Introduction

Most environmental scientists and natural resource managers view long-term monitoring as a good thing. To fulfill their mandates and meet their goals, natural resource management and conservation organizations need information on the current status and patterns of change in high-priority resources, critical ecological processes, and stressors of high concern. To inform policy makers and the general public as well as management organizations, government agencies may have mandates for assessing the condition of selected natural resources in perpetuity because of the special importance of these resources to society and because of the possibility of both suspected and unforeseen changes to these resources. More directly, these organizations need information for assessing whether current management is effectively maintaining the state of managed systems and populations within the desired range of conditions, and for reducing uncertainty affecting management performance.

Moreover, there is incredibly high scientific value in many long-term data sets collected for management and conservation purposes, as well as data collected as part of long-term ecological research programs. Natural systems usually are characterized by complex temporal dynamics and interactions often not evident from a collection of short-term research studies. Data from long-term monitoring can be invaluable for empirical examination of hypotheses about spatial and temporal dynamics – for example, about community dynamics, population growth and density dependence, and influences of infrequent extreme climatic events. With the possibility of rapid and major changes to the Earth's climate, there is unprecedented recognition of the importance of existing long-term data sets and demand for new monitoring studies (e.g. see Chapter 22).