Effective ecological monitoring requires a multi-scaled approach.

Environmental monitoring data is fundamental to our understanding of environmental change and is vital to evidence-based policy and management. However, different types of ecological monitoring, along with their different applications, are often poorly understood and contentious. Varying definitions and strict adherence to a specific monitoring type can inhibit effective ecological monitoring, leading to poor program development, implementation, and outcomes. In an effort to develop a more consistent and clear understanding of environmental monitoring programs we review previous monitoring classifications and support the widespread adoption of three succinct categories of monitoring, namely targeted, surveillance and landscape monitoring. Landscape monitoring is conducted over large areas, provides spatial data, and enables us to address questions related to where and when environmental change is occurring. Surveillance monitoring uses standardised field methods to inform on what is changing in our environments and the direction and magnitude of that change, whilst targeted monitoring is designed around testable hypotheses over defined areas and is the best approach for determining the cause of environmental change. This classification system is ideal because it can incorporate different interests and objectives, and as well as different spatial scales and temporal frequencies. It is both comprehensive and flexible, while also providing valuable structure and consistency across distinct ecological monitoring programs. To support our argument, we examined the ability of each monitoring type to inform on six key types of questions that are routinely posed to ecological monitoring programs, such as where and when change is occurring, what is the magnitude of that change, and how to manage that change. As we demonstrate, each type of ecological monitoring has its own strengths and weaknesses, which should be carefully considered relative to the desired results. Using this scheme, users can compare how well different types of monitoring can answer different ecological questions, allowing scientists and managers to design programs best suited to their needs. Finally and most importantly, we assert that for our most serious environmental challenges, it is essential that we include information at each of these monitoring scales to inform on all facets of environmental change. This will be best achieved through close collaboration between practitioners of each form of monitoring. With a renewed understanding of the importance of each monitoring type along with greater commitment to monitor cooperatively, we will be well placed to address some of our greatest environmental challenges.