Michael J. Gormally

A comparison of plant and carabid beetle communities in an Irish oak woodland with a nearby conifer plantation and clearfelled site

In 1996, plant and carabid beetle communities were examined in a semi-natural oak woodland (Derryclare Wood) and compared with communities of a nearby mature conifer plantation and a plantation clearfelled in 1994. At each site, 10 quadrats (2 m×2 m) and 10 pitfall traps were used to sample the ground vegetation and carabid beetle communities, respectively. Forty-one plant species were recorded in the oak woodland while 38 species were found in the clearfelled site and 19 species in the conifer plantation. The median plant-species richness per quadrat was significantly greater (p<0.01) in the oak woodland (16.5) than in the other two sites and the clearfelled site (11) was significantly more species-rich (p<0.02) than the conifer plantation (6.5). A total of 21 carabid species (895 individuals) were captured, with 74.5, 13.9 and 11.6% of individuals being caught at the oak woodland, clearfelled site and conifer plantation, respectively. The median number of carabid species per pitfall trap was significantly greater (p<0.01) in the oak woodland (6) than in the clearfelled site (3.5) and conifer plantation (2). In addition, median species richness per pitfall trap was significantly higher in the clearfelled site than in the conifer plantation at p<0.02. Median diversity per pitfall trap was also significantly less in the conifer plantation (1.19) than in the oak woodland (2.43, p<0.01) and clearfelled site (1.55, p<0.05). While the Sorenson similarity index for both vegetation and carabids shows that the conifer plantation and the clearfelled site were most similar in species composition; nevertheless, the clearfelled site has demonstrated signs of increasing species richness only 2 years after clearfelling. It is concluded that while semi-natural woodlands support a greater range of species than conifer plantations, clearfelled areas which are not replanted can enhance species richness within commercial conifer plantations.

A comparison of the efficacy of pond-net and box sampling methods in turloughs - Irish ephemeral aquatic systems

Two methods were used to sample aquatic macroinvertebrates in three turloughs. Turloughs are systems that flood periodically from groundwater, in response to local rainfall patterns and contain rare aquatic species and assemblages. The first method used a standard pond net that was swept through the water column, while the second involved fixing a rectangular, open-bottomed box to the substrata and removing all organisms with a net. Similar overall sampling effort was applied to each method and individual box samples were found to take longer to gather than pond net samples. The box method, however, gave the maximum yield for a given sampling effort. Significantly more beetle species and individuals were recorded per unit area of bottom at all three turloughs using the box method. Multivariate analysis segregated samples, firstly according to site and secondly, with respect to method. The box method is a viable alternative to sampling with a pond net. It is more quantitative, objective, specific and reliable. This is particularly important in habitats distinguished by rare species and assemblages, and for which monitoring is driven by legislative needs.

Ground flora and associated arthropod communities of forest road edges in Connemara, Ireland

Forest road edges in a conifer plantation in Connemara, Ireland weresampled for ground flora and associated terrestrial invertebrates along thenorthern edge of a forest road bordered by conifers (Conifer 1 site),broadleaves (Broadleaf site) and a clearfelled area (Open site). In addition,the southern edges of the road bordered by a clearing (Scallop site) and of anadjacent forest road bordered by conifers (Conifer 2 site) were sampled. Medianground plant species richness per quadrat was lower at the Conifer sites than atthe other sites. A positive relationship between plant species richness andlight levels was apparent. Median arthropod morphospecies richness per sweep wassignificantly greater (P < 0.01) at the Broadleaf site(39.0) than at the Conifer 2 site (25.5). Median morphospecies richness forHemiptera was significantly greater at the Open (7.0) and Broadleaf (6.5) sitesthan at the Conifer 1 site (2.0, P < 0.001) and Conifer2 site (2.0, P < 0.01). For Diptera, medianmorphospecies richness was significantly greater at the Open site (13.5) than atthe Conifer 1 site (6.0, P < 0.01), Conifer 2 site (6.0,P < 0.001) and Scallop site (8.0, P< 0.05). There was a positive relationship between plant species richness andarthropod morphospecies richness with stronger species richness relationshipsevident between plants and Diptera and between plants and Hemiptera,respectively. The results of this study suggest that open spaces and broadleafplantings in this commercial conifer plantation in the west of Ireland could beimportant for biodiversity.

The flora and carabid beetle fauna of a mature and regenerating semi-natural oak woodland in south-east Ireland

Abstract An investigation of the plant and carabid beetle communities of a mature and adjacent regenerating oak woodland site was carried out from June to September (1999) in County Wexford, south-east Ireland. Phytosociological classification (using 10 m ×10 m quadrats) identified the mature site as belonging to the coryletosum sub-association of the Blechno–Quercetum association. Vegetation was recorded in ten 2 m ×2 m quadrats at each site within which pitfall traps were placed to sample carabids. Median plant species richness per quadrat was greater in the regenerating site (11) than in the mature site (9.5), although this was not statistically significant. The median species richness of carabids per pitfall trap in the mature site (6) was significantly greater than in the regenerating site (3.5) at P

Conservation implications of land use practices on the plant and carabid beetle communities of two turloughs in Co. Galway, Ireland

Turloughs, which are unique to Ireland and are priority habitats under the European Habitats Directive, are seasonally flooded depressions found predominantly in the west of Ireland. In 1999, adjacent fields with different stocking densities were selected within two turloughs and plant/carabid beetle communities investigated using releves and pitfall traps, respectively. Overall a positive relationship between % soil moisture and plant/carabid species richness was detected and there was a negative correlation between % cover of bare ground (caused by poaching) and carabid species richness. In one turlough, the number of ruderal plant species was markedly higher in the field where the stocking density was more than twice that of the adjacent field. The results suggest that, while edaphic factors (such as soil moisture) play a role in determining the plant/carabid communities of the turloughs, high stocking levels, which cause excessive poaching, are likely to seriously affect both communities.

Hydrology and management of turloughs (temporary lakes) affect marsh fly (Sciomyzidae: Diptera) communities

Abstract.  1. Hydrology and management affect dipteran communities in wetlands and they, themselves, have the potential to influence prey communities.

RIPARIAN ZONE CREATION IN ESTABLISHED CONIFEROUS FORESTS IN IRISH UPLAND PEAT CATCHMENTS: PHYSICAL, CHEMICAL AND BIOLOGICAL IMPLICATIONS

COFORD (The National Council for Forest Research and Development in Ireland) & coordinated by Coillte Teoranta and Marine Institute

Conservation implications of grazing practices on the plant and dipteran communities of a turlough in Co. Mayo, Ireland

Turloughs, which are classified as priority habitats under the European Habitats Directive, are seasonally flooded depressions found almost exclusively in Ireland. In 2001, three adjacent fields with different stocking densities were selected and plant/dipteran communities within the same vegetation zone of each field (site) were investigated using quadrats and sweep netting, respectively. There was a significant positive relationship between Diptera morphospecies richness/Diptera abundance and mean vegetation height (P < 0.001). However, no significant relationship between Diptera morphospecies richness and plant species richness was found. Median Diptera morphospecies richness per sweep was lower at the site with the highest stocking density (17) than at the other two sites (22 and 31, respectively). Total species richness of Sciomyzidae was greater at the least grazed site (7) than at the more heavily grazed sites (2 and 1, respectively). The results suggest that an evaluation of turlough management practices based on plant communities alone is not sufficient and that at least some areas within the turlough basin remain ungrazed on a rotational basis to ensure maximum diversity of Diptera.

Sexual dimorphism and the impact of temperature on the pupal and adult stages of Sepedon spinipes spinipes, a potential biological control agent of fascioliasis

The malacophagous feeding behaviour of larvae of members of the family Sciomyzidae makes the group ideal for the selection of potential biological control agents of snail hosts of trematode diseases. The aim of this study was to investigate the effects of temperature (14 °C, 17 °C, 20 °C, 23 °C, and 26 °C) on the pupal and adult stages of Sepedon spinipes spinipes (Scopoli) (Diptera: Sciomyzidae). Larval prey density effects on the pupal stage and the extent of sexual dimorphism within the species are also assessed. Optimum growth conditions for the pupal stage and pre‐oviposition/oviposition periods, and female fecundity are identified for mass culturing purposes. The tendency of mature third instar larvae to engage in wandering behaviour is highlighted, and the biological control implications of such behaviour are discussed. Female puparia were significantly (P<0.001) heavier than males for both larval prey densities. Such sexual dimorphism would enable the prediction of adult sex from puparial weight prior to eclosion, thereby facilitating culture establishment. The effect of three food types [honey/yeast mixture only, crushed Radix balthica (L.) (Gastropoda: Pulmonata: Lymnaeidae) only, and honey/yeast mixture plus a crushed snail] on adult longevity (laboratory conditions) was also determined and the results suggest that adults live longest when provided with a crushed snail and a honey/yeast mixture.

A Comparison of Ground Beetle (Carabidae: Coleoptera) Communities in an Organic and Conventional Potato Crop

ABSTRACT An investigation of the carabid and plant communities of a conventional and an organic potato crop was carried out in the west of Ireland from June to September 1999. At each site, carabids were sampled using 15 pitfall traps, and 2 × 2 m quadrats were used to assess weed and potato cover. A total of 17 carabid species (672 individuals) were trapped during the study with 11 species common to both sites. 82.4% of individuals were captured at the organic site compared with 17.6% at the conventional site. The reciprocal Berger-Parker diversity index was 3.4 and 2.2 for the organic and conventional sites, respectively. Pterostichus niger and P. melanarius constituted 48.3% of the total catch and were the most abundant of all species captured. However, of the catch at each site, Bembidion bruxellense (44.9%) and P. niger (29.1%) were the most abundant species at the conventional and organic sites, respectively. A total of 13 weed species were identified, 11 of which were found exclusively in the organic field. A positive relationship between weed species richness and carabid species richness was apparent with r (Spearman Rank Correlation Coefficient) = 0.679, p < 0.001). The relationship was stronger between carabid species richness and weed cover (r = 0.704, p < 0.001). Differences between the sites appear to be related to weed cover although other possible factors are discussed.