Climate and Biodiversity

Chapter 5

Importance of Mountains – Islands of Biodiversity

• Rapid change as elevation changes – Many different biomes, high

diversity• Contain majority of the world’s

forests– High diversity, endemics, refuge

• Regulate climate– Snow tops reflect radiation

• Key in the hydrological cycle– STOREHOUSES OF WATER

Ecological Role of Mountains

Fig. 5-17, p. 90

Watersheds

• Rivers begin in mountains or at higher elevation

• Surface water becomes runoff into streams

• Watersheds or drainage basins deliver runoff, sediment, and dissolved substances to streams

• Streams join to form rivers

Three Zones in the Downhill Flow of Water

• Source zone– Mtn headwater streams flow

swiftly down steep slopes and cut a deep V-shaped valley. Rapids and waterfalls are common

• Transition zone– Low-elevation streams

merge and flow down gentler slopes. The valley broadens and the river begins to meander

• Floodplain zone– At an even lower elevation a

river wanders and meanders slowly across a broad nearly flat valley. At its mouth, it may divide into may separate channels as it flows across a delta built up of river borne sediments and into the sea.

Rain and snowLake

RapidsGlacier

Waterfall

Source Zone

Flood plain

Tributary

Transition Zone

Depositedsediment

Oxbow lake

Floodplain Zone

Salt marsh

WaterSediment

Delta

Ocean

Fig. 5-31, p. 102

Stepped Art

Three Zones of a Watershed

Watersheds

• Nutrients in the water– Come from

surrounding ecosystems• Leaves• Feces• Insects• Surface

water runoff brings biomass

Freshwater Wetlands

• Inland wetlands– Marshes– Swamps– Prairie potholes– Floodplains– Arctic tundra

Freshwater Wetlands• Ecological services

– Extremely productive (shelter and food for many, including fish)

– High species diversity– Increased nutrient cycling– Absorb runoff to decrease flooding and

then release water slowly (groundwater recharge)

– Large filters of pollutants and sediments (like a sponge) – water purification, erosion control

– Protection from storm surge

Freshwater Wetlands

• Economic services– Recreation (boating, birding, wildlife

viewing, walking, fishing)– Fisheries– Trapping and hunting– Commercial harvest (nuts, berries,

cranberries, grains, fish, peat, forestry)– Medicine

Human Impacts on Freshwater Systems

• Dams and canals fragment 40% of world’s largest rivers– Decrease flow of sediments

• Flood control levees alter rivers– Increase speed, cut away sediments

• Cities and farmlands add pollutants– Overload filter

• Many wetlands drained or filled– Increased flooding and erosion, decreased

storm protection

Coastal Wetlands – Ecological Services

• Provide the same services as freshwater wetlands

• COASTAL DUNES – – Protection from erosion, high tides and

storm surge– Dune grass and plant roots hold sand in

place

• Nesting for endangered & threatened species– Piping plover, Loggerhead sea turtles

• Development should occur beyond second dunes– Economic value often outweighs ecologic

Animation: Lake Turnover

Animations/turnover.html

EL NINO