scholarly journals Vegetation–environment relationships of an inland boreal salt pan

1991 ◽  
Vol 69 (4) ◽  
pp. 722-732 ◽  
Author(s):  
C. A. Burchill ◽  
N. C. Kenkel
Keyword(s):  
Organic Matter ◽  
Species Richness ◽  
Salinity Gradient ◽  
Vegetation Pattern ◽  
Vegetation Composition ◽  
Soil Factors ◽  
Secondary Importance ◽  
Salt Pans ◽  
Salt Pan ◽  
Species Groups

Vegetation composition and community structure of boreal inland salt pans near the shore of Dawson Bay, Lake Winnipegosis, Manitoba, were examined. Eight vegetation associations and eight species groups were described from the site. Most of the vegetation associations were dominated by a single graminoid or graminoid-like species. Species composition in the most saline areas was similar to that of prairie salt pans to the south, whereas the vegetation of less saline areas showed affinities to both prairie and boreal forest. Examination of vegetation–environment relationships indicated that soil salinity was the moost important factor determining vegetation pattern. Other soil factors such as nutient levels, bulk density, and percent organic matter were of secondary importance. Species richness increased with decreasing salinity, but trends in Shannon–Weaver diversity and evenness along the salinity gradient were more complex. Despite the salinity gradient being environmentally continuous, strong vegetational discontinuities were noted. It is suggested that these discontinuities arose through interspecific competitive interaction and displacement mediated by differences in the salt tolerance of species. Key words: competition, discontinuity, gradient, halophyte, plant community, salinity.

scholarly journals Soil carbon and plant diversity distribution at the farm level in the savannah region of Northern Togo (West Africa)

2008 ◽  
Vol 5 (5) ◽  
pp. 4107-4127 ◽  
Author(s):  
M.-T. Sebastià ◽  
E. Marks ◽  
R. M. Poch
Keyword(s):  
Organic Matter ◽  
Species Richness ◽  
Soil Organic Matter ◽  
West Africa ◽  
Plant Species ◽  
Plant Diversity ◽  
Soil Degradation ◽  
Organic Matter Content ◽  
Matter Content ◽  
Vegetation Composition

Abstract. In western Africa, soil organic matter is a source of fertility for food provision and a tool for climate mitigation. In the Savannah region, strong soil degradation linked to an increase in population threatens organic matter conservation and agricultural yield. Soil degradation is also expected to impact biodiversity and, with it, increase the vulnerability of ecosystem goods and services, including the storage of soil organic carbon. Studies of land use, plant species composition and soil fertility were conducted for a conservation project at a demonstration farm in Northern Togo (West Africa), host to various management regimes. Results showed a low organic matter content of the surface soil horizons, often around 0.5%. The highest values were found in a sacred forest within the farm (2.2%). Among crops, rice had the highest soil organic matter, around 1%. In a survey of grasslands, pastures showed the highest organic matter content, with vegetation composition differing from grazed fallows and abandoned grasslands. Plant species richness showed a positive relationship with soil organic matter (R2adj=41.2%), but only by the end of the wet season, when species richness was also highest. Sampling date had a strong effect on vegetation composition. Results showed a strong influence of human activity on soil formation and distribution, and also on plant diversity. The soil characteristics found under the permanent forest suggest a high potential of the soils of the region for improvement of both agricultural yields and as a potential carbon sink relevant to global change policies.

scholarly journals DOM degradation by light and microbes along the Yukon River-coastal ocean continuum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Brice K. Grunert ◽  
Maria Tzortziou ◽  
Patrick Neale ◽  
Alana Menendez ◽  
Peter Hernes
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Salinity Gradient ◽  
Coastal Ocean ◽  
Interactive Effects ◽  
The Arctic ◽  
Yukon River ◽  
Spring Freshet ◽  
Dom Composition

AbstractThe Arctic is experiencing rapid warming, resulting in fundamental shifts in hydrologic connectivity and carbon cycling. Dissolved organic matter (DOM) is a significant component of the Arctic and global carbon cycle, and significant perturbations to DOM cycling are expected with Arctic warming. The impact of photochemical and microbial degradation, and their interactive effects, on DOM composition and remineralization have been documented in Arctic soils and rivers. However, the role of microbes, sunlight and their interactions on Arctic DOM alteration and remineralization in the coastal ocean has not been considered, particularly during the spring freshet when DOM loads are high, photoexposure can be quite limited and residence time within river networks is low. Here, we collected DOM samples along a salinity gradient in the Yukon River delta, plume and coastal ocean during peak river discharge immediately after spring freshet and explored the role of UV exposure, microbial transformations and interactive effects on DOM quantity and composition. Our results show: (1) photochemical alteration of DOM significantly shifts processing pathways of terrestrial DOM, including increasing relative humification of DOM by microbes by > 10%; (2) microbes produce humic-like material that is not optically distinguishable from terrestrial humics; and (3) size-fractionation of the microbial community indicates a size-dependent role for DOM remineralization and humification of DOM observed through modeled PARAFAC components of fluorescent DOM, either through direct or community effects. Field observations indicate apparent conservative mixing along the salinity gradient; however, changing photochemical and microbial alteration of DOM with increasing salinity indicate changing DOM composition likely due to microbial activity. Finally, our findings show potential for rapid transformation of DOM in the coastal ocean from photochemical and microbial alteration, with microbes responsible for the majority of dissolved organic matter remineralization.

scholarly journals Salinity and freshwater discharge determine rotifer distribution at the Mossoró River Estuary (Semiarid Region of Brazil)

2010 ◽  
Vol 70 (3) ◽  
pp. 551-557 ◽  
Author(s):  
AMA. Medeiros ◽  
JEL. Barbosa ◽  
PR. Medeiros ◽  
RM. Rocha ◽  
LF. Silva
Keyword(s):  
Species Richness ◽  
Rainy Season ◽  
Salinity Gradient ◽  
River Estuary ◽  
Positive Influence ◽  
Freshwater Discharge ◽  
The Other ◽  
Semiarid Region ◽  
Inverse Estuary ◽  
Species Richness And Abundance

The present study aimed at evaluating differences in rotifer distribution in three estuarine zones in an inverse estuary located in the Semiarid Region of Brazil. Zones were chosen based on their proximity to the ocean and river border as a means of reflecting a horizontal salinity gradient. High freshwater discharge during the rainy season was the major determinant of rotifer composition. On the other hand, due to higher salinity values during the dry season, very low values of species richness and abundance were observed in all zones. Therefore, the study highlights the constraints of salinity and the positive influence of seasonality and river proximity on rotifer species in a semiarid estuarine environment.

Interaction of dissolved organic matter with Hg(II) along salinity gradient in Boston Lake

2014 ◽  
Vol 52 (12) ◽  
pp. 1072-1077 ◽  
Author(s):  
Rehemanjiang Wufuer ◽  
Ying Liu ◽  
Shuyong Mu ◽  
Wenjuan Song ◽  
Xue Yang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Salinity Gradient

Plant species richness mediates the effects of vegetation structure, but not soil fertility, on insect gall richness in a savanna in Brazil

2017 ◽  
Vol 33 (3) ◽  
pp. 197-204 ◽  
Author(s):  
Walter Santos de Araújo
Keyword(s):  
Organic Matter ◽  
Species Richness ◽  
Soil Organic Matter ◽  
Plant Height ◽  
Plant Species ◽  
Vegetation Structure ◽  
Plant Species Richness ◽  
Plant Abundance ◽  
Insect Galls ◽  
Insect Gall

Abstract:The present study aims to investigate the effects of vegetation structure (plant abundance and height) and soil characteristics (soil organic matter and macronutrients) on insect gall richness, and determine the extent to which these effects are mediated by the indirect effects of plant species richness. The study was performed in forty-nine 100-m2 savanna plots in Parque Nacional das Emas (Brazil) and sampled a total of 985 individual plants of 71 plant species and 97 insect gall morphotypes. Cecidomyiidae (Diptera) induced the most insect galls (38.1%), and the plant family Myrtaceae had the greatest richness of insect gall morphotypes (16). Path analysis of plant abundance, plant height, soil macronutrients, soil organic matter and plant species richness explained 73% of insect gall richness. The results show that soil macronutrient quantity has a direct positive effect on insect gall richness, whereas plant abundance and plant height had only indirect positive effects on insect gall richness via the increase in plant species richness. These findings showed that both plant-related and environment-related factors are important to induce insect gall richness in Neotropical savannas, and that plant species richness should be taken into account to determine the richness of insect galls.

scholarly journals Assessing the Contribution of Seasonality, Tides, and Microbial Processing to Dissolved Organic Matter Composition Variability in a Southeastern U.S. Estuary

2021 ◽  
Vol 8 ◽  
Author(s):  
Rachel P. Martineac ◽  
Alexey V. Vorobev ◽  
Mary Ann Moran ◽  
Patricia M. Medeiros
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Critical Role ◽  
Bacterial Cells ◽  
Secondary Importance ◽  
Relative Contribution ◽  
Doc Concentration ◽  
Compositional Changes ◽  
Dom Composition

Uncovering which biogeochemical processes have a critical role controlling dissolved organic matter (DOM) compositional changes in complex estuarine environments remains a challenge. In this context, the aim of this study is to characterize the dominant patterns of variability modifying the DOM composition in an estuary off the Southeastern U.S. We collected water samples during three seasons (July and October 2014 and April 2015) at both high and low tides and conducted short- (1 day) and long-term (60 days) dark incubations. Samples were analyzed for bulk DOC concentration, and optical (CDOM) and molecular (FT-ICR MS) compositions and bacterial cells were collected for metatranscriptomics. Results show that the dominant pattern of variability in DOM composition occurs at seasonal scales, likely associated with the seasonality of river discharge. After seasonal variations, long-term biodegradation was found to be comparatively more important in the fall, while tidal variability was the second most important factor correlated to DOM composition in spring, when the freshwater content in the estuary was high. Over shorter time scales, however, the influence of microbial processing was small. Microbial data revealed a similar pattern, with variability in gene expression occurring primarily at the seasonal scale and tidal influence being of secondary importance. Our analyses suggest that future changes in the seasonal delivery of freshwater to this system have the potential to significantly impact DOM composition. Changes in residence time may also be important, helping control the relative contribution of tides and long-term biodegradation to DOM compositional changes in the estuary.

scholarly journals Relationship between moth (night active Lepidoptera) diversity and vegetation characteristics in southern Sweden

2020 ◽  
Vol 24 (6) ◽  
pp. 1005-1015
Author(s):  
Torbjörn Tyler
Keyword(s):  
Species Richness ◽  
Community Composition ◽  
Plant Diversity ◽  
Vascular Plant ◽  
Habitat Characteristics ◽  
Vegetation Composition ◽  
Vascular Plant Diversity ◽  
Site Characteristics ◽  
Tree Canopy Cover ◽  
Wide Range

Abstract The diversity and community composition of moths (both macro- and micromoths) at 32 sites, representing a wide range of habitat types (forests, grasslands, wetlands, agricultural and urban areas) within a restricted region in central Scania, southern-most Sweden, was investigated by use of light moth traps and compared with vascular plant species richness and habitat characteristics. The results revealed a highly significant general association between vegetation composition and the composition of the moth community and multivariate (CCA) analyses indicated light availability and soil fertility parameters (pH and macronutrients) to be the habitat characteristics that best correlated with moth community composition. Less strong, but still significant, positive relationships between moth abundance and local vascular plant diversity were also revealed. Moth species richness was positively correlated with diversity of woody plant genera in the neighborhood, but not with local vascular plant diversity in general. As for more general site characteristics, there were tendencies for higher moth richness and abundance at sites with more productive soils (well-drained, high pH, high nutrient availability), while shading/tree canopy cover, management, soil disturbance regimes and nectar production appeared unrelated to moth community parameters. It is concluded that local moth assemblages are strongly influenced by site characteristics and vegetation composition. Implications for insect conservation: The results show that obtaining moth data on a local scale is useful for conservation planning and does not need to be very cumbersome. Local moth assemblages monitored are indeed related to local site characteristics of conservation relevance.

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