmosis → H2O goes out of the plant → plant dies

%%osmosis%% = the movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cell's partially permeable membrane. Until they the amount is equal on both sides

2 solutions

  1. %%concentration of salt plant cells%% >>> concentration of salt soil → plant can absorb H2O

    example: samphire = a salt-tolerant succulent

  2. %%salt glands on leaves%% → secrete excess salt

    example: mangrove

%%Carnivorous plants%%

→ adjustment to %%poor soil%%

example: Venus fly trap (= VFT)

  • %%nitrogen-poor soil%% → VFT cannot fixate enough nitrogen → no assimilation of protein compounds →%%shortage nutrients%% → %%compensate%% it with %%digesting insects%%
  • %%attracts%% insects by secreting %%nectar-like substance%%
  • %%reproduction%% → grow %%a flower on a high stem%% above the leaves → %%no dange%%r for insects → insects can %%pollinate%% → forming seeds → flower dies

Adjustment to %%light competition%%

  • %%growth speed%%

    grasses = fast growers →take away light herbaceous plants → development of %%rosette%% =

    a circular arrangement of leaves or of structures resembling leaves →ground cover → grasses can’t grow

example: plantoga major, daisy

  • %%growth period%%

    forest herbs growth is in spring → almost no competition → summer → dense foliage → stops sunlight → after seed forming → the plant dies above ground →made enough nutrients during spring → stored in rhizomes

  • %%growth direction crown%%

    to lessen competition → plants grow in other direction → depends on place example: oak

    • open field
    • wide
    • branched
    • symmetrical
    • forest
    • less side branches
    • grows in height
    • forest edge
    • asymmetrical
    • grows to the edge of the forest

  • %%leaf mosaic%% = the arrangement of foliage in most plants (as in the common ivy) in such a pattern as to expose the maximum number of leaves to the direct rays of the sun with little loss of intervening space.

Epiphytes

%%epiphyte%% = an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it.

example: orchids