1. Fill in the paragraph using the word bank provided.
abiotic  factors  climax community mix
ecosystems  quicker  primary succession natural disaster
remains pioneer  species moss
lichen  soil  succession 
lava  secondary succession break-down
(1)  ________________________ are constantly changing. Both (2) ________________________ and biotic factors change in every ecosystem.  One type of ecosystem change is called (3) ___________. This results in one community replacing another over time.  This process might begin on bare  rock formed from the cooling of molten (4) ________________________.  This process begins when (5) ________________ & (6) ________________, also known as the (7) ________________________, begin living on and (8) _________________ bare rock.  When these organisms die, their remains (9) _______________ with the rock pieces to form a thin layer of (10) __________________________. This process of establishing and developing an ecosystem in a previously uninhabited area is called (11) ___________________________.  The mature community that eventually forms is called the   (12) ________________.  Sometimes that community is destroyed by a (13) ____________________.  A new community will replace the destroyed one through the process of (14) ___________________.  This process happens much (15) ___________ because the soil usually (16) ______________.

2. (1) Ecosystems are constantly changing
(1)  Ecosystems are constantly changing. Both (2)abiotic factors and biotic factors change in every ecosystem.  One type of ecosystem change is called (3) succession. This results in one community replacing another over time.  This process might begin on bare  rock formed from the cooling of molten (4) lava.  This process begins when (5) moss & (6) lichen, also known as the (7)pioneer species, begin living on and (8) break-down bare rock.  When these organisms die, their remains (9) mix with the rock pieces to form a thin layer of (10) soil. This process of establishing and developing an ecosystem in a previously uninhabited area is called (11) primary succession.  The mature community that eventually forms is called the   (12) climax community.  Sometimes that community is destroyed by a (13) natural disaster.  A new community will replace the destroyed one through the process of (14) secondary succession.  This process happens much (15) quicker because the soil usually (16) remains.