Peatland Degradation Reduces Microbial Richness and Alters Microbial Functions in an Australian Peatland

Peatland ecosystems cover only 3 % of the world’s land area, however they store one-third of the global soil carbon (C). Peatlands play a central role in global C cycling as they contain more organic C than any other terrestrial ecosystem. Microbial communities are the main drivers of C decomposition in peatlands, yet we have limited knowledge of their structure and function. We investigated the vertical stratification of prokaryote and fungal communities from Wellington Plains peatland in the Australian Alps. Within the peatland complex, bog peat was sampled from the intact peatland and dried peat from the degraded peatland along a vertical soil depth gradient (i.e., acrotelm, mesotelm and catotelm). We analysed the prokaryote and fungal community structure, predicted functional profiles of prokaryotes using PICRUSt and assigned soil fungal guilds using FUNGuild. We found that the structure and the function of prokaryotes was vertically stratified in the intact bog. Carbon, manganese, nitrogen, lead and sodium best explained the prokaryote composition. Prokaryote richness was significantly higher in the intact bog acrotelm compared to degraded bog acrotelm. Fungal composition remained similar across the soil depth gradient, however there was a considerable increase in saprotroph abundance and decrease in endophyte abundance along the vertical soil depth gradient. The abundance of saprotrophs and plant pathogens was two-fold higher in the degraded bog acrotelm. Manganese, nitrogen, electrical conductivity and water table level (cm) best explained the fungal composition. Our results demonstrate that both fungal and prokaryote communities are shaped by soil abiotic factors and peatland degradation reduces microbial richness and alters microbial functions. Thus, current and future changes to the environmental conditions in these peatlands may lead to altered microbial community structure and associated functions which may have implications for broader ecosystem function changes in peatlands.

A comparison of collecting methods in relation to the diversity of Collembola in scree habitats

We compared the species composition, relative abundances and life form structure of subterranean Collembola (Hexapoda) captured by two different methods along a depth gradient of five forested scree sites in the Western Carpathians, Slovakia: (1) high-gradient extraction of soil samples, and (2) collection using subterranean traps. Our results showed that the soil samples were more efficient in covering species richness at the majority of the sites. The body size of the captured animals depended remarkably on the sampling method. Extraction was more effective in collecting smaller, less active hemi- and euedaphic forms of Collembola, while collection by subterranean traps favoured both motile ground-dwelling as well as relatively large, active euedaphobionts. Additionally, different trends in the vertical stratification of Collembola life forms and their relative abundances were detected by the two methods. Atmobionts and epigeonts, forming the greater part of the communities in traps compared to soil samples, were distributed along the entire scree profiles, but their relative abundance and species numbers had a strongly decreasing trend with depth. Moreover, motile, large hemi- and euedaphic forms had high relative abundances in traps in the middle and deeper scree levels at three sites. In contrast, in soil samples the hemi- and euedaphobionts with small body size were abundant on the surface of the MSS sites. Thus, soil sampling applied before installation of subterranean traps may serve as an appropriate complementary technique to obtain a more complete pattern of Collembola diversity in forested scree habitats.

Response of Benthic Fauna to Habitat Heterogeneity in a Shallow Temperate Lake

We investigated the response of benthic macroinvertebrates in the eulittoral, infralittoral, and sublittoral zones, in two segments of the freshwater Lake Wicko on the coast of the Baltic Sea. Our results showed that the morphometry of lakes plays a major role as a factor structuring the macroinvertebrates communities. Two parts of the lake, different in size and depth, show decreasing differences in the trophic state, abundance, diversity and number of indicator species of benthic fauna with the depth gradient. The most significant differences were observed between the littoral zones of both segments. Similar environmental conditions in the sublittoral zones corresponded to the simplified structure of the benthic macroinvertebrates communities. In the infralittoral zone, the most significant differences between the two segments, were recorded for mollusks and large crustaceans as well as the Oligochaeta/Chironomidae abundance ratio. In the sublittoral zone, the diversity of chironomids differed most strongly. Lower species diversity was found in the part of the lake with a slight depth decrease. Shredders reached significantly higher values in eulittoral and infralittoral of the deeper lake segment. Average Score Per Taxon increased with a depth gradient. We recommend testing benthic macroinvertebrates in lakes with different morphometrics individually for each depth zone.

Response of Hybrid Bermudagrass and Manilagrass to Soil Moisture Using Water-table Depth Gradient Tanks

Previous research involving turfgrass response to soil moisture used methodology that may compromise root morphology or fail to control outside environmental factors. Water-table depth gradient tanks were employed in the greenhouse to identify habitat specialization of hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] and manilagrass [Zoysia matrella (L.) Merr.] maintained at 2.5 and 5.1 cm. Turfgrass quality (TQ), normalized difference vegetation index (NDVI), canopy temperature (CT), and root biomass (RB) were used as metrics for plants grown in monoculture in sandy clay loam soil. Mowing height did not affect growth of turfgrass species in response to soil moisture. Turfgrass quality, NDVI, and RB were greatest, whereas CT was lowest at wetter levels [27- to 58-cm depth to the water-table (DWT)] of each tank where plants were growing at or above field capacity. However, bermudagrass RB was greatest at 27-cm DWT, whereas manilagrass RB at 27-cm DWT was lower than RB at 42.5- to 73.5-cm DWT in 2013 and lower than all other levels in 2014. Both species responded similarly to droughty levels (120- to 151-cm DWT) of the tanks. Turfgrass quality, NDVI, and RB were lowest, whereas CT was highest at higher droughty levels. Bermudagrass may be more competitive than manilagrass when soil moisture is high whereas both species are less competitive when soil moisture is low.