Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Biomes, Landscapes, Restoration, and Management Chapter 5

Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

Biomes, Landscapes, Restoration, and Management

Chapter 5


Outline:

• Terrestrial Biomes• Aquatic Ecosystems• Human Disturbance• Landscape Ecology• Restoration Ecology• Ecosystem Management


TERRESTRIAL BIOMES

• Biomes - Areas sharing similar climate, topographic and soil conditions, and roughly comparable communities. Temperature and Precipitation are among

the most important determinants in biome distribution.

Most terrestrial biomes are identified by the dominant plants of their communities.



Deserts

• Characterized by low moisture levels and precipitation that is infrequent and unpredictable from year to year.

• Wide daily and seasonal temperature fluctuations.

• Soils are easily disturbed by human activities, and slow to recover.

• Plants exhibit water conservation characteristics.


Grasslands

• Communities of grasses, seasonal herbaceous flowering plants, and open savannas.

• Few trees due to inadequate rainfall.• Large daily and seasonal temperature

fluctuations.• Frequent grass fires.• Historic grazing by roaming herds of large

ungulates.


Tundra

• Treeless• Very short growing season, with cold harsh

winters.• Damage slow to heal

Arctic Tundra exhibits low productivity, diversity and resilience.

Alpine Tundra receives intense solar radiation, hot daytime summer ground temperatures, and potential droughts.


Conifer Forests

• Cone-Bearing• Plants reduce water loss by evolving thin,

needle-like evergreen leaves with thick waxy coating. Can survive harsh winters or extended

droughts and accomplish photosynthesis even under poor conditions.

• Fire often plays role in maintenance.


Conifer Forests

• Boreal Forest - Northern Conifer Forest Broad band of mixed coniferous and

deciduous trees between 45° and 60° N latitude.

Moist and cool climate with abundant streams and wetlands.

• Taiga - Northernmost edge of boreal forest Species-poor. Harsh climate limits

productivity and resilience.- Produce large peat bogs.


Conifer Forests

• Temperate Rainforest Wettest portion of coniferous forests of

Pacific Northwest. Mild temperatures, and very abundant

precipitation. (>250 cm)- Canopy condensation is major form of

precipitation.


Broad Leaf Deciduous Forest

• Temperate regions support lush summer plant growth when water is plentiful. Deciduous leaves an adaptation to

freezing temperatures.• Eastern half of US was covered with broad

leaf deciduous forest when European settlers arrived. Much of that was harvested a century ago for timber. Now large areas have re-grown and are

again approaching old-growth status.


Mediterranean

• Characterized by warm, dry summers and cool, moist winters.

• Fires are a major factor in plant succession.• Referred to as Chaparral in California.

Biodiversity hotspot


Tropical Moist Forests

• Humid tropical regions support one of most complex and biologically rich biomes.

• Ample rainfall and uniform temperatures. Cloud Forests - High mountains where fog

and mist keep vegetation continually wet.


Tropical Moist Forests

Tropical Rainforests - More than 200 cm annual rainfall with warm-hot temperatures year-round.

- 90% nutrients tied up in living organisms.- Rapid decomposition and nutrient cycling.- Thins soil cannot support continued

cropping, and cannot resist erosion.


Tropical Seasonal Forests

• Semi-evergreen and partly deciduous forests tending toward open woodlands and grassy savannas. Characterized by distinct wet and dry

seasons with hot temperatures year-round


AQUATIC ECOSYSTEMS

• Saltwater ecosystems cover vastly more total area and contain much greater volume of water than all freshwater bodies combined. Oceans hold bulk of world’s water.

• Aquatic ecosystems are influenced by local characteristics of climate, soil, and resident communities, and also by adjacent terrestrial ecosystems.


Critical Aquatic Characteristics

• Dissolved Substances• Suspended Matter• Depth• Temperature• Flow Rate• Bottom Characteristics• Internal Convective Currents• Connectivity to Other Aquatic Ecosystems


Vertical Component

• Vertical stratification is an important aspect of many aquatic ecosystems. Organisms tend to form distinctive vertical

sub-communities.- Benthos - Bottom sub-community.

Low oxygen levels- Thermocline - Distinctive temperature

transition zone that separates warm upper layer and deeper cold layer.



Estuaries

• Estuaries - Bays or semi-enclosed bodies of brackish water that form where rivers enter the ocean. Usually carry rich sediments.

- Fan-shaped sediment deposit (delta) formed on shallow continental shelves.


Wetlands

• Land surface is saturated or covered with water at least part of the year. Swamps - Wetlands with trees Marshes - Wetlands without trees Bogs and Fens - Waterlogged soils that

tend to accumulate peat.• Water usually shallow enough to allow full

sunlight penetration.• Trap and filter water, and store runoff.


Coastal

• Barrier Islands - Low, narrow, sandy islands that form offshore from a coastline. Protect inland shores from surf. Prized for human development.

- Loss of vegetation triggers erosion.• Coral Reefs - Accumulated calcareous

skeletons of colonial organisms (coral). Depth limited by light penetration. Among most endangered communities.


Barrier Islands


HUMAN DISTURBANCE

• By some estimates, humans preempt about 40% of net terrestrial primary productivity.

• Temperate broad-leaved deciduous forests are the most completely human-dominated biome. Tundra and Arctic Deserts are the least disturbed.

• About half of all original wetlands in the US have been degraded over the past 250 years.


LANDSCAPE ECOLOGY

• Landscape Ecology - The study of reciprocal effects of spatial patterns on ecological processes. Spatial patterns shape, and are shaped by,

ecological processes occurring in them. Considers humans an element of most

landscapes.- Few places, if any, are devoid of human

impacts.



Patchiness and Heterogeneity

• Landscape ecologists claim all landscapes consist of similar mosaics of discrete, bounded patches with different biotic or abiotic composition. Predominate cover type acts as a matrix in

which other patch types are embedded.- Landscape heterogeneity can exist

across a wide range of scales.


Landscape Dynamics

• Boundaries between habitat patches are considered significant. Dynamics between patches may be of

greater importance than processes within each patch.

- Departs from classic ecological focus, and aligns with conservation biology.


RESTORATION ECOLOGY

• Restoration Ecology - Seeks to repair or reconstruct damaged ecosystems. Restoration - Active manipulation to re-

create species composition and ecosystem processes as close to pre-disturbance state as possible.

Rehabilitation - Attempt to rebuild ecological structure or function without necessarily achieving original conditions.


Restoration Ecology

Remediation - Cleaning chemical contaminants from a polluted area by physical or biological methods.

- Living organisms are highly effective cleaning agents for many contaminants.

Reclamation - Chemical or physical manipulations of severely degraded sites.

- Historically - irrigation projects to transform wetlands and deserts into agricultural production.


Restoration Ecology

Re-creation - Attempts to construct new biological communities on a severely disturbed site where basically nothing is left to restore.

Mitigation - Developers and government agencies are often required to mitigate damage caused in one area by re-creating a comparable biological community somewhere else.


Restoration Ecology Questions:

• Is the best strategy to avoid destruction in the first place, or is nature a simple social creation to be molded ?

• Under what conditions can / should we walk away let nature heal itself ?

• What role should community / plant authenticity place in restoration ? Which historic state should an area be

restored to ?


ECOSYSTEM MANAGEMENT

• Ecosystem Management - Attempts to integrate ecological, economic, and social goals in a unified systems approach.

• Most resource agencies (Federal and state) are attempting to identify endangered landscapes and implement ecosystem management as their guiding policy. Turning away from commodity production

and commercial / recreational resource use as top priority.


Ecosystem Management Critiques

• We do not understand ecosystems in the detail necessary to manage them as single entities.

• In developing countries, immediate needs of the poor will hamper enforcement of environmental protection.

• Preservation / Management


Summary:

• Terrestrial Biomes• Aquatic Ecosystems• Human Disturbance• Landscape Ecology• Restoration Ecology• Ecosystem Management


Documents

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Biomes, Landscapes, Restoration, and Management Chapter 5