AQUATIC AND MARSHY VEGETATION IN THE CENTER OF THE LOWER PLAIN OF SOMES RIVER: GENERAL CHARACTERISATION

Aiming to a larger study of vegetation of the lower Some Plain (Romania), this short paper summarises the outcome of the floristic inventories performed in aquatic and marshy vegetation, which was dominant in the area until about three centuries ago when the extended wetland drainage has started. By using the phytosociological method, 20 plant associations assigned to four vegetation classes were distinguished. Without presenting phytosociological tables at this first stage, the syntaxonomical framework, distribution and species composition of the revealed plant communities are briefly discussed by reference to the process of wetland drying and successional change as well as to newly formed anthropogenic lakes. The conservative value of some plant community types is emphasized by mentioning the presence of several endangered species that are included in the European-level Habitats Directive and various regional or national red lists/books.

Successional change, restoration success, and resilience in boreal mixedwood vegetation communities over three decades

Long-term studies of vegetation succession can inform restoration of degraded forests. We examined resilience of a boreal mixedwood vegetation community, asking whether treatments employed to restore wood production in a degraded ecosystem could also restore diversity and composition of vegetation communities. The Inga Lake trial, established in 1987 in northeastern British Columbia, used mechanical, fire, and chemical and manual treatments, encompassing a gradient of restoration effort, and tree planting to restore a shrubland to white spruce (Picea glauca (Moench) Voss) forest. We monitored vascular plant, bryophyte, and macrolichen composition five times over 31 years on five to seven treatments replicated five times. We used mixed-effects models and nonmetric multidimensional scaling to compare diversity and composition among treatments and with mature reference forests. Low- to high-effort restoration created a gradient from broadleaf- to spruce-dominated overstories. Diversity increased with restoration effort. Four of 253 taxa occurred in mature forests only. There was no evidence that lower versus higher effort treatments followed divergent successional pathways toward broadleaved versus spruce reference communities. Our results suggest that these mixedwood vegetation communities lie within a broad domain of successional attraction that confers high ecological resilience to disturbance. Gap cuttings to stimulate understory re-initiation and provide woody debris are recommended to complete the restoration.

Mining Contamination Disrupts Successional Change in Salt Marshes

<p>Salt marshes can generally be considered as sinks for metals. Research into salt marshes in Cornwall, UK suggests those estuaries heavily impacted by mining contamination are characterised by a less diverse vegetation compared with a significantly less-polluted site. Assessment using the National Vegetation Classification on the mid-marsh confirmed an Armeria maritima-dominated community was to be found in the most metal-enriched salt marsh of Restronguet Creek. However, this plant was co-dominant with Plantago maritima in the moderately contaminated marsh of Lelant and not present at all in the Camel, which has been subject to limited mining related contamination. Using canonical correspondence analysis, vegetation abundance data was compared with geochemical variables within the sediment. Metals were studied using extractions to signal bioavailability. P. maritima was not associated with the very high metal levels found in Restronguet Creek. A. maritima, had some association with soluble copper and was closer to the bulk of metals than P. maritima. As tolerance to adverse conditions and competitiveness are mutually exclusive, A. maritima, therefore, exists in a successional relationship with P. maritima. A. maritima then appears to be outcompeted by P. maritima in marshes with low metal loadings. Moderately high metal content results in a loss of competitiveness by P. maritima allowing A. maritima to co-dominate. In extremely metal-rich estuaries, however, P. maritima is unable to compete, allowing A. maritima to colonize the mid-marsh. Vegetation community may, therefore, be useful as an indicator of the level of metal contamination.</p>

Restoring a butterfly hot spot by large ungulates refaunation: The case of the Milovice military training range, Czech Republic

Background: Refaunation by large ungulates represents a cost-efficient approach to managing natural biotopes. We studied butterflies inhabiting grasslands of the former Milovice military training range in the Czech Republic, grazed since 2015 by a combination of Exmoor pony (“wild” horse), Tauros cattle (“aurochs”) and European wisent. Methods: We compared presence-absence patterns from two surveys preceding the refaunation, one immediately after military use termination (early 1990s), the other prior to the refaunation (2009), with the current (2016–19) results of monitoring 8 grazed and 8 ungrazed plots. We analysed the life history, climatic and conservation-related traits of recorded butterflies to gain insights into the ungulates’ impacts. Results: Following the termination of military use, several poorly mobile species displaying broad oceanity niches were lost. Newly gained species are more mobile and prefer warmer continental conditions. Currently, numbers of butterfly species do not differ between refaunated and neglected plots, but the former hosted higher abundances. Butterflies developing on coarse grasses and shrubs inclined towards neglected plots, whereas refaunated plots supported species developing on small forbs. Conclusion: The changes in species composition following the cessation of military use are attributable to successional change, coupled with climate-driven expansion of thermophilous and mobile species. By blocking succession, large ungulates support butterflies depending on competitively poor plants. Preserving butterflies of late-successional stages is ensured by the diverse setting of the reserves and by the relatively low ungulate densities.

Quantifying successional change and ecological similarity among Cretaceous and modern cold-seep faunas

Accurately recognizing analogues between fossil and modern ecosystems allows paleoecologists to more fully interpret fossil assemblages and modern ecologists to leverage the fossil record to address long-term ecological and environmental changes. However, this becomes increasingly difficult as taxonomic turnover increases the dissimilarity between ecosystems. Here we use a guild-based approach to compare the ecological similarity of Cretaceous cold-seep assemblages preserved in the Pierre Shale surrounding the Black Hills and modern cold-seep assemblages from five previously recognized biofacies. We modify modern assemblage data to include only those taxa with fossilizable hard parts greater than 5 mm in length to make these modern data sets more comparable to potential fossil analogues. We find that while the Black Hills assemblages are more similar in ecological guild composition to the modern thyasirid biofacies, subsets share similarities in ecological structure to the lucinid and mussel-bed biofacies. The fossil seep assemblages are also more similar to one another than are modern assemblages belonging to the same biofacies, despite greater geographic and temporal dissimilarity among the fossil samples. Furthermore, guild-level ordination analyses show a secondary faunal gradient that reflects community succession in the hard substrate–dominated modern assemblages and reveals a parallel faunal gradient in the soft sediment–dominated Cretaceous assemblages, consistent with a gradient in the influence of seep fluids on the faunas. Thus, while the Black Hills assemblages are quite homogeneous in their composition, they capture ecological variation similar to successional patterns in modern seep systems.

Oomycetes during 120,000 years of temperate rainforest ecosystem development

The occurrence of plant-associated oomycetes in natural ecosystems and particularly during long-term ecosystem development is largely unknown, despite the importance of many oomycetes as plant pathogens. Using DNA sequencing from roots, we investigated the frequency and host relationships of plant-associated oomycete communities along a 120 000 year glacial chronosequence, comprising site ages with rapid compositional change (“early succession”; 5, 15, and 70 years old soil); relatively stable higher-diversity sites (“mature”, 280, 500, 1000, 5000, 12000 years); and ancient, nutrient-limited soils with declining plant diversity and stature (“retrogression”, 60 000, 120 000 years). Plant-associated oomycetes were frequent in all three early successional sites, occurring in 38 – 65% of plant roots, but rare (average 3%) in all older ecosystems. Oomycetes were highly host specific, and more frequent on those plant species that declined most strongly in abundance between ecosystem ages. The results support the particular importance of plant-associated oomycetes in early succession (up to 70 years). High host specificity and correlations of abundance of oomycete inside roots with declining plant species are consistent with oomycete-driven successional change.