the amount of land in each of the various categories of developed lands is 

 given in table 10-6. Urban areas occupy approximately 50% of the developed 

 system, ranging from 16% in northeastern Maine to 62% in southeastern Maine. 

 Residences, which include seasonal and year-round residences and farmsteads, 

 occupy 33% of the developed system. Roads account for about 12%, and 

 railroads only about 1% of coastal Maine. 



Biota 



In addition to people, the biota of developed land consists mainly of exotic 

 (non-native) species of plants and animals that have been introduced 

 intentionally (garden plants, trees, dogs, and cats) or accidentally (weeds, 

 pigeons, rats, and mice). The trophic structure of developed systems is 

 simple. The primary producers in suburban areas, golf courses, city parks, 

 and rural residences are lawns, gardens, and shade trees that are maintained 

 by watering, pruning, fertilizing, mulching, and by poisoning their 

 competitors. Although no data are available the productivity of these plants 

 is probably high because of the intensive care that is given them. Primary 

 consumers (most of which are considered pests) are insects or other 

 invertebrates whose populations are controlled by spraying with pesticides, as 

 well as some vertebrates, including mice, voles, rabbits, hares, and 

 woodchucks. Important secondary consumers are songbirds, such as the robin, 

 house sparrow, song sparrow, starling, catbird, northern oriole, cardinal, 

 mockingbird, as well as mice, cats, dogs, and perhaps raccoons and skunks. 



In highly developed urban areas, essentially no primary production takes 

 place. Vacant lots may support a few species of weeds and small lawns may 

 exist but generally the concrete and buildings reduce the productivity to near 

 zero. The animals that do exist are able to do so because of the presence of 

 people. Pigeons, starlings, rats, mice, dogs, and cats exist on the food or 

 garbage provided by people, or in isolated small patches of habitat such as 

 are found in vacant lots. 



There is probably a well-developed decomposer system in suburban areas. High 

 levels of organic matter (grass clippings, leaves, and garden residue) and 

 nutrients (mulch and fertilizer) are added to the soil to promote fertility, 

 which also enhances decomposer activity. This is nearly nonexistent in 

 cities, however. In general, decomposer activity is unable to handle the 

 excess waste produced by people, and additional sewage treatment facilities 

 and sanitary land fills are needed to properly dispose of this material. 



Abiotic Features 



The local climate in urban areas is modified by the presence of concrete and 

 buildings and particulate matter added to the air (LeBlanc and Rao 1973). 

 Temperatures in cities are slightly warmer than those in nearby vegetated 

 areas because of the absorptive and radiative properties of concrete. Wind 

 velocity is also approximately 20% to 30% lower in cities than in open areas, 

 which also helps to maintain slightly higher temperatures. Particulate matter 

 in the air may be up to 10 times higher in cities than in rural areas. This 

 causes a 15% to 20% reduction in solar radiation and, because the particles 

 serve as nuclei for raindrop formation, precipitation is increased 5% to 10%. 



10-7 



10-80 



