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Krakatau Natural Experiment

Krakatau Natural Experiment. Kim: Foto. After the eruption. Before the eruption. What happened in Krakatau?. Most of the island disappeared and islands in the vicinity were stripped of their wildlife.

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Krakatau Natural Experiment

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  1. KrakatauNatural Experiment

  2. Kim: Foto

  3. After the eruption Before the eruption

  4. What happened in Krakatau? • Most of the island disappeared and islands in the vicinity were stripped of their wildlife.

  5. In a fewmonths, scientistsarrived on theislandtoinvestigatetheeffect of theexplosion. Theydiscoveredthat not evenonespecies of plantoranimalwasfound. Theisland had beencompletelysterilized. • Thecase of Krakatau, is an example of a primarysuccession.

  6. Succession • Succession is the change in species composition in an ecosystem over time. • It may occur on bare ground where the process begins from soil formation, or where no soil has already formed. This is primary succession.

  7. Primary Succession

  8. If it occurs on an already established community with developed soil, where vegetation is suddenly destroyed, then it is secondary succession.

  9. Recovery in Krakatau • Tostudy how naturewouldrecover, scientistspaidannualvisitstoKrakataubetween 1883 and 1935. • Eventually, life didappear on Krakatau (Rakata) in May 1884, in the form of a smallspider. • HOW DID THIS SPIDER REACH TO THE ISLAND? • ThenbySeptember 1884, a fewblades of grassweregrowing

  10. After 3 years since thediscovery of thespider, therewere “nofewerthanfifteenfloweringplants, andshrubs – mostlybeachplants (mosses, andferns)” implicatingarrivalbysea. • Accordingtoscientists, by 1887, therewere dense fields of grasses of “AlangAlang” native of Java, which is alsousuallythefirsttogrowafter a forest fire.

  11. Number of plantspeciesfound on Krakatau

  12. Afterabout 40 years, theforestcanopyclosed, andtherewasbarelyanyopenterrainremaining. It has beendebatedwhethertherewas a chancethatsome of thespeciesthatfirstappeared on theisland had alreadyexisted in Krakatoa as survivors. • But thattheory is usuallydismissedandprimarysuccession is morelikelybecause Krakatau had been blasted and bombed by searing heat, and then buried under ash. The growth of new plants and species took place in the absence of soil, on bare rock.

  13. Anak Krakatau • Due to recent volcanic eruptions, succession on the Krakatau islands have been disrupted. • For example, in the 1930s, new volcanic activity caused the formation of the small island volcano known as the Anak Krakatau (child of Krakatau)

  14. Anak Krakatau • Primary succession has occured on this particular island too. • But frequent eruptions have cleared this island of vegetation several times. (secondary succession)

  15. Effects on Other Islands • The eruptions of Anak Krakatau have also disturbed succession occuring on the islands of Sertung and Punjang. • However, because of wind patterns, Krakatau (Rakata) has not been affected by these volcanic eruptions. For this reason the recovery from the initial 1883 explosion is studied from there.

  16. Current Situation • Theforest in Krakataucurrentlydoeslook dense andmature. • But after 100 yearsafterthe 1883 eruption in 1983, a total of about 300 species of plants had returnedtotheislands. • This is quitesmallcomparedtothesimilarareas on thenearbymainlandwhichhavesomewherebetween 1200 and 1500 plantspecies. WHY?

  17. Future of Krakatau • For the forests in Krakatau to reach a similar biodiversity, scientists estimate it will take more than 1000 years.

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