Keeping watch: the science of environmental monitoring

It is easy to look at a list of birds or plants found in an area and imagine that this is a final and definitive statement of what is there. Yet the natural world is full of change; very little - if anything - is fixed or final. Species increase or decrease, forests expand or contract, even rivers change course and coastlines shift. Some changes are part of short-term natural rhythms: we are all familiar with the seasonal fluctuations as migrating birds come and go and annual plants flower and die. Yet other changes are longer-term and of greater significance, as some species colonise a site while others decline or even become extinct locally. Although such changes have always occurred, with mounting human pressure on all environments they seem to be occurring more rapidly. Increasingly, for more and more species, the changes are more of loss than gain.

Monitoring may involve study of insects such as this Large Red Damselfly

Methods of monitoring

Monitoring change in an environment has to be done in a scientific and objective way. Anecdotal evidence, such as someone's comment that "there used to be more bats here," while interesting, is of very limited value. Is this witness's memory accurate? How many more is "more?" Better data is needed, and preferably data that can be expressed in figures. This sounds easy but, in practice, it is much harder. It is simple enough to count the number of trees in a field but how do you quantify the number of snails in a wood or the number of swallows flying over a pond? Over the years, ecologists have developed various techniques of sampling and estimating the abundance of a species in an area. While not perfect, these methods allow the acquisition of numerical data and with that, the use of statistics to plot trends and make correlations.

The value of monitoring

Having such numerical data is not just vital for doing "proper" science, it is also essential for conservation.

• With accurately monitored numerical data, subtle trends can be detected well before they become noticeable to the casual observer. This is important; by the time that a species has declined to the point that its decrease is widely noticed, it may be too late to do anything about it.
• Having such quantified data is useful in making a case for conservation action. To be able to say "our research shows that the numbers of this species are only 44% of what they were ten years ago" makes a far stronger argument than "we feel that numbers have fallen."
• When management for conservation is undertaken in an area, monitoring is vital. With structures as complex as ecosystems, the results of any conservation actions must be monitored to ensure that the management strategies are actually achieving what they were intended to do.

Environmental monitoring is needed to ensure that changes to a site, such as this new storm drainage ditch at the UK Minet site, work as planned.

Features of monitoring

Although the methods of monitoring plants, birds, insects and other organisms vary, two features are common to all such programs:

• The value of any monitoring project increases with time so that the most valuable programs are those that have been going for years. This sort of long-term data is essential in order to see beyond the inevitable short-term fluctuations in natural systems. Take, for instance, the numbers of a butterfly species in an area. If the data over two years shows a decrease in numbers this may not be very significant - it may simply be a temporary decline, perhaps due to a cold spring. But if the figures show an overall decline over five or ten years, then this suggests that there is a real cause for concern.
• The second feature of this long-term monitoring is that it always requires much hard and unspectacular work. A great deal of monitoring is, almost by definition, routine and it generally involves long and often unsocial hours of study. Monitoring birds, for example, may quite literally mean "getting up with the lark" while monitoring bats is a nocturnal occupation. Yet the results are worth it: to have continuous long-term results on species numbers is to possess a vital tool for seeing the way the natural world is changing.

The idea of long-term environmental monitoring is consistent with A Rocha's emphasis on doing conservation through long-term involvement in an area. Furthermore, the A Rocha tradition of having a residential field centre near the conservation area greatly facilitates monitoring by staff and volunteers. A Rocha maintains a strong commitment to long-term environmental monitoring; it may be both undramatic and demanding but it is also irreplaceable.

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This website has a number of examples of A Rocha monitoring programs such as plants in the Algarve, birds in Lebanon's Bekaa Valley and Rollers in France. As the site develops we intend to add further examples.