Diversity of energy fluxes and interactions between arthropod communities: from soil to cave

Abstract

Abstract The vertical distribution of a species may directly indicate the stage of organic matter decomposition in which it takes part. Observations have so far been limited to superficial layers, but studies on the continuum from the litter to underground biotopes, through the recently discovered superficial underground compartment, open new perspectives in the analyses of matter and energy fluxes. Sampling at different levels, from leaf litter to caves, using pitfall traps and sunken tubes, has revealed the existence of exchanges of organic matter and Arthropoda between different layers. The importation of energy from soil to cave follows two routes: passive and active. For the passive route, I measured dissolved substances in water at five levels. For the active route, I evaluated the migrations of insects and other invertebrates (downwards as well as upwards). For the analysis of arthropod communities, using the notion of functional groups, I showed the existence of links between two components, hypogean species, and endogean-epigean species, defining an ecotone along the vertical gradient ‘soil to cave’. The superficial underground compartment is not isolated, but is rather a whole food web with epigean and endogean organisms penetrating and interlinking with another web of hypogean origin.