scholarly journals Urbanization increases floral fidelity of pollinators

2021 ◽  
Author(s):  
Sevan Suni ◽  
Erin Hall ◽  
Evangelina Bahu
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Plant Species ◽  
Invasive Plants ◽  
Plant Species Diversity ◽  
Individual Plant ◽  
Native Plant ◽  
Natural Areas ◽  
Short Term ◽  
Urban Sites

Understanding how urbanization alters functional interactions among pollinators and plants is critically important given increasing anthropogenic land use and declines in pollinator populations. Pollinators often exhibit short-term specialization, and visit plants of the same species during one foraging trip. This facilitates plant receipt of conspecific pollen – pollen on a pollinator that is the same species as the plant on which the pollinator was foraging. Conspecific pollen receipt facilitates plant reproductive success and is thus important to plant and pollinator persistence. We investigated how urbanization affects short term specialization of insect pollinators by examining pollen loads on insects’ bodies and identifying the number and species of pollen grains on insects caught in urban habitat fragments and natural areas. We then assessed possible drivers of differences between urban and natural areas, including frequency dependence in foraging, species richness and diversity of the plant and pollinator communities, floral abundance, and the presence of invasive plant species. Pollinators were more specialized in urban fragments than in natural areas, despite no differences in the species richness of plant communities across site types. These differences were likely driven by higher specialization of common pollinators, which were more abundant in urban sites. Pollinators were also more specialized when foraging on invasive plants across sites, and floral abundance of invasive plants was higher in urban sites. Our findings reveal strong effects of urbanization on pollinator fidelity to individual plant species and have implications for the maintenance of plant species diversity in small habitat fragments. The higher fidelity of pollinators to invasive plants suggests that native species may receive fewer visits by pollinators. Therefore, native plant species diversity may decline in urban sites without continued augmentation of urban flora or removal of invasive species.

SGS Biodiversity Theme: impact of plant biodiversity on the productivity and stability of grazing systems across southern Australia

2003 ◽  
Vol 43 (8) ◽  
pp. 961 ◽  
Author(s):  
D. R. Kemp ◽  
W. McG. King ◽  
A. R. Gilmour ◽  
G. M. Lodge ◽  
S. R. Murphy ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Plant Species ◽  
Native Species ◽  
Management Practices ◽  
Plant Species Diversity ◽  
Native Plant ◽  
Total Species Richness ◽  
Grazing Systems ◽  
Sustainable Grazing

The relationships between productivity and plant species diversity were assessed using data from the Sustainable Grazing Systems (SGS) 10 national experiment sites. Each site applied up to 7 different management treatments. Sites varied in the amount of data available for analysis. Plant species diversity was assessed in terms of both the total and native species present at each site. More than 200 plant taxa were recorded over the period of the experiment, about one-third of which were native. In the majority of cases, the native species present within a treatment remained there throughout the experiments, even when fertilised and oversown with introduced species. The number of native species increased by 1 or 2 over the 3–4 years of each experiment where grasslands were less intensively used (average herbage mass >2 t DM/ha), but decreased in more heavily grazed treatments. Native grasses made much greater contributions to herbage mass than other native species. Of the more than 70 native plant species found, the most numerous were broadleaf species, which tended to be more variable under management treatments. As total species richness increased, there was a tendency for pasture productivity to be less, for the mean standing herbage mass to be less and for seasonal growth to be less stable. This depended upon experiments and tended to apply at the sites with higher annual pasture growth rates. All treatments had >10 plant species within the small (about 1.5 ha) paddocks used and larger paddocks often had many more. It was apparent from the high plant species richness at each site (about 25–100 species) that many more niches exist in these paddocks than the number of species usually sown in a pasture. Opportunities to redesign pasture mixtures to exploit more of the resources available obviously exist. Understanding of the relationships among management practices, productivity and plant species diversity is limited, but will become important as we seek more sustainable grazing systems. The studies analysed here suggested that where the herbage mass was maintained between 2 and 4 t DM/ha then species were maintained and productivity was optimised.

Impacts of erosion control treatments on native vegetation recovery after severe wildfire in the Eastern Cascades, USA

2010 ◽  
Vol 19 (4) ◽  
pp. 490 ◽  
Author(s):  
Erich K. Dodson ◽  
David W. Peterson ◽  
Richy J. Harrod
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Native Species ◽  
Plant Cover ◽  
Plant Species Richness ◽  
Tree Regeneration ◽  
Vegetation Recovery ◽  
Native Vegetation ◽  
Individual Plant ◽  
Native Plant

Slope stabilisation treatments like mulching and seeding are used to increase soil cover and reduce runoff and erosion following severe wildfires, but may also retard native vegetation recovery. We evaluated the effects of seeding and fertilisation on the cover and richness of native and exotic plants and on individual plant species following the 2004 Pot Peak wildfire in Washington State, USA. We applied four seeding and three fertilisation treatments to experimental plots at eight burned sites in spring 2005 and surveyed vegetation during the first two growing seasons after fire. Seeding significantly reduced native non-seeded species richness and cover by the second year. Fertilisation increased native plant cover in both years, but did not affect plant species richness. Seeding and fertilisation significantly increased exotic cover, especially when applied in combination. However, exotic cover and richness were low and treatment effects were greatest in the first year. Seeding suppressed several native plant species, especially disturbance-adapted forbs. Fertilisation, in contrast, favoured several native understorey plant species but reduced tree regeneration. Seeding, even with native species, appears to interfere with the natural recovery of native vegetation whereas fertilisation increases total plant cover, primarily by facilitating native vegetation recovery.

Effect of a grazing ban on restoring the degraded alpine meadows of Northern Tibet, China

2015 ◽  
Vol 37 (1) ◽  
pp. 89 ◽  
Author(s):  
W. N. Zhang ◽  
H. Ganjurjav ◽  
Y. Liang ◽  
Q. Z. Gao ◽  
Y. F. Wan ◽  
...  
Keyword(s):  
Species Diversity ◽  
Plant Species ◽  
Microbial Biomass Carbon ◽  
Plant Species Diversity ◽  
Early Years ◽  
Individual Plant ◽  
Root Mass ◽  
Alpine Meadows ◽  
Northern Tibet ◽  
Free Grazing

Banning of grazing is a widely used means of restoring degraded rangeland in China. However, little is known about the time required to restore degraded alpine meadows through the use of a grazing ban. Height and cover of individual plant species and total cover, herbage mass and root mass of each plot of a grazing ban and communal free-grazing alpine meadows in Northern Tibet were examined. Soil samples were also collected and total organic carbon, microbial biomass carbon, total phosphorus and ammonium nitrogen contents were measured. The results showed that both the level of plant species diversity and herbage mass were higher in areas of a grazing ban than in communal free-grazing land without a grazing ban. No significant differences in root mass and soil nutrient contents were observed. There was a higher plant species diversity and herbage mass in the early years of a grazing ban but there was a subsequent decline. It is suggested that some grazing after a grazing ban may be necessary according to the dynamics of ecosystem responses with time.

scholarly journals Rhizosphere Microbial Population and Plant Species Diversity as Influenced by Chromolaena odorata Invasion

2018 ◽  
Vol 6 (4) ◽  
pp. 36
Author(s):  
Solomon A. Adejoro ◽  
Lekan C. Aguda
Keyword(s):  
Species Diversity ◽  
Plant Species ◽  
Microbial Population ◽  
Block Design ◽  
Plant Species Diversity ◽  
Soil Microbiome ◽  
Native Plant ◽  
Chromolaena Odorata ◽  
Soil Microbial ◽  
Soil Microbial Population

Invasive plant species have been commonly implicated to cause loss in plant species diversity. Attention had however not been paid to the effects of these species loss on the soil microbiome. A study was conducted in 18 farmers’ fields within three states in southwestern Nigeria to examine the effect of Siam weed (Chromolaena odorata) invasion on native plant diversity as well as on the rhizosphere microbial population using randomized complete block design. Results indicated significant losses in plant species diversity and reduction in density per square meter compared with adjacent non infested fields. Results further showed C. odorata invasion exerted diverse influence on soil microbial population. Relationships were subsequently established among plant density, species diversity; and soil microbial population. Further studies were also recommended to accommodate more microbiological indices.

scholarly journals A six-year grazing exclusion changed plant species diversity of a Stipa breviflora desert steppe community, northern China

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4359 ◽  
Author(s):  
Xing Wang ◽  
Xinguo Yang ◽  
Lei Wang ◽  
Lin Chen ◽  
Naiping Song ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Environmental Factors ◽  
Plant Species ◽  
Northern China ◽  
Plant Species Diversity ◽  
Desert Steppe ◽  
Diversity Patterns ◽  
Shannon Diversity ◽  
Steppe Community

Excluding grazers is one of most efficient ways to restore degraded grasslands in desert-steppe communities, but may negatively affect the recovery of plant species diversity. However, diversity differences between grazed and fenced grasslands in desert-steppe are poorly known. In a Stipa breviflora desert steppe community in Northern China, we established six plots to examine spatial patterns of plant species diversity under grazed and fenced conditions, respectively. We addressed three aspects of species diversity: (1) The logistic, exponential and power models were used to describe the species-area curve (SAR). Species richness, abundance and Shannon diversity values change differently with increasing sampling areas inside and outside of the fence. The best fitted model for SAR was the logistic model. Excluding grazers had a significant impact on the shape of SAR. (2) Variograms was applied to examine the spatial characteristics of plant species diversity. We found strong spatial autocorrelations in the diversity variables both inside and outside the fence. After grazing exclusion, the spatial heterogeneity decreased in species richness, increased in abundance and did not change in Shannon diversity. (3) We used variance partitioning to determine the relative contributions of spatial and environmental factors to plant species diversity patterns. Environmental factors explained the largest proportion of variation in species diversity, while spatial factors contributed little. Our results suggest that grazing enclosures decreased species diversity patterns and the spatial pattern of the S. breviflora desert steppe community was predictable.

scholarly journals Responses of Individual Plant Species, Functional Groups, α- and β-Diversity to Short-Term Grazing Exclusion under Severe Drought Episode in Long-Term Grazed Alfa-Steppes

2020 ◽  
Author(s):  
Yacine Kouba ◽  
Saifi Merdes ◽  
Badreddine Saadali ◽  
Haroun Chenchouni
Keyword(s):  
Species Diversity ◽  
Functional Groups ◽  
Plant Species ◽  
Beta Diversity ◽  
Management Practice ◽  
Alpha Diversity ◽  
Individual Plant ◽  
Severe Drought ◽  
Short Term ◽  
Grazing Exclusion

Grazing exclusion has been proved to be one of the main measures for rehabilitating degraded arid steppes. However, the effect of this management practice on plant species diversity and composition is ambiguous, specially under prolonged droughts. Concurrently considering the responses of individual plant species, diversity of functional groups, α-diversity, and β-diversity (and its components) may be crucial to the holistic understanding of grazing exclusion effects on plant communities under drought conditions. Here, we investigated the response of these diversity measures to short-term sheep exclusion under severe drought episode in arid steppes of Alfa-grass (Stipa tenacissima) with a long evolutionary history of livestock grazing. Individual species responses were tested based on species occurrence and abundance in either grazed or grazing-excluded steppes, in addition, we used indicator species analysis to assess the strength of the association between plant species and management type. Likewise, α-diversity, abundance- and incidence-based β-diversity, as well as the functional groups’ diversities were quantified using Hill Numbers and compared between the two management types. Sheep grazing exclusion enabled the recovery of various Alfa-steppe indicator species and improved the size of regional species pool, overall α-diversity, and the diversity of therophytes. This management practice decreased the abundance-based β-diversity and the nestedness-resultant fraction of the incidence-based β-diversity at the local scale, while at the landscape scale increased the abundance-based β-diversity and its balanced variation fraction and reduced the incidence-based β-diversity and its turnover component. Furthermore, protection from grazing altered β-diversities scaling patterns by maintaining higher balanced variation in species abundance at large spatial scale and greater abundance-gradient in species composition at the fine-scale. Our results suggest that the implementation of short-term grazing exclusion in degraded arid steppes would be the appropriate management practice for vegetation restoration and plant diversity conservation during prolonged drought periods.

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