scholarly journals Opposing community assembly patterns for dominant and non-dominant plant species in herbaceous ecosystems globally

2021 ◽  
Author(s):  
Carlos Alberto Arnillas ◽  
Elizabeth Borer ◽  
Eric Seabloom ◽  
Juan Alberti ◽  
Selene Baez ◽  
...  
Keyword(s):  
Dominant Species ◽  
Plant Competition ◽  
Environmental Filtering ◽  
Environmental Drivers ◽  
Environmental Constraints ◽  
Dominant Plant Species ◽  
Evolutionary Consequences ◽  
Abiotic Influences ◽  
The Impact ◽  
Phylogenetic Dispersion

Dominant and non-dominant plants could be subject to different biotic and abiotic influences, partially because dominant plants modify the environment where non-dominant plants grow, causing an interaction asymmetry. Among other possibilities, if dominant plants compete strongly, they should deplete most resources forcing non-dominant plants into a more constrained niche space. Conversely, if dominant plants are constrained by the environment, they might not fully deplete available resources but instead ameliorate some of the environmental constraints limiting non-dominants. Hence, the nature of the interactions between the non-dominants could be modified by dominant species. However, when plant competition and environmental constraints have similar effects on dominant and non-dominant species no difference is expected. By estimating phylogenetic dispersion in 78 grasslands across five continents, we found that dominant species were clustered (underdispersed), suggesting dominant species are likely organized by environmental filtering, and that non-dominant species were either randomly assembled or overdispersed. Traits showed similar trends, but insufficient data prevented further analyses. Furthermore, several lineages scattered in the phylogeny had more non-dominant species, suggesting that traits related to non-dominants are phylogenetically conserved and have evolved multiple times. We found some environmental drivers of the dominant—non-dominant disparity. Our results indicate that assembly patterns for dominants and non-dominants are different, consistent with asymmetries in assembly mechanisms. Among the different mechanisms we evaluated, the results suggest two complementary hypotheses seldom explored: (1) Non-dominant species include lineages adapted to thrive in the environment generated by the dominant species. (2) Even when dominant species reduce resources to non-dominant ones, dominant species could have a stronger effect on—at least—some non-dominants by ameliorating the impact of the environment on them, than by depleting resources and increasing the environmental stress to those non-dominants. The results show that the dominant–non-dominant asymmetry has ecological and evolutionary consequences fundamental to understand plant communities.

scholarly journals Impacts of Environmental Factors on Head and Neck Cancer Pathogenesis and Progression

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 389
Author(s):  
Marisol Miranda-Galvis ◽  
Reid Loveless ◽  
Luiz Paulo Kowalski ◽  
Yong Teng
Keyword(s):  
Head And Neck Cancer ◽  
Environmental Factors ◽  
Head And Neck ◽  
Neck Cancer ◽  
Molecular Mechanisms ◽  
Metastatic Cancer ◽  
Environmental Drivers ◽  
Cancer Pathogenesis ◽  
Gene Environment ◽  
The Impact

Epidemiological and clinical studies over the past two decades have provided strong evidence that genetic elements interacting with environmental components can individually and collectively influence one’s susceptibility to cancer. In addition to tumorigenic properties, numerous environmental factors, such as nutrition, chemical carcinogens, and tobacco/alcohol consumption, possess pro-invasive and pro-metastatic cancer features. In contrast to traditional cancer treatment, modern therapeutics not only take into account an individual’s genetic makeup but also consider gene–environment interactions. The current review sharpens the focus by elaborating on the impact that environmental factors have on the pathogenesis and progression of head and neck cancer and the underlying molecular mechanisms involved. Recent advances, challenges, and future perspectives in this area of research are also discussed. Inhibiting key environmental drivers of tumor progression should yield survival benefits for patients at any stage of head and neck cancer.

scholarly journals Invasive Scots Pine, Pinus sylvestris, Replacing Corema, Corema conradii, Heathland in the Annapolis Valley, Nova Scotia

2005 ◽  
Vol 119 (2) ◽  
pp. 237 ◽  
Author(s):  
Paul M. Catling ◽  
Susan Carbyn
Keyword(s):  
Pinus Sylvestris ◽  
Scots Pine ◽  
Vascular Plants ◽  
Dominant Species ◽  
Vascular Plant ◽  
Agricultural Crops ◽  
Deschampsia Flexuosa ◽  
Natural Habitats ◽  
Annapolis Valley ◽  
The Impact

Examination of air photos from 1930, 1970 and 2002 revealed stands of the European Scots Pine (Pinus sylvestris) invading remnants of natural Corema (Corema conradii) heathland in the Annapolis valley. To document the impact of the introduced pines, four natural habitats were compared with two adjacent habitats already invaded by the pines. All surveyed habitats had been dominated by Corema heath based on air photos taken in 1930. Twenty 1 m2 quadrats were used to record presence and cover of vascular plants at each site. The invasive alien pines reduce the native cover to 12%. Vascular plant biodiversity is reduced to less than 42% and the cover of the heathland dominant, Corema conradii, is reduced from over 100 % to less than 2%. with Deschampsia flexuosa becoming the dominant species. The modified ecosystem and loss of biodiversity has economic impacts through loss of pollinators of agricultural crops and loss of germplasm of native crop relatives.

scholarly journals The impact of the provision of water for game on the woody vegetation around a dam in the Kruger National Park

Koedoe ◽  
1991 ◽  
Vol 34 (2) ◽  
Author(s):  
I. Thrash ◽  
P.J. Nel ◽  
G.K. Theron ◽  
J. Du P. Bothma
Keyword(s):  
Relative Density ◽  
Woody Plants ◽  
National Park ◽  
Dominant Species ◽  
Canopy Cover ◽  
Kruger National Park ◽  
Woody Vegetation ◽  
Colophospermum Mopane ◽  
The Impact ◽  
Combretum Apiculatum

Quantitative inventory surveys were done on the woody vegetation in permanently marked plots at distance intervals from the Wik-en-Weeg Dam, Kruger National Park, in 1973. The surveys were repeated in 1990 so that changes in the community composition, the density and the canopy cover and the survival of the woody vegetation could be determined in relation to distance from the dam. Relationships with distance from the dam were shown for the relative density ofCombretumapiculatum in all height classes, the relative canopy cover of the second height class of woody plants, the relative canopy cover of C. apiculatum plants, the survival of all height classes of woody plants and the survival of C. apiculatum and Colophospermum mopane plants. It was concluded that the provision of water for game at the Wik-en-Weeg Dam had an impact on the woody vegetation in the vicinity. The relationships of parameters of the two dominant species, Combretum apiculatum and Colophospermum mopane, with distance from the dam were compared. Combretum apiculatum parameters were more sensitive to impact associated with the dam than those of Colophospermum mopane.

scholarly journals Plant communities of the Karkas Hunting-Prohibited Region, Isfahan-Iran

2008 ◽  
Vol 54 (No. 8) ◽  
pp. 347-358
Author(s):  
S.J. Khajeddin ◽  
H. Yeganeh
Keyword(s):  
Plant Communities ◽  
Random Sampling ◽  
Dominant Species ◽  
Sampling Method ◽  
Bare Soil ◽  
Cluster Analyses ◽  
Isfahan Province ◽  
Biogeographic Region ◽  
The Impact ◽  
Interesting Area

The Karkas mountainous region is a very interesting area for its big game wildlife and rare species in the Irano-Touranian biogeographic region. It is essential to study the plant communities and the impact of environmental factors, to protect and rehabilitate these ecosystems. The studied region is located in the Isfahan province, central Iran, with the area of about 92 100 ha. The aim of the study was to identify the plant communities of the Karkas Hunting-Prohibited Region. Vegetation cover was sampled using a stratified random sampling method and the entities were preliminarily segmented with the physiognomic-floristic-ecologic method. 10 × 10 m quadrates (100 m<sup>2</sup>) were used to estimate the species cover, litter, stone, gravel and bare soil percentages. Plant communities were classified using cluster analyses and denderogram construction. The results confirmed the importance of the climatic and topographic factors that affect the establishment of the plant communities. Plant habitats in the region are mosaics and cause ecoton formations, so diversities in species combinations increase. The species diversity of the communities was measured using the Shannon coefficient; it varied from 2.26 to 0.39. According to cluster analyses, there are 15 different plant communities, but when the second dominant species were considered, some communities were further divided into sub-communities.

scholarly journals The Life and Times of a Learning Technology System

2013 ◽  
Vol 8 (3) ◽  
pp. 24-41 ◽  
Author(s):  
Claus Pahl
Keyword(s):  
Factor Model ◽  
High Impact ◽  
Learning Technology ◽  
Environmental Constraints ◽  
Web Based ◽  
Technology System ◽  
Web Based Learning ◽  
Change Factor ◽  
Long Life ◽  
The Impact

With the inception of the web now being more than 20 years ago, many web-based learning technology systems (LTS) have had a long life and have undergone many changes, both affecting content and infrastructure technologies. A change factor model can capture the various factors causing LTS to change. Methods for change-aware design of LTS have been suggested. The purpose of this investigation is, firstly, to add empirical results to aspects of these models and methods in order to show the relevance of such a change factor model by specifically looking at an LTS that has been developed, maintained and extended over a period of 20 years. Secondly, these results shall be used to develop a conceptual model capturing and assessing the impact of change. A key observation is an unexpectedly high impact of environmental constraints on the LTS, but also new opportunities emerging over time have had dramatic changes as their consequence.

scholarly journals Dynamics of Cyanobacteria and Related Environmental Drivers in Freshwater Bodies Affected by Mitten Crab Culturing: A Study of Lake Guchenghu, China

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2468
Author(s):  
Hongmin Li ◽  
Huihui Chen ◽  
Xiaohong Gu ◽  
Zhigang Mao ◽  
Qingfei Zeng ◽  
...  
Keyword(s):  
Environmental Variables ◽  
Phytoplankton Biomass ◽  
Dominant Species ◽  
N:P Ratio ◽  
Water Bodies ◽  
Environmental Drivers ◽  
Mitten Crab ◽  
Total Phytoplankton ◽  
Freshwater Bodies ◽  
Harmful Species

Mitten crab aquaculture is prevalent in China, however, knowledge about the threat of cyanobacteria in mitten crab aquaculture-impacted water bodies is limited. Here, seasonal variations of cyanobacteria and their relationships with environmental factors were investigated for Lake Guchenghu area. Results suggested the changes of cyanobacteria community in crab ponds distinguished from the adjacent lake. In the lake, cyanobacterial biomass (3.86 mg/L, 34.6% of the total phytoplankton) was the highest in autumn with the dominance of Oscillatoria, Aphanocapsa and Pesudanabaena. By contrast, in crab ponds, cyanobacteria (46.80 mg/L, 97.2% of the total phytoplankton biomass) were the most abundant in summer when Pesudanabaena and Raphidiopsis were the dominant species. Of particular note was that obviously higher abundance of filamentous and potentially harmful species (e.g., Raphidiopsis raciborskii and Dolichospermum circinale) were observed in ponds compared to the lake. Specifically, water depth (WD), permanganate index (CODMn), total phosphorus (TP), N:P ratio, and NO 2 −-N were the key environmental variables affected cyanobacteria composition. For crab ponds, N:P ratio, water temperature (WT) and TP were the potential environmental drivers of cyanobacteria development. This study highlighted the fact that mitten crab culture had non-negligible influences on the cyanobacteria community and additional attention should be paid to the cyanobacteria dynamics in mitten crab culture-impacted water bodies, especially for those potentially harmful species.

scholarly journals Understanding the impact of plant competition on the coupling between vegetation and the atmosphere

2015 ◽  
Vol 120 (11) ◽  
pp. 2212-2228 ◽  
Author(s):  
Marloes P. van Loon ◽  
Stefan C. Dekker ◽  
Niels P. R. Anten ◽  
Max Rietkerk ◽  
Jordi Vilà-Guerau de Arellano
Keyword(s):  
Plant Competition ◽  
The Impact

Quantifying the Impact of Arbuscular Mycorrhiza on Plant Competition

1997 ◽  
Vol 85 (4) ◽  
pp. 541 ◽  
Author(s):  
A. R. Watkinson ◽  
R. P. Freckleton
Keyword(s):  
Arbuscular Mycorrhiza ◽  
Plant Competition ◽  
The Impact

scholarly journals Evaluation of Sustainable Urban Development under Environmental Constraints: A Case Study of Jiangsu Province, China

2020 ◽  
Vol 12 (3) ◽  
pp. 1049
Author(s):  
Yaqiong Wang ◽  
Guanghui Yuan ◽  
Ying Yan ◽  
Xueliang Zhang
Keyword(s):  
Sustainable Development ◽  
Urban Development ◽  
Jiangsu Province ◽  
Sustainable Urban Development ◽  
Undesirable Outputs ◽  
Environmental Constraints ◽  
Index Analysis ◽  
The Impact ◽  
Desirable And Undesirable Outputs ◽  
The City

Sustainable development is a long-term solution for urban development and a guideline for urban development. Only by better coordination around the population, resources, and environment can the city achieve sustained and steady development. In order to evaluate the efficiency of sustainable urban development under environmental constraints, this paper takes 13 prefecture-level cities in Jiangsu Province as an example. To address the infeasibility problem in the Malmquist-Luenberger (M-L) index, a modified M-L index analysis method based on the new directional distance function (DDF) is adopted. Combined with the consideration of desirable and undesirable outputs, a linear programming model for sustainable urban development evaluation is constructed to provide a scientific decision-making basis for sustainable development of the city. The results show that the growth of sustainable urban development efficiency is not only related to desirable outputs but also affected by undesirable outputs. Technical change is the main driver of most sustainable urban development efficiency growth. However, efficiency changes also affect the sustainable development potential of cities to a certain extent. Through the modified M-L index analysis, we analyze the characteristics of different regions of Jiangsu Province, the changes in efficiency and the impact of technological innovation on sustainable urban development, and give policy recommendations to promote sustainable urban development.

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