Browsing by Author "Gyan P. Sharma"

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Aboveground-belowground interactions: Implication for invasiveness
(CRC Press, 2013) Priyanka Srivastava; Gyan P. Sharma; A.S. Raghubanshi
The AG-BG-coupled influence acts through a variety of interactions, which could be positive, negative, or neutral (Zak et al. 1994, Wardle 2002, Bardgett and Wardle 2003). Plants comprise a major component of AG and are the source of nutrients to soil biota, which is considered to be the major component of BG. Plants provide organic carbon to surface and subsurface soil decomposers and resources to root herbivores, pathogens, and symbiotic mutualists. Soil is a complex mix of organic and inorganic matter and has abundant microorganisms for nutrient mineralization and cycling, which regulates the. © 2013 by Taylor and Francis Group, LLC.
Dynamics of the functional groups in the weed flora of dryland and irrigated agroecosystems in the Gangetic plains of India
(2008) Anamika Singh; Gyan P. Sharma; Akhilesh S. Raghubanshi
The relative abundance of the weed functional types in dryland and irrigated rice in the Kharif (summer) crop field and dryland lentil and wheat in the irrigated Rabi (winter) crop field was studied at the agricultural farm of Banaras Hindu University, Varanasi, India. A total of 22 species, belonging to 17 families, was recorded in the dryland and irrigated rice ecosystems and 18 species, belonging to eight families, were recorded in the dryland lentil and irrigated wheat ecosystems. The Importance Value Index (IVI) of the hemicryptophytes showed an increasing trend with the crop growth period in the case of the dryland rice, whereas in the irrigated rice plots, a reduction in the IVI of the hemicryptophytes, with a related increase in the importance of the therophytes, was observed as the crop attained maturity. Also, the trend of a decreased IVI was observed for the geophytes in the fertilized dryland rice plots. The principal components analysis (PCA) ordination showed the uniqueness of the crop plot in terms of weed species composition. The PCA analysis of the functional types on the basis of the crop plots indicated that the hemicryptophyte and therophyte weed species composition was heavily altered at the initial and final sampling, although the weed flora was dominated by the therophytes and geophytes. These results suggest the prioritization of hierarchical temporal management options for the functional weed types in different crop plots and that this approach warrants further investigation. © 2008 The Authors.
Effect of Lantana camara L. cover on local depletion of tree population in the Vindhyan tropical dry deciduous forest of India
(Corvinus University of Budapest, 2007) Gyan P. Sharma; A.S. Raghubanshi
The dry deciduous forest of northern India is being progressively invaded by an alien invasive woody shrub Lantana camara L. (Lantana). The invasion of lantana threatens the survival of many species. This study examines the demographic instability of tree species at different levels of lantana cover. Based on proportion of seedlings of a species in its total population (seedling+sapling+adult), about 39.5% and 60% of total 38 species exhibited local demographic instability at different levels of lantana cover for the first and the second census respectively. This decline in species could be attributed to altered microenvironment (light, pH and temperature) beneath the lantana bushes. The study concludes that the presence of lantana shrub as dense understorey perturbs the seedling recruitment of native tree species in the forest and this leads to differential depletion of native trees. © 2007, Penkala Bt.
How Lantana invades dry deciduous forest: A case study from Vindhyan highlands, India
(2010) Gyan P. Sharma; Akhilesh S. Raghubanshi
Invasion by exotic species is among the most important global-scale problems experienced by natural ecosystems. Studies document that floristic changes that emerge after habitat fragmentation may be due to invasion by exotic weeds. When either habitat modification or the introduction of foreign species results in changes in the community, then native species populations could undergo local decline or extinction. The present study provides a qualitative and quantitative overview of the effects of habitat fragmentation on the invasive success of Lantana camara as well as the subsequent effects of this invader on ecosystem structure and function in the Vindhyan dry deciduous forest of India. © International Society for Tropical Ecology.
Ingress of lantana in dry tropical forest fragments: Edge and shade effects
(2008) Purnima Raizada; Gyan P. Sharma; A.S. Raghubanshi
[No abstract available]
Invasive species: Ecology and impact of Lantana camara invasions
(CABI Publishing, 2011) Gyan P. Sharma; Akhilesh S. Raghubanshi
[No abstract available]
Lantana invasion alters soil nitrogen pools and processes in the tropical dry deciduous forest of India
(2009) Gyan P. Sharma; A.S. Raghubanshi
Invasive species can alter the soil nutrient pools and processes in ecosystems that they invade by altering the quality and quantity of litter inputs. Studies have shown the impact of vegetative understory invasions on soil nitrogen (N) availability in forest ecosystems. In the dry deciduous Vindhyan forest of India we studied the effect of one of the world's most noxious weeds, lantana (Lantana camara L.) on soil N availability and N-mineralization beneath the forest canopy and lantana canopy. We observed that the lantana litter inputs increase with increasing lantana cover and the chemical composition of lantana litter was also very much different from the native forest species litter. High N, low lignin content of the lantana litter and favorable microclimate beneath lantana canopy favored faster decomposition and release of N. This alteration in litter inputs and chemistry beneath the lantana canopy positively and significantly altered soil N availability, N-mineralization, and total soil N. The results imply that a positive feed back nutrient cycle might exist beneath the lantana canopy which may favor its growth (cover) by increasing the nutrients beneath its canopy. © 2009 Elsevier B.V. All rights reserved.
Lantana invasion: An overview
(2005) Gyan P. Sharma; Akhilesh S. Raghubanshi; Jamuna S. Singh
We review the key features of Lantana (Lantana camara L.), an invasive plant species considered to be among the world's 10 worst weeds. Lantana occurs in diverse habitats and on a variety of soil types, and its spread is encouraged by animal activities and by human disturbances, such as cultivation, road construction, and changes in fire regimes. Lantana is morphologically distinct in the different regions of its invasive range compared to those regions in its native range. The biological attributes contributing to the success of Lantana as an invader species include: fitness homeostasis, phenotypic plasticity, dispersal benefits from destructive foraging activities, widespread geographic range, vegetative reproduction, fire tolerance, better competitive ability compared to native flora, and allelopathy. Mechanical, chemical and biological options for the eradication and control of Lantana are available. It is emphasized that ecosystem-level consequences of Lantana invasion, particularly on the biodiversity of native flora, are little understood and studies are needed to fulfill this knowledge gap. © 2005 Blackwell Publishing Asia Pty Ltd.
Leaf traits and herbivory as indicators of ecosystem function
(2011) Prajjwal Dubey; Gyan P. Sharma; A.S. Raghubanshi; J.S. Singh
Plant functional types bridge the gap between plant physiology and ecosystem processes. In the present article, we review the plant functional traits and their response to grazing, and discuss how this affects the nutrient dynamics of the system under the pressure of herbivory. The results also strengthen the management of ecosystems being grazed by herbivores.
Plant invasions along roads: A case study from central highlands, India
(2009) Gyan P. Sharma; A.S. Raghubanshi
Road sides provide suitable conditions for the establishment and growth of non-native species. The phenomenon of non-native species spread through roads has further increased due to rapid anthropogenic developments. Here we intend to investigate the status of native and non-native species and how the species richness and diversity change in a perpendicular road transect across the three different road use types in the central highlands of India. Presence of 55 non-native species was recorded, of the total 71 species along the road sides. Non-native species richness significantly increased with increasing road use type. Although, the species diversity significantly decreased from road verges to the forest interior in all the road use types. Indicating the role of non-native propagule spread through the roads into the interior forest landscapes. The study gives a management implication, to restrict the non-native species spread from the road sides to the forest interior, irrespective of road use types. © Springer Science+Business Media B.V. 2008.
Plant invasions: Emerging trends and future implications
(2005) Gyan P. Sharma; J.S. Singh; A.S. Raghubanshi
Invasive species are a growing problem for the world, both ecologically and economically. The impact of invasive species on native species and ecosystems has been immense. Invasion is considered to be an important driver of global change. The impact on economy by these species is evident. The cost of impact which invasive species cause is now estimated to range from millions to billions of dollars and eventually it would be severe for all ecosystems. The various aspects of invasion related to ecology and economy have been summarized to give an insight into the problem and presumed solutions to invasion. Prediction of invasiveness is intricate, but economic and ecological outcome, either good or bad of species invasion, will soon pervade all countries and societies.
Plastic responses to different habitat type contribute to Hyptis suaveolens poit. Invasiveness in the dry deciduous forest of India
(2009) Gyan P. Sharma; A.S. Raghubanshi
[No abstract available]
Urbanization and road-use determines calotropis procera distribution in the Eastern Indo-Gangetic Plain, India
(2010) Gyan P. Sharma; Manoj Kumar; Akhilesh S. Raghubanshi
[No abstract available]