High‐mountain areas provide excellent opportunities to study the effects of combined abiotic stresses on plant physiology given their variety of steep ecological gradients, low anthropogenic ...disturbance and remarkable levels of taxonomic diversity. Efficient photoprotective and antioxidant scavenging mechanisms are vital for survival in high‐mountain plants, having its altitudinal and seasonal variations determined by environmental or ontogenetic factors such as the decrease in mean temperatures and water availability. A number of stress indicators have been described in order to rapidly assess plant fitness in high‐mountain environments. For instance, carbon isotope (δ13C) and proline content as drought and temperature stress indicators, because of their link to water‐use efficiency and osmotic adjustment; photosynthetic pigments, related to phenology, nutrient status, light and temperature stress; and non‐structural carbohydrate accumulation in response to mild or brief drought conditions. The present review unveils the wide research opportunities available for the study of adaptive responses in high‐mountain plants via stress indicators, and calls attention to the substantial knowledge gap existing between alpine zones and other mountainous regions, such as Mediterranean high‐mountains. The aim is to grant a more holistic understanding of the physiological mechanisms driving plant life in high altitudes and improve the predictions of the effects of changing environments in these species and across ecological scales.
Increasing evidence indicates that in wild ecosystems plant viruses are important ecological agents, and with potential to jump into crops, but only recently have the diversity and population ...dynamics of wild plant viruses begun to be explored. Theory proposes that biotic factors (e.g., ecosystem biodiversity, host abundance, and host density) and climatic conditions would determine the epidemiology and evolution of wild plant viruses. However, these predictions seldom have been empirically tested. For 3 years, we analyzed the prevalence and genetic diversity of
species in preserved riparian forests of Spain. Results indicated that potyviruses were always present in riparian forests, with a novel generalist potyvirus species provisionally named Iberian hop mosaic virus (IbHMV), explaining the largest fraction of infected plants. Focusing on this potyvirus, we analyzed the biotic and climatic factors affecting virus infection risk and population genetic diversity in its native ecosystem. The main predictors of IbHMV infection risk were host relative abundance and species richness. Virus prevalence and host relative abundance were the major factors determining the genetic diversity and selection pressures in the virus population. These observations support theoretical predictions assigning these ecological factors a key role in parasite epidemiology and evolution. Finally, our phylogenetic analysis indicated that the viral population was genetically structured according to host and location of origin, as expected if speciation is largely sympatric. Thus, this work contributes to characterizing viral diversity and provides novel information on the determinants of plant virus epidemiology and evolution in wild ecosystems.
Neophyte invasions in European grasslands Axmanová, Irena; Kalusová, Veronika; Danihelka, Jiří ...
Journal of vegetation science,
March/April 2021, 2021-03-00, 20210301, 2021-03, Letnik:
32, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Questions
The human‐related spread of alien plants has serious environmental and socioeconomic impacts. Therefore, it is important to know which habitats are most threatened by invasion and why. We ...studied a wide range of European grasslands to assess: (a) which alien species are the most successful invaders in grasslands; (b) how invasion levels differ across European regions (countries or their parts) and biogeographical regions; and (c) which habitat types are the most invaded.
Location
Europe.
Methods
We selected 97,411 grassland vegetation plots from the European Vegetation Archive (EVA) and assigned a native or alien status to each of the 8,212 vascular plant species found in these plots. We considered only neophytes (alien species introduced after 1500 AD), which we further divided according to their origin. We compared the levels of invasion using relative neophyte richness in the species pool, relative neophyte richness and cover per plot, and percentages of invaded plots among regions and habitats.
Results
Only 536 species, representing 6.5% of all grassland vascular plant species, were classified as neophytes. These were mostly therophytes or hemicryptophytes with low habitat specificity. Most of them were present in very few plots, while only three species were recorded in more than 1% of all plots (Onobrychis viciifolia, Erigeron annuus and Erigeron canadensis). Although invasion levels were generally low, we found more invaded plots in the Boreal and Continental regions. When considering only non‐European neophytes, the Pannonian region was the most invaded. Among different grassland habitats, sandy grasslands were most invaded, and alpine and oromediterranean grasslands least invaded.
Conclusions
In general, natural and semi‐natural European grasslands have relatively low levels of neophyte invasions compared with human‐made habitats or alluvial forests, as well as with grasslands on other continents. The most typical neophytes invading European grasslands are species with broad ecological niches.
We provide the first overview of neophyte invasion patterns in European grasslands based on the most comprehensive data set of vegetation plots existing to date. In general, natural and semi‐natural European grasslands have relatively low levels of neophyte invasions compared with European man‐made habitats, riparian vegetation or with grasslands on other continents. The most typical neophytes are therophytes with broad niches.
Foundation species can change plant community structure by modulating important ecological processes such as community assembly, yet this topic is poorly understood. In alpine systems, cushion plants ...commonly act as foundation species by ameliorating local conditions. Here, we analyze diversity patterns of species' assembly within cushions and in adjacent surrounding open substrates (83 sites across five continents) calculating floristic dissimilarity between replicate plots, and using linear models to analyze relationships between microhabitats and species diversity. Floristic dissimilarity did not change across biogeographic regions, but was consistently lower in the cushions than in the open microhabitat. Cushion plants appear to enable recruitment of many relatively stress-intolerant species that otherwise would not establish in these communities, yet the niche space constructed by cushion plants supports a more homogeneous composition of species than the niche space beyond the cushion's influence. As a result, cushion plants support higher α-diversity and a larger species pool, but harbor assemblies with lower β-diversity than open microhabitats. We conclude that habitats with and without dominant foundation species can strongly differ in the processes that drive species recruitment, and thus the relationship between local and regional species diversity.
The study of ecological succession to determine how plant communities re-assemble after a natural or anthropogenic disturbance has always been an important topic in ecology. The understanding of ...these processes forms part of the new theories of community assembly and species coexistence, and is attracting attention in a context of expanding human impacts. Specifically, new successional studies provide answers to different mechanisms of community assemblage, and aim to define the importance of deterministic or stochastic processes in the succession dynamic. Biotic limits, which depend directly on biodiversity (i.e., species competition), and abiotic filtering, which depends on the environment, become particularly important when they are exceeded, making the succession process more complicated to reach the previous disturbance stage. Plant functional traits (PFTs) are used in secondary succession studies to establish differences between abandonment stages or to compare types of vegetation or flora, and are more closely related to the functioning of plant communities. Dispersal limitation is a PFT considered an important process from a stochastic point of view because it is related to the establishing of plants. Related to it the soil seed bank plays an important role in secondary succession because it is essential for ecosystem functioning. Soil compounds and microbial community are important variables to take into account when studying any succession stage. Chronosequence is the best way to study the whole process at different time scales. Finally, our objective in this review is to show how past studies and new insights are being incorporated into the basis of classic succession. To further explore this subject we have chosen old-field recovery as an example of how a number of different plant communities, including annual and perennial grasslands and shrublands, play an important role in secondary succession.
The aim of this work was to study the sensibility to warming of soil organic matter (SOM) decomposition in Mediterranean high mountain areas. Thus, we investigated the effects of temperature, C ...availability and vegetation in a Mediterranean high-mountain area in relation to SOM decomposition patterns. Along an altitudinal gradient (from 2100 to 2380ma.s.l.) in Central Spain mountains, we assessed the altitudinal shifts in soil organic C (SOC), soil nitrogen (N), dissolved organic carbon (DOC), microbial biomass C (MBC), microbial respiration, microbial respiration sensitivity to temperature (Q10) and C availability index (CAI). Furthermore, we tested the differences in SOM decomposition rates between grasslands and shrub vegetation. SOC, DOC, N content, MBC, microbial respiration and CAI decreased, while Q10 increased with increasing altitude. In the grassland, MBC and microbial respiration were positively correlated to SOM. Q10 was positively correlated to pH and negatively correlated to substrate-induced microbial respiration. Soils below shrubs showed lower microbial respiration rates, lower CAI, and higher Q10 than soils below grassland. However MBC, DOC and soil N content were higher below shrubs. The results suggest that a rise in temperature would enhance SOM decomposition rates in grasslands more dramatically at higher altitudes, since they are more sensitive to temperature increases. The SOC accretion observed below shrubs may be due to the lower respiration rate of soil microorganisms, possibly determined by lower C substrate availability below shrubs. This result suggests a higher recalcitrance of shrub litter compared to grassland litter. Nevertheless, SOC in shrubland may be released at a higher rate due to its higher temperature sensitivity.
•Soil organic C and microbial activity decreased with altitude under grassland.•Q10 of soil microbial respiration increased with altitude under grassland.•Microbial activity was lower in soils under shrubs.•Q10 of microbial respiration and soil organic C contents were higher under shrubs.•Altitude and vegetation led differences in organic matter decomposition.
Aims
Ellenberg‐type indicator values are expert‐based rankings of plant species according to their ecological optima on main environmental gradients. Here we extend the indicator‐value system ...proposed by Heinz Ellenberg and co‐authors for Central Europe by incorporating other systems of Ellenberg‐type indicator values (i.e., those using scales compatible with Ellenberg values) developed for other European regions. Our aim is to create a harmonized data set of Ellenberg‐type indicator values applicable at the European scale.
Methods
We collected European data sets of indicator values for vascular plants and selected 13 data sets that used the nine‐, ten‐ or twelve‐degree scales defined by Ellenberg for light, temperature, moisture, reaction, nutrients and salinity. We compared these values with the original Ellenberg values and used those that showed consistent trends in regression slope and coefficient of determination. We calculated the average value for each combination of species and indicator values from these data sets. Based on species’ co‐occurrences in European vegetation plots, we also calculated new values for species that were not assigned an indicator value.
Results
We provide a new data set of Ellenberg‐type indicator values for 8908 European vascular plant species (8168 for light, 7400 for temperature, 8030 for moisture, 7282 for reaction, 7193 for nutrients, and 7507 for salinity), of which 398 species have been newly assigned to at least one indicator value.
Conclusions
The newly introduced indicator values are compatible with the original Ellenberg values. They can be used for large‐scale studies of the European flora and vegetation or for gap‐filling in regional data sets. The European indicator values and the original and taxonomically harmonized regional data sets of Ellenberg‐type indicator values are available in the Supporting Information and the Zenodo repository.
This paper introduces a harmonized data set of Ellenberg‐type indicator values applicable at the European scale. We collected 13 regional data sets of indicator values for vascular plants compatible with Ellenberg scales and calculated a new data set of Ellenberg‐type indicator values for 8,908 European vascular plant species.
Aim
Alpine habitats support unique biodiversity confined to high‐elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and ...isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups.
Location
European mountains below 50° N.
Time period
Between 1928 and 2019.
Major taxa studied
Vascular plants.
Methods
We compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non‐alpines. We used species–area relationships to test the influence of the extent of alpine areas on regional richness, and mixed‐effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions.
Results
Pool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non‐alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non‐alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions.
Main conclusions
Besides area effects, edaphic, topographic and spatio‐temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post‐glacial environmental filtering, while non‐alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles.
Aims We assessed the temporal changes on microbial biomass in relation to changes in soil moisture, dissolved organic carbon and plant biomass during the summer season in a Mediterranean ...high-mountain grassland. Methods Temporal variations were tested by two-way ANOVA. The relationships among microbial biomass, plant biomass, soil water content, soil organic carbon, dissolved organic carbon and total soil nitrogen during the summer season were assessed by means of structural equation modeling. Results Microbial biomass did not show variation, while dissolved organic carbon and root biomass decreased throughout the summer. Aboveground plant biomass peaked in the middle of the summer, when soil water content was at its minimum. Soil water content directly and negatively affected soil microbial biomass, and positively affected dissolved organic carbon. Moreover soil microbial biomass and dissolved organic carbon were negatively related. Plant biomass effects on soil microbial biomass were driven by root biomass, which indirectly affected soil microbial biomass through effects on soil organic carbon and soil nitrogen. Conclusions The temporal dynamic of microbial biomass during the summer season appeared to differ from previous observations in temperate alpine communities, and indicated the drought resistance of the microbial community during the summer in Mediterranean high-mountain grasslands. During the dry period, microbial biomass may play an alternative role in soil carbon conservation.
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