The importance of livestock grazing at woodland-grassland interface in the conservation of rich oakwood plant communities in temperate Europe

Traditional husbandry fostered rich semi-open oakwood communities composed of forest and non-forest species. In the eastern Carpathian region, silvo-pastoralism was commonplace by the mid-1900s. This study aimed to determine the state of the preservation of the ecotonal character of grassland-woodland interfaces in formerly pastured cultural landscapes of SE-Polish Carpathian foothills and W-Ukrainian Ciscarpathia in the context of land-use change. In the first region, despite the long-lasting history of forest grazing amongst mainly arable land, the post-WWII collapse of husbandry and the imposed ban on forest grazing, has led to swift development of dense undergrowth and establishment of impermeable ecological woodland-open habitat barrier. As a result, former silvo-pastoral oakwoods developed the features of the Tilio-Carpinentum forest community although some forest species have not yet moved in due to their poor dispersibility. The much younger oakwoods in the Ukrainian study region are remnants of the sparsely treed grasslands, some of which had been ploughed in the mid 20th century. Their semi-open canopy structure, maintained through repetitive grass burning, contributes to the communities ecotonal character, but without regular livestock-led plant “spill-over” from the grassland, the oakwoods remain species-poor. The restoration of species-rich semi-open oak woods requires “unsealing” the forest-grassland interface, reducing the degree of canopy closure, and opening that zone up to extensive grazing—an important seed dispersal vector.

Cyanobacteria and Algae in Clouds and Rain in the Area of puy de Dôme, Central France

ABSTRACT The atmosphere contains diverse living microbes, of which the heterotrophic community has been the best studied. Microbes with other trophic modes, such as photoautotrophy, have received much less attention. In this study, culture-independent and dependent methods were used to examine the presence and diversity of oxygenic photoautotrophic microbes in clouds and rain collected at or around puy de Dôme Mountain, central France. Cloud water was collected from the summit of puy de Dôme (1,465 m above sea level [a.s.l.]) for cultivation and metagenomic analysis. Cyanobacteria, diatoms, green algae, and other oxygenic photoautotrophs were found to be recurrent members of clouds, while green algae affiliated with the Chlorellaceae were successfully cultured from three different clouds. Additionally, rain samples were collected below the mountain from Opme meteorological station (680 m a.s.l.). The abundance of chlorophyll a-containing cells and the diversity of cyanobacteria and green algae in rain were assessed by flow cytometry and amplicon sequencing. The corresponding downward flux of chlorophyll a-containing organisms to the ground, entering surface ecosystems with rain, varied with time and was estimated to be between ∼1 and >300 cells cm−2 day−1 during the sampling period. Besides abundant pollen from Pinales and Rosales, cyanobacteria of the Chroococcidiopsidales and green algae of the Trebouxiales were dominant in rain samples. Certain members of these taxa are known to be ubiquitous and stress tolerant and could use the atmosphere for dispersal. Overall, our results indicate that the atmosphere carries diverse, viable oxygenic photoautotrophic microbes and acts as a dispersal vector for this microbial guild. IMPORTANCE Information regarding the diversity and abundance of oxygenic photoautotrophs in the atmosphere is limited. More information from diverse locations is needed. These airborne organisms could have important impacts upon atmospheric processes and on the ecosystems they enter after deposition. Oxygenic photoautotrophic microbes are integral to ecosystem functioning, and some have the potential to affect human health. A better understanding of the diversity and the movements of these aeolian dispersed organisms is needed to understand their ecology, as well as how they could affect ecosystems and human health.

An Ant-Plant Mesocosm Experiment Reveals Dispersal Patterns of Myrmecochorous Plants

For Central European herbs, ants are one common dispersal vector acting at relatively small spatial scales. Though extensively studied concerning the different benefits to plants, specific dispersal patterns mediated by ants have been reportedly very sparsely and without any validation. Thus, we studied the seed dispersal pattern of a set of myrmecochorous plant species in a novel mesocosm experiment. We examined the seed dispersal distances of four forest herbs (Hollow Root–Corydalis cava (L.) Schweigg. & Körte, Alpine Squill–Scilla bifolia L., and Common Dog-violet–Viola riviniana Rchb. and the annual Ivy-leaved Speedwell–Veronica hederifolia L.) by the red ant Myrmica ruginodis Nylander in 8.25 m² large plots under natural conditions with and without ants. In the presence of Myrmica ants, the bulb geophytes C. cava and S. bifolia showed a significantly higher fraction of dispersed seedlings and a maximum dispersal distance of 322 cm. Estimated by nearest neighbor analyses, distances between single C. cava seedlings were significantly higher in ant plots than in exclosures without ants. The annual species Veronica hederifolia showed a few dispersed seedlings in ant plots only, while the diplochorous hemicryptophyte Viola riviniana germinated in a widely scattered manner with distances up to 241 cm due to ballochorous dispersal in both ant and exclosure plots, but with a maximum of 324 cm only by means of ants. Our results indicate the escape from the mother plant and dispersal for distance as an important benefit for myrmecochorous species, potentially accompanied by benefits through reduced competition.

Chelonocytherois omutai gen. et sp. nov. (Crustacea: Ostracoda) from the back of loggerhead sea turtles

Chelonocytherois omutai gen. et sp. nov., is found on the back of female loggerhead sea turtles on the nesting beach of the Yakushima Island, Kagoshima Prefecture, Japan. The present study provides the first species-level identification and description of Ostracoda as sea turtle epibionts. The new genus and species, which belongs to the family Paradoxostomatidae Brady and Norman, 1889, can clearly be distinguished from other genera by the morphology of the carapace and the appendages. Especially, the quite large sieve structure on the pore system of the carapace is characteristic to this genus. Although a similar structure is also found in the commensal ostracod genus Redekea de Vos, 1953, the new genus has distinctive mandibular and maxillular morphologies. From examination of the appendages, C. omutai gen. et sp. nov. seems to be an epibiotic species associated with sea turtles, but not a strictly commensal species. Additionally, the nearly complete 18S rRNA gene sequence is determined for C. omutai gen. et sp. nov. for future molecular phylogenetic studies. Since the sea turtles migrate across the oceans in their ontogenetic stages, they may play a role as a long-distance dispersal vector for C. omutai gen. et sp. nov.

Can pathogens optimize both transmission and dispersal by exploiting sexual dimorphism in their hosts?

Pathogens often rely on their host for dispersal. Yet, maximizing fitness via replication can cause damage to the host and an associated reduction in host movement, incurring a trade-off between transmission and dispersal. Here, we test the idea that pathogens might mitigate this trade-off between reproductive fitness and dispersal by taking advantage of sexual dimorphism in their host, tailoring responses separately to males and females. Using experimental populations of Daphnia magna and its bacterial pathogen Pasteuria ramosa as a test-case, we find evidence that this pathogen can use male hosts as a dispersal vector, and the larger females as high-quality resource patches for optimized production of transmission spores. As sexual dimorphism in dispersal and body size is widespread across the animal kingdom, this differential exploitation of the sexes by a pathogen might be an unappreciated phenomenon, possibly evolved in various systems.

Forest passerines as a novel dispersal vector of viable bryophyte propagules

Animal dispersal influences the community structure and diversity of a wide variety of plant taxa, yet the potential effects of animal dispersal in bryophytes (hornworts, liverworts, and mosses) is poorly understood. In many communities, birds use bryophyte-abundant niche space for foraging and gathering nest material, suggesting that birds may play a role in bryophyte dispersal. As highly motile animals with long migratory routes, birds potentially provide a means for both local and long-distance bryophyte dispersal in a manner that differs greatly from passive, aerial spore dispersal. To examine this phenomenon, we collected and germinated bryophyte propagules from the legs, feet and tails of 224 birds from 34 species within a temperate forest community. In total we found 1512 spores, and were able to germinate 242 bryophyte propagules. In addition, we provide evidence that topical (externally-carried) spore load varies by bird species and behaviour. Tail feather spore abundance is highest in bark and foliage gleaning species and is positively correlated with tarsal length. Together, these data suggest that a variety of forest birds exhibit the potential to act as dispersal vectors for bryophyte propagules, including an abundance of spores, and that understanding the effects of animal behaviour on bryophyte dispersal will be key to further understanding this interaction.

High potential of sub-Mediterranean dry grasslands for sheep epizoochory

There is a general decline of grasslands across Europe due to habitat loss and degradation. Ensuring plant dispersal thus becomes a key process for preserving grassland patches in all scales. We examined diaspore dispersal by sheep epizoochory in the pastures of the North Adriatic Karst (NW Slovenia) and determined the qualitative and quantitative features of diaspores in fur. We recorded 25,650 diaspores of 141 plant taxa (with 107 taxa and 23,350 diaspores determined to species level), using three different methods: (i) the “whole-coat method”, (ii) the “part-of-thecoat method” and (iii) a “seedling emergence method”. A comparison of these techniques revealed that the “wholecoat method” provided the highest number of diaspores and plant species. All diaspores were clustered into five emergent groups based on seven functional traits (diaspore weight, length, width, height, volume, specific weight and the diaspore surface structure). Our research revealed that sheep represent an important dispersal vector, since about half of the plant species recorded in the pastures were found as diaspores in fur. This study contributes to knowledge about the modes of seed dispersal in seminatural grasslands. Taking into account that livestock play a key role in vegetation dynamics, understanding their effects on seed dispersal is essential for conservation and restoration of these species-rich grassland communities.