Ecosystem degradation I.Terrestrial A.Forests B.Grasslands, savanna & shrublands C.Chaparral D.Desert II.Marine & Estuarine A.Marine Life Zones – habitat heterogeneity B.Marine habitats for development C.Marine Habitats as Disposal Sites D.Marine resources for food III.Freshwater A.Lotic systems B.Lentic systems C.Wetlands

What’s degrading terrestrial ecosystems? 1)Population growth 2)Industrialization 3)Urbanization 4)Intensive agricultural and forestry production  Each cause large amounts of waste and pollution to be generated. This places pressure on the environment in terms of suitable waste disposal sites, pollution, and changes to the atmospheric composition, with effects for climate stability. –Population growth also leads to expansion of agriculture to meet the demand for food. This means that areas of natural habitat are converted to other land uses, either in large sections, or piecemeal, fragmenting the natural habitat.

I.Terrestrial Ecosystems A.Forests Forests are dominated by trees where the tree canopy covers at least 10% of the ground area. Forest types: –Boreal Forest – Canada & Northern Eurasia –Temperate Forest – evergreen & deciduous –Tropical Forest – “rain-forests” ~1/2 of the world’s forest cover has been removed for croplands, pastures, mining, & settlements

Deforestation Degrades habitat, disrupts water cycle & carbon cycle Alters ecosystem functions

forest fragmentation based on 1-km resolution land-cover maps for the globe (from Ritters et al. 2000)

B. Grassland, savanna & shrubland Drier than temperate forest, dependant upon fire & seasonal drought, grazing important, sensitive to change In grasslands most of the carbon stock is in the soil. What’s happening to these ecosystems? 1)Heavily converted for agriculture, livestock, urbanization. –In U.S. alone: 97% tallgrass, >60% mixedgrass/shortgrass, 20% sub- tropical grass have been converted

II. Aquatic Ecosystems A.Marine Life Zones – habitat heterogeneity Atmospheric conditions, Oxygen levels, Amount of Sunlight, geography & % dissolved solids create different “zones” –Influences the composition and distribution of biological communities –Estuaries – tidal water bodies located where a river/stream enters the sea –Oceans

B. Marine habitats for development Traditionally, provided shelter to coastal communities (60% of the human population lives within 100km of a coast):

Open cut iron-ore mining at Cockatoo Island in Buccaneer Archipelago (Australia) is triggering a massive coral die off as mine wastes are discharged directly into the ocean

C. Marine Habitats as Disposal Sites Direct or indirect – dumping sites for wastes and byproducts of human activities Sewage, animal wastes discharged directly into the sea/rivers flowing into sea Garbage, pollution Agricultural runoff Ballast water from ships Erosion due to deforestation

D. Marine Resources for FOOD Destructive practices now widely used

A scallop dredge, for instance, consists of a 15-foot-wide steel frame dragging a large chain bag through the seabed. One dredge weighs more than a ton — empty — and most boats tow two at a time.

Globally, more than a billion hooks are set each year on lines that are often more than 100 km in length.

III. Freshwater Ecosystems A.Lotic systems B.Lentic systems C.Wetlands

A. Lotic systems – “flowing water” Riparian community affected by: Climate – temp. and precipitation Topography – rage and erosive force, dependent upon stream morphology Vegetative cover – rate of erosion/ sedimentation Soil types – rate of erosion, chemical characteristics, turbidity Land use patterns – rate of erosion, runoff material

1). Stream habitat features –Gravel, rubble, boulder provide large surface areas points of attachment Cover divert current force

2) Stream chanellization

B. Lentic systems Lakes & Ponds, Puddles

Lake typology Due to their concave nature, a lake lives through many stages to maturity a)Oligotrophic –Young, deep and steep banked –Blue or green water, clear –High oxygen level –Littoral plants limited, phytoplankton poor –Deep water salmonid fishes

Lake typology cont. b)Eutrophic –Shallow, broad littoral zone –Brownish green in color –Low oxygen level –Littoral plants abundant –Abundant phytoplankton

Anthropogenic eutrophication Nutrients released, triggering chain of events

C. Wetlands Lands transitional between terrestrial and aquatic systems where the water table is at or near the surface or the land is covered by shallow water