Trophic network assessment of grassland ecosystem status

Ecological networks capture the organisms (identities) within the system and multiple interactions between them. Such interactions serve for the exchange of the conservative substances, such as energy and matter, creating the complex structure and behavior of ecological systems. Network organization can be considered as the reflection of ecosystem structure and functions. Network view of systems, as a fundamentally different way of system assess, gave rise to a fast development and acceptance of a new powerful analytical tool named “Network Analysis”. Series of network measures have grown up around the Network Analysis. However the linking of network properties to the ecosystem status is limited because of the gaps concerning the levels and directions of network measures interrelations with empirical ecosystem parameters. Network indicator-based reference values (warning thresholds, standards) are also needed in order to transfer Network Analysis results into the ecosystem decision-making. The aim of current paper is to incorporate Network Analysis tools and empirical comparative analysis of grasslands in Chernivtsi Region in order to assess their ecosystem status. Our results show that most of the network indices demonstrate positive associations with each other, but negative relations with network synergism. It shows that the objective measures of system-wide properties express in different ways a general intuition about the nature of network organization. Our results also shows the contribution of each network property under the study to the ecosystem status by assessing of the interrelations between trophic network measures and the empirically derived parameters of the study grasslands, such as: plant biomass, insect species biodiversity, cattle density, soil microbial groups, soil acidity, and geographical location. In the framework of the current paper we also establish the network indicator-based reference values for grassland ecosystems, linked to the physic-geographic area of Carpathian Mountains, Ukraine. Eventually, we assessed the deviations of the network properties from their reference values and showed the warning status of grassland ecosystems to invoke consequently further precaution.