Download Terrestrial Biomes

Terrestrial Biomes
Characterization, Stressors, and
Changes
Biomes of the World
Temperature & Precipitation
Raunkiaer's life forms. Plants with specific
distribution of dormant buds are better
suited to different biomes.
(a) phanerophytes
(b) nanophanerophytes - chamaephytes,
(c) hemicryptophytes
(d) Geophytes
(e) Therophytes
(f) epiphytes
Life form
Ph (a)
Ch (b)
H (c)
G/HH (d)
Th (e)
World standard
46
9
26
6
13
Tropical
61
6
12
5
16
Desert
10
17
20
6
46
Mediterranean
12
6
50
18
19
Warm Temperate
8
6
50
18
19
Arctic
1
22
66
15
2
Alpine
-
25
68
4
4
Raunkiaer's life form spectrum in the world
Tropical: Ph Warm temperate: H
Arid (desert and Mediterranean): Th
Alpine and arctic: H/G (woody) and Perennials + long-day plant
Climate vs. Continent
Life-form Spectra: Traits that vary with
climate such as perennating organ or
tissues that give rise to new growth
the following season
Life forms are more alike in similar
climates on different continents than
they are in different climates on the
same continent
Tropical Forests
• Centered on the Equator
• Little seasonal variation
• High yearly rainfall
• Constant Warm Temperature
• Layered vegetative cover
• > half of all terrestrial species
• Highest Biodiversity & Primary
Productivity
2-3 kg/m2-yr
• Leached Soils dominated by fungi
• Multiple sub-biomes dependent
on seasonal patterns of
precipitation, elevation, soils
The global distribution of land and ocean net primary production (NPP)
estimated from spectral data gathered by NASA's MODIS satellite
Savannah
• Transitional biome between
tropical rainforests and
deserts
– Seasonal precipitation
– Consistently warm
temperatures
• Mixed grasses and small trees
– Drought deciduous
– Fire balances grasses & trees
• Dominant Herbivores
– Consume 60% of biomass/yr
• Net Primary Productivity
– 0.4 – 0.6 kg/m2-yr
– Dependent on soil depth
Desert
• Most occur between 15-30° N & S
– Regional high pressure
– Less than 250 mm/yr precipitation
• Rain Shadows a result of Topography
• 26-35% of Earth’s land surface
• Highly variable in biodiversity,
productivity, and types of organisms
– Perennial shrubs
•
•
extensive roots
Small gray, white or light green leaves
– Annual herbs
•
•
Long-term seed storage in soil
Rapid growth/life cycle
– NPP
•
•
0-0.12 kg/m2-yr
Dependent on precipitation, drainage systems,
soils
Distribution of arid land
Dry air descends at 30° latitude, drawing moisture from the soil and contributing to
the creation of arid climates.
Chaparral/
Mediterranean
• 30-40° N & S
– Hot dry summers
– Cool moist winters
• Convergent Evolution
– Evergreens and Sclerophytes
– Therophytes
• Net Primary Productivity
– 0.3-0.6 kg/m2-yr
– Dependent on water
availability, soil, age of system
• Fires aid in nutrient cycling
– flowering
– seed germination
• California
Temperate Grassland
• Interior of continents
– Large seasonal temperature and
precipitation variations
– Grade into temperate forests
and deserts with shifting borders
•
•
Precipitation (i.e. drought)
Disturbance (i.e. fire)
• Grasses spread underground
– rhizomes, leaves grow from the
bottom up, decay-resistant
– Favored by fire, drought, grazing
– Tall-grass = high precipitation
– Short-grass = low precipitation
• Net Primary Productivity
– 0.4-1 kg/m2-yr
• Support large herds of
herbivores (bison, horses,
etc.)
Temperate
Deciduous Forest
• Mid-Latitudes – cool winters, warm
summers, high year-round
precipitation
• Net Primary Productivity
–
–
–
–
–
0.6-1.5 kg/m2-yr
Leaf litter = nutrient recycling
Trees – 20-30 m tall
Shrubs – up to 5 m tall
Herbaceous plants as ground cover
• Niche Partitioning is prevalent
– Increased complexity and biodiversity
with forest height
Patterns of terrestrial NPP at different timescales in
a temperate forest
1. Daily/Seasonal NPP
variations
a) Solar radiation
b) Precipitation
c) Length of growing
season
2. Annual NPP variations
due to longer-term
trends in climate
3. Decadal patterns of
NPP track changes in
ecological succession
(Gough et al. 2007, 2008).
Coniferous Forest
• High latitude
– Long cold winters
– Short cool summers
• Low Biodiversity
– Overstory of Evergreen Trees:
needle-leaved and drought
tolerant (1-4 sp.)
– Ground cover: herbs and
mosses
– Shallow roots rely on
mycorrhizae for nutrients
• Low Net Primary Productivity
– 0.2-0.6 kg/m2-yr
– Dependent on precipitation,
frost-free days, soil drainage
– Flooded areas – acidic, anoxic
 peat
• Slow decomposition, leached
soils, permafrost
Tundra:
Arctic & Alpine
• Poleward of the Coniferous forests
– Very short growing season
– Most of the year is below 0°C
– High Winds
• Very low Net Primary Productivity
– 0.1-0.2 kg/m2-yr
– Dependent on snowfall depth and
drainage
• Low Biodiversity
– Mosses, lichens, and low-growing
shrubs with rounded canopies and
closely spaced leaves and branches
•
•
Reduces wind speeds
Increases solar radiation absorption
– 3% of world’s flora Hemicryptophytes
– Low nutrient soils
•
Lichen fix N
– Animals hibernate or migrate
Consequences of Change on the Biomes and Us
Putting Ecology Studies Together to Understand
the Impacts of Global Changes
Sustaining Ecosystems
Examining the
relative
importance of
various types of
stabilizing species
interactions and
the effect of these
interactions on
biodiversity and
ecosystem
functioning and
stability
Impacts of Potential Stressors on Species
Interactions