An indicator system for life-support functions of the soil in relation to biodiversity
Een indicatorsysteem voor life support functies van de bodem in relatie tot biodiversiteit
26 May 2012, PDF |
90 pages |
Schouten AJ , Brussaard L , Ruiter PC de , Siepel H , Straalen NM van
RIVM Report 712910005
In the summer of 1994 the Dutch government ratified the UNCED Biodiversity Convention of Rio de Janeiro 1992. The different national laws and programs for environmental protection, nature management and water quality control, formally meet the obligations of the convention. Nevertheless, a strategic action plan has been designed to fill up the gaps in biodiversity aims, research, technology and international politics. One of the activities in the Strategic Plan of Action (SPA) is the development of policy objectives on biodiversity for outside the (protected) nature areas. In the cultivated areas sustainable use of ecosystems and maintenance of functions are the main objectives. The total number of essential ecological processes is referred to as the Life Support System (LSS). The soil is significant in supporting life support functions. Most functions stem from activities of soil organisms. In this context there is a need for an indicator system that detects threats to the breakdown of life support functions. The development of such an instrument is also of importance for regular reports on 'The environmental balance' and the 'National environmental outlook'. The indicator system for life support functions of the soil is based on the following hypothesis: The threat of vital soil processes can be expressed by comparing the number of species in functional groups in a certain area with reference numbers (undisturbed locations). A proces is assumed to continue to exist with fewer species, in which case the risk of instability and uncontrolled fluctuations will increase. Since the indicator system is designed from a functional point of view, a selection had to be related to the most important life support functions in the soil. Moreover, the aim was to obtain a representative view (section) of the soil ecosystem, in which a food web model for the quantification of several life support functions could be used. Processes belonging to these functions were then listed, including the responsible groups of soil organisms. The ultimate indicators were chosen on the basis of a criteria list of for example: possibilities for measurement in a monitoring programme, sampling ease, cost of analysis, and diversity of species and functional groups. The selection procedures resulted in a set of 12 indicatory variables, giving indicators in the form of diversity within functional groups, a number of bacterial degradation routes and model predictions on nitrogen mineralization from the food web and system stability.