Published on November 27, 2007
Urban Ecology: Urban Ecology Outline Setting Definitions of “Urban” Definitions of “Ecology” Definitions of Urban Ecology Global Perspective Setting: Setting “The UN forecasts that by 2025, 60% of the world’s population will live in urban areas, as compared to 29% in 1950.” (H. Sukopp. 1998. Urban Ecology—Scientific and Practical Aspects. in Urban Ecology, eds J. Breuste, H. Feldmann, and O. Uhlmann. Springer-Verlag, Berlin. Pgs. 714.) It is likely that more than 12 cities will have over 20 million inhabitants; some will have over 30 million. Coupled to population increases is urban spatial increase. The size or area of cities are growing or expanding. Urban Ecology: Urban Ecology What is “urban”? What is “ecology”? Slide4: Definition of Urban/Metropolitan US Census Bureau Definition, 1990 Urban consists of: Places of 2,500 or more persons in ‘incorporated’ areas Cities, villages, towns, boroughs, etc Actual census designated places of 2,500 or more people US Census definition, 2000: Urban is defined as “ all territory, population, and housing units located within an urbanized area (UA) or an urban cluster (UC).” UAs and UCs are delineated by boundaries that encompass densely settled territory. Areas that have a population density of at least 1000 people per square mile, and The surrounding areas that have a population density of at least 500 people per square mile. Slide5: Definition of Urban/Metropolitan, cont. Examples of city population densities: Atlanta, GA: 3,005 people per square mile (pmi-2) Boston, MA: 11,317 pmi-2 Chicago, IL: 12,024 pmi-2 Mexico City, Mexico: 17,200 pmi-2 New York, NY: 23,740 pmi-2 Tokyo, Japan: 33,670 pmi-2 Jakarta, Indonesia: > 40,000 pmi-2 Anchorage, AK (largest city in Alaska): 149 pmi-2 Slide6: Definition of Urban/Metropolitan, cont. A definition also might include the materials present in urban areas. For example, when a lot of people live close together, there is a lot of, or a dense covering of, artificial surfaces. These surfaces are impervious, hard surfaces. Slide7: Definition of Urban/Metropolitan In 1990, US Census Bureau Definition Urban consists of: Places of 2,500 or more persons in ‘incorporated’ areas Cities, villages, towns, boroughs, etc Actual census designated places of 2,500 or more people Therefore, places not classified as urban, above, are considered ‘rural’ by definition. However, because of this definition, both urban and rural can exist in metropolitan or nonmetropolitan areas. Slide8: What is Metropolitan? US Census Bureau Metropolitan Area (MA) is a large population nucleus (center) together with adjacent communities that have high degrees of economic and social integration with that nucleus. There can be more than one population center or nucleus The population nucleus is considered the Central City(s). Each MA must contain a CC of 50,000 people and the total MA population must be at least 100,000. MAs can contain one or more central counties. Urban Ecology: Urban Ecology What is “urban”? What is “ecology”? Ecology: Ecology “…the scientific study of the distribution and abundance of species and their causes.” (S. Hubbell, 2001. The Unified Neutral Theory of Biodiversity and Biogeography.) “The scientific study of the distribution and abundance of organisms and the interactions that determine distribution and abundance.” (Townsend, Harper, Begon, 2000. Essentials of Ecology.) ‘”…the comprehensive science of the relationship of the organism to the environment.”’ Originally--Oekologie (Ernst Haeckel, 1866.) “The subject of ecology is the relation of living organisms including human beings to their environment. This makes ecology the most important and all-embracing of the sciences.” Italics added. (R. Peters, 1995. A Critique for Ecology.) Urban Ecology: Urban Ecology Thus, urban ecology can be used or defined in two different ways: First, it describes urban design programs or designs that incorporate political, infrastructure (roads, sewers, etc.) and economic considerations. Second, it refers to the area of biology that is concerned with urban areas. Concerned in terms of the relationship, interactions, types, and numbers of species found within urban habitats. Biomes: Biomes Biomes Are large-scale (temporal and spatial) areas of similar vegetation and climatic characteristics. Ex. Tundra: Tundra The tundra has a circumpolar distribution The vast majority is in the northern hemisphere However, it occurs in Antarctica and extreme southern South America Very cold winters, short warm summers (lots of sunlight in summer) Plant life is low-growing, no trees. During summer there is a great amount of life: birds, caribou, rodents, insects. Muskox, caribou, many birds, snowy owl, Polar Bear, wolves, Arctic fox. Takes along time for this system to recover from environmental impacts. Slide16: Boreal Forest The Boreal forest is found between 50o and 60o N. latitude. Long cold winters (can be colder than Tundra) short warm summers. It is also referred to as the Taiga. It is relatively homogenous in plant community structure: dominated by conifers: spruce, larch, firs. Lichens and mosses are important components of this forest. In summer there is a profusion of life: birds, mammals, insects. This biome covers more area than any other biome: 12 x 106 sq. km Slide17: Temperate Forest The Temperate Forest Biome is one of the most altered biomes. It is found in eastern North America, western Europe, and eastern Asia. Areas where there has been much urbanization and where people have lived for along time. Humans have used the trees for many purposes, plus cleared much of it for farmland or cities. This biome is generally composed of broad-leaved deciduous trees. (Trees that lose all their leaves simultaneously) However, coniferous trees are present and can be found in forest type stands (ex. Southern United States.) This biome is found in areas of moderate rainfall: 20-60 inches per year. Winters can be cold to cool, 3-4 months long, summers warm to hot, precipitation throughout the year. Slide18: The World’s grasslands occur in five major areas: Great Plains of North America, Pampas of South America, the Veldt of South Africa, the Steppes of Central Eurasia, and Australia. Soils are deep, and rich. One of the reasons that many of these areas also support large-scale agriculture. Rainfall is generally between 10-25 inches per year. Grassland areas are “continental” usually. Continental refers to center of a continent away from the moderating influence of oceans. Grasslands can have very cold winters, and hot summers. Some areas experience over 120o F swing between winter lows and summer high temperatures. Grasslands Chaparral: Chaparral Chaparral is found in areas with a Mediterranean climate A climate of hot, dry summers and mild wet winters. Found in s. California, Chile, around the Mediterranean sea, and western Australia. Chaparral is forms dense thickets of shrubs, herbs and some trees. Many of the plants have adaptations to drought tolerance as rain may not fall for several months during summer. These adaptations include: thick, leathery leaves. Plants are xerophytic (adapted to dry conditions) Because of the dry summers, fires can occur and are often rather prevalent. Many plants have adapted to the fires. Some plants have seeds which are not released until after a fire. Others are full of volatile oils which cause the plant to burn quickly. (less heat) Desert: Desert Deserts are generally found between 30 and 40 N and S of the Equator. Soils can be rocky with areas of sand. But, desert soils can be productive. Water is what is often limiting. Deserts can be hot or cold. Hot deserts (Sahara, Chihuahuan, Khalahari) Can have daytime temperatures well above 100o F. Cold deserts (Great Basin) have hot summers but can be quite cold during winter. All deserts are dry < 12 inches of rain per year. (Thus, the largest “desert” in the world would be Antarctica, has not had measurable rainfall in centuries) Cacti, euphorbs, annual plants that sprout and bloom during short periods of rainfall. Animals are often nocturnal Tropical Savannas: Tropical Savannas Tropical Savannas are expansive grassland areas that are dotted with trees. Tropical savannahs occur on the drier side of tropical wet and dry climate regions and in subtropical steppes. The African Savannah is the world's largest and probably most well-known savannah with herds of animals grazing on the tall grasses and giraffes browsing on the trees. Tropical Savannahs can also be found in South America, India and, to a lesser degree, Australia. This biome is also experiencing human impacts: population growth, urbanization, agriculture: good soils. Tropical Forests 1: Tropical Forests 1 The Tropical Rain Forest, also known as selva, is the most complex biome in the world. It is always warm and wet. Tropical Rain Forests have a layered structure Emergents, or tall trees, poke above the canopy up to 135 feet. Middle layer forming a canopy of intertwined branches. There is a lower layer of shade-tolerant trees, but the forest floor is open due the fact that little sunlight reaches the forest floor. Many trees have leaves with “drip tips” that channel the water off the leaves. The soils are not high in nutrients because the biomass holds most of the nutrients. Tropical Forests 2: Tropical Forests 2 Tropical Deciduous Forests occur in tropical wet and dry seasons. During the dry season some of the trees lose their leaves so light can reach the forest floor. Consequently, it is rather jungle-like in the Tropical Deciduous Forest. The trees here are typically not as close together as in the Tropical Rain Forest. There is much in terms of environmental impacts: deforestation, population growth, urbanization. Probably hold the bulk of the globes biodiversity. Alpine: Alpine The word alpine comes from the Latin word alpes, which means high mountains. This system follows the mountain chains of the world. Note the connectedness of the Worlds alpine chains: Rocky Mountains, from Alaska to Mexico then the Mexican highlands. High areas in central America then the Andes over all of South Amerca. The Alps from the France/Italy through the Balkans. Rift valley chains in Africa. High mountains from Turkey through Iran to Himalayas to southeast asia. Alpine vegetation is found scattered in the mountainous regions of the world. Plants here have to contend with harsh conditions: cold temperatures, high winds, and heavy snowfall. Therefore, alpine vegetation grows low to the ground above the krummholz (small, stunted tree growth at the margin of the trimberline in alpine regions.