Ground-active Arthropods Research Articles

Effectiveness of afforested shrub plantation on ground-active arthropod communities and trophic structure in desertified regions

In desertified regions, the mobile sand land, and afforested shrubland of different ages (i.e., 6, 15, 24 and 36years) in addition to the naturally restored grassland were selected in order to evaluate their consequences on taxonomic and trophic structures, and the diversity of ground-active arthropods. The taxa-specific responses to the land conversion were found within functional groups. The activity density of predator Labiduridae and Carabidae, and herbivore Tenebrionidae decreased, while that of herbivore Melolonthidae and omnivore Formicidae increased markedly (p<0.05) from the mobile sand land to the afforested shrubland, regardless of shrubland ages. The taxa richness of herbivores also increased markedly (p<0.05) from the mobile sand land to the afforested shrubland, regardless of shrubland ages. However, there was little effect of land conversion on the activity density and richness of detritivores due to the lack of litter on the surface of soils. Different functional groups of ground-active arthropods responded in a different way to the land conversion. The total density and Simpson index decreased, while the taxa richness and Shannon index increased markedly (p<0.05) from the mobile sand land to afforested shrubland, regardless of shrubland ages. It was suggested that the afforested shrub plantations of different ages had similar implications on the trophic structure and diversity indices as was close to the naturally restored grassland (except for Shannon index). The Shannon index in the grazed afforested shrubland of 24years that was close to the naturally restored grassland was markedly (p<0.05) lower compared with the other afforested plantations. In conclusion, the afforested shrubland was an option for the stabilization of mobile sand land and biodiversity recovery of degraded ecosystems, regardless of shrub ages. Furthermore, the grazing management on afforested shrubland could improve the effectiveness of this recovery process.

Effects of fertiliser and grazing on the arthropod communities of a native grassland in south-eastern Australia

Abstract An experiment commenced in 1998 to test the effects of superphosphate fertiliser application and grazing on production and botanical composition of a native grassland in south-eastern Australia. Superphosphate application resulted in an increase in sheep production but a decline in native perennial grasses and an increase in exotic annual grasses. The study reported here aimed to determine if arthropod assemblages showed changes in community composition on the same experimental plots. The experiment was conducted in grassland dominated by the native perennial wallaby grass, Austrodanthonia duttoniana, and consisted of six replicated treatments that were designed to improve grassland and domestic livestock productivity. Treatments consisted of a control (no fertiliser), three levels of annually applied superphosphate (62.5, 125, and 250 kg ha−1), and two treatments aimed to raise soil pH (superphosphate plus lime, and sewage ash). Soil properties were measured annually and sheep stocking rates were increased over the duration of the experiment according to increases in available forage. Soil and ground-active arthropod populations were sampled from all plots in spring 2001. Fertiliser application and grazing increased the relative abundance of introduced Acari and Collembola, and changed the community composition of Formicidae and Coleoptera. Lime and sewage treatments had variable effects on taxa. Improving the productivity of native grassland with superphosphate led to a decline in plant and arthropod biodiversity through reduced abundance and/or local extinction of native species and increased dominance of introduced species. These findings support the need to protect and restore a representative network of native grassland ecosystems within the agricultural zone of south-eastern Australia.

Identifying performance indicators of the effects of forest management on ground-active arthropod biodiversity using hierarchical partitioning and partial canonical correspondence analysis

Biodiversity conservation in Australian native hardwood production forest is a central aim of sustainable forest management. However, the effects of timber extraction and fuel-reduction burning on the biodiversity of forest invertebrates are poorly understood. In this study, we use hierarchical partitioning and partial canonical correspondence analysis to examine the independent effects of these management practices on the richness and composition of ground-active ant and beetle assemblages. The study makes use of survey data from two types of production forest widespread in north-east New South Wales, New England Blackbutt ( Eucalyptus campanulata, R. Baker and H.G. Smith) and Messmate/Forest Ribbon Gum ( E. obliqua, L’Hér and E. nobilis, L. Johnson and K. Hill). Pitfall-trapped ants, and beetles from the families Carabidae, Scarabaeidae and Pselaphidae, were sorted to morphospecies and these survey data, together with habitat data, were used to explore two questions: (1) how much variation in the richness and composition of the arthropod assemblages at survey sites could be accounted for (independently) by logging and fire history? and (2) were other habitat variables better able to (independently) account for variation in arthropod richness and composition? Answers to these questions were used to identify potential performance indicators of the effects of forest management practices on ground-active arthropod biodiversity. Our analyses found that in New England Blackbutt forest sites, where selective logging was at low intensity, logging history explained little variation in arthropod richness or composition. By contrast, a strong influence of fire history and correlated habitat variables was evident. Fire history also explained significant variation in Messmate/Forest Ribbon Gum forest, but in this forest type, where logging intensity was higher, the influence of logging history was also apparent. This study finds support for the use of measures of ant richness, percent cover of sub-canopy (5–15 m above ground level) and ground-layer characteristics (litter depth, % cover of litter and bare ground) as performance indicators, because these attributes are relatively easy to measure, are affected by forest management, and are indicative of the effects of forest management on ground-active arthropod biodiversity.