Understanding 100 years of farmland biodiversity loss

/ Author: Masja de Ree
Butterflies on small blue flowers
© Hollandse Hoogte
The agricultural sector in the Netherlands is highly advanced. We are now the world’s second largest agricultural exporter. This has had a side effect, namely a decline in farmland biodiversity over the past hundred years. Statistics Netherlands (CBS) has been able to quantify this decline for the first time. ‘With the help of new methods, we’re now able to monitor plant and animal species reliably over a longer period of time,’ says CBS researcher Arco van Strien.

For many years, CBS has been collecting objective figures on the trends in plant and animal species in the Netherlands. Van Strien explains: ‘From around 1990 onwards, we have been taking measurements using standardised field methods. But in order to monitor the natural environment effectively, you need information that covers a longer period of time.’ He cites the example of grassland butterflies: when you look back on the past two decades, their populations show little change. But when you consider the development over the past 100 years, you’ll see a very large decline. Van Strien continues: ‘A longer time series offers a wider perspective. Up until this year, we could not compile any, because there were no standardised data available for periods much longer ago. Thanks to new statistical methodology and the digitalisation of old data, we’ve recently been successful in conducting reliable analyses that are based on other data, for example data from archives and collections.’

Objective data for the policy debate

In the meantime, CBS has established historical time series on butterflies, mushrooms, birds and farmland flora. ‘There is a great deal of public interest in biodiversity,’ says Van Strien. ‘The international community considers it important to protect nature, and in order to do so, you need objective data.’ We are seeing a deteriorating trend in particular areas, but there is definitely some improvement as well, he stresses. ‘For example, the dragonfly population has been in good shape for years. Wild mushrooms have made a comeback as well. This demonstrates that efforts towards natural conservation are paying off.’

Environmental Data Compendium

All biodiversity statistics compiled by CBS are published, with explanations, onto the Environmental Data Compendium. This website provides information about the state of the environment, nature, landscape and spatial developments in the Netherlands. The Compendium is a collaboration between CBS, the Netherlands Environmental Assessment Agency (PBL), the University of Wageningen and the National Institute for Public Health and the Environment (RIVM). It is freely accessible to everyone and is used by many, including researchers and students, but also the general public. Van Strien explains: ‘Likewise, it offers interesting information for policymaking. The Netherlands has to comply with a large number of international environmental policy directives. The Compendium provides the figures that form the core of mandatory reporting.’

‘CBS monitors the quality of monitoring schemes and the resulting data for us’

Quality of monitoring schemes

An important user of the biodiversity statistics is the PBL Netherlands Environmental Assessment Agency. Arjen van Hinsberg, who collaborates on the Compendium on behalf of PBL, says: ‘We draw on the data from the Compendium for our policy reports, for instance in the Environmental Balance (Balans van de Leefomgeving) and our report on provincial nature conservation policies (Lerende Evaluatie van het Natuurpact). CBS is our information provider in terms of the actual situation and trends in the natural environment, based on data on species within the Ecological Monitoring Network (NEM). CBS monitors the quality of monitoring schemes and the resulting data for us. More and more, the Compendium is becoming the engine that produces the latest basic data we can draw on.’

Policy assessments

In its policy assessments, PBL links the objective information to the goals and ambitions that were set out in government policies. Van Hinsberg: ‘In view of adjustments to policies, changes in the formulation of goals, or issues like decentralised implementation of policies on nature conservation and nature management, which has moved to the provincial level, it has become crucial to also keep a sharp eye on the evidence base and to refine it where necessary. For example, there is now a greater need for provincial indicators and for data on insect mortality, an area of widespread concern. In addition, PBL has long harboured the wish to look back further than 1990 in order to find answers to questions on the size of the historical loss of biodiversity.’

Natural Capital Accounts for the Netherlands
CBS is also conducting experimental research to study the contribution of nature to the economy. The initial outcomes of this new research will be published in the near future as the Natural Capital Accounts for the Netherlands. This entails calculating nature’s contribution to GDP based on the various ways in which people use nature as producers and consumers. A publication on this subject is currently underway.