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Chapter 5 : Biomes, Landscapes, Restoration & Management • Major terrestial and aquatic biomes & factors that determine their distribution • Humans disturbance of each ecossytem • Principles of landscape ecology and ecosystem management • Evaluation of the effects of restoration, replacement or substituting ecosystems and resources damaged by humans Terrestrial Biomes • Biomes are broad types of biological communities with similar climatic and topographic conditions with comparable communities. • Temperature and precipitation are the two most important factors influencing the type of biome found in a location. Deserts • Desert biomes are characterized by low moisture levels and infrequent, unpredictable precipitation (2 - 4 in. annual precipitation) • Desert plants have adapted to prevent water loss (leaf adaptations, water-storage tissues, thick epidermal layers) and to discourage predation (thorns and spines). • Warm, dry descending air creates broad desert bands in continental interiors about 30o north latitude. • Not all deserts are hot. Those found at high latitudes and elevations can be cool or even cold. • Desert animals also have adapted to fight the heat and conserve water. Many have adopted burrowing behaviors to escape the sun, and many produce highly concentrated urine and feces in order to conserve water. • Desert soils are easily disturbed by human activities (off-roading, overgrazing, etc.) and take large amounts of time to recover. Grasslands: Prairies and Savannas • Grasslands are moderately dry areas of abundant grasses, herbaceous flowering plants, and open savannas. Seasonal cycles for precipitation and temperature contribute to the rich growth. • Grasslands have few trees due to inadequate rainfall and frequent grassfires. • In some parts of the world, native people use fire to create grasslands for grazing while in other parts, fire suppression has greatly reduced the amount of native grasslands. Tundra • Climates in high mountain areas or at far northern or southern latitudes are often too harsh for trees. This treeless landscape, called tundra, is characterized by a very short growing season, harsh winters, and the potential for frost any month of the year. • The arctic tundra is a biome of low productivity, low diversity, and low resilience. Only the upper layer of soil thaws during the summer while the lower is permafrost and impermeable to plant roots. • The alpine tundra differs from the arctic tundra. High, thin mountain air permits intense solar radiation causing many plants to have deep pigmentations. The sloping of the land allows for better drainage, increasing the chances of drought. There is also a wide day-night temperature range. • Although the tundra may swarm with life during the brief growing season, few species are able to survive the harsh winter. Dominant tundra plants are mosses, lichens, grasses, sedges, and dwarf shrubs. Flocks of migratory birds and bloodsucking insects reside in the arctic wetlands. Larger animals (musk ox, caribou, mountain goats) must be specially adapted to deal with the climate and sparse food supply. • Damage to the tundra is slow to heal because of the short growing season. For example, truck tire ruts and bulldozer tracks from the oil and natural gas industries may take centuries to repair. Conifer Forests • Coniferous forests are characterized by limited moisture which has caused the vegetation to develop thin, needlelike evergreen leaves with a thick waxy coating. • The boreal (northern coniferous forest) stretches in a broad band of mixed coniferous and deciduous trees around the world between 45o and 60o north latitude. Among the dominant conifers are spruce, pine, hemlock, cedar, and fir. Mosses and lichens form most of the ground cover. • Wetlands abound in this biome, especially on recently glaciated landscapes. The taiga is the far northern border between the coniferous forest and the arctic tundra. • Cold temperatures and wet soil inhibit full decay of organic matter. This semidecayed matter is called peat. • The southern pine forest is characterized by a warm, moist climate and sandy soil. • The coniferous forests of the Pacific coast are characterized by mild temperatures and abundant precipitation which results in luxuriant plant growth and huge trees. • The wettest part of the coastal forest becomes temperate rainforest. Broad-Leaved Deciduous and Evergreen Forests • Forests of broad-leaved trees where rainfall is plentiful are called deciduous forests. Trees found here are able to produce summer leaves and shed them at the end of the growing season. These include oak, maple, birch, ash, and elm trees. Mediterranean/Chaparral/Thorn Shrub • Mediterranean climates are characterized by warm, dry summers and cool, moist winters. Evergreen shrubs, scrub oaks, and pines dominate this landscape. • Fires play an important role in plant succession here. • In California, this landscape is called chaparral (Spanish for thicket) and is inhabited by jackrabbits, mule deer, chipmunks, lizards, and bird species. • In drier areas, this landscape is dominated by spiny plants giving it the name thorn shrub. • This biome is considered to be a hotspot for biological diversity. Tropical Moist Forests • Tropical moist forests are characterized by ample rainfall and uniform temperatures. • Cool cloud forests are found high in mountains and cannot resist erosion from the abundant rains. Tropical Seasonal Forests • Tropical regions characterized by distinct wet-dry seasons with hot temperatures all year round give rise to tropical seasonal forests. These areas are dominated by semi-evergreen or partly deciduous forests tending toward open woodland or grassy savannas. • Tropical rainforests occur where rainfall is abundant (>200 cm per year) and temperatures are hot year round. • The soil of these forest types tends to be old, thin, and nutrient poor yet the number of species present is mind-boggling. It is estimated that onehalf to two-thirds of all terrestrial plants and insects live in tropical forests. • Nutrient cycling is also unique here. Almost all nutrients are tied up in the bodies of organisms. • The forest relies on rapid decomposition and recycling of dead organisms to maintain nutrient supplies. Aquatic Ecosystems Freshwater and Saline Ecosystems • Freshwater ecosystems include standing waters of ponds and lakes as well as flowing waters of rivers and streams. • Freshwater ecosystems are influenced by climate, soil, resident communities, and by the terrestrial ecosystems surrounding them. • Availability of essentials for life is influenced by dissolved substances, suspended matter, depth, temperature, flow rate, bottom characteristics, internal convective currents, and connections with other aquatic systems. • Vertical stratification is an important aspect of standing water ecosystems, especially in regard to gradients of light, temperature, nutrients, and oxygen. Stratification of these essentials results in the stratification of biological communities in the water as well. • The bottom sub-community is called the benthos and is made up of low oxygen tolerating organisms. • Deep lakes are stratified into an upper epilimnion, a middle thermocline, and a lower hypolimnion. • Humans utilize freshwater systems a great deal for food, recreation, transportation, and industrial uses. • Not all freshwater systems have what we think of as "fresh" water. Some may be salty (Dead Sea, Great Salt Lake) while others may contain high levels of minerals or be highly alkaline. Estuaries & Wetlands: Transitional Communities • Estuaries are bays of brackish water that form where rivers enter the ocean. • They contain rich sediments that support a multitude of aquatic life and are important as "nurseries" to a variety of species. • A fan shaped sediment deposit at the mouth of a river is called a delta. • Wetlands are ecosystems in which the land surface is covered by standing water at least part of the year. • There are three types of wetlands; swamps (contain trees), marshes (no trees), and bogs and fens (may or may not have trees, tend to accumulate peat, low productivity). • Wetlands are major breeding, nesting, and migration staging areas for waterfowl and shorebirds. • Wetlands perform a variety of useful functions including detoxification of substances in water, clarifying water, and helping replenish underground aquifers. • Wetland areas are being destroyed or degraded by human processes at an alarming rate. Shorelines and Barrier Islands • Ocean shorelines are also particularly rich in life-forms, many of which grow attached to solid substrates such as exposed rock. • Barrier islands are low, narrow, sandy islands that form offshore from a coastline. • They protect inland shores from the onslaught of the surf. Human activity also destroys these fragile ecosystems quite easily. • Coral reefs form in clear, warm, tropical seas. They are the accumulated skeletons of innumerable tiny colonial animals called corals. They support a wide variety of interesting organisms. Reefs are among the most endangered biological communities on earth. Human Disturbance • Humans have become the dominant organisms over most of the earth and have damaged or disturbed more than half the world's ecosystems. • Conversion of natural habitat to human use is the largest single cause of loss of biodiversity. • Temperate broad-leaved forests are the most completely humandominated of any major biome. • Mediterranean climates are also generally desirable for human habitation, leading to conflict between human preferences and biological values. • Tundra and arctic deserts are among the least disturbed biomes in the world. That is changing, however, with the discovery of large reserves of oil and natural gas. Landscape Ecology • Landscape ecology is the study of reciprocal effects of spatial pattern on ecological processes. Reciprocal effects refers to the fact that complex spatial patterns shape, and are in turn shaped by, the ecological processes that occur in them. • Landscape ecology considers humans important elements of most landscapes and take them into account in their studies. Patchiness and Heterogeneity • Landscape ecologists claim that if we look closely, all landscapes consist of similar mosaics of discrete, bounded patches with different abiotic or biotic composition. Often a predominant or continuous cover type acts as a matrix in which other patch types appear to be embedded. • Landscape heterogeneity can exist across a wide range of scale from Yellowstone Park to the effects of soil crumb size and insect burrows in a few square centimeters of soil. Landscape Dynamics • Time and space are of special concern in landscape ecology. • The boundaries between habitat patches are considered especially significant by landscape ecologists. Edges can induce, inhibit, or regulate movement of materials, energy, or organisms across a landscape. • There are many similarities between landscape ecology and conservation biology. Restoration Ecology Restoration ecology seeks to repair or reconstruct ecosystems damaged by humans or natural forces. Defining Some Terms • Restoration involves active manipulation of nature to re-create species composition and ecosystem processes as close as possible to the state that existed before human disturbance. • Rehabilitation refers to an attempt to rebuild elements of structure or function in an ecological system without necessarily achieving complete restoration to its original condition. • Remediation is a process of cleaning chemical contaminants from a polluted area by physical or biological methods. • Reclamation is used to describe chemical or physical manipulations carried out in severely degraded sites, such as open pit mines or largescale construction. • Re-creation attempts to construct a new biological community on a site so severely disturbed that there is virtually nothing left to restore. Conflicting Views of Restoration • There are conflicting views over the effectiveness and ideology of different approaches to protecting nature. Two of the different camps are preservationists and restorationists. • Preservationists argue that the best strategy is to avoid destructive projects in the first place. Restorationists counter that we are unlikely to preserve more than small areas in pristine form. They believe that we should use science to repair damage done by destructive projects. • An important question to consider is the place of humans in nature. Are we members of the biological community or are we separate from it? Tools of Restoration • There are many different ways to approach restoration. Curtis Prairie at the University of Wisconsin-Madison was restored through intensive horticultural and animal control methods. • Sometimes, an alien species must be removed before native species may take hold again. For example, in Hawaii, feral pigs that root out native plants and eat native birds are being hunted and removed. • Successional restoration uses fire to discourage invasion of exotic species. In southern Kansas, fire and native bison have been introduced to restore a 16,000 ha tall grass prairie. Letting Nature Heal Itself Sometimes to reestablish a healthy ecosystem, all we have to do is walk away and leave it alone. The DMZ between North and South Korea is a perfect example. An area shattered by war that has been left alone for almost 50 years has become a thriving wild life refuge. Authenticity An important question in restoration is authenticity. How important is it to restore a particular place to an exact replica of its original ecosystem? If a similar, healthy community can be restored, is that good enough or must an exact replica be created? Back To What? Another important question is what our goals in restoration should be. For example, if a preserve is damage due to a hurricane or fire, should we use science to tidy up the area or let natural processes take care of it? Also, if pollen grains preserved in sediment near a river show the area was a marsh 1000 years ago, should we restore the area to marshland? Creating Artificial Ecosystems Sometimes artificial ecosystems may be created to solve human problems. For example, Arcata, California, created a wetland to deal with it sewage waste from the city. The wetland allowed for detoxification of the water and for a beautiful nature preserve. Ecosystem Management Ecosystem management is a relatively new discipline in environmental science that attempts to integrate ecological, economic, and social goals in a unified systems approach to make environmental management decisions. Table 5.2 -- Principles of ecosystem management • Managing across whole landscapes, watersheds, or regions over an ecological time scale. • Considering human needs and promoting sustainable economic development and communities. • Maintaining biological diversity and essential ecosystem processes. • Utilizing cooperative institutional arrangements. • Integrating science and management. • Generating meaningful stakeholder and public involvement and facilitating collective decision-making. • Adapting management over time, based on conscious experimentation and routine monitoring. A Brief History of Ecosystem Management • While the term ecosystem management is relatively new, a few ecologists had the foresight to advocate many specific elements of this science fifty years ago. • In 1970, environmental policy expert Lynton Caldwell wrote that we should use ecosystems as the basis for public land policy. • Currently, many state and federal natural resource agencies in the United States are attempting to implement ecosystem management as their guiding policy. Principles and Goals of Ecosystem Management • There are several important differences between the current integrated approach to ecosystem management and traditional policies of the past. • Hierarchical context: A focus on any one level of the biodiversity hierarchy is insufficient. Ecosystem managers must see interconnections between all levels. • Ecological boundaries: Rather than divide administrative units by political boundaries, natural units should be managed in an integrated fashion. • Data collection and routine monitoring: To function correctly, ecosystem management requires ongoing research and data collection so that successes and failures may be recognized and evaluated. • Adaptive management: Ecosystem management assumes that scientific knowledge is provisional and regards management plans as learning processes or continuous experiments where incorporating the results of previous actions allows managers to remain flexible and adapt to uncertainty. • Organizational change: Implementing ecosystem management requires changes in agency structure and ways of doing business. • Humans in nature: People cannot be separated from nature. • Values: Regardless of the role of scientific knowledge, human values play a dominant role in ecosystem management goals. Table 5.3 -- Ecosystem management goals maintain viable populations of native species in situ. • Represent, within protected areas, all native ecosystem types across their natural range of variation. • Protect essential ecological processes such as nutrient cycles, succession, hydrologic processes, etc. • Manage over long enough time periods to sustain the evolutionary potential of species and ecosystems. • Accommodate human use and occupancy within these constraints. Critiques of Ecosystem Management • There are many criticisms of ecosystem management. Many ecologists say that due to their chaotic, unpredictable nature, we will never understand ecosystems and developing policies to manage them is a waste of time. • Many people also fear that effective ecosystem management will allow humans to believe we can do damage to nature and that at may be repaired.