scholarly journals Decades of Recovery From Sheep Grazing Reveal No Effects on Plant Diversity Patterns Within Icelandic Tundra Landscapes

2021 ◽  
Vol 8 ◽  
Author(s):  
Martin A. Mörsdorf ◽  
Virve T. Ravolainen ◽  
Nigel G. Yoccoz ◽  
Thóra Ellen Thórhallsdóttir ◽  
Ingibjörg Svala Jónsdóttir
Keyword(s):  
Species Richness ◽  
Plant Growth ◽  
Plant Communities ◽  
Plant Diversity ◽  
Management Practices ◽  
Spatial Scales ◽  
Plant Productivity ◽  
Community Diversity ◽  
Growth Forms ◽  
Diversity Patterns

Tundra plant communities are often shaped by topography. Contrasting wind exposure, slopes of different inclination and landforms of different curvature affect habitat conditions and shape plant diversity patterns. The majority of tundra is also grazed by ungulates, which may alter topographically induced plant diversity patterns, but such effects may depend on the spatial scales of assessments. Here we ask whether topographically induced patterns of within (alpha) and between (beta) plant community diversity are different in contrasting grazing regimes. We studied plant communities within tundra landscapes that were located in the North and Northwest of Iceland. Half of the studied landscapes were grazed by sheep, whereas the other half was currently un-grazed and recovering for several decades (up to 60 years). Alpha and beta diversity were assessed on explicitly defined, nested spatial scales, which were determined by topographical units. Although we contrasted currently grazed vegetation to vegetation that witnessed several decades of grazing recovery, we found no statistically significant differences in plant diversity patterns. We relate these findings to the low resilience of our study system toward grazing disturbances, which has important implications for management practices in the tundra. Effects of topography on species richness were only found for specific spatial scales of analyses. Species rich topographical units were associated with relatively large biomass of plant growth forms that promote nutrient availability and potential plant productivity in the tundra, such as forbs. This suggests that biomass of such plant growth forms within habitats can be a useful proxy of potential plant productivity and may predict spatial patterns of plant species richness in tundra.

scholarly journals Climate and plant community diversity in space and time

2020 ◽  
Vol 117 (9) ◽  
pp. 4464-4470 ◽  
Author(s):  
Susan Harrison ◽  
Marko J. Spasojevic ◽  
Daijiang Li
Keyword(s):  
Plant Community ◽  
Plant Diversity ◽  
Phylogenetic Diversity ◽  
Spatial Scales ◽  
Community Diversity ◽  
Niche Conservatism ◽  
Space And Time ◽  
Drying Trend ◽  
Functional And Phylogenetic Diversity ◽  
Over Time

Climate strongly shapes plant diversity over large spatial scales, with relatively warm and wet (benign, productive) regions supporting greater numbers of species. Unresolved aspects of this relationship include what causes it, whether it permeates to community diversity at smaller spatial scales, whether it is accompanied by patterns in functional and phylogenetic diversity as some hypotheses predict, and whether it is paralleled by climate-driven changes in diversity over time. Here, studies of Californian plants are reviewed and new analyses are conducted to synthesize climate–diversity relationships in space and time. Across spatial scales and organizational levels, plant diversity is maximized in more productive (wetter) climates, and these consistent spatial relationships are mirrored in losses of taxonomic, functional, and phylogenetic diversity over time during a recent climatic drying trend. These results support the tolerance and climatic niche conservatism hypotheses for climate–diversity relationships, and suggest there is some predictability to future changes in diversity in water-limited climates.

scholarly journals The use of Shanon Weiners diversity index in the assessment of floral diversity and equitability of Neni–Nimo Watershed in Anaocha L.G.A. of Anambra State, Nigeria

2021 ◽  
Vol 16 (2) ◽  
pp. 155-158
Author(s):  
Ezenwatah Ifeoma Susan ◽  
Ukpaka Chukwujekwu Gratius ◽  
Onyemeka Regland Michael ◽  
Afulukwe Stella Chinyere ◽  
Okoye Elochukwu Chidubem Sunday
Keyword(s):  
Species Richness ◽  
Plant Growth ◽  
Diversity Index ◽  
Block Design ◽  
Species Abundance ◽  
P Value ◽  
Growth Forms ◽  
Anambra State ◽  
Floral Diversity ◽  
Current Usage

The study on the floral diversity of Neni-Nimo watershed in Anaocha L.G.A. of Anambra State was conducted between November 2009 and July 2020. The aim of the study was to find out the species richness and the floral biodiversity of the watershed. In this study, the watershed was divided into three sites, the forested site, the fallow site and the current usage site. The experiment was laid out in a Randomized Complete Block Design. The ecological methods used in this study are the Point Centred Plotless Count sampling technique for areas dominated by trees while the Plot Count technique using quadrats were used for sampling the areas dominated by forbs, shrubs, climbers and grasses. The vegetation data collected was used to estimate the species richness of the different plant growth forms, the diversity and equitability of the various growth forms encountered were calculated using Shanon Weiners diversity index. The Shanno Weiners diversity index shows that the forested areas had the highest floral biodiversity than the fallow and current usage area. Regression analysis shows that a significant relationship exists between species abundance and floral biodiversity at a p-value of <0.05 for all plant growth forms in the watershed except for grasses and as abundance increases, diversity also increases.

scholarly journals Resource enrichment combined with biomass removal maintains plant diversity and community stability in a long-term grazed grassland

2020 ◽  
Vol 13 (5) ◽  
pp. 611-620
Author(s):  
Feng-Wei Xu ◽  
Jian-Jun Li ◽  
Li-Ji Wu ◽  
Xiao-Ming Lu ◽  
Wen Xing ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Plant Diversity ◽  
Primary Productivity ◽  
Management Practices ◽  
Light Exposure ◽  
Community Stability ◽  
Water Addition ◽  
Biomass Removal

Abstract Aims Long-term heavy grazing reduces plant diversity and ecosystem function by intensifying nitrogen (N) and water limitation. In contrast, the absence of biomass removal can cause species loss by elevating light competition and weakening community stability, which is exacerbated by N and water enrichment. Hence, how to maintain species diversity and community stability is still a huge challenge for sustainable management of worldwide grasslands. Methods We conducted a 4-year manipulated experiment in six long-term grazing blocks to explore combination of resource additions and biomass removal (increased water, N and light availability) on species richness and community stability in semiarid grasslands of Inner Mongolia, China. Important Findings In all blocks treated with the combination of resource additions and biomass removal, primary productivity increased and species richness and community stability were maintained over 4 years of experiment. At both species and plant functional group (PFG) levels, the aboveground biomass of treated plants remained temporally stable in treatments with the combination of N and/or water addition and biomass removal. The maintenance of species richness was primarily caused by the biomass removal, which could increase the amount of light exposure for grasses under resource enrichment. Both species asynchrony and stability of PFGs contributed to the high temporal stability observed in these communities. Our results indicate that management practices of combined resource enrichment with biomass removal, such as grazing or mowing, could not only enhance primary productivity but also maintain plant species diversity, species asynchrony and community stability. Furthermore, as overgrazing-induced degradation and resource enrichment-induced biodiversity loss continue to be major problems worldwide, our findings have important implications for adaptive management in semiarid grasslands and beyond.

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.

scholarly journals Plant diversity changes in a nature reserve: a probabilistic sampling method for quantitative assessments

2019 ◽  
Vol 34 ◽  
pp. 145-161 ◽  
Author(s):  
Stefano Chelli ◽  
Enrico Simonetti ◽  
Giandiego Campetella ◽  
Alessandro Chiarucci ◽  
Marco Cervellini ◽  
...  
Keyword(s):  
Species Richness ◽  
Monitoring System ◽  
Plant Diversity ◽  
Management Practices ◽  
Sampling Design ◽  
Nature Reserve ◽  
Vegetation Types ◽  
Probabilistic Sampling ◽  
Compositional Changes ◽  
Over Time

Species pool conservation is critical for the stability of ecosystem processes. However, climate and land use changes will likely affect biodiversity, and managers of protected areas are under increasing pressure to monitor native species diversity changes by approaches that are scientifically sound and comparable over time. Here we describe a plant diversity monitoring system in use since 2002 in the “Montagna di Torricchio” Nature Reserve (LTER_EU_IT_033), a Central Apennines representative area of 317 ha, most of which is under strict protection. The aim of this paper was to assess changes in plant species richness over time and to deduce the patterns of species assemblage. The monitoring system was based on a probabilistic sampling design representative of the different physiognomic vegetation types occurring in the Reserve. A total of 34 plots (10×10m) were sampled in 2002, 2003 and 2015, and their species presence/absence and relative coverage were estimated. Repeated measure ANOVA was used to test for plot-level and ecosystem-based changes in species richness along the study period. Temporal nestedness and temporal turnover metrics were used to assess patterns of species’ compositional changes. The results showed significantly different levels of species richness depending on the year, with the lowest value in 2003, probably linked to extreme drought events. Forest systems were comparatively stable, demonstrating the capacity to buffer interannual climate variability. Regarding compositional changes along the entire period (2002–2015), we found random patterns of both temporal nestedness and turnover, indicating stability in species composition. However, we also showed the contemporary occurrence of species loss and species replacement processes, considering the dry year 2003, a finding which should be further explored through fine-scale studies to unravel mechanisms of community assembly under drought. The use of a probabilistic sampling design representative of the different physiognomic vegetation types proved to be advantageous in monitoring the Nature Reserve vegetation and collecting reliable quantitative information. This data, in turn, provides the basis for improvements in management practices and proposed adaptation measures.

scholarly journals Dominant shrub species are a strong predictor of plant species diversity along subalpine pasture-shrub transects

Alpine Botany ◽  
2020 ◽  
Vol 130 (2) ◽  
pp. 141-156
Author(s):  
Tobias Zehnder ◽  
Andreas Lüscher ◽  
Carmen Ritzmann ◽  
Caren M. Pauler ◽  
Joel Berard ◽  
...  
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Diversity ◽  
Beta Diversity ◽  
Spatial Scales ◽  
Strong Predictor ◽  
Shrub Encroachment ◽  
Swiss Alps ◽  
Shrub Cover ◽  
Shrub Species

Abstract Abandonment of pastures and successional shrub expansion are widespread in European mountain regions. Moderate shrub encroachment is perceived beneficial for plant diversity by adding new species without outcompeting existing ones, yet systematic evidence is missing. We surveyed vegetation along 24 transects from open pasture into shrubland across the Swiss Alps using a new protocol distinguishing different spatial scales, shrub cover of each plot (2 × 2 m) and larger-scale zonal cover along the transect. Data were analysed using generalized linear models of shrub cover, shrub species and environmental conditions, such as geology, aspect or soil. Most shrub communities were dominated by Alnus viridis (62% of transects) and Pinus mugo (25%), and the rest by other shrub species (13%). These dominant shrub species explained vegetation response to shrub cover well, without need of environmental variables in the model. Compared to open pasture, A. viridis resulted in an immediate linear decline in plant species richness and a marginal increase in beta-diversity (maximally + 10% at 35% cover). Dense A. viridis hosted 62% less species than open pasture. In P. mugo, species richness remained stable until 40% shrub cover and dropped thereafter; beta-diversity peaked at 35% cover. Hence, scattered P. mugo increases beta-diversity without impairing species richness. In transects dominated by other shrubs, species richness and beta-diversity peaked at 40–60% shrub cover (+ 23% both). A. viridis reduced species richness in a larger area around the shrubs than P. mugo. Therefore, effects of shrub encroachment on plant diversity cannot be generalized and depend on dominant shrub species.

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