Environmental Problems, Their Causes, and Sustainability 1

chambers where temperature, light, CO 2 , humidity,and other variables can be controlled carefully.Such systems make it easier for scientists to carryout controlled experiments. In addition, such laboratoryexperiments often are quicker and cheaper thansimilar experiments in the field.But there is a catch. We must consider whetherwhat scientists observe and measure in a simplified,controlled system under laboratory conditions takesplace in the same way in the more complex and dynamicconditions found in nature. Thus the results oflaboratory research must be coupled with and supportedby field research.SystemsMeasurementDataAnalysisDefine objectivesIdentify and inventory variablesObtain baseline data on variablesMake statistical analysis ofrelationships among variablesDetermine significant interactionsWhat Is Systems Analysis? SimulatingEcosystemsEcologists develop mathematical and other modelsto simulate the behavior of ecosystems.Since the late 1960s, ecologists have made increasinguse of systems analysis to develop mathematical andother models that simulate ecosystems. Computersimulation of such models can help us understandlarge and very complex systems (such as rivers,oceans, forests, grasslands, cities, and climate) thatcannot be adequately studied and modeled in fieldand laboratory research. Figure 4-36 outlines the majorstages of systems analysis.Researchers can change values of the variables intheir computer models to project possible changes inenvironmental conditions, help anticipate environmentalsurprises, and analyze the effectiveness of variousalternative solutions to environmental problems.However, simulations and projections made usingecosystem models are no better than the data and assumptionsused to develop the models. Thus carefulfield and laboratory ecological research must be usedto provide the baseline data and determine the causalrelationships between key variables needed to developand test ecosystem models.Why Do We Need Baseline Ecological Data?Understanding What We HaveWe need baseline data on the world’s ecosystems sowe can see how they are changing and develop effectivestrategies for preventing or slowing their degradation.According to a 2002 ecological study published by theHeinz Foundation, scientists have less than half of thebasic ecological data they need to evaluate the statusof ecosystems in the United States. Even fewer data areavailable for most other parts of the world.Before we can understand what is happening toan ecosystem, community, or population and how bestSystemModelingSystemSimulationSystemOptimizationConstruct mathematical modeldescribing interactions amongvariablesRun the model on a computer,with values entered for differentvariablesEvaluate best ways to achieveobjectivesFigure 4-36 Major stages of systems analysis. (Modified datafrom Charles Southwick)to prevent harmful environmental changes, we need toknow its current condition. In other words, we needbaseline data about its components, physical and chemicalconditions, and how well it is functioning.By analogy your doctor would like to have baselinedata on your blood pressure, weight, and howwell your organs and other systems are functioning asrevealed by blood and other basic tests. Then whensomething happens to your health the doctor can runnew tests and compare the results with the baselinedata to determine what has changed and use this tocome up with a treatment.Ecologists call for a massive program to developbaseline data for the world’s ecosystems. If we do notknow how many elephants are in Africa, we cannotdetermine whether their populations are declining orincreasing.If we could see the bounty and beauty of naturethe way it was 100 or 200 years ago, we would be outragedat what we have lost. But it is easy for us not tomiss what we never saw or experienced.http://biology.brookscole.com/miller1485