V. G. Onipchenko

Plot-scale evidence of tundra vegetation change and links to recent summer warming

Temperature is increasing at unprecedented rates across most of the tundra biome(1). Remote-sensing data indicate that contemporary climate warming has already resulted in increased productivity ov ...

Linking litter decomposition of above‐ and below‐ground organs to plant–soil feedbacks worldwide

Conceptual frameworks relating plant traits to ecosystem processes such as organic matter dynamics are progressively moving from a leaf-centred to a whole-plant perspective. Through the use of meta-analysis and global literature data, we quantified the relative roles of litters from above- and below-ground plant organs in ecosystem labile organic matter dynamics. We found that decomposition rates of leaves, fine roots and fine stems were coordinated across species worldwide although less strongly within ecosystems. We also show that fine roots and stems had lower decomposition rates relative to leaves, with large differences between woody and herbaceous species. Further, we estimated that on average below-ground litter represents approximately 33 and 48% of annual litter inputs in grasslands and forests, respectively. These results suggest a major role for below-ground litter as a driver of ecosystem organic matter dynamics. We also suggest that, given that fine stem and fine root litters decompose approximately 1.5 and 2.8 times slower, respectively, than leaf litter derived from the same species, cycling of labile organic matter is likely to be much slower than predicted by data from leaf litter decomposition only. Synthesis. Our results provide evidence that within ecosystems, the relative inputs of above- versus below-ground litter strongly control the overall quality of the litter entering the decomposition system. This in turn determines soil labile organic matter dynamics and associated nutrient release in the ecosystem, which potentially feeds back to the mineral nutrition of plants and therefore plant trait values and plant community composition.

Functional traits predict relationship between plant abundance dynamic and long-term climate warming

Significance Although the response of the Plant Kingdom to climate change is acknowledged as one of the fundamental feedback mechanisms of environmental changes on the Earth, until now, the response of plant species to in situ climate warming has been described at the level of a few fixed plant functional types (i.e. grasses, forbs, shrubs etc.). This approach is very coarse and inflexible. Here, we show that plant functional traits (i.e., plant features) can be used as predictors of vegetation response to climate warming. This finding enlarges possibilities for forecasting ecosystem responses to climate change. Predicting climate change impact on ecosystem structure and services is one of the most important challenges in ecology. Until now, plant species response to climate change has been described at the level of fixed plant functional types, an approach limited by its inflexibility as there is much interspecific functional variation within plant functional types. Considering a plant species as a set of functional traits greatly increases our possibilities for analysis of ecosystem functioning and carbon and nutrient fluxes associated therewith. Moreover, recently assembled large-scale databases hold comprehensive per-species data on plant functional traits, allowing a detailed functional description of many plant communities on Earth. Here, we show that plant functional traits can be used as predictors of vegetation response to climate warming, accounting in our test ecosystem (the species-rich alpine belt of Caucasus mountains, Russia) for 59% of variability in the per-species abundance relation to temperature. In this mountain belt, traits that promote conservative leaf water economy (higher leaf mass per area, thicker leaves) and large investments in belowground reserves to support next year’s shoot buds (root carbon content) were the best predictors of the species increase in abundance along with temperature increase. This finding demonstrates that plant functional traits constitute a highly useful concept for forecasting changes in plant communities, and their associated ecosystem services, in response to climate change.

Population strategies in severe environments: Alpine plants in the northwestern Caucasus

. This study attempts to show a differentiation into strategy types among plant species of four alpine communities in the northwestern Caucasus, Russia. Four groups of population characteristics (traits) were examined: above-ground biomass, seed size, seed yield and occurrence of a persistent seed bank. In addition, values for relative growth rate and a morphology index were estimated. Agglomerative Cluster Analysis and Principal Component Analysis were applied to a data set with 42 species from these communities and six species characteristics. In the Geranium gymnocaulon meadow, the most productive community, large gaps occur created by wild boars and bears. Here, the response of 13 species to disturbance was also analysed. Strategy types were approached both according to Grime: ‘competitive’, ‘ruderal’, ‘stress-tolerating’ and according to Ramensky, Rabotnov and Romanovsky: ‘violent’ ≈ dominant (V), ‘explerent’ ≈ explorative (E) and ‘patient’ ≈ endurant (P). Differentiation into strategy types was more obvious in productive alpine grasslands than in lichen heaths and snowbed communities. The grassland dominants Festuca varia, Geranium gymnocaulon and Hedysarum caucasicum showed a more or less ‘violent’ strategy. Species approaching an Estrategy, e.g. Matricaria caucasica, Sibbaldia procumbens and Gnaphalium supinum, were also found in the grasslands but prevailed in the snowbed communities. Species with a ‘patient’ strategy prevailed in the lichen heaths. We conclude that plant strategy types are well-differentiated, this is also seen in plant communities occurring under severe high-mountain conditions. We also suggest that the approaches by Grime and Ramensky/Rabotnov/Romanovsky are not so similar as has been assumed earlier and that the R/R/R types are better differentiated and ecologically better interpretable. We emphasize the gradient character of strategy ‘types’ and would characterize plant species by the degree of adaptation to conditions: (1) from small seed size and large persistent seed bank to large seed size and absence of a seed bank; (2) from high to low biomass and seed production, with relative growth rate as a less important partially correlated trait.

A rediscovered treasure: mycorrhizal intensity database for 3000 vascular plant species across the former Soviet Union

The symbiosis between vascular plants and mycorrhizal fungi is paramount for carbon and nutrient cycling in most of the worlds ecosystems. Most vascular plant species are associated with mycorrhizal fungal partners, and the association is essential for the carbon and nutrition economies of both partners. However, despite its clear importance, data on this symbiosis are lacking: for most vascular plant species, mycorrhizal type is unknown. Very rarely is there data on the levels of mycorrhizal infection intensity in multiple habitats. We translated and digitized a huge data set on vascular plant mycorrhizal intensity throughout the former Soviet Union, previously available only as a hard copy appendix of the doctoral thesis of Ivan A. Selivanov published in Russian in 1976 and not accessible to the international research community. We updated the taxonomic plant nomenclature to the International Plant Name Index and adjusted mycorrhizal and ecological terminology according to the modern international literature. The database contains 7445 records on mycorrhizal infection type and intensity of 2970 plant species from 155 families, in 154 sites, situated across the former Soviet Union (mostly on the territory of the current Russia, Ukraine, and Kazakhstan), comprising together extensive geological, topographic, and climatic gradients. The data set includes percentage infection for each species–site combination for arbuscular, ericoid, arbutoid, endo-mycorrhizal, dark septate, orchid- and ecto-mycorrhizal fungi. Each record has a detailed description of geography. For many records, soils and host plant community are described. Most of the sites are natural; 10 sites are situated in botanical gardens. For 1291 species the intensity of mycorrhizal infection is quantified in multiple plant communities (2–57). The remaining species are described at single sites. Selivanov developed his own methods for quantifying mycorrhizal infection intensity. These methods are comparable, but not identical to, the methodology commonly used today. Based on our own sampling of 99 plant species collected in two distant sites (Caucasus [Russia] and Abisko [Sweden]), we provide a simple equation for data conversion between the two methods. The availability of this database will help to provide answers to important questions concerning biogeochemical cycling, climate change impacts, and co-evolution of plants and fungi. The complete data sets corresponding to abstracts published in the Data Papers section of the journal are published electronically in Ecological Archives at 〈http://esapubs.org/archive〉. (The accession number for each Data Paper is given directly beneath the title.)

Plant interactions in alpine tundra: 13 years of experimental removal of dominant species

AbstractPlant species responses to the removal of each of the five dominant species were studied in an alpine tundra of the Teberda reserve of northwestern Caucasus, Russia, for 13 years. While dominant plant species (Anemone speciosa Adam ex G.Pritz, Antennaria dioica [L.] Gaertn., Festuca ovina L., Trifolium polyphyllum C.A. May, Carex sempervirens Vill., C. umbrosa Host, C. caryophyllea Latourr.) on the average increased the number of their shoots relative to the control after the removal of their presumed competitors, most subordinate species in the community responded negatively to the removal of dominants. The latter group may therefore depend on the dominant plants for survival in the harsh alpine environment, and not be as much affected by competition. Most species showed consistently either negative or positive responses for the whole duration of the experiment. Experimental removal of only one species in each treatment produced a coordinated response from a number of species, which suggests pres...

Experimental Investigation of Fertilization and Irrigation Effects on an Alpine Heath, Northwestern Caucasus, Russia

Abstract We investigated the response of an alpine lichen heath plant community to an increase in soil nutrient and water availability. A 5-yr experiment—including additions of calcium, phosphorus, nitrogen, and nitrogen + phosphorus as well as irrigation—was conducted in northwestern Caucasus, Russia, at 2800 m above sea level. Number of plants and generative shoots per species were counted annually. The plant-community composition started to change during the second year of treatments. Plant density and flowering of the community is co-limited by nitrogen and phosphorus. Irrigation and calcium additions caused minimal changes. The total number of forb plants per square meter was not influenced by treatments, whereas the total number of graminoid plants slightly increased in response to P treatment and strongly increased in response to N + P treatment. Forbs responded to N and N + P treatments by an increase in the number of generative shoots. Individual species differed in their response to treatments. Only clonal species responded to experimental treatments, except for one annual nonclonal species, which increased its abundance in response to irrigation. Biodiversity estimated by the Shannon-Wiener index decreased under N + P treatment. Species number was not affected by any of the treatments.

Climate, soil and plant functional types as drivers of global fine‐root trait variation

Summary Ecosystem functioning relies heavily on below-ground processes, which are largely regulated by plant fine-roots and their functional traits. However, our knowledge of fine-root trait distribution relies to date on local- and regional-scale studies with limited numbers of species, growth forms and environmental variation. We compiled a world-wide fine-root trait dataset, featuring 1115 species from contrasting climatic areas, phylogeny and growth forms to test a series of hypotheses pertaining to the influence of plant functional types, soil and climate variables, and the degree of manipulation of plant growing conditions on species fine-root trait variation. Most particularly, we tested the competing hypotheses that fine-root traits typical of faster return on investment would be most strongly associated with conditions of limiting versus favourable soil resource availability. We accounted for both data source and species phylogenetic relatedness. We demonstrate that: (i) Climate conditions promoting soil fertility relate negatively to fine-root traits favouring fast soil resource acquisition, with a particularly strong positive effect of temperature on fine-root diameter and negative effect on specific root length (SRL), and a negative effect of rainfall on root nitrogen concentration; (ii) Soil bulk density strongly influences species fine-root morphology, by favouring thicker, denser fine-roots; (iii) Fine-roots from herbaceous species are on average finer and have higher SRL than those of woody species, and N2-fixing capacity positively relates to root nitrogen; and (iv) Plants growing in pots have higher SRL than those grown in the field. Synthesis. This study reveals both the large variation in fine-root traits encountered globally and the relevance of several key plant functional types and soil and climate variables for explaining a substantial part of this variation. Climate, particularly temperature, and plant functional types were the two strongest predictors of fine-root trait variation. High trait variation occurred at local scales, suggesting that wide-ranging below-ground resource economics strategies are viable within most climatic areas and soil conditions.

Mycorrhiza, vegetative mobility and responses to disturbance of alpine plants in the Northwestern Caucasus.

The hypothesis of a trade-off between vegetative mobility and mycorrhizal infection has been examined. The rate of root arbuscular-mycorrhizal (AM) infection and the extent of vegetative mobility (clonal with annual mobility more than 2 cm, clonal with annual mobility less than 2 cm, and non-clonal) was determined for 77 species in four alpine grassland communities in the Teberda Nature Reserve, the Northwest Caucasus, Russia. The percentage of AM species was similar (74–77%) in all four communities. The mean rate of AM root infection did not differ significantly between four communities. It was shown that vegetatively mobile species (annual mobility>2 cm) had on average a lower rate of root AM infection than species with low or no vegetative mobility. Our results conform with the mycorrhizal infection-vegetative mobility trade-off hypothesis.Gap-preferring species in a highly disturbed alpine meadow (burrowing activity of small and large mammals) had lower rate of root AM infection than species preferring undisturbed microsites. This pattern was also found within two larger families, viz.Poaceae andAsteraceae.

Comparative analysis of the floristic richness of alpine communities in the Caucasus and the Central Alps

. Species richness of selected alpine plant communities in the Teberda Biosphere Reserve (Northwestern Caucasus) and the Davos area (Central Alps) was compared in series of plots from 0.0025 to 100 m2. Communities developing under similar ecological conditions and with similar syntaxonomic positions were compared in order to estimate the role of recent environment versus regional historical factors in determining plant community structure and diversity. The floristic richness of the Caucasian and Alpic fens was very similar. The Grasslands and Meadows were quite similar as to floristic richness for plots > 25 cm × 25 cm, but the Caucasian communities had fewer species in smaller plots. The Lichen heath at Teberda was richer than the Caricetum curvulae cetrarietosum for all plot sizes, except the two smallest ones. On the other hand, the plots of the Salix Snowbed community were richer in species than the Caucasian snowbeds for all plot sizes. The Rhododendron Shrubland plots were very similar as to floristic richness in larger plots (4 — 100 m2). Generally, most Alpic communities near Davos were richer in species at small plot sizes than the corresponding communities from Teberda. Caucasian communities were floristically less similar to each other — and thus more discrete — than the Alpic ones. The possible role of different factors controlling floristic richness of the communities is discussed. Our results suggest that recent ecological conditions have a big influence on local floristic diversity and may lead to high similarities between ecologically similar communities from different regions. In addition, the general floristic richness of a regions as well as island effects should be taken into account.