Ecosystems in Transition Ecosystems are dynamic – they change as the Earth changes. This process is called succession. Organisms that thrive during the early stages of succession are called pioneer species. Those only found in later stages are called climax species. Ecosystem succession takes two forms, depending on the starting point. Any disturbance will initiate the cycle of succession

Primary succession occurs when a new ecosystem develops where there was none before. Occurs in areas completely lacking soil and devoid of vegetation Lava flows, glacier retreat, new islands, sand dunes Because there is no soil initially, this is a very long process A combination of wind, water, and pioneer species such as lichens break down rock into soil. Once the soil has enough organic matter, small plants and shrubs can be supported. Over time, trees spout and become dominant.

Secondary succession occurs when a disturbance changes an established ecosystem. Soil is still present, therefore the process is faster – pioneer species appear within days or weeks. Fire, flood, volcanic eruption, clear-cutting, etc.

Old-field succession – form of secondary succession that occurs when farm land is abandoned or left fallow

Secondary succession also occurs in ponds – as sediment and plants build up over time, a pond will fill in and can eventually become forest

What type of succession is this?

Succession and People People frequently cause succession - both intentionally and unintentionally Clearing a lot of its native trees will trigger succession Mowing and maintaining your grass is a continual battle against the natural succession process Often the areas around new development will be altered by the development Rapid development of an area can lead to mudslides and erosion that can trigger succession

Hispaniola (“The Spanish Island”) is an island that Christopher Columbus took possession of during his voyage of 1492. The island is now divided into the countries Haiti and the Dominican Republic Columbus Landing on Hispaniola, 1492. Artist: Theodor de Bry, 1594.

Five mountain ranges run through the island. Hispaniola had a wide variety of ecosystems, ranging from arid plains to lush tropical forests. Five mountain ranges run through the island. Los Haitises National Park, Dominican Republic

As the island was colonized, most of its indigenous tribes died out from diseases and harsh working conditions in Spanish gold mines. By 1517, the indigenous population was down to from an estimated 250,000 to 14,000. They were replaced with 14,000 African slaves and 1,000 Spanish colonists on the island. The slave population revolved in 1804, winning independence from France for Haiti, their part of the island. France demanded 150 million Francs as restitution for lost property, which was paid with lumber from the island’s forests.

The peasants began clearing and farming on the forested hills. In Haiti, a combination of a severe hurricane in 1954 and increased demand for charcoal lead to further deforestation. The peasants began clearing and farming on the forested hills. The thin rainforest soil was quickly depleted and began experiencing severe erosion.

Today, only about 2% of Haiti’s original forest cover remains. Even this remains at risk, because most of the people depend on charcoal as a source of heat. The lack of forests has made the country much more susceptible to flooding, mudslides, and erosion.

Neighboring Dominican Republic, which gained its independence with much less strife, is the second largest economy in the Caribbean.

Haiti’s hopes for recovery hinge on its ability to speed the process of ecological succession – to encourage reforestation and find an alternative fuel to charcoal.