|
Top Dying Disease
Top dying disease is a disease that affects ''Heritiera fomes'', a species of mangrove tree known as "sundri", a characteristic tree of the estuarine complex of the Ganges–Brahmaputra Delta in Bangladesh and West Bengal. Although an increase in certain trace elements in the sediment deposited where these trees grow may be a factor in the incidence of the disease, its cause has not been fully established. __TOC__ History About 63% of the trees growing in the Sundarbans are ''Heritiera fomes''. Sporadic instances of top dying disease had been noticed in these trees earlier in the twentieth century but the disease became more acute and extensive after about 1970. An inventory of trees in the Sundarbans in 1985 recorded 45 million diseased trees with nearly half of these having more than half their crown affected. No causal agent has been discovered and the dieback is thought to be the result of stressful conditions, perhaps caused by an increase in the heavy metal concentration of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heritiera Fomes
''Heritiera fomes'' is a species of mangrove tree in the family Malvaceae. Its common names include sunder, sundri, jekanazo and pinlekanazo. It is the dominant mangrove tree species of the Sundarbans of Bangladesh and India, and comprises about 70% of the trees in the area. ''H. fomes'' is a major timber-producing tree. It is threatened by over-harvesting, water diversions in the Ganges Basin, fluctuations in salinity due to upstream and coastal development and top dying disease. The International Union for Conservation of Nature has assessed it as being "endangered". Description ''Heritiera fomes'' is a medium-sized evergreen tree growing to a height of . The roots are shallow and spreading and send up pneumatophores. The trunk develops buttresses and is grey with vertically fissured bark. Trees with girths of used to be found but these large trees have mostly been harvested for their timber. The trunk has few large branches and the canopy is open. The leathery leaves are ellip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mangrove
A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in several plant families. They occur worldwide in the tropics and subtropics and even some temperate coastal areas, mainly between latitudes 30° N and 30° S, with the greatest mangrove area within 5° of the equator. Mangrove plant families first appeared during the Late Cretaceous to Paleocene epochs, and became widely distributed in part due to the plate tectonics, movement of tectonic plates. The oldest known fossils of Nypa fruticans, mangrove palm date to 75 million years ago. Mangroves are salt-tolerant trees, also called halophytes, and are adapted to live in harsh coastal conditions. They contain a complex salt filtration system and a complex root system to cope with saltwater immersion and wave action. They are ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
West Bengal
West Bengal (, Bengali: ''Poshchim Bongo'', , abbr. WB) is a state in the eastern portion of India. It is situated along the Bay of Bengal, along with a population of over 91 million inhabitants within an area of . West Bengal is the fourth-most populous and thirteenth-largest state by area in India, as well as the eighth-most populous country subdivision of the world. As a part of the Bengal region of the Indian subcontinent, it borders Bangladesh in the east, and Nepal and Bhutan in the north. It also borders the Indian states of Odisha, Jharkhand, Bihar, Sikkim and Assam. The state capital is Kolkata, the third-largest metropolis, and seventh largest city by population in India. West Bengal includes the Darjeeling Himalayan hill region, the Ganges delta, the Rarh region, the coastal Sundarbans and the Bay of Bengal. The state's main ethnic group are the Bengalis, with the Bengali Hindus forming the demographic majority. The area's early history featured a succession ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sundarbans
Sundarbans (pronounced ) is a mangrove area in the delta formed by the confluence of the Padma, Brahmaputra and Meghna Rivers in the Bay of Bengal. It spans the area from the Baleswar River in Bangladesh's division of Khulna to the Hooghly River in India's state of West Bengal. It comprises closed and open mangrove forests, land used for agricultural purpose, mudflats and barren land, and is intersected by multiple tidal streams and channels. Sundarbans is home to the world's largest area of mangrove forests. Four protected areas in the Sundarbans are enlisted as UNESCO World Heritage Sites, viz. Sundarbans West (Bangladesh), Sundarbans South (Bangladesh), Sundarbans East (Bangladesh) and Sundarbans National Park (India). Despite these protections, the Indian Sundarbans were considered endangered in a 2020 assessment under the IUCN Red List of Ecosystems framework. The Sundarbans mangrove forest covers an area of about , of which forests in Bangladesh's Khulna Division ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forest Dieback
Forest dieback (also "", a German loan word) is a condition in trees or woody plants in which peripheral parts are killed, either by pathogens, parasites or conditions like acid rain, drought, and more. These episodes can have disastrous consequences such as reduced resiliency of the ecosystem, disappearing important symbiotic relationships and thresholds. Some tipping points for major climate change forecast in the next century are directly related to forest diebacks. Definition Forest dieback refers to the phenomenon of a stand of trees losing health and dying without an obvious cause. This condition is also known as forest decline, forest damage, canopy level dieback, and stand level dieback. This usually affects individual species of trees, but can also affect multiple species. Dieback is an episodic event and may take on many locations and shapes. It can be along the perimeter, at specific elevations, or dispersed throughout the forest ecosystem. Forest dieback presents i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heavy Metal (chemistry)
upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead">lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals are generally defined as metals with relatively high density, densities, atomic weights, or atomic numbers. The criteria used, and whether metalloids are included, vary depending on the author and context. In metallurgy, for example, a heavy metal may be defined on the basis of density, whereas in physics the distinguishing criterion might be atomic number, while a chemist would likely be more concerned with chemical property, chemical behaviour. More specific definitions have been published, but none of these have been widely accepted. The definitions surveyed in this article encompass up to 96 out of the 118 known chemical elements; only mercury, lead and bismuth meet all of them. Despite this lack of agreement, the term (plural or singular) is widely used in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown (botany)
The crown of a plant refers to the total of an individual plant's aboveground parts, including stems, leaves, and reproductive structures. A plant community canopy consists of one or more plant crowns growing in a given area. The crown of a woody plant (tree, shrub, liana) is the branches, leaves, and reproductive structures extending from the trunk or main stems. Shapes of crowns are highly variable. The major types for trees are the excurrent branching habit resulting in conoid shapes and decurrent (deliquescent) branching habit, resulting in round shapes. Crowns are also characterized by their width, depth, surface area, volume, and density. Measurements of crowns are important in quantifying and qualifying plant health, growth stage, and efficiency. Major functions of the crown include light energy assimilation, carbon dioxide absorption and release of oxygen via photosynthesis, energy release by respiration, and movement of water to the atmosphere by transpiration. Thes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Pathogens And Diseases
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria). By one definition, plants form the clade Viridiplantae (Latin name for "green plants") which is sister of the Glaucophyta, and consists of the green algae and Embryophyta (land plants). The latter includes the flowering plants, conifers and other gymnosperms, ferns and their allies, hornworts, liverworts, and mosses. Most plants are multicellular organisms. Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria. Their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic or mycotrophic and have lost the ability ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mangroves
A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in several plant families. They occur worldwide in the tropics and subtropics and even some temperate coastal areas, mainly between latitudes 30° N and 30° S, with the greatest mangrove area within 5° of the equator. Mangrove plant families first appeared during the Late Cretaceous to Paleocene epochs, and became widely distributed in part due to the movement of tectonic plates. The oldest known fossils of mangrove palm date to 75 million years ago. Mangroves are salt-tolerant trees, also called halophytes, and are adapted to live in harsh coastal conditions. They contain a complex salt filtration system and a complex root system to cope with saltwater immersion and wave action. They are adapted to the low-oxygen conditions of water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.JPG "Click for more on -> Mangrove")
