scholarly journals The impact of spatial isolation and local habitat conditions on colonization of recent forest stands by ectomycorrhizal fungi

2018 ◽  
Vol 429 ◽  
pp. 84-92 ◽  
Author(s):  
Margaux Boeraeve ◽  
Olivier Honnay ◽  
Nele Mullens ◽  
Kris Vandekerkhove ◽  
Luc De Keersmaeker ◽  
...  
Keyword(s):  
Ectomycorrhizal Fungi ◽  
Habitat Conditions ◽  
Forest Stands ◽  
Spatial Isolation ◽  
The Impact ◽  
Local Habitat

scholarly journals Impact du chancre hypoxylonien sur le tremble de 2 unités de gestion du Québec

1982 ◽  
Vol 58 (3) ◽  
pp. 139-142
Author(s):  
Louis Archambault
Keyword(s):  
Populus Tremuloides ◽  
Forest Stands ◽  
Management Units ◽  
Hypoxylon Mammatum ◽  
The Impact

A survey was conducted in the management units of Portneuf and Grand-Portage, Québec to determine the impact of Hypoxylon canker (Hypoxylon mammatum (Wahl.)) on aspen (Populus tremuloides Michx.). In 78 forest stands (2340 stems) of Portneuf, sampling revealed 2.6% of stems (2.0% of volume) affected or dead. In the 82 Grand-Portage stands (2460 stems) 4.1% of stems (2.8% of volume) were affected or dead. Other analyses were carried out on the frequency of the disease in relation to stand characteristics.Although annual losses which represent only a sixth of this evaluation are relatively low, we must emphasize that they are cumulative over the whole life of the stands. Moreover, the importance of the impact could increase if aspen was widely used.

scholarly journals Is the impact of eutrophication on phytoplankton diversity dependent on lake volume/ecosystem size?

2016 ◽  
Author(s):  
Didier L. Baho ◽  
Stina Drakare ◽  
Richard K. Johnson ◽  
Craig R. Allen ◽  
David G. Angeler
Keyword(s):  
Species Diversity ◽  
Growing Season ◽  
Phytoplankton Diversity ◽  
Habitat Features ◽  
Anthropogenic Stressors ◽  
Lake Volume ◽  
Ecosystem Size ◽  
Phytoplankton Communities ◽  
The Impact ◽  
Local Habitat

<p>Research focusing on biodiversity responses to the interactions of ecosystem size and anthropogenic stressors are based mainly on correlative gradient studies, and may therefore confound size-stress relationships due to spatial context and differences in local habitat features across ecosystems. We investigated how local factors related to anthropogenic stressors (<em>e.g.,</em> eutrophication) interact with ecosystem size to influence species diversity. In this study, constructed lake mesocosms (with two contrasting volumes: 1020 (shallow mesocosms) and 2150 (deep mesocosms) litres) were used to simulate ecosystems of different size and manipulated nutrient levels to simulate mesotrophic and hypertrophic conditions. Using a factorial design, we assessed how the interaction between ecosystem size and nutrients influences phytoplankton diversity. We assessed community metrics (richness, diversity, evenness and total biovolumes) and multivariate community structure over a growing season (May to early November 2011). Different community structures were found between deep and shallow mescosoms with nutrient enrichment: Cyanobacteria dominated in the deep and Charophyta in the shallow mesocosms. In contrast, phytoplankton communities were more similar to each other in the low nutrient treatments; only Chlorophyta had generally a higher biovolume in the shallow compared to the deep mesocosms. These results suggest that ecosystem size is not only a determinant of species diversity, but that it can mediate the influence of anthropogenic effects on biodiversity. Such interactions increase the uncertainty of global change outcomes, and should therefore not be ignored in risk/impact assessment and management.</p>

Assessing the impact of local habitat variables and landscape context on riparian birds in agricultural, urbanized, and native landscapes

2008 ◽  
Vol 17 (8) ◽  
pp. 1923-1935 ◽  
Author(s):  
David Luther ◽  
Jodi Hilty ◽  
Jack Weiss ◽  
Caitlin Cornwall ◽  
Missy Wipf ◽  
...  
Keyword(s):  
Landscape Context ◽  
Riparian Birds ◽  
The Impact ◽  
Local Habitat ◽  
Habitat Variables

Changes in spider assemblages along grassland and savanna grazing gradients in northern Australia

2004 ◽  
Vol 26 (1) ◽  
pp. 3 ◽  
Author(s):  
T. B. Churchill ◽  
J. A. Ludwig
Keyword(s):  
Grazing Intensity ◽  
Perennial Grasses ◽  
Patch Type ◽  
Habitat Changes ◽  
The Family ◽  
Shrub Canopy ◽  
Annual Grasses ◽  
Dry Seasons ◽  
The Impact ◽  
Local Habitat

Spiders are beneficial predators that respond to those land uses that modify their habitat. Cattle grazing is an extensive land use across northern Australian rangelands, yet the impact of grazing on spider habitat is poorly understood. In this study, we evaluated the way in which spider assemblages varied between grassland and savanna habitats in the Victoria River District of the Northern Territory, and also between dry and wet seasons in the savanna habitat. We also investigated changes in spider assemblages, and some common taxa, with distance from cattle watering points, which was used as a surrogate for a gradient in grazing intensity. Spiders were sampled using pitfall traps and sweep nets along two distance from water-grazing gradients. The first gradient was in savanna on calcareous red loam soils at Kidman Springs, and the second was in grassland on cracking black clays at Mount Sanford. Ordinations revealed that spider assemblages differed between grassland and savanna, and between the late-wet and late-dry seasons in savanna. Spider assemblages also markedly changed along the two distance-grazing gradients in response to habitat changes. For example, orb weavers in the family Araneidae increased in abundance as the cover of perennial grasses and litter increased with distance from water; this response was consistent for both grassland and savanna gradients. Patch type was also important to the distribution of spiders. For example, more individuals of Habronestes sp. were caught when the local habitat was patches of perennial grasses rather than patches of annual grasses and litter, bare ground, or tree-shrub canopy. These results suggest that spiders are good indicators of the habitat changes that may occur with grazing in the rangelands of Australia.

scholarly journals Phosphite and mycorrhizal formation in seedlings of three Australian Myrtaceae

2000 ◽  
Vol 48 (6) ◽  
pp. 725 ◽  
Author(s):  
Kay Howard ◽  
Bernie Dell ◽  
Giles E. Hardy
Keyword(s):  
Ectomycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Phytophthora Cinnamomi ◽  
Fold Increase ◽  
Native Plant ◽  
Negative Effects ◽  
Eucalyptus Marginata ◽  
Collar Rot ◽  
The Impact ◽  
Different Levels

Currently in Western Australia, phosphite is being used to contain the root and collar rot pathogen, Phytophthora cinnamomi, in native plant communities. There have been reports of negative effects of phosphite on arbuscular mycorrhiza (AM), so there are concerns that it may have a deleterious effect on other mycorrhizal fungi. Two glasshouse experiments were undertaken to determine the impact of phosphite on eucalypt-associated ectomycorrhizal fungi. In the first experiment, non-mycorrhizal seedlings of Eucalyptus marginata, Eucalyptus globulus and Agonis flexuosa were sprayed to runoff with several concentrations of phosphite, and then planted into soil naturally infested with early colonising mycorrhizal species. Assessments were made of percentage of roots infected with mycorrhizal fungi. There was no significant effect on ectomycorrhizal formation but there was a four-fold increase in AM colonisation of A. flexuosa roots with phosphite application. In the second experiment, E. globulus seedlings mycorrhizal with Pisolithus, Scleroderma and Descolea were treated with different levels of phosphite and infection of new roots by ectomycorrhizal fungi was assessed. There was no significant effect on ectomycorrhizal formation when phosphite was applied at the recommended rate (5 g L–1), while at 10 g L–1 phosphite significantly decreased infection by Descolea.

scholarly journals The current state of the ornithological fauna of the Krasnoyarsk Reservoir

2020 ◽  
Vol 9 (3) ◽  
pp. 28-31
Author(s):  
Olga V. Bulycheva ◽  
Aleksander A. Baranov
Keyword(s):  
Hydrological Regime ◽  
Hydroelectric Power Station ◽  
Hydroelectric Power ◽  
Habitat Conditions ◽  
Biotopic Distribution ◽  
Geological Processes ◽  
Current State ◽  
Key Points ◽  
The Yenisei River ◽  
The Impact

This paper discusses the current state of the avifauna on the territory of the Krasnoyarsk Reservoir. To date, the species composition of birds in the study area has not been studied, although it is worth noting the need to study the distribution of birds in this area. The construction of the Krasnoyarsk hydroelectric power station led to changes in the hydrological regime of the Yenisei River with subsequent flooding of the surrounding territory, as a result of which various geological processes of collapse of the Krasnoyarsk Reservoir banks are observed. Bank metamorphoses can also influence the spatial distribution of birds and creation of new ornithocomplexes. Our ecological and faunal analysis was carried out over two years (20182019) at nine key points along the bank lines of the Krasnoyarsk Reservoir within a radius of one kilometer from the water to identify the impact of geological changes in the banks on the nature of bird placement. The key areas of the study were determined, taking into account various biotopic habitat conditions that attract birds. Monitoring of avifauna on the territory of the Krasnoyarsk Reservoir will allow us to assess the degree of influence of changes in the geological processes of the banks on the spatial and biotopic distribution of birds, and it is also possible to forecast the disappearance or movement of some species and subspecies on this territory.

scholarly journals Risk assessment for COVID-19 transmission at household level in sub-Saharan Africa: evidence from DHS

Genus ◽  
2021 ◽  
Vol 77 (1) ◽  
Author(s):  
Olusesan Ayodeji Makinde ◽  
Joshua O. Akinyemi ◽  
Lorretta F. Ntoimo ◽  
Chukwuedozie K. Ajaero ◽  
Dorothy Ononokpono ◽  
...  
Keyword(s):  
Elderly Person ◽  
Household Wealth ◽  
Sub Saharan Africa ◽  
Transmission Risk ◽  
Demographic And Health Surveys ◽  
Elderly Persons ◽  
Habitat Conditions ◽  
African Countries ◽  
Household Level ◽  
The Impact

AbstractHousehold habitat conditions matter for diseases transmission and control, especially in the case of the novel coronavirus (COVID-19). These conditions include availability and adequacy of sanitation facilities, and number of persons per room. Despite this, little attention is being paid to these conditions as a pathway to understanding the transmission and prevention of COVID-19, especially in Africa, where household habitat conditions are largely suboptimal. This study assesses household sanitation and isolation capacities to understand the COVID-19 transmission risk at household level across Africa. We conducted a secondary analysis of the Demographic and Health Surveys of 16 African countries implemented between 2015 and 2018 to understand the status of households for prevention of COVID-19 transmission in home. We assessed handwashing capacity and self-isolation capacity using multiple parameters, and identified households with elderly persons, who are most at risk of the disease. We fitted two-level random intercept logit models to explore independent relationships among the three indicators, while controlling for the selected explanatory variables. Handwashing capacity was highest in Tanzania (48.2%), and lowest in Chad (4.2%), varying by household location (urban or rural), as well as household wealth. Isolation capacity was highest in South Africa (77.4%), and lowest in Ethiopia (30.9%). Senegal had the largest proportion of households with an elderly person (42.1%), while Angola (16.4%) had the lowest. There were strong, independent relationships between handwashing and isolation capacities in a majority of countries. Also, strong associations were found between isolation capacity and presence of older persons in households. Household capacity for COVID-19 prevention varied significantly across countries, with those having elderly household members not necessarily having the best handwashing or isolation capacity. In view of the age risk factors of COVID-19 transmission, and its dependence on handwashing and isolation capacities of households, each country needs to use the extant information on its risk status to shape communication and intervention strategies that will help limit the impact of the disease in its population across Africa.

scholarly journals Complex effects of acidification, habitat properties and fish stock on littoral macroinvertebrate assemblages in montane standing waters

2022 ◽  
Author(s):  
Jana Petruželová ◽  
Jindřiška Bojková ◽  
Jan Sychra ◽  
Vanda Šorfová ◽  
Vendula Polášková ◽  
...  
Keyword(s):  
Species Composition ◽  
Water Chemistry ◽  
Water Levels ◽  
Habitat Characteristics ◽  
Fish Stock ◽  
Littoral Vegetation ◽  
Habitat Properties ◽  
Standing Waters ◽  
The Impact ◽  
Local Habitat

Littoral macroinvertebrates in acidified waterbodies are affected by the interaction of acidification and local environmental conditions. Understanding the interplay of these factors in the structuring of communities is essential for interpreting responses to and/or recovery from acidification. Here, we analyse the species composition and richness of littoral macroinvertebrates in a range of acidified montane standing waters in relation to water chemistry, littoral characteristics and fish stock. The main species composition gradients were related to pH and conductivity; however, considerable variation along these gradients was associated with local habitat characteristics (changing water levels and littoral structure) and concentration of ionic aluminium and dissolved organic carbon. Although fish stock effects were confounded by correlated acidity, we observed a significant decline in abundance of macroinvertebrates vulnerable to fish predation at sites with fish stock. Overall, littoral macroinvertebrates of acidic waterbodies were diverse due to the heterogeneity of local habitat properties, despite they were dominated by acid-tolerant species. Acidic humic sites with dense, heterogeneous littoral vegetation were species-rich, hosting numerous habitat specialists and rare species, while chronically acidified lakes with high aluminium concentrations and sparse littoral vegetation had species-poor assemblages, characteristic of strong acid-stress. Water level manipulation resulted in serious assemblage impoverishment, overriding the effects of more favourable water chemistry. This study shows that the littoral fauna of acidic waterbodies is structured by complex effects induced by local factors in addition to acidity, resulting in acid-stressed assemblages with relatively high variability, emphasising a need to analyse local habitat factors when evaluating the impact of acidification on macroinvertebrates.

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