page_title: Phumdi
section_title: Ecological composition
hierarchical_section_title: Phumdi / Ecological composition
context_page_description: Phumdis are a series of floating islands, exclusive to the Loktak Lake in Manipur state, in northeastern India. They cover a substantial part of the lake area and are heterogeneous masses of vegetation, soil and organic matter, in different stages of decay. The largest single mass of phumdi is in the southeastern part of the lake, covering an area of 40 km². This mass constitutes the world’s largest floating park, named Keibul Lamjao National Park. The park was formed to preserve the endangered Eld's deer subspecies, called sangai in the Meitei language, indigenous to this area.
  Phumdis are used by the local people for constructing their huts for fishing and other livelihood uses, and are inhabited by about 4000 people. Athapums are artificial circular phumdis, built by the villagers as enclosures for fish farming; aquaculture has caused proliferation of the phumdis in the lake.
context_section_description: The floating mass of matted vegetation, organic debris, and soil that constitutes a phumdi has a thickness that varies from a few centimetres to two metres. Its humus is black in colour and porous, with a spongy texture. Only 20% of a phumdi's thickness floats above the water surface; the other 80% remains submerged. Before the construction of the Loktak Hydroelectric Project, the park area containing phumdis was merely marshy land, but since the commissioning of the project, two ecosystems have emerged. One, the body of open water, covers one-third of the area and the other, the phumdi, covers the remaining two-thirds. 
  The life-cycle of the phumdis has generally been subject to seasonal variation. During the monsoon season when the water level is high, the phumdis float, but during the dry season, as the water level falls, the phumdis touch the lake bed and absorb nutrients from it. When the wet season returns, they again float, and the biomass, which has enough nutrients stored in the plants' roots, survives. However, the contemporary situation, with high water levels in the lake throughout the year, has meant that the process of 'feeding' on lake–bottom nutrients has been seriously disturbed, resulting in a loss of biomass and a thinning of the islands each year. In January 1999, it was reported that a large section of phumdi in the north of the park had shattered into pieces and drifted away from the park area, threatening the habitat of the sangai.
  Changes in the water regime due to the construction of the Ithai barrage across the Manipur River have caused changes in the vegetation composition of the phumdis. A study was instituted, from October 2005 to July 2006, to record the vegetation composition and productivity of phumdis in areas of ranging thickness, water depth and soil pH, accumulating data in both summer and winter. The study recorded 83 plant species of 21 families (Poaceae and Cyperaceae formed the dominant families); 81 species were recorded in summer and 48 in winter.
  The Diversity indices of the plant species were recorded; they were a richness of 48, diversity of 0.29 and evenness of 0.47 in summer. In winter, the respective figures were 81, 0.17 and 0.52. Species richness was found to be different in 48 samples of thin phumdis, 53 samples of thick phumdis and 14 samples on hard ground. The eight plant communities identified during winter and summer were Capillipedium, Leersia hexandra, Oenanthe javanica, Phragmites karka, Kyllinga triceps, Pteridium aquilinum, Zizania latifolia and Persicaria perfoliata. Zizania latifolia recorded the highest productivity with (13.90 ± 5.01) g/m² for winter and (102.96 ± 26.03) g/m² for summer. Greater productivity was recorded in summer (65.96 g/m²) than winter (15.76 g/m²). Variation of productivity of annuals and perennials were noted according to seasons and type of phumdis.
caption: A sangai Manipuri deer which thrives on phumdis
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