Indicate the model of succession that best fits each of the following scenarios:
ID: 63653 • Letter: I
Question
Indicate the model of succession that best fits each of the following scenarios:
Scenario 1: After an open-pit mining company finishes mining an area, the company fills their mine pit with soil and rock that was removed during the mining process. Unfortunately, the rock contains high levels of heavy metals that are toxic to most plants. As part of their reclamation process, the company seeds the area with a plant called Bioaccumulatus that absorbs these metals from the soil. Over time, the concentration of heavy metals in the soil is reduced and native plants are able to seed in from surrounding areas and survive on the site. As soil toxicity continues to decline, the native plant community outgrows and eventually replaces the Bioaccumulatus.
Scenario 2: A timber company clearcuts a stand of mature Douglas-fir, then goes bankrupt due to a shady investment deal and cannot afford to follow up their harvest with any planting activities. Salmonberry and blackberries regenerate rapidly after the harvest from a seed bank and rhizomes in the soil. Although there are scattered Douglas-fir trees to provide seed, the tasty berry species form a dense shrub layer that creates too much shade for Douglas-fir seedlings to establish. The salmonberry and blackberry ultimately retain their hold on the site for several decades
Explanation / Answer
Primary succession occurs in lifeless areas in which the soil is not capable of sustaining life due to lava flown from volcano, accumulation of toxic metals from mines and rocks left over due to retreating glacier etc.
Secondary succession occurs in areas where a previous community are existed and later replaced with another community.
The scenario 1 is categorized under primary succession in which the Bioaccumulatus plants are planted for the first time to absorb the toxic heavy metal species. The Bioaccumulatus out grows native plant community and replaces all over the land.
The scenario 2 is categorized under secondary succession because once clear cut trees are regenerated with Salmonberry and blackberry that are retained for a long time.