31: Terrestrial ecosystems - deserts, tundra and peatlands

pattern of movement of air masses

descending dry air absorbs moisture

ascending moist air releases moisture

2 multiple choice options

descending dry air _____ moisture creating _____ conditions

absorbs, arid

desert location is determined by

- global atmospheric circulation

- rain shadows

- continental interiors

physical characteristics of deserts

- low and unpredictable rainfall

- high evaporation

- hot or cold temperature

- large diurnal variation in temperature

deserts can be ___ or ___

hot or cold

deserts have _____ and _______ rainfall

low and unpredictable

deserts have high _______

evaporation

deserts have large ______ variation in temperatures

diurnal

desert plant adaptations

1. avoid drought: carefully timed phenology (annual life cycle, seasonal flowering)

2. tolerate drought

how do desert plants avoid drought?

carefully timed phenology (annual life cycle and seasonal flowering)

how do desert plants tolerate drought?

intensification of water absorption & reduced transpiration

how do desert plants increase water absorption?

shallow spreading succulents roots, deep tap roots, dew/fog traps

how do desert plants reduce water loss?

sunken stomata, reduced stomatal opening, hairy/rolling leaves, retain dead leaves around stem, deciduous shed leaves

CAM

crassulacean acid metabolism photosynthesis

how does CAM work?

stomata remain closed during the day to reduce water loss.

during the night, organic acids accumulate in chlorophyll and are converted to carbon dioxide during the day.

this increases photosynthesis and reduces transpiration.

desert raunkiaer plant life forms

highest = therophytes

lowest = phanerophytes

tundra climate

cold, low precipitation, permafrost, short growing season

tundra has ___ precipitation

low

permafrost is characteristic of

tundra

tundra has a ___ growing season

short

tundra has ___ botanical diversity

low

tundra has ___ trees

no - all plants are low in stature (<30cm)

tundra has ____ rooting

shallow

biome raunkiaer plant life forms

tundra has ____ nutrient system due to low temperature and low precipitation

low

the ______ has the lowest nutrient cycling rates of any ecosystem

arctic

peatlands

partially decayed organic matter of plant origin formed under wet, anaerobic conditions

in peatlands, production of organic matter is greater than

decomposition

peatland distribution

areas of high rainfall and impeded drainage - natural wetlands

examples of peatlands

bogs, lakes, swamps, reedswamps, fens

raised bog development

lake -> reedswamp -> fen -> raised bog

raised bogs and blanket bogs are

ombrotrophic

fen bogs are

minerotrophic

blanket bogs are found in regions where

>1200mm rain and >200 rain days

ombrotrophic

water and nutrients supplied by rain water

minerotrophic

water and nutrients supplied by groundwater

ombrotrophic bog system is very

acidic

(low in nutrients and bases)

peatlands are exploited for

fuel, horticulture, waste water treatment, forestry, agriculture

peatlands are conserved for

wildlife, regional water table, landscape, tourism, archives, carbon sink

irish peatland carbon storage

4 Gt Co2

1 Gt

1 billion tons

carbon storage has _____ over the last 1,000 years

increased