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. & Korte, 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

Ready for change: seed traits contribute to the high adaptability of mudflat species to their unpredictable habitat

Question A better understanding of species distribution and establishment requires in-depth information on their seed ecology. We hypothesised that seed traits of mudflat species may indicate a strong environmental adaptation in their highly specialised habitat. Furthermore, we asked the question, do seeds of mudflat species have a specific trait value to contribute high adaptability to small-scale variation in their unpredictable habitat? Location Central Europe. Methods Seeds of 30 typical mudflat species were used to measure 15 traits that govern seed dispersal (buoyancy and production), persistence (seed desiccation, mass and persistence in soil), and germination and establishment (germination response to different light, temperature and oxygen conditions). Cluster analysis and phylogenetic principal components analysis (pPCA) were conducted to define potential mudflat species functional groups as per their ecological optima. Results Seed production and seed mass displayed extremely high variation while seed buoyancy, desiccation and persistence in soil showed almost no variation. All study species produced buoyant, desiccation-tolerant and long-term persistent seeds. Germination and establishment traits also displayed similarity in their responses to different germination treatments as the majority (73%) of species has a moderate seed germination niche width. They germinated well under light/aerobic conditions irrespective to temperature fluctuations. The cluster analysis and pPCA separated species into three potential plant functional groups as 'true', 'flood-resistant' and 'facultative', mudflat species. Conclusion Moderate variation in the seed traits of mudflat plants suggests they employ different ecological strategies that seem highly predictive to the peculiarity of their specific micro-habitats, which are largely controlled by the hydroperiod gradient. It implies that seed trait information, which further needs to be tested for their adaptability, can advance our understanding of how community composition at the micro-habitat level depends on trait values of participating species

Plant community persistence strategy is elevation‐specific

Aims Persistence plays a key role in both plant population and community dynamics as it allows withstanding temporarily habitat conditions unsuitable for growth and reproduction. Plants can exploit three different strategies to persist in situ (building soil seed banks, increasing adult longevity and/or clonal reproduction), the dominance of which in a community might vary along environmental gradients. Yet, their relative role in plant persistence has never been investigated. Location The Bavarian Alps, Germany. Methods We collected data on seed soil persistence, adult longevity and clonality for 290 species occurring in 18 grasslands located along an elevational gradient of 1,000 metres and examined their contribution to persistence in a community. Linear models were used to estimate the relationship between elevation and these persistence strategies. Results We found that dominance of a certain persistence strategy varied depending on environmental variability. Specifically, persistence in lowlands was mainly achieved by persistent and dense soil seed banks along with extended clonal growth (larger spread distances and higher number of offspring). Contrastingly, the main persistence strategy in the alpine communities was increased adult longevity. Conclusions The changes in relative contribution of each strategy to community persistence along the elevational gradient are interrelated suggesting a trade-off among them. We conclude that this trade-off plays an important role in species co-existence and community assembly, and might be useful to understand vegetation dynamics under ongoing climate change and improve restoration efforts of upland ecosystems

Hydrology regime and hydrology recruitment niche predict changes in plant community composition across a pond habitat

Questions Niche differentiation is widely accepted as a key mechanism important for species coexistence. Seed germination and seedling survival were recognized as important contributors to niche segregation and could be a crucial filter for determining species' distributions and community composition. Only a little is known about the direct relationship between hydrology recruitment niche, hydrology regimes, and community composition. Therefore, the main aim of this study is to identify the changes in the composition of a pond community with respect to the hydrological regime and predict them by the recruitment niche of species. Location The Gloggere pond in the Altdorfer forest (47.848 N, 9.698 E, Ravensburg vicinity, Upper Swabia, Baden-Wuerttemberg, Germany). Methods A transect with 46 permanent plots was established throughout the Gloggere pond, and species percentage cover was recorded in September 1992–1995, 2006, and 2017. Pond drawdown was implemented in 1993. Sediment samples were collected in March 1995 across the transect, and a pot germination experiment with six hydrological treatments was performed. The hydrology recruitment niche from the seed bank germination experiment was compared with the field hydrology niche to show the importance of the hydrology regime for community composition. Results The hydrological regime determined the community composition in both the germination experiment and the field. Species-specific hydrology niche from the field correlated with species-specific recruitment niche measured in the germination experiment. Conclusions Our results support the importance of recruitment niche as a driver of community composition for pond areas. For understanding and predicting changes in plant community composition, it is necessary to combine knowledge about the recruitment niche and the ability of seeds’ survival in the sediment along a hydrological gradient with knowledge about abiotic filters, biotic interactions, and species-specific traits. Recognizing the recruitment niche is useful for better predicting the effect of future environmental changes, especially in the context of climate change and conservation management

The Teddy tool v1.1: temporal disaggregation of daily climate model data for climate impact analysis

Climate models provide the required input data for global or regional climate impact analysis in temporally aggregated form, often in daily resolution to save space on data servers. Today, many impact models work with daily data; however, sub-daily climate information is becoming increasingly important for more and more models from different sectors, such as the agricultural, water, and energy sectors. Therefore, the open-source Teddy tool (temporal disaggregation of daily climate model data) has been developed to disaggregate (temporally downscale) daily climate data to sub-daily hourly values. Here, we describe and validate the temporal disaggregation, which is based on the choice of daily climate analogues. In this study, we apply the Teddy tool to disaggregate bias-corrected climate model data from the Coupled Model Intercomparison Project Phase 6 (CMIP6). We choose to disaggregate temperature, precipitation, humidity, longwave radiation, shortwave radiation, surface pressure, and wind speed. As a reference, globally available bias-corrected hourly reanalysis WFDE5 (WATCH Forcing Data methodology applied to ERA5) data from 1980–2019 are used to take specific local and seasonal features of the empirical diurnal profiles into account. For a given location and day within the climate model data, the Teddy tool screens the reference data set to find the most similar meteorological day based on rank statistics. The diurnal profile of the reference data is then applied on the climate model. The physical dependency between variables is preserved, since the diurnal profile of all variables is taken from the same, most similar meteorological day of the historical reanalysis dataset. Mass and energy are strictly preserved by the Teddy tool to exactly reproduce the daily values from the climate models. For evaluation, we aggregate the hourly WFDE5 data to daily values and apply the Teddy tool for disaggregation. Thereby, we compare the original hourly data with the data disaggregated by Teddy. We perform a sensitivity analysis of different time window sizes used for finding the most similar meteorological day in the past. In addition, we perform a cross-validation and autocorrelation analysis for 30 globally distributed samples around the world that represent different climate zones. The validation shows that Teddy is able to reproduce historical diurnal courses with high correlations &gt;0.9 for all variables, except for wind speed (&gt;0.75) and precipitation (&gt;0.5). We discuss the limitations of the method regarding the reproduction of precipitation extremes, interday connectivity, and disaggregation of end-of-century projections with strong warming. Depending on the use case, sub-daily data provided by the Teddy tool could make climate impact assessments more robust and reliable.</p