The Role of Plant Size and Nutrient Concentrations in Associations between Medicago, and Rhizobium and/or Glomus

2000 ◽  
Vol 43 (2) ◽  
pp. 221-226 ◽  
Author(s):  
N. Goicoechea ◽  
M.C. Antolin ◽  
M. Sanchez-Diaz
Keyword(s):  
Plant Size ◽  
Nutrient Concentrations

scholarly journals A Model Study on the Role of Wetland Zones in Lake Eutrophication and Restoration

2001 ◽  
Vol 1 ◽  
pp. 605-614 ◽  
Author(s):  
J.H. Janse ◽  
W. Ligtvoet ◽  
S. Van Tol ◽  
A.H.M. Bresser
Keyword(s):  
Nutrient Loading ◽  
Predatory Fish ◽  
Nutrient Concentrations ◽  
Fish Stock ◽  
Mixing Rate ◽  
Marsh Vegetation ◽  
Model Calculations ◽  
Critical Loading ◽  
Marsh Area

Shallow lakes respond in different ways to changes in nutrient loading (nitrogen, phosphorus). These lakes may be in two different states: turbid, dominated by phytoplankton, and clear, dominated by submerged macrophytes. Both states are self-stabilizing; a shift from turbid to clear occurs at much lower nutrient loading than a shift in the opposite direction. These critical loading levels vary among lakes and are dependent on morphological, biological, and lake management factors. This paper focuses on the role of wetland zones. Several processes are important: transport and settling of suspended solids, denitrification, nutrient uptake by marsh vegetation (increasing nutrient retention), and improvement of habitat conditions for predatory fish. A conceptual model of a lake with surrounding reed marsh was made, including these relations. The lake-part of this model consists of an existing lake model named PCLake[1]. The relative area of lake and marsh can be varied. Model calculations revealed that nutrient concentrations are lowered by the presence of a marsh area, and that the critical loading level for a shift to clear water is increased. This happens only if the mixing rate of the lake and marsh water is adequate. In general, the relative marsh area should be quite large in order to have a substantial effect. Export of nutrients can be enhanced by harvesting of reed vegetation. Optimal predatory fish stock contributes to water quality improvement, but only if combined with favourable loading and physical conditions. Within limits, the presence of a wetland zone around lakes may thus increase the ability of lakes to cope with nutrients and enhance restoration. Validation of the conclusions in real lakes is recommended, a task hampered by the fact that, in the Netherlands, many wetland zones have disappeared in the past.

scholarly journals Effects of fragmentation on plant adaptation to urban environments

2017 ◽  
Vol 372 (1712) ◽  
pp. 20160038 ◽  
Author(s):  
Jonathan Dubois ◽  
Pierre-Olivier Cheptou
Keyword(s):  
Reproductive Traits ◽  
Urban Ecosystems ◽  
Terrestrial Ecosystems ◽  
Plant Size ◽  
Urban Environments ◽  
Trait Variation ◽  
Fragmented Habitats ◽  
Dispersal Traits ◽  
Neutral Markers

Urban ecosystems are relatively recent and heavily human-altered terrestrial ecosystems with a surprisingly high diversity of animals, plants and other organisms. Urban habitats are also strongly fragmented and subject to higher temperatures, providing a compelling model for studying adaptation to global change. Crepis sancta (Asteraceae), an annual Mediterranean wasteland weed, occupies fragmented urban environments as well as certain unfragmented landscapes in southern France. We tested for shifts in dispersal, reproductive traits and size across a rural–urban gradient to learn whether and how selection may be driving changes in life history in urban and fragmented habitats. We specifically compared the structure of quantitative genetic variation and of neutral markers (microsatellites) between urban and rural and between fragmented and unfragmented habitats. We showed that fragmentation provides a better descriptor of trait variation than urbanization per se for dispersal traits. Fragmentation also affected reproductive traits and plant size though one rural population did conform to this scheme. Our study shows the role of fragmentation for dispersal traits shift in urban environments and a more complex pattern for other traits. We discuss the role of pollinator scarcity and an inhospitable matrix as drivers of adaptation. This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.

Species Size and Reproductive Economy in Herbaceous Vegetation

2016 ◽  
Author(s):  
Amanda Tracey
Keyword(s):  
Species Coexistence ◽  
Plant Size ◽  
Future Research ◽  
Traditional Theory ◽  
Old Field ◽  
Critical Question ◽  
Self Fertilization ◽  
Reproductive Economy ◽  
Competition For Resources

According to traditional theory, larger plants generaly have an advantage with respect to competition, especially for light. It seems a paradox then that most species that coexist within natural vegetation are relatively small; specis size distributions are right-skewed at virtually every scale. The critical question then becomes: if bigger is better in competition for resources, why then are there so many small plants? A potential explanation for this paradox is that smaller species may have greater reproductive economy-i.e. the ability to reproduce despite suppression from intense competition. Selection for greater reproductive economy may be associated with smaller seed sizes, increased rates of self-fertilization and/or clonality, and in the case of this study, smaller size at reproductive maturity. Random plots in an old field at Queen's University Biological Station were sampled and the largest and smallest reproductive individuals of each species were collected, dried and weighed - to test the hypothesis that smaller species can reproduce at a smaller proportion of their maximum potential plant sizes. The results did not support this, but the hypothesis that smaller plants have greater reproductive economy could not be rejected as it was not possible to record data for the largest possible plant size for each species (since even the largest plants were subjected to competition from neighbours). This provides a focus for future research. Understanding the role of plant size in affecting the process of species assembly has important implications for species coexistence and mechanisms of biodiversity preservation, and thus efforts involving conservation and ecosystem management.

scholarly journals Role of nutrient concentrations and water movement on diatom’s productivity in culture

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ida Orefice ◽  
Margherita Musella ◽  
Arianna Smerilli ◽  
Clementina Sansone ◽  
Raghu Chandrasekaran ◽  
...  
Keyword(s):  
Water Movement ◽  
Nutrient Concentrations

scholarly journals Contribution of Internal Nutrients Loading on the Water Quality of a Reservoir

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1409 ◽  
Author(s):  
Hye Won Lee ◽  
Yong Seok Lee ◽  
Jonggun Kim ◽  
Kyoung Jae Lim ◽  
Jung Hyun Choi
Keyword(s):  
Water Quality ◽  
Sediment Load ◽  
Transport Model ◽  
Three Dimensional ◽  
Algal Growth ◽  
Nutrient Concentrations ◽  
Internal Load ◽  
Phosphorus Flux

Sediment plays an important role in the water quality of a lake by acting as both a nutrient source and sink. The amount of phosphorus and nitrogen in the water depends on the internal load from the sediment as well as the external load. To estimate the effects of sediment load on the water quality of a reservoir, we applied a three-dimensional hydrodynamic and transport model based on the benthic chamber experimental results at Euiam Lake, South Korea. As shown in the sensitivity analysis results, the eutrophication period could be significantly extended by a change of phosphorus flux rates from the sediments. The increased phosphorus flux from the sediments intensifies the algal growth of Euiam Lake, which could cause serious algal bloom during spring and fall. This study provides information on nutrient concentrations in the sediment of Euiam Lake, verifies the role of the sediment as a source or sink of nutrients, and evaluates the effect of sediment release of nutrients and contaminants on water quality. This research is a useful tool in determining the effects of internal load in lakes and establishing the operation guideline for sediment management in order to maintain feasible water quality for beneficial use.

scholarly journals Growth and Foliar Nutrient Concentrations of Crape Myrtle in Response to Disparate Climate and Fertilizer Placement in Large Nursery Containers

1996 ◽  
Vol 14 (1) ◽  
pp. 9-12
Author(s):  
Chris A. Martin ◽  
John M. Ruter
Keyword(s):  
Sonoran Desert ◽  
Root Zone ◽  
Plant Size ◽  
Nutrient Concentrations ◽  
Fertilizer Placement ◽  
The North ◽  
Foliar Nutrient ◽  
Foliar Nutrient Concentrations ◽  
Central Arizona ◽  
Desert Climate

Abstract A study was replicated in different climates [central Arizona (arid, Sonoran desert) and southwestern Georgia (humid, temperate)] to evaluate effects of controlled-release fertilizer placement in a bark-based container substrate on growth and foliar nutrient concentrations of Lagerstroemia indica L. × L. fauriei Koehne ‘Muskogee’ in large (#7) containers. Plants in Arizona were smaller with higher shoot-to-root ratios and higher levels of N, K, P, Fe, and Cu and lower levels ofCa and Zn in foliage compared with plants in Georgia. Differences in meteorological factors such as higher maximum and minimum temperatures and solar radiation, lower rainfall, and higher container root-zone temperatures, leachate electrical conductivity and nitrate concentrations were coincident with the smaller size and higher foliar nutrient concentration of Arizona plants. Fertilizer placed at the north exposure of container substrate increased plant size in Arizona. However, compared with growth of plants in Georgia, fertilizer placement at the north exposure in Arizona was not enough to entirely alleviate size inhibition caused by the arid Sonoran desert climate.

scholarly journals OVERSOWING WHITE CLOVER INTO CLEARED AND UNIMPROVED NORTH ISLAND HILL COUNTRY - THE ROLE OF MANAGEMENT, FERTILISER, INOCULATION, PELLETING AND RESIDENT RHIZOBIA.

1986 ◽  
pp. 43-51
Author(s):  
M.J. Macfarlane ◽  
P.M. Bonish
Keyword(s):  
White Clover ◽  
Practical Method ◽  
Plant Size ◽  
Hill Country ◽  
Inoculant Strain ◽  
Water Rate ◽  
Fertiliser Application ◽  
Steep Slopes ◽  
Suppression Effects

The roles of inoculation, pelleting and fertiliser were examined when white clover was oversown into recently cleared North Island hill country with a low resident white clover rhizobia population. Inoculation aided establishment at some sites. Recovery of inoculant strain from plants and soil was generally low, initial nodulation by the inoculant strain being replaced by expanding resident rhizobial populations. Pelleting was necessary to ensure inoculant survival on seed and inoculant establishment. Fertiliser application at oversowing consistently increased seedling and later plant size. Grazing managements (pre and post-oversowing), treading and chemical sward suppression effects were assessed on paddock scale oversowings of white clover into unimproved hill pastures. Pre-oversowing grazing to 900 kg DM/ha or less, and frequent post-oversowing grazings, were necessary to control competition from the resident sward. The use of paraquat: diquat at a low rate was required to maximise establishment. Reducing the water rate with herbicide from 200 to 60 litres/ha maintained high establishment on steep slopes and attained 80% of potential on easy slopes. Additional treading was a practical method of increasing establishment. Keywords: White clover, Trifolium repens, oversowing, establishment, rhizobia, competition, fertiliser, inoculation, pelleting, paraquat, diquat, treading, hill country.

The role of plant size in the selection of glyphosate resistance inSorghum halepense

2018 ◽  
Vol 74 (11) ◽  
pp. 2460-2467 ◽  
Author(s):  
Martin Vila-Aiub ◽  
Cecilia Casas ◽  
Pedro E Gundel
Keyword(s):  
Glyphosate Resistance ◽  
Plant Size ◽  
Selection Of
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