1997 Environmental Science Institute
Land Use and Biodiversity
This study of land use and land cover is model for teachers to follow. It is intended to provide students insight about global connections and give a sense of environmental integrity by first developing a sense of place. Using Geographical Information Systems, or GIS for short, in the classroom helps students to gain a "sense of place" by personalizing how they view their own neighborhood and realizing the myriad of connections to the global life system we call the Earth. "Sense of place" is an essential component for instilling in citizens a sense of environmental stewardship. GIS is a way of looking at data from our environment within a spatial context. GIS involves mapping data and interpreting the relationships among that data and making inferences. GIS data can be mapped and analyzed through use of computer programs such as ArcView.
Human settlement and associated landscape changes have taken their toll on native wildlife across the planet - for the most part through habitat elimination or alteration. We are now at a critical juncture with respect to both our attitudes and actions relative to wildlife habitat if there is going to be any meaningful preservation of biodiversity in our natural wildlife heritage. One thing is certain - for these species to survive there must be sufficient space to meet their minimal needs, and often some means of travel between disconnected habitat spaces. Soon after the year 2000 the U.S. population will reach ~300 million. Can wildlife still have their place in the midst of so many people and their demands on the land?
A network of streams and tributaries from the headwaters to the mouth of a river is called a river system. The land area that drains rain and snow melt to a river is called a watershed, each tributary to the river is part of a smaller watershed. Many watersheds have been altered as result of human needs for water, food, recreation, transportation, etc. Growing demands have led to pollution of streams and rivers. Unwise land use further degrades water quality. A river may be less healthy where it passes through farmland than where it passes through forested lands due to fertilizer runoff and sedimentation. As water flows through land being used for different purposes it picks up contaminants which change the quality of the water. Both additive and subtractive effects may be seen., therefore it is important to measure the quality of a river over long periods of time to detect changes in a river ecosystem, including the land around the river as well as the water in it.
Urban environments differ from agricultural and wild lands in many respects. Two obvious features are buildings and walls. These objects modify their adjacent microclimates by absorbing solar energy, radiating heat, and providing shade. Buildings and walls can be used to actively manipulate the microenvironment to benefit agriculture. In this inquiry we chose to study the microclimatic effects on the north and south sides of some large, brick buildings.
Quadrants bordering cropland or pasture land will be selected, and we will identify every tree species encountered within that quadrant. Species composition and diversity would be compared among quadrants collected at the forest edge, along the transect, into the forest interior . Quantitative emphasis would be on plant species, but composition and diversity of animals would be noted as well. The numerical data will be entered into a spreadsheet application, imported into a graphing application and a scientific visualization program such as Spyglass.
Is there a higher nitrate concentration in water from rural areas when compared to urban areas? It is hypothesized that surface water obtained from agricultural practices will contain higher levels of nitrate concentrations when compared to water obtained from urban/suburban areas.
Exotic or alien species have been introduced to the United States over the years, accidentally or purposefully. An alien (exotic) species is defined as any organism introduced artificially into a habitat. These species have been brought into the environment by humans or were carried by animals, vehicles, and even clothing. Some exotics have found their niches and have even helped a particular ecosystem. Many popular game fish, such as the rainbow and brown trout and the tiger musky, are "alien", non-invasive species. However, some exotics actually harm ecosystems and contribute to the loss of biodiversity. These species are usually free from predators, pathogens and competition. An invasive exotic is the Purple Loosestrife ( Lythrum salicaria ) which aggressively crowds out native plants and can completely dominate its ecosystem. Economically it causes impact by clogging irrigation or drainage ditches on farmlands.
Duckweed, a monocot aquatic species of plants, is a natural purifier of water. Duckweed is capable of treating wastewater, namely nitrates and phosphates, by absorbing the compounds and converting it to biomass and water. It will only survive under certain conditions and is not found in all areas. Presently, duckweed is being used in some areas as a biological means of wastewater treatment and as biomass to feed livestock. Unfortunately, duckweed can become so prolific that it overtakes an aquatic ecosystem, reducing the amount of dissolved oxygen present and lowering the plant and animal population present. If duckweed populations are to be maintained and used effectively for water purification, an understanding of its physical and biological needs must be attained. This project will look at the characteristic traits of aquatic ecosystems which limit the growth of duckweed.
What fire does within natural ecosystems is commonly misunderstood. As a force in the environment, fire is neither entirely good nor entirely bad. Our usual single-minded response to a fire in our environment is to extinguish it as quickly as possible. Most of us look on fire as a terribly destructive force but everyone should know of its regenerative effects in natural systems. Fire can stimulate growth, eliminate competition by invading weed species, induce seed germination, and do many other "good" things. Fire-adapted species of the tall-grass prairies survive occasional burning by having underground buds. Fire has never not been a force in nature; species and ecosystems have evolved in concert with fire for millions of years. At critical seasons, suppressing fire can cause more undesirable change in certain biomes than would allowing fires to burn.
Princeton University's surroundings include a unique wetland area that is host to a wide diversity of environmental influences. There is a bird sanctuary, some stream effluent, and a varied and rich plant life that integrate in a way to have a healthy ecological impact on the area. One such impact is the ability to filter out unwanted nitrates. An investigation that could confirm this would lead not only to preservation of a needed resource, but contribute to the investigation of other wetland areas across the country and their potential contribution as a natural biofilter alternative and/or supplement to present water filtration systems. The hypothesis of our project is that the level of nitrates introduced into the Princeton wetland is higher than the level of nitrates that is leaving the wetland.
The hypothesis in this project is that various land use practices in the Princeton area have widely varying impacts on soil erosion and runoff. A comparison between suburban drainage and crop drainage was examined to determine erosion differences. A topographic map was used to find two appropriate drainage areas (approximately the same elevation, gradient, etc.) with two different types of land uses, agricultural and suburban. Measurements were made on both areas and then compared. Embedded in this project is an experiment designed to be performed by students in which two characteristics of a stream or river, the amount of water it carries the amount of sediment carried by the water, is measured. This data is then used to make a crude estimate of the erosion rate for two different land uses (crop & suburban) and compare results to the amount of rainfall during a seven day period.
Abstracts by Linda Padwa.