Ant Diversity in Croatian p eat bogs

1. FOREST 1 FOREST EDGE BOG 1 Epimedio-Carpinetum betuli Epimedio-Carpinetum betuli Rynchosporetum albae pH = 4,5 Ant Diversity in Croatian peat bogs 1-5 Jelena Bujan1, Andreja Brigić2, Ana Ješovnik1 1Croatian Myrmecological Society, Gortanova 14, Zagreb, Croatia (jelena.bujan@gmail.com, ana.mrav@gmail.com) 2Department of Zoology, Division of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, Croatia (andrejab@biol.pmf.hr) INTRODUCTION Peat bogs are rare and exceedingly localised habitats in Croatia. Due to their small size, isolation and drainage, and especially to progressive vegetation succession following the abandonment of traditional human activities, these habitats are among the critically endangered habitats in Croatia. The aim of this study was: (1) to investigate structure of ant communities on peat bogs and surrounding habitats; (2) to determine whether species which are bog specialists exist in Croatian acidophilic peat bogs. STUDY AREA This study was conducted on two Croatian acidophilic bogs and their surrounding habitats that differ in size and variety of microhabitats (Figure 1 and 2). FOREST 2 BOG 2 Epimedio-Carpinetum betuli Drosero – Caricetumstellulatae pH = 4,6 Fig 2. Đon močvar is the largest(10 ha) and oldest peat bog in Croatia that encompasses a mosaic of different habitats. Nowadays, with abandonment of traditional land use, main threat to bog vegetation is succession. Fig 1.Dubravica bog area decreased drastically during the last 50 years (to only about 605m2) due to water table changes and vegetation succession. RESULTS AND DISCUSSION A total of 22 ant species and 16 697 individuals were caught. The highest number of individuals (13 584) was recorded at bog 1, where M. rubra made 87% of the total catch(Table 1). Together with M. ruginodis, these two species made 99% of the catch at this site. Regarding the highest number of specimens of M. rubra found during the summer months, the high abundance of this species is probably the result of colony budding. Kruskal-Wallis ANOVA (Multiple Comparison test) showed statistically significant difference in ant abundance data between bog 1 and forest edge (p<0,05) and bog 1 and forest 1 (p<0,01). Forest edge and forest 1 didnot show any statistical differences (p>0,05). MATERIALS AND METHODS Ants were collected by pitfall traps(5 traps per site; Ø 7,5 cm), between April and December in 2008. Traps were partially filled with a saturated sodium chloride solution. To calculate the diversity of the ant assemblages Simpson (1-λ') and Shannon-Wiener indices (H') were used. Evenness was estimated using Pielou evenness. A cluster analysis was constructed on Bray-Curtis similarity.The analyses were carried out using the PRIMER program. Abundance data at Dubravica peat bog were analysed using Kruskal-Wallis ANOVA followed by Multiple Comparisons test (STATISTICA). Table 2. Diversity of ant species at studied sites calculated using Shannon – Wiener and Simpson indices. Evenness was calculated using Pielou index. Table 1. Abundance and dominance of ant species collected during one vegetation season on five researched sites. Sites are including following habitats: bog 1 – as. Rynchosporetum albae, forest edge, bog 2 – as. Drosero – Caricetumstellulatae, forest sites 1 and 2 – as. Epimedio – Carpinetum betuli. Dominant species are colored. Fig 3. Clustering of all sites based on Bray-Curtis similarity index. Analysis was conducted using the presence-absence data. Tyrphophilous species M. scabrinodis was found on both peat bogs and forest sites. However, its abundance was significantly lower at smaller bog. This is probably caused by competition and strong dominance of M. rubra and M. ruginodis that might haveexcluded M. scabrinodis by occupying all available nesting sites. Furthermore, the peat bog size might have impacted the abundance of tyrphophilous M. scabrinodis. Due to both, the high variety of different microhabitats and consequently of nesting sites and significantly larger size of bog 2, the competition among the Myrmica species is not so strong and thus all three species are probably present. Overall, the cluster analyses (based on presence-absence data) show that geographically close sites have similar ant fauna. On the contrary, both peat bog sites from different bogs did not show high similarity (Figure 3). Diversity was generally lower at peat bog sites, possibly due to extremely harsh conditions on bogs and strong dominance of Myrmica species (Table 2). • CONCLUSION • True bog specialists, such as Formica uralensis and F. picea were not found, while tyrphophilous M. scabrinodiswas more abundant at bigger bog. • Differences in species richness and ant abundance amongst acidophilic peat bogs are most likely due to the varying bog size, water table and vegetation composition. • Absence of bog specific ant fauna in Croatian peat bogs is most likely due to specific types of peat bogs which are small in size and isolated habitats. • Similar to flora and carabid beetle fauna of peat bogs, it appears that the ant fauna on Croatian bogs is impoverished. Acknowledgements: