scholarly journals Thermo-erosion gullies boost the transition from wet to mesic tundra vegetation

2016 ◽  
Vol 13 (4) ◽  
pp. 1237-1253 ◽  
Author(s):  
Naïm Perreault ◽  
Esther Lévesque ◽  
Daniel Fortier ◽  
Laurent J. Lamarque
Keyword(s):  
Species Richness ◽  
Soil Moisture ◽  
Plant Species ◽  
Plant Communities ◽  
Stable State ◽  
Plant Species Richness ◽  
Arctic Ecosystems ◽  
Erosion Processes ◽  
Short Period ◽  
Ice Wedge

Abstract. Continuous permafrost zones with well-developed polygonal ice-wedge networks are particularly vulnerable to climate change. Thermo-mechanical erosion can initiate the development of gullies that lead to substantial drainage of adjacent wet habitats. How vegetation responds to this particular disturbance is currently unknown but has the potential to significantly disrupt function and structure of Arctic ecosystems. Focusing on three major gullies of Bylot Island, Nunavut, we estimated the impacts of thermo-erosion processes on plant community changes. We explored over 2 years the influence of environmental factors on plant species richness, abundance and biomass in 62 low-centered wet polygons, 87 low-centered disturbed polygons and 48 mesic environment sites. Gullying decreased soil moisture by 40 % and thaw-front depth by 10 cm in the center of breached polygons within less than 5 years after the inception of ice wedge degradation, entailing a gradual yet marked vegetation shift from wet to mesic plant communities within 5 to 10 years. This transition was accompanied by a five times decrease in graminoid above-ground biomass. Soil moisture and thaw-front depth changed almost immediately following gullying initiation as they were of similar magnitude between older (> 5 years) and recently (< 5 years) disturbed polygons. In contrast, there was a lag-time in vegetation response to the altered physical environment with plant species richness and biomass differing between the two types of disturbed polygons. To date (10 years after disturbance), the stable state of the mesic environment cover has not been fully reached yet. Our results illustrate that wetlands are highly vulnerable to thermo-erosion processes, which drive landscape transformation on a relative short period of time for High Arctic perennial plant communities (5 to 10 years). Such succession towards mesic plant communities can have substantial consequences on the food availability for herbivores and carbon emissions of Arctic ecosystems.

scholarly journals Thermo-erosion gullies boost the transition from wet to mesic vegetation

2015 ◽  
Vol 12 (15) ◽  
pp. 12191-12228 ◽  
Author(s):  
N. Perreault ◽  
E. Lévesque ◽  
D. Fortier ◽  
L. J. Lamarque
Keyword(s):  
Plant Species ◽  
Plant Species Richness ◽  
Above Ground Biomass ◽  
Arctic Ecosystems ◽  
Carex Aquatilis ◽  
Erosion Processes ◽  
Vegetation Shift ◽  
Ice Wedge ◽  
Mechanical Erosion ◽  
Time Decrease

Abstract. Continuous permafrost zones with well-developed polygonal ice-wedge networks are particularly vulnerable to climate change. Thermo-mechanical erosion can initiate the development of gullies that lead to substantial drainage of adjacent wet habitats. How vegetation responds to this particular disturbance is currently unknown but has the potential to strongly disrupt function and structure of Arctic ecosystems. Focusing on three major gullies of Bylot Island, Nunavut, we aimed at estimating the effects of thermo-erosion processes in shaping plant community changes. Over two years, we explored the influence of environmental factors on plant species richness, abundance and biomass studying 197 polygons that covered the whole transition from intact wet to disturbed and mesic habitats. While gullying decreased soil moisture by 40 % and thaw front depth by 10 cm in breached polygons, we observed a gradual vegetation shift within five to ten years with mesic habitat plant species such as Arctagrostis latifolia and Salix arctica replacing wet habitat dominant Carex aquatilis and Dupontia fisheri. This transition was accompanied by a five time decrease in graminoid above-ground biomass in mesic sites. Our results illustrate that wetlands are highly vulnerable to thermo-erosion processes that may rapidly promote the decrease of food availability for herbivores and reduce methane emissions of Arctic ecosystems.

scholarly journals The invasive herb Lupinus polyphyllus can reduce plant species richness independently of local invasion age

2021 ◽  
Author(s):  
Marju Prass ◽  
Satu Ramula ◽  
Miia Jauni ◽  
Heikki Setälä ◽  
D. Johan Kotze
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Community ◽  
Plant Communities ◽  
Vascular Plant ◽  
Plant Species Richness ◽  
Ecological Impacts ◽  
Plant Community Composition ◽  
Lupinus Polyphyllus ◽  
Local Invasion

AbstractThe ecological impacts of invasive species may change or accumulate with time since local invasion, potentially inducing further changes in communities and the abiotic environment. Yet, time since invasion is rarely considered when investigating the ecological impacts of invasive non-native species. To examine the effect of time since invasion on the ecological impacts of Lupinus polyphyllus, a perennial nitrogen-fixing herb, we surveyed vascular plant communities in the presence and absence of L. polyphyllus in young, intermediate, and old semi-natural grassland sites (ca. 5, 10, 15 years representing both time since lupine invasion and plant community age). We analyzed vascular plant community composition, vascular plant species richness, and the cover of various ecological plant groups and L. polyphyllus. In contrast to our hypotheses, we found no change in the mean cover of L. polyphyllus (about 35%) with time since local invasion, and an ordination did not suggest marked changes in plant community composition. L. polyphyllus was associated with lower species richness in invaded plant communities but this effect did not change with time since invasion. Invaded plant communities were also associated with lower occurrence of generalist, oligotrophic (low-nutrient-adapted) and copiotrophic (nutrient-demanding) species but no temporal dynamics were detected. We conclude that even the intermediate cover of L. polyphyllus can reduce plant species richness, but the ecological impact caused by this invader might not dramatically change or accumulate with time since invasion.

Effects of biotic and abiotic indices on soil water content in a decade-long grassland biodiversity experiment

2020 ◽  
Author(s):  
Christine Fischer ◽  
Sophia Leimer ◽  
Christiane Roscher ◽  
Janneke Ravenek ◽  
Hans de Kroon ◽  
...  
Keyword(s):  
Species Richness ◽  
Soil Moisture ◽  
Organic Carbon ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Functional Groups ◽  
Plant Species ◽  
Plant Species Richness

&lt;p&gt;Soil moisture is the dynamic link between climate, soil and vegetation and the dynamics and variation are affected by several often interrelated factors such as soil texture, soil structural parameters (soil organic carbon) and vegetation parameters (e.g. belowground- and aboveground biomass). For the characterization of soil moisture, including its variability and the resulting water and matter fluxes, the knowledge of the relative importance of these factors is of major challenge. Because of the spatial heterogeneity of its drivers soil moisture varies strongly over time and space. Our objective was to assess the spatio-temporal variability of soil moisture and factors which could explain that variability, like soil properties and vegetation cover, in in a long term biodiversity experiment (Jena Experiment).&lt;/p&gt;&lt;p&gt;The Jena Experiment consist 86 plots on which plant species richness (0, 1, 2, 4, 8, 16, and 60) and functional groups (legumes, grasses, tall herbs, and small herbs) were manipulated in a factorial design Soil moisture measurements were performed weekly April to September 2003-2005 and 2008-2013 in 0.1, 0.2, 0.3, 0.4, and 0.6 m soil depth using Delta T theta probe.&lt;/p&gt;&lt;p&gt;The analysis showed that both plant species richness and the presence of particular functional groups affected soil water content, while functional group richness per se played no role. Plots containing grasses was consistently drier than average at the soil surface in all observed years while plots containing legumes comparatively moister, but only up to the year 2008.&lt;/p&gt;&lt;p&gt;Interestingly, plant species richness led to moister than average subsoil at the beginning of the experiment (2003 and 2004), which changed to lower than average up to the year 2010 in all depths.Shortly after establishment, increased topsoil water content was related to higher leaf area index in species&amp;#8208;rich plots, which enhanced shading. In later years, higher species richness increased topsoil organic carbon, likely improving soil aggregation. Improved aggregation, in turn, dried topsoils in species&amp;#8208;rich plots due to faster drainage of rainwater.&lt;/p&gt;&lt;p&gt;Our decade&amp;#8208;long experiment shows that besides abiotic factors like texture, soil water patterns are consistently affected by biotic factors such as species diversity and plant functional types, but also properties that originate from biotic-abiotic interactions such as soil structure. Especially the effect of plant species richness propagated to deeper soil layers 8 years after the establishment of the experiment, and while originally caused by shading it was later related to altered soil physical characteristics in addition to modification of water uptake depth. Functional groups affected soil water distribution, likely due to plant traits affecting root water uptake depths, shading, or water&amp;#8208;use efficiency. Our results highlight the role of vegetation composition for soil processes and emphasize the need for long-term experiments to discover diversity effects in slow reacting systems like soil.&lt;/p&gt;

Plant species richness is not consistently associated with productivity in experimental subalpine meadow plant communities

2015 ◽  
Vol 50 (3) ◽  
pp. 207-217 ◽  
Author(s):  
Ziqiang Yuan ◽  
Kailiang Yu ◽  
Howard Epstein ◽  
Katia Stefanova ◽  
Rong Zhang
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Communities ◽  
Plant Species Richness ◽  
Subalpine Meadow

scholarly journals Effects of plant species diversity on nematode community composition and diversity in a long-term biodiversity experiment

Oecologia ◽  
2021 ◽  
Author(s):  
Peter Dietrich ◽  
Simone Cesarz ◽  
Tao Liu ◽  
Christiane Roscher ◽  
Nico Eisenhauer
Keyword(s):  
Species Richness ◽  
Community Composition ◽  
Plant Species ◽  
Plant Communities ◽  
Plant Diversity ◽  
Plant Species Richness ◽  
Resource Quality ◽  
Plant Feeding ◽  
Shoot Mass

AbstractDiversity loss has been shown to change the soil community; however, little is known about long-term consequences and underlying mechanisms. Here, we investigated how nematode communities are affected by plant species richness and whether this is driven by resource quantity or quality in 15-year-old plant communities of a long-term grassland biodiversity experiment. We extracted nematodes from 93 experimental plots differing in plant species richness, and measured above- and belowground plant biomass production and soil organic carbon concentrations (Corg) as proxies for resource quantity, as well as C/Nleaf ratio and specific root length (SRL) as proxies for resource quality. We found that nematode community composition and diversity significantly differed among plant species richness levels. This was mostly due to positive plant diversity effects on the abundance and genus richness of bacterial-feeding, omnivorous, and predatory nematodes, which benefited from higher shoot mass and soil Corg in species-rich plant communities, suggesting control via resource quantity. In contrast, plant-feeding nematodes were negatively influenced by shoot mass, probably due to higher top–down control by predators, and were positively related to SRL and C/Nleaf, indicating control via resource quality. The decrease of the grazing pressure ratio (plant feeders per root mass) with plant species richness indicated a higher accumulation of plant-feeding nematodes in species-poor plant communities. Our results, therefore, support the hypothesis that soil-borne pathogens accumulate in low-diversity communities over time, while soil mutualists (bacterial-feeding, omnivorous, predatory nematodes) increase in abundance and richness in high-diversity plant communities, which may contribute to the widely-observed positive plant diversity–productivity relationship.

Diversity of the Western Carpathian flysch grasslands: Do extremely species-rich plant communities coincide with a high diversity of snails?

Biologia ◽  
2014 ◽  
Vol 69 (2) ◽  
Author(s):  
Jana Dvořáková ◽  
Kristina Merunková ◽  
Zdenka Preislerová ◽  
Michal Horsák ◽  
Milan Chytrý
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Plant Species ◽  
Plant Communities ◽  
Abiotic Factors ◽  
Local Environment ◽  
Plant Species Richness ◽  
Snail Species ◽  
Local Species ◽  
White Carpathians

AbstractUpland fringes of the White Carpathians (Czech Republic) are known to support grasslands with the world’s highest local plant species richness. We investigated whether this unusually high plant richness has a parallel in snail communities, whether patterns of species composition of snail and plant communities in grasslands co-vary and how they are affected by local environment and landscape history. We compared plant and snail communities of dry to mesic grasslands in three neigh bouring regions: (1) hilly lowland of the Central Moravian Carpathians, (2) upland fringes and (3) upland of the White Carpathians. Both snail and plant communities exhibited a strong gradient in species composition associated with altitude, annual temperature and precipitation, soil calcium and pH. However, there was no correlation between local species richness of plants and snails in individual plots. The upland fringes of the White Carpathians were richest in snail species, probably due to intermediate environmental conditions, supporting the occurrence of species with contrasting environmental requirements. The highest local numbers of plant species were also recorded there, although differences among regions were not significant. The regional species richness of plants was also highest in the upland fringes, whereas that of snails was highest in the hilly lowland. Similarities in the diversity patterns of plants and snails among regions suggest the importance of regional factors for local richness, although local abiotic factors, which are partly correlated with the three regions, also influence local species composition and richness.

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