Abstract
We assessed the abundance and composition of nematode communities in soil under herbaceous vegetation in reclaimed landfill sites at different ages after closure (3, 10 and 14 years) compared to those in neighboring semi-natural grazed grasslands (reference sites). We further applied network analysis based on the co-occurrence patterns of nematodes. Nematode abundance decreased between 3 and10 years of regeneration, but significantly increased from 10 to 14 years of regeneration. The number and identity of genera were comparable along the succession; however, there were dissimilarities in community composition during early- and mid-succession. The diversity, community composition and abundance at the sites after 14 years of regeneration converged with those at the reference sites. Moreover, changes during succession were not accompanied by the maturation of the soil food web, as demonstrated by Enrichment and Channel indices. In all the networks, centrality and modularity metrics differed significantly from those for random networks, whereas cohesion metrics showed no difference. All the networks exhibited Small-worldness indices higher than one, demonstrating that the networks of the interactions among genera at all the sites shared features that matched both random and non-random networks. The succession trajectory in reclaimed landfills was represented by a sequence of changes that differed in relation to the variable under consideration; network parameters tended to converge with those of a relatively resistant reference community, while the Enrichment and Channel indices did not. Additionally, the succession trajectory was not linear or steady; only the Channel index and Worldness index showed linear responses to succession time. However, across all the successional stages, the resource status remained basal or degraded while the nematode communities had an enhanced ability to cope with sudden changes.
Highlights
Since the field of ecological succession was established, this process has been modeled as the progressive and directional change in the structure and the dynamics of biological communities [1].recent mainstream models tackle succession as a complex procedure leading to polyphasic and frequently unpredictable outcomes [2,3]
Recent mainstream models tackle succession as a complex procedure leading to polyphasic and frequently unpredictable outcomes [2,3]. This is because a plethora of factors contribute to the routes of succession, which are grouped into three main categories: environmental constraints, species autoecology, and species interactions [2]
Thirty-two nematode genera were recorded in our study area
Summary
Since the field of ecological succession was established, this process has been modeled as the progressive and directional change in the structure and the dynamics of biological communities [1].recent mainstream models tackle succession as a complex procedure leading to polyphasic and frequently unpredictable outcomes [2,3]. Studies that used nematode communities as tools to depict the route of restoration under different restoration schemes [6,7,8,9] focused on nematode abundance, diversity and functional indices. This is because nematodes are assumed to reflect (at least to some extent) the maturity level of the community and its ability to cope with disturbance events [10,11,12]. Patterns in abundance reflect the numerical responses of different taxa to common environmental factors, rather than biotic interactions or the interactions of biota with abiotic factors [13]
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