E.M. Papatheodorou^{1, 2,}, G. Hatzoudis¹, P. Kapagianni¹, I. Tsiripidis³, G.P. Stamou²

Our aim was to assess step by step the evolution of the herbaceous plant community in reclaimed landfill areas by network analysis techniques. We examined the network of interactions among the members of the plant community at two levels; global and local. The experiment was conducted at one landfill that contained three reclaimed sites of different ages after closure (2 years [R2], 9 years [R9] and 13 years [R13]), plus a neighbor seminatural grazed grassland (SM-NAT). In R2 and R9 sites, the plant community consisted of almost 20 species; among them legumes like Melitotus albus and strong competitors like the exotic Solanum elaeagnifolium. The high heterogeneity of the interspecific relationships, the limited number of influential species and the moderate network centrality, recorded in R2 and R9 sites, were signs of competition for habitat exploitation. In contrast, the higher number of species (around 30), the relatively low heterogeneity of interspecific relationships and the even distribution of influence among many species in R13 and SM-NAT sites indicated moderation of competition. The global network metrics in sites R13 and SM-NAT appeared to converge although the composition of the community did not. The local scale analysis revealed the coexistence of two separate and well organized faction/communities within the same site (Mediterranean and widespread species), while within most factions the analysis distinguished further sub-categories like those formed by species of poor habitats and species of disturbed habitats. The identification of critical scales provides powerful theoretical and practical means for conservation and restoration practices.

biocommunity structure, reclamation, glocal approach, ego networks, network metrics, small worlds