[5.1] TERRESTRIAL BIOMES
CHAPTER 5 – BIOMES AND BIODIVERSITY [5.1] TERRESTRIAL BIOMES Biomes = large biological communities; broad, regional types of ecosystems o Classified according to average annual temperature and precipitation (rainfall and snowfall) o Characterized by biodiversity - Biodiversity = the number and variety of different biological species that live in each biome o Create much of the structure and functions of an ecosystem o Generate emergent properties: Productivity = the rate at which plants produce biomass Varies from warm to cold climates, and from wet to dry environments Homeostasis = stability Depends on biodiversity and productivity Resilience = the ability to recover from disturbance Depends on biodiversity and productivity - There are 9 major biome types, which can be further divided into smaller classes o Many temperature controlled biomes occur in latitudinal bands E.g., tropical forests occur near the equator E.g., expansive grasslands occur near or beyond the tropics o Some biomes are named for their latitudes E.g., tropical rainforests occur between Tropic of Cancer and Tropic of Capricorn E.g., arctic tundra lies near or above the Arctic Circle - Temperature and precipitation change with elevation and latitude o Vertical zonation = vegetation zones defined by altitude - Understanding climate graphs o Moisture availability depends on temperature and precipitation o Evaporation depends on temperature o When evaporation (or temperature) exceeds precipitation, then dry climates o When precipitation exceeds evaporation (or temperature), then moist climates Tropical moist forests are warm and wet year-round - Cloud forests = occur high in the mountains where fog and mist keep vegetation wet all the time - Tropical rainforests = occur where rainfall is abundant and temperatures are warm to hot year-round - One of the most complex and biologically rich biome types in the world - Ample rainfall and uniform temperatures - Soil tends to be thin, acidic, and nutrient-poor - Distinctive nutrient cycles o About 90% of all the nutrients are contained in the bodies of the living organisms o Rapid decomposition, recycling, and incorporation of dead organic material immediately back into living biomass Tropical seasonal forests have annual dry seasons - Distinct wet and dry seasons - Year-round hot temperatures - Often open woodlands that grade into savannas - Tropical seasonal forests = drought-tolerant forests that look brown and dormant in the dry season but burst into vivid green during rainy months o Dry much of the year, but periodic rain to support plant growth o Many of the trees and shrubs in a seasonal forest are drought-deciduous o Drought-deciduous = lose leaves and cease growing when no water is available - More attractive than tropical moist forests for human habitation -
o More degradation due to settlement o Fewer insects, parasites, and fungal diseases o Healthier place for humans to live - Soil has higher nutrient levels and is more agriculturally productive (compared to tropical moist forests) - Highly endangered Tropical savannas and grasslands are dry most of the year - Savannas = open grasslands or grasslands with sparse tree cover - Annual drought and rainy seasons - Year-round warm temperatures - Rainy season is less abundant than in a forest (e.g., too little rainfall to support forests) - During dry seasons, fires can sweep across a grassland o Killing off young trees o Keeping the landscape open - Many adaptations to survive drought, heat, and fires o Deep, long-lived roots Seek groundwater Persist when leaves and stems above the ground die - After a fire or drought, fresh green shoots grow quickly from the roots o Susceptible to grazing pressure from domestic livestock Deserts are hot or cold, but always dry - Precipitation is sporadic and low - Vegetation is sparse, but can be diverse - Most plants and animals are adapted to survive long droughts, extreme heat, and often extreme cold o Water-storing leaves and stems o Thick epidermal layers to reduce water loss o Salt tolerance - Many plants are drought-deciduous - Most desert plants bloom and set seed quickly after rainfall - Warm, dry, high-pressure climate conditions o Desert regions = occur at about 30° north and south o Extensive deserts = occur in continental interiors (rain is rare; evaporation rates are high) - Many animals are specially adapted o Nocturnal o Get moisture from seeds and plants o Highly concentrated urine and nearly dry feces to eliminate body waste without losing moisture - Sparse, slow-growing vegetation is quickly damaged by off-road vehicles - Soils recover slowly - Vulnerable to overgrazing o Livestock are destroying much of the plant cover o Bare, dry soil becomes drifting sand Without plant roots and organic matter Soil loses its ability to retain what rain does fall Land becomes progressively drier and more bare o Restabilization is extremely difficult Temperate grasslands have rich soils - Occur at mid-latitudes on all continents - Enough rain to support abundant grass but not enough for forests - Extreme temperatures, dry conditions, and periodic fires - High plant and animal diversity - Complex, diverse mix of grasses and forbs (flowering herbaceous plants)
Deep roots help to survive drought, fire, and extreme heat and cold Deep roots, together with an annual winter accumulation of dead leaves on the surface, produce thick, organic-rich soils - Many have been converted to farmland - Vulnerable to overgrazing o Excessive grazing eventually kills even deep-rooted plants o As ground cover dies off, soil erosion results, and unpalatable weeds spread Temperate scrublands have summer drought - Dry environments - Shrubs, trees, and grass are drought-adapted - Very biologically rich - Mediterranean climate = hot season coincides with the dry season to produce hot, dry summers and cool, moist winters - Evergreen shrubs = small, leathery, sclerophyllous (hard, waxy) leaves that form dense thickets - Scrub oaks, drought-resistant pines, or other small trees cluster in sheltered valleys - Periodic fires - Chaparral = annual spring flowers often bloom profusely, especially after fires - Many animals are drought-tolerant - Does not cover a very large total area - Contains a high number of unique species - Considered a “hot-spot” for biodiversity - Highly desired for human habitation Temperate forests can be evergreen or deciduous - Wide range of precipitation conditions - Occur mainly between about 30° and 55° latitude - Nutrients are held within the soil and made available for new plant growth - Deciduous forests = broad-leaved trees that lose their leaves in the winter (e.g., maples, birch, aspen, alder) o Year-round precipitation o Winters near or below freezing o Rainfall is plentiful o Loss of green chlorophyll pigments in autumn o Dense canopy in summer o Diverse understory in spring Spring ephemeral (short-lived) plants produce lovely flowers Vernal (springtime) pools support amphibians and insects Shelter a great diversity of songbirds o Most of the eastern deciduous forests were cut for firewood, lumber, and industrial uses, and cleared for farmland when European settlers first came to North America Many of these regions have now returned to deciduous forest, but the dominant species may have changed o Moist, moderate climates o Able to regrow quickly o Human impacts are extensive (e.g., deforestation) Most native species are somewhat threatened - Coniferous forests = evergreen, cone-bearing trees (e.g., pines, hemlocks, spruce, cedar, fir) o Occur in a wide range of environmental conditions o Occur where moisture is limited In cold climates, moisture is unavailable (frozen) in winter In hot climates, there are seasonal droughts Sandy soils hold little moisture and often occupied by conifers -
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Thin, waxy leaves (needles) help these trees reduce moisture loss Provide most wood products in North America and other regions Temperate rainforests = coastal forests that grow in extremely wet conditions Cool, rainy forest often enshrouded in fog o Leaf drip = condensation in the canopy Major form of precipitation in the understory o Year-round mild temperatures o Abundant but often seasonal precipitation o Often experience dry summers o Able to survive winter cold o Dominate the boreal forests, or the northern forests o Slow-growing Cold temperatures Short frost-free growing season Moderate precipitation o Trees are cold-tolerant and drought-tolerant o Favorite places for hunting, fishing, recreation, and extractive resource use o Taiga = the extreme, ragged edge of the boreal forest, where forest gradually gives way to open tundra Extreme cold and short summer limits the growth rate of trees Tundra can freeze in any month - Year-round below freezing temperatures - Only small, hardy vegetation can survive - Tundra = treeless landscape o Occurs at high latitudes or on mountaintops o Growing season of only two to three months o May have frost any month of the year - Considered a variant of grasslands because it has no trees - Considered a very cold desert because water is unavailable (frozen) most of the year - Plant diversity is relatively low - Frost can occur in summer - Too cold for most human activities - Not as badly threatened as other biomes - Problems o Global climate change may be altering the balance of some tundra ecosystems o Air pollution from distant cities tends to accumulate at high latitudes o Overabundant populations of snow geese threatens costal tundra in eastern Canada o Oil and gas drilling threatens tundra in Alaska and Siberia - Arctic tundra = short growing season and low productivity o During midsummer, 24-hour sunshine supports a burst of plant growth and insect life o Birds migrate to the Arctic every year Feast on the abundant invertebrate and plant life Raise their young Carry energy and protein from high latitudes to low latitudes o Essential for global biodiversity, especially for birds - Alpine tundra = occur on or near mountaintops o Environmental conditions and vegetation similar to arctic tundra o Short, intense growing season o Everything must flower at once in order to produce seeds in a few weeks before snow arrives o Many plants have deep pigmentation and leathery leaves to protect against UV light
[5.2] MARINE ENVIRONMENTS Biological communities in oceans and seas are poorly understood, but are probably as diverse and complex as terrestrial biomes - Most marine communities depend on photosynthetic organisms, like land-based systems o Algae or phytoplankton support the marine food web, rather than trees and grasses Phytoplankton = tiny, free-floating photosynthetic plants o Photosynthetic activity tends to be greatest near coastlines, where nitrogen, phosphorus, and other nutrients wash offshore and fertilize primary producers o Ocean currents contribute to the distribution of biological productivity Open ocean communities vary from surface to hadal zone - Ocean systems can be described by depth and proximity to shore o Littoral zones = shoreline environment Intertidal zone = area exposed to low tides o Pelagic zones = water column; surface of ocean Epipelagic zone Has photosynthetic organisms Mesopelagic zone Bathypelagic zone o Benthic zones = bottom of the ocean Abyssal zone Hadal zone o Continental shelf = broad, relatively shallow, undersea region along a continent's coast, which may reach a few or hundreds of kilometers from shore - Open ocean has long been known as a biological desert o Relatively low productivity or biomass production o Sea mounts = undersea mountain chains and islands Support many commercial fisheries Support much newly discovered biodiversity o Currents carry nutrients far from shore and support biological productivity o Free-floating mats of brown algae support species diversity - Deep-sea thermal vent communities were completely unknown o Based on microbes that capture chemical energy, mainly from sulfur compounds released from thermal vents o Rely on chemosynthesis, not photosynthesis, for energy o Thermal vents = jets of hot water and minerals on the ocean floor Heated by magma below the ocean crust heats Organisms on the vents are adapted to survive both extreme temperatures and intense water pressure o Thousands of microscopic organisms have been discovered Tidal shores support rich, diverse communities - Shoreline communities o Vary with depth, light, and temperature o Support incredible diversity and help stabilize shorelines - Coral reefs o Occur where there is little runoff from shore o Occur where water is shallow, clear, and warm for sunlight to reach the photosynthetic algae (e.g., to support photosynthesis) o Among the best-known marine systems Extraordinary biological productivity -
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Diverse and beautiful organisms o Colonies of minute, colonial animals (“coral polyps”) that live symbiotically with photosynthetic algae Calcium-rich coral skeletons shelter algae (and other species) Algae nourish the coral animals o Unable to tolerate abundant nutrients in the water Nutrients support plankton (tiny floating plants and animals), which block sunlight o Among the most endangered biological communities Sediment from coastal development, farming, sewage, or other pollution can reduce water clarity and smother coral Can be damaged or killed by: Destructive fishing practices (e.g., dynamite, cyanide poison) Changes temperature Invasive fish Diseases Coral bleaching = the whitening of reefs due to stress; often followed by coral death Sea-grass (or eel-grass) beds o Occupy shallow, warm, sandy coastlines o Support rich communities of grazers (e.g., snails, turtles) Mangroves o Diverse group of salt-tolerant trees o Grow in shallow, tidal mudflats along warm, calm marine coasts o Stabilize shorelines o Blunt the force (e.g., speed, height, turbulence) of storms o Build land by trapping sediment and organic material o Provide shelter, nurseries, and food for marine and terrestrial species o Devastated by human activities Clear-cut for timber Cleared to make room for fish and shrimp ponds Poisoned by sewage and industrial waste near cities Estuaries and salt marshes o Estuaries = bays where rivers empty into the sea, mixing fresh water with salt water o Salt marshes = shallow wetlands flooded regularly or occasionally with seawater Occur on shallow coastlines, including estuaries o High biological productivity and diversity o Enriched by nutrients washing from the land o Calm, warm, and nutrient-rich o Rivers provide nutrients and sediments o Muddy bottom supports emergent plants (leaves that emerge above the water surface) and young forms of crustaceans (e.g., crabs, shrimp, mollusks) o Threatened by sewage and other contaminants Tide pools o Tide pools = depressions in a rocky shoreline that are flooded at high tide but retain some water at low tide o Violent, wave-blasted shoreline environment o Support fascinating life-forms o Remain rocky where wave action prevents most plant growth or sediment (mud) accumulation o Extreme conditions (e.g., frigid flooding at high tide, hot sunshine at low tide) make life impossible for most species
[5.7] BIODIVERSITY PROTECTION Hunting and fishing laws protect useful species - To conserve the resource for future human use rather than to preserve wildlife for its own sake - Examples of conservation measures o Restoring habitat o Planting food crops o Transplanting breeding stock o Building shelters or houses o Protecting during breeding season The Endangered Species Act (ESA) protects habitat and species - One of our most powerful tools for protecting biodiversity and environmental quality o Defends rare and endangered organisms o Provides mechanisms for reducing species losses o Helps protect habitat that benefits a whole biological community and safeguards valuable ecological services - ESA provides: 1) Criteria for identifying species at risk 2) Directions for planning for their recovery 3) Assistance to landowners to help them find ways to meet both economic needs and the needs of a rare species 4) Enforcement of measures for protecting species and their habitat - ESA identifies three degrees of risk o Endangered species = considered in imminent danger of extinction o Threatened species = likely to become endangered in the future o Vulnerable species = naturally rare or have been locally depleted by human activities to a level that puts them at risk Often candidates for future listing as endangered species - The number of listed species in different taxonomic groups reflects much more about the kinds of organisms that humans consider interesting and desirable than the actual number in each group o Vertebrate subspecies, local races, ecotypes, or entire species can be listed o Invertebrates make up about 75% of all known species, but only 9% of invertebrates are considered worthy of protection Recovery plans aim to rebuild populations - Once a species is listed, the Fish and Wildlife Service (FWS) prepares a recovery plan o Details how populations will be stabilized or rebuilt to sustainable levels o Include many different kinds of strategies Buying habitat areas Restoring habitat Reintroducing a species to its historic ranges Captive breeding programs Negotiating the needs of a species and the people who live in an area o Help landowners prepare Habitat Conservation Plans Specific management approaches that identify steps to conserve particular pieces of critical habitat - International Paper and other corporations have collaborated with the FWS to devise management strategies that conserve specified amounts of damaged tree stands while harvesting other areas o Restrict cutting of some trees o Ensure that the FWS will not interfere further with management of the timber, as long as the provisions of the plan continue to protect the red-cockaded woodpecker
Red-cockaded woodpecker populations have stabilized Timber companies have gained goodwill and sustainable forestry certification for products - Restoration can be slow and expensive - Disproportionate funding can result from political and emotional preferences for charismatic species - Scientifically established designations o Keystone species (e.g., prairie dogs, bison) Major effects on ecological functions Elimination would affect many other members of the biological community o Indicator species (e.g., brook trout) Tied to specific biotic communities, successional stages, or environmental conditions Reliably found under certain conditions but not others o Umbrella species (e.g., northern spotted owl, tiger, gray wolf) Require large blocks of relatively undisturbed habitat to maintain viable populations Saving the habitat also benefits other species o Flagship species (e.g., giant panda) Especially interesting or attractive organisms to which people react emotionally Motivate the public to preserve biodiversity Contribute to conservation Landowner collaboration is key - Cooperation between federal, state, and local agencies, and private and tribal landowners is critical - On the one hand… o ESA is controversial Protecting a species is legally enforceable Protection can require that landowners change their plans for their property - On the other hand… o Many landowners and communities appreciate the value of biodiversity on their land and like the idea of preserving species for their grandchildren to see o Others (e.g., International Paper) can afford to allow some dying trees for woodpeckers and benefit from goodwill generated by preserving biodiversity - A number of provisions protect landowners and serve as incentives for landowners to participate in developing habitat conservation plans o Permits can be issued to protect landowners from liability if a listed species is accidentally harmed during normal land-use activities o Candidate Conservation Agreement = FWS helps landowners reduce threats to a species in an effort to avoid listing it at all o Safe Harbor Agreement = if landowners voluntarily implement conservation measures, then the FWS will not require additional actions that could limit future management options The ESA has seen successes and controversies - Hundreds of species have been held off from extinction (e.g., recovered, delisted) - Many people are dissatisfied with the slow pace of listing new species o Hundreds of species are classified as “warranted but precluded” (deserving of protection but lacking funding or local support) o Partly because political and legal debates can drag on for years Political opposition is especially fierce when large profits are at stake Many countries have species protection laws - International agreements have also been developed - Convention on International Trade in Endangered Species (CITES) o Provides a critical conservation strategy o Blocks the international sale of wildlife and their parts o Far from perfect
Smugglers Impossible to inspect all transport containers and ships High price of these products makes the risk of smuggling worthwhile o Provides a legal structure for restricting this trade o Raises public awareness of the real costs of the trade in endangered species Habitat protection may be better than species protection - Growing numbers of scientists, land managers, policy makers, and developers are arguing that we need a rational, continent-wide preservation of ecosystems that supports maximum biological diversity o More effective than species-by-species battles While spending millions of dollars to breed individual plants or animals in captivity, they have no natural habitat where they can be released While flagship species are reproducing well in zoos and wild animal parks, the ecosystems that they formerly inhabited have disappeared o Protected areas are different from unprotected areas, which may contain more endangered species than protected areas Gap analysis = to look for unprotected landscapes, or gaps in the network of protected lands, that are rich in species Map protected conservation areas Map high-biodiversity areas Overlay the two maps Identify priority spots for conservation efforts o Four re-management principles for protecting biodiversity in a large-scale, long-range approach 1) Protect enough habitat for viable populations of all native species in a given region 2) Manage at regional scales large enough to accommodate natural disturbances (e.g., fire, wind, climate change). 3) Plan over a period of centuries, so that species and ecosystems can continue to evolve 4) Allow for human use and occupancy at levels that do not result in significant ecological degradation
o More degradation due to settlement o Fewer insects, parasites, and fungal diseases o Healthier place for humans to live - Soil has higher nutrient levels and is more agriculturally productive (compared to tropical moist forests) - Highly endangered Tropical savannas and grasslands are dry most of the year - Savannas = open grasslands or grasslands with sparse tree cover - Annual drought and rainy seasons - Year-round warm temperatures - Rainy season is less abundant than in a forest (e.g., too little rainfall to support forests) - During dry seasons, fires can sweep across a grassland o Killing off young trees o Keeping the landscape open - Many adaptations to survive drought, heat, and fires o Deep, long-lived roots Seek groundwater Persist when leaves and stems above the ground die - After a fire or drought, fresh green shoots grow quickly from the roots o Susceptible to grazing pressure from domestic livestock Deserts are hot or cold, but always dry - Precipitation is sporadic and low - Vegetation is sparse, but can be diverse - Most plants and animals are adapted to survive long droughts, extreme heat, and often extreme cold o Water-storing leaves and stems o Thick epidermal layers to reduce water loss o Salt tolerance - Many plants are drought-deciduous - Most desert plants bloom and set seed quickly after rainfall - Warm, dry, high-pressure climate conditions o Desert regions = occur at about 30° north and south o Extensive deserts = occur in continental interiors (rain is rare; evaporation rates are high) - Many animals are specially adapted o Nocturnal o Get moisture from seeds and plants o Highly concentrated urine and nearly dry feces to eliminate body waste without losing moisture - Sparse, slow-growing vegetation is quickly damaged by off-road vehicles - Soils recover slowly - Vulnerable to overgrazing o Livestock are destroying much of the plant cover o Bare, dry soil becomes drifting sand Without plant roots and organic matter Soil loses its ability to retain what rain does fall Land becomes progressively drier and more bare o Restabilization is extremely difficult Temperate grasslands have rich soils - Occur at mid-latitudes on all continents - Enough rain to support abundant grass but not enough for forests - Extreme temperatures, dry conditions, and periodic fires - High plant and animal diversity - Complex, diverse mix of grasses and forbs (flowering herbaceous plants)
Deep roots help to survive drought, fire, and extreme heat and cold Deep roots, together with an annual winter accumulation of dead leaves on the surface, produce thick, organic-rich soils - Many have been converted to farmland - Vulnerable to overgrazing o Excessive grazing eventually kills even deep-rooted plants o As ground cover dies off, soil erosion results, and unpalatable weeds spread Temperate scrublands have summer drought - Dry environments - Shrubs, trees, and grass are drought-adapted - Very biologically rich - Mediterranean climate = hot season coincides with the dry season to produce hot, dry summers and cool, moist winters - Evergreen shrubs = small, leathery, sclerophyllous (hard, waxy) leaves that form dense thickets - Scrub oaks, drought-resistant pines, or other small trees cluster in sheltered valleys - Periodic fires - Chaparral = annual spring flowers often bloom profusely, especially after fires - Many animals are drought-tolerant - Does not cover a very large total area - Contains a high number of unique species - Considered a “hot-spot” for biodiversity - Highly desired for human habitation Temperate forests can be evergreen or deciduous - Wide range of precipitation conditions - Occur mainly between about 30° and 55° latitude - Nutrients are held within the soil and made available for new plant growth - Deciduous forests = broad-leaved trees that lose their leaves in the winter (e.g., maples, birch, aspen, alder) o Year-round precipitation o Winters near or below freezing o Rainfall is plentiful o Loss of green chlorophyll pigments in autumn o Dense canopy in summer o Diverse understory in spring Spring ephemeral (short-lived) plants produce lovely flowers Vernal (springtime) pools support amphibians and insects Shelter a great diversity of songbirds o Most of the eastern deciduous forests were cut for firewood, lumber, and industrial uses, and cleared for farmland when European settlers first came to North America Many of these regions have now returned to deciduous forest, but the dominant species may have changed o Moist, moderate climates o Able to regrow quickly o Human impacts are extensive (e.g., deforestation) Most native species are somewhat threatened - Coniferous forests = evergreen, cone-bearing trees (e.g., pines, hemlocks, spruce, cedar, fir) o Occur in a wide range of environmental conditions o Occur where moisture is limited In cold climates, moisture is unavailable (frozen) in winter In hot climates, there are seasonal droughts Sandy soils hold little moisture and often occupied by conifers -
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Thin, waxy leaves (needles) help these trees reduce moisture loss Provide most wood products in North America and other regions Temperate rainforests = coastal forests that grow in extremely wet conditions Cool, rainy forest often enshrouded in fog o Leaf drip = condensation in the canopy Major form of precipitation in the understory o Year-round mild temperatures o Abundant but often seasonal precipitation o Often experience dry summers o Able to survive winter cold o Dominate the boreal forests, or the northern forests o Slow-growing Cold temperatures Short frost-free growing season Moderate precipitation o Trees are cold-tolerant and drought-tolerant o Favorite places for hunting, fishing, recreation, and extractive resource use o Taiga = the extreme, ragged edge of the boreal forest, where forest gradually gives way to open tundra Extreme cold and short summer limits the growth rate of trees Tundra can freeze in any month - Year-round below freezing temperatures - Only small, hardy vegetation can survive - Tundra = treeless landscape o Occurs at high latitudes or on mountaintops o Growing season of only two to three months o May have frost any month of the year - Considered a variant of grasslands because it has no trees - Considered a very cold desert because water is unavailable (frozen) most of the year - Plant diversity is relatively low - Frost can occur in summer - Too cold for most human activities - Not as badly threatened as other biomes - Problems o Global climate change may be altering the balance of some tundra ecosystems o Air pollution from distant cities tends to accumulate at high latitudes o Overabundant populations of snow geese threatens costal tundra in eastern Canada o Oil and gas drilling threatens tundra in Alaska and Siberia - Arctic tundra = short growing season and low productivity o During midsummer, 24-hour sunshine supports a burst of plant growth and insect life o Birds migrate to the Arctic every year Feast on the abundant invertebrate and plant life Raise their young Carry energy and protein from high latitudes to low latitudes o Essential for global biodiversity, especially for birds - Alpine tundra = occur on or near mountaintops o Environmental conditions and vegetation similar to arctic tundra o Short, intense growing season o Everything must flower at once in order to produce seeds in a few weeks before snow arrives o Many plants have deep pigmentation and leathery leaves to protect against UV light
[5.2] MARINE ENVIRONMENTS Biological communities in oceans and seas are poorly understood, but are probably as diverse and complex as terrestrial biomes - Most marine communities depend on photosynthetic organisms, like land-based systems o Algae or phytoplankton support the marine food web, rather than trees and grasses Phytoplankton = tiny, free-floating photosynthetic plants o Photosynthetic activity tends to be greatest near coastlines, where nitrogen, phosphorus, and other nutrients wash offshore and fertilize primary producers o Ocean currents contribute to the distribution of biological productivity Open ocean communities vary from surface to hadal zone - Ocean systems can be described by depth and proximity to shore o Littoral zones = shoreline environment Intertidal zone = area exposed to low tides o Pelagic zones = water column; surface of ocean Epipelagic zone Has photosynthetic organisms Mesopelagic zone Bathypelagic zone o Benthic zones = bottom of the ocean Abyssal zone Hadal zone o Continental shelf = broad, relatively shallow, undersea region along a continent's coast, which may reach a few or hundreds of kilometers from shore - Open ocean has long been known as a biological desert o Relatively low productivity or biomass production o Sea mounts = undersea mountain chains and islands Support many commercial fisheries Support much newly discovered biodiversity o Currents carry nutrients far from shore and support biological productivity o Free-floating mats of brown algae support species diversity - Deep-sea thermal vent communities were completely unknown o Based on microbes that capture chemical energy, mainly from sulfur compounds released from thermal vents o Rely on chemosynthesis, not photosynthesis, for energy o Thermal vents = jets of hot water and minerals on the ocean floor Heated by magma below the ocean crust heats Organisms on the vents are adapted to survive both extreme temperatures and intense water pressure o Thousands of microscopic organisms have been discovered Tidal shores support rich, diverse communities - Shoreline communities o Vary with depth, light, and temperature o Support incredible diversity and help stabilize shorelines - Coral reefs o Occur where there is little runoff from shore o Occur where water is shallow, clear, and warm for sunlight to reach the photosynthetic algae (e.g., to support photosynthesis) o Among the best-known marine systems Extraordinary biological productivity -
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Diverse and beautiful organisms o Colonies of minute, colonial animals (“coral polyps”) that live symbiotically with photosynthetic algae Calcium-rich coral skeletons shelter algae (and other species) Algae nourish the coral animals o Unable to tolerate abundant nutrients in the water Nutrients support plankton (tiny floating plants and animals), which block sunlight o Among the most endangered biological communities Sediment from coastal development, farming, sewage, or other pollution can reduce water clarity and smother coral Can be damaged or killed by: Destructive fishing practices (e.g., dynamite, cyanide poison) Changes temperature Invasive fish Diseases Coral bleaching = the whitening of reefs due to stress; often followed by coral death Sea-grass (or eel-grass) beds o Occupy shallow, warm, sandy coastlines o Support rich communities of grazers (e.g., snails, turtles) Mangroves o Diverse group of salt-tolerant trees o Grow in shallow, tidal mudflats along warm, calm marine coasts o Stabilize shorelines o Blunt the force (e.g., speed, height, turbulence) of storms o Build land by trapping sediment and organic material o Provide shelter, nurseries, and food for marine and terrestrial species o Devastated by human activities Clear-cut for timber Cleared to make room for fish and shrimp ponds Poisoned by sewage and industrial waste near cities Estuaries and salt marshes o Estuaries = bays where rivers empty into the sea, mixing fresh water with salt water o Salt marshes = shallow wetlands flooded regularly or occasionally with seawater Occur on shallow coastlines, including estuaries o High biological productivity and diversity o Enriched by nutrients washing from the land o Calm, warm, and nutrient-rich o Rivers provide nutrients and sediments o Muddy bottom supports emergent plants (leaves that emerge above the water surface) and young forms of crustaceans (e.g., crabs, shrimp, mollusks) o Threatened by sewage and other contaminants Tide pools o Tide pools = depressions in a rocky shoreline that are flooded at high tide but retain some water at low tide o Violent, wave-blasted shoreline environment o Support fascinating life-forms o Remain rocky where wave action prevents most plant growth or sediment (mud) accumulation o Extreme conditions (e.g., frigid flooding at high tide, hot sunshine at low tide) make life impossible for most species
[5.7] BIODIVERSITY PROTECTION Hunting and fishing laws protect useful species - To conserve the resource for future human use rather than to preserve wildlife for its own sake - Examples of conservation measures o Restoring habitat o Planting food crops o Transplanting breeding stock o Building shelters or houses o Protecting during breeding season The Endangered Species Act (ESA) protects habitat and species - One of our most powerful tools for protecting biodiversity and environmental quality o Defends rare and endangered organisms o Provides mechanisms for reducing species losses o Helps protect habitat that benefits a whole biological community and safeguards valuable ecological services - ESA provides: 1) Criteria for identifying species at risk 2) Directions for planning for their recovery 3) Assistance to landowners to help them find ways to meet both economic needs and the needs of a rare species 4) Enforcement of measures for protecting species and their habitat - ESA identifies three degrees of risk o Endangered species = considered in imminent danger of extinction o Threatened species = likely to become endangered in the future o Vulnerable species = naturally rare or have been locally depleted by human activities to a level that puts them at risk Often candidates for future listing as endangered species - The number of listed species in different taxonomic groups reflects much more about the kinds of organisms that humans consider interesting and desirable than the actual number in each group o Vertebrate subspecies, local races, ecotypes, or entire species can be listed o Invertebrates make up about 75% of all known species, but only 9% of invertebrates are considered worthy of protection Recovery plans aim to rebuild populations - Once a species is listed, the Fish and Wildlife Service (FWS) prepares a recovery plan o Details how populations will be stabilized or rebuilt to sustainable levels o Include many different kinds of strategies Buying habitat areas Restoring habitat Reintroducing a species to its historic ranges Captive breeding programs Negotiating the needs of a species and the people who live in an area o Help landowners prepare Habitat Conservation Plans Specific management approaches that identify steps to conserve particular pieces of critical habitat - International Paper and other corporations have collaborated with the FWS to devise management strategies that conserve specified amounts of damaged tree stands while harvesting other areas o Restrict cutting of some trees o Ensure that the FWS will not interfere further with management of the timber, as long as the provisions of the plan continue to protect the red-cockaded woodpecker
Red-cockaded woodpecker populations have stabilized Timber companies have gained goodwill and sustainable forestry certification for products - Restoration can be slow and expensive - Disproportionate funding can result from political and emotional preferences for charismatic species - Scientifically established designations o Keystone species (e.g., prairie dogs, bison) Major effects on ecological functions Elimination would affect many other members of the biological community o Indicator species (e.g., brook trout) Tied to specific biotic communities, successional stages, or environmental conditions Reliably found under certain conditions but not others o Umbrella species (e.g., northern spotted owl, tiger, gray wolf) Require large blocks of relatively undisturbed habitat to maintain viable populations Saving the habitat also benefits other species o Flagship species (e.g., giant panda) Especially interesting or attractive organisms to which people react emotionally Motivate the public to preserve biodiversity Contribute to conservation Landowner collaboration is key - Cooperation between federal, state, and local agencies, and private and tribal landowners is critical - On the one hand… o ESA is controversial Protecting a species is legally enforceable Protection can require that landowners change their plans for their property - On the other hand… o Many landowners and communities appreciate the value of biodiversity on their land and like the idea of preserving species for their grandchildren to see o Others (e.g., International Paper) can afford to allow some dying trees for woodpeckers and benefit from goodwill generated by preserving biodiversity - A number of provisions protect landowners and serve as incentives for landowners to participate in developing habitat conservation plans o Permits can be issued to protect landowners from liability if a listed species is accidentally harmed during normal land-use activities o Candidate Conservation Agreement = FWS helps landowners reduce threats to a species in an effort to avoid listing it at all o Safe Harbor Agreement = if landowners voluntarily implement conservation measures, then the FWS will not require additional actions that could limit future management options The ESA has seen successes and controversies - Hundreds of species have been held off from extinction (e.g., recovered, delisted) - Many people are dissatisfied with the slow pace of listing new species o Hundreds of species are classified as “warranted but precluded” (deserving of protection but lacking funding or local support) o Partly because political and legal debates can drag on for years Political opposition is especially fierce when large profits are at stake Many countries have species protection laws - International agreements have also been developed - Convention on International Trade in Endangered Species (CITES) o Provides a critical conservation strategy o Blocks the international sale of wildlife and their parts o Far from perfect
Smugglers Impossible to inspect all transport containers and ships High price of these products makes the risk of smuggling worthwhile o Provides a legal structure for restricting this trade o Raises public awareness of the real costs of the trade in endangered species Habitat protection may be better than species protection - Growing numbers of scientists, land managers, policy makers, and developers are arguing that we need a rational, continent-wide preservation of ecosystems that supports maximum biological diversity o More effective than species-by-species battles While spending millions of dollars to breed individual plants or animals in captivity, they have no natural habitat where they can be released While flagship species are reproducing well in zoos and wild animal parks, the ecosystems that they formerly inhabited have disappeared o Protected areas are different from unprotected areas, which may contain more endangered species than protected areas Gap analysis = to look for unprotected landscapes, or gaps in the network of protected lands, that are rich in species Map protected conservation areas Map high-biodiversity areas Overlay the two maps Identify priority spots for conservation efforts o Four re-management principles for protecting biodiversity in a large-scale, long-range approach 1) Protect enough habitat for viable populations of all native species in a given region 2) Manage at regional scales large enough to accommodate natural disturbances (e.g., fire, wind, climate change). 3) Plan over a period of centuries, so that species and ecosystems can continue to evolve 4) Allow for human use and occupancy at levels that do not result in significant ecological degradation
