07 Jan

Plant Biodiversity Situation in India

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Content

• International Day of Forests
• Natural Vegetation in India (Source – Geography NCERT)
• India State of Forest Report, 2021
• Key Highlights of the 2021 Survey
• Mangroves
• Mangroves Alliance for Climate (MAC)
• UNESCO World Heritage Forests: India’s Sundarbans among 5 sites with highest ‘blue carbon’ globally
• Grasslands
• Famous Grasses in India
• Bamboos
• Seagrasses
• Recent Initiatives towards enhancing Green Cover: Miyaki Forests
• Orchids in India
• Exotic Alien Plant Species
• Invasive Plant Species in India

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• The latest estimate of plant diversity in India stands at 54,733 taxa including 21849 angiosperms, 82 gymnosperms, 1310 pteridophytes, 2791 bryophytes, 2961 lichens, 15504 fungi, 8979 algae, and 1257 microbes. These represent around 14% of total recorded plant species in the world.

Group	No. of taxa in India	Percentage of plant diversity in India
Virus/Bacteria	1257	2.29
Algae	8979	16.4
Fungi	15504	28.33
Lichens	2961	5.41
Bryophytes	2791	5.11
Pteridophytes	1310	2.39
Gymnosperms	82	0.15
Angiosperms	21849	39.92
Total	54733	100

1) INTERNATIONAL DAY OF FORESTS

• 21st March is observed as the International Day of Forests (IDF) by the United
• The year 2022 marked a decade of IDF.
  • The UN had proclaimed 21st March as the International Day of Forests in 2012.
• The day celebrates and raises awareness about the importance of all types of
• The theme for 2023 was ‘Forests and Health’, which calls for giving, and not just taking, recognizing that healthy forests will bring healthy people.
• Organizers are the UN Forum on Forests and the Food and Agriculture Organizations (FAO) of the UN, in collaboration with Governments, the collaborative partnerships on forests and other relevant organizations.

 2) NATURAL VEGETATION IN INDIA (SOURCE – GEOGRAPHY NCERT)

• Natural vegetation is the plant cover that grows without any human intervention and is adapted to the local climate and soil conditions. It plays an important role in maintaining ecological balance and supports a wide range of flora and fauna. It is also known as virgin vegetation.
  • Thus, cultivated crops and fruits, orchards from part of vegetation but not natural vegetation.
• On the basis of certain common features such as pre-dominant vegetation type and climatic regions, Indian forests can be divided into following types:
  • Tropical Evergreen and Semi Evergreen Forests
  • Tropical Deciduous Forests
  • Tropical Thorn Forests
  • Montane Forests
  • Littoral and Swamp Forests
• Details about each forest types:

A) TROPICAL EVERGREEN AND SEMI EVERGREEN FORESTS:

They are found in warm and humid areas with an annual precipitation over 200 cm and a mean annual temperature above 22 degree C.

Distribution in India: Western Slopes of Western Ghats, Hills of North-eastern region, Andaman and Nicobar Islands.

Tropical Evergreen Forests are well stratified with layers closer to the ground.

• • • They are covered with shrubs and creepers, with short structured trees followed by tall variety of trees.
    • No definite time for trees to shed their leaves. Therefore, these forests appear green all the year round.
    • Some commercially important trees are ebony, mahogany, rosewood, rubber, cinchona.

Semi Evergreen Forests are found in the less rainy part of this region. They have a mixture of evergreen and moist deciduous trees.

• • • The undergrowing climbers provide an evergreen character to these forests.
    • Main spcies are white Cedar, hollock and kail

B) TROPICAL DECIDUOUS FORESTS

• Most widespread forests in India. They are also called monsoon forests and are spread over regions receiving rainfall between 70-200 cm. Trees shed leaves once a year four six to eight weeks in dry summer.
• The tropical deciduous forests are found in central and southern India .
• The deciduous forests can be further classified into moist deciduous forests and dry deciduous forests based on the amount of rainfall received.
• Moist Deciduous Forests are more pronounced in the region which record rainfall between 100-200 cm. They are found in NE states along the foothills of Himalayas, eastern slopes of western ghats, and Odisha.
  • Mains species – Teak, Sal, Bamboos, Shisham, sandalwood, kair, kusum, arjun, semul, mulberry, Mahua etc.
• Dry Deciduous are found in areas where rainfall range from 70-100 cm. It acts as transition between moist deciduous and thorn forests. They are found in rainier area of Peninsula and plains of UP and Bihar.
  • In the higher rainfall area of the peninsular India and northern plains, these forests have a parkland landscape with open stretches in which teak and other trees interspersed with patches of grass are common. As the dry season begin, the trees shed their leaves and forest appears like vast grassland with naked trees all around.
  • Main Vegetation: Tak, Sal, Peepal, Neem, Tendu, etc.

C) TROPICAL THORN FORESTS

• Areas with rainfall less than 50 cm.
• Consist of variety of grasses and shrubs
• It includes, semi-arid areas of south west Punjab, Haryana, Rajasthan, Gujarat, MP and UP. In these areas plants remain leafless for most part of the year and give an expression of scrub vegetation.
• Important Plant Species:
  • Acacia, palms, euphorbias, and cacti are the main plant
  • Ber, date palm, khair, neem, palas etc are also common.
  • Tussocky grass grows upto a height of 2m as the undergrowth

D) MONTANE FORESTS

• In Mountainous region, the decrease in temperature with increasing altitude leads to corresponding change in natural vegetation. We see a succession of vegetation from tropical to tundra region.
  • The Wet Temperate type of forests are found between 1,000 m to 2000 m height. Here, Evergreen broad leaf trees, such as oaks, chestnuts dominate.
  • The Temperature forests containing coniferous trees are found between 15,00 and 3,000 metres. It include, pine deodar, silver firs, spruce and cedar. These forests are generally found in southern slope of Himalayas, places having high altitudes in southern and north eastern India.
    • Temperate grasslands are common at higher
  • At height above 3,600 metres temperature forests and grasslands give way to Alpine vegetation. Silver fir, junipers, pines and birches are the common trees of these forests. However, they become progressively stunted as they approach the snowline. Ultimately through shrubs and scrubs, they merge into Alpine grasslands. These are used extensively for grazing by nomadic tribes, like Gujjars, and Bakarwals.
  • At higher altitudes Mosses and Lichens are part of the tundra vegetation.

E) LITTORAL AND SWAMP FORESTS:

• Mangrove Forests are found in areas of coasts influenced by tides.
  • Sundari trees provide durable hard timber.
  • Palm, coconut, keora, agar. Etc. also grow in some parts of the delta.

1. INDIA STATE OF FOREST REPORT, 2021

• Introduction
  • Published by Forest Survey of India, MoEF&CC, GoI.
  • Biennial report
  • Provides state/district wise forest cover of the country and changes thereon wrt previous assessment.
  • The forest cover assessment is a wall-to-wall mapping exercise based on remote sensing supported by intensive ground verification and field data from National Forest Inventory.
• About Forest Survey of India
  • It was founded in 1976 as a key National Survey Organization under Ministry of Environment Forest and Climate Change. It is headquartered in Dehradun.
  • It conducts forest surveys, conducts research to monitor changing land and forest resources, implements social forestry.
• Reports
  • ISFR
  • ‘The Reports on Inventory of Wood Consumption’.
• Some other Basic Information
  • Forest cover classified into three density classes.
    • Very Dense Forest (canopy density > 70%)
    • Moderately Dense Forest (40-70% of canopy density)
    • Open Forest (10-40% of canopy density)
  • Scrub (degraded forest lands with density less than 10%) -> not counted in forest cover
  • Non-Forest (land not included in any of the above 4 categories (includes water bodies))
• Forest Cover and Recorded Forest Area
  • Forest Cover: All land more than 1 hectare in area with a tree canopy of more than 10%, irrespective of land use, ownership, and legal status. It may include even orchards, bamboo, palm etc. and is assessed through remote sensing.
  • Recorded Forest Area/Forest Area: Refers to all geographical areas recorded as ‘Forests’ in government record.
  • Note: There may be areas under Forest Area which will not be covered under definition of Forest cover. Similarly, there will be areas outside Forest Area which may be included in forest cover.

 1) KEY HIGHLIGHTS OF THE 2021 SURVEY

• India’s total forest cover: 13 lakh sq km (21.71% of India’s total area)
  • In 2011, the total area under forest cover was 21.05%. So, there has been an increase of 3.14 percent in the forest cover over 2011.
  • This increase in total forest cover is mainly attributed to increase in very dense forest, which rose by 19.54 per cent between 2011 and 2021. Open forest also improved by 6.71 per cent, while moderately dense forest declined by 4.32 per cent between 2011 and 2021.
    • Causes of Concern?
      • Decline in Natural Forests:
      • Decline in North-East India
        • Importance of NE: It accounts for 98% of total geographical area but 23.75% of total forest cover.
  • The Forest cover has increased by 1,540 sq km since 2019.
• Total Forest and Tree Cover: 8.09 lakh sq km (24.62% of India’s total area).
  • There has been a 1,540 sq km increase in forest cover and 721 sq km increase in tree cover since the last report in 2019.
• Total Mangrove cover in the country is 4,992 sq km which is 15% of the country’s total geographical area.
  • As per the ISFR 2021, there has been a net increase of 17 sq km in the mangrove cover of the country compared to 2019 assessment.
  • Very Dense (29.55%), Moderately Dense (29.67%), and Open Mangroves (40.78%).
    • Odisha (8 sq km), Maharashtra (4 sq km) and Karnataka (3 sq km) have shown most increase.
• Bamboo Forests have grown from 13,882 million culms (stems) in 2019 to 53,336 million culms in 2021.
• The total carbon stock in forests was estimated to be 7,204 million tonnes, an increase of 4 million tonnes from 2019.
• States with more than 33% of area under forest cover: 17 states
  • 5 States/Uts: Lakshadweep, Mizoram, Andaman & Nicobar Islands, Arunachal Pradesh and Meghalaya have more than 75% forest cover.
  • 12 States/Uts: Manipur, Nagaland, Tripura, Goa, Kerala, Sikkim, Uttarakhand, Chhattisgarh, Dadra & Nagar Haveli and Daman & Diu, Assam, and Odisha have forest cover between 33% and 75%.
• Top 5 States in terms of Forest Cover
  • Madhya Pradesh (11% of the total forest cover), Arunachal Pradesh (9%), Chhattisgarh (8%), Odisha (7%), and Maharashtra (7%).
• Top 5 States by % of Geographical Area under Forest Cover

 

• • Note: The above data has not included islands of A&N and Lakshadweep as they are UTs:
    • Lakshadweep (90%) A&N Islands: 75%

• Assessment of Forest Cover in tiger reserves, tiger corridors and Gir Forest which house the Asiatic Lion.
  • In Tiger Corridors the forest cover has increased by 37.15 sq km (0.32%) between 2011 – 2021.
  • In Tiger Reserves the forest cover has decreased by 22.6 sq km (0.04%) between 2011-2021.
  • Forest cover has increased in 20 tiger reserves in these 10 years and decreased in 32.
    • Pakke Tiger Reserve (in Arunachal Pradesh) has the highest forest cover at 97%.

2. MANGROVES    

• Introduction
  • Mangroves are salt tolerant plant communities found in tropical and sub-tropical intertidal regions of the world. They are a group of 70 species of trees, shrubs and ferns. Mangrove areas are characterized by high rainfall (100 – 300 cm) and high temperature (26 degree C – 35 degree C).
  • Mangrove species exhibit a variety of adaptation in morphology, anatomy, and physiology to survive in water logged, highly saline soils and cyclone and tide prone environment.
  • They show convergent adaptations to saline, oxygen deficient, habitats. The ‘true mangroves’ exhibit all or few of the typical mangrove adaptations:
    1. Tolerance to Salinity; Salt filtering or exuding system
    2. Tolerance to oxygen deficient soil
    3. Stilt or knee roots, Aerial Roots (pneumatophores)
       • Note: Aerial roots project above the mud and have small openings (lenticles) through which air enters, passing through the soft spongy tissues to the roots beneath the mud. This acts as site of oxygen intake for the submerged roots.
    4. Succulents (thick fleshy leaves)
    5. Viviparous Seedlings

Vivipary is a phenomenon that involves seeds germinating prematurely while they are still inside or attached to the parent plant or fruits. Many mangrove species show vivipary. The ovum is fertilized while still on the parent tree and grows by a combination of photosynthesis and acquisition of nutrients from the parent until it may reach a length of 50 cm

• • These features allow these species, belonging to different families and genus survive along the coasts. Some prominent mangrove genera are Avicennia, Rhizophora, Sonneratia, Brugueira, etc.
• Global Distribution of Mangroves:
  • • The distribution and diversity of mangroves is higher in the tropical Indo-West Pacific region and goes on reducing the subtropical, Atlantic, Caribbean, and Eastern Pacific regions.
  • Continental Distribution:
    • As per the India State of Forest Report (ISFR), 2021, globally around 113 countries have mangrove forests with highest continental distribution in Asia, followed by Africa, North and Central America, South America and Oceania.
  • Country wise distribution:
    • More than 40% of the total area of Mangroves was reported to be in just four countries: Indonesia (19%), Brazil (9%), Nigeria (7%), and Mexico (6%).
• Mangroves in India:
  • India has 3.3% of the world’s mangroves. Important species of Mangrove ecosystem in India include Avicennia officinalis, Rhizophora mucronata, Sonneratia Alba, Avicennia Alba, Bruguira cylindrica, Heritiera littoralis, Phoenix paludosa, Morinda citrifolia & Ceriops tagal.
  • Sundarban, located in the northern Bay of Bengal is the world’s largest single patch of Mangrove forests. It is spread over approx. 10,000 sq km, in BD and India. It was the first mangrove forest to be brought under scientific management as early as in 1892.
    • GoI, had set up a National Mangroves Committee in 1976 to advise the government on issues related to conservation and development of mangroves in the country.
• Importance:
  • Protection against Tsunamis, Storm Surges and Soil Erosion
  • Enhance Sediment deposition: Act as a zone of land accretion
  • Reduces sea water pollution
  • Biodiversity: They act as fertile breeding ground for many fish species and other marine fauna.
  • Economy: They act as important source of livelihood for the coastal communities dependent on collection of honey, tannins, wax and fishing
  • Fight Climate Change: Important carbon sink
• Factors harming Mangrove Ecosystem:
  • Land Reclamation for agriculture.
  • Industrialization along the coastlines
  • Discharge of untreated domestic sewage and industrial effluents

 1) MANGROVES ALLIANCE FOR CLIMATE (MAC)

• Mangrove Alliance for Climate (MAC) (Nov 2022)
  • Why in news?
    • Launch of Mangrove Alliance for Climate (MAC) on the sidelines of COP 27 (Nov 2022)
• Details
  • Mangrove Alliance for Climate (MAC) is an initiative led by UAE and Indonesia. It also includes India, Sri Lanka, Australia, and Spain.
  • It seeks to educate  and  spread  awareness  worldwide  on  the  role  of  mangroves  in  curbing global warming and its potential as a solution for climate change.
  • The inter governmental  alliance   works on a voluntary  basis  meaning  that there are no  real  checks  and  balances  to  hold  the  members  accountable.  Instead, the parties will design their own commitments and deadlines regarding planting and restoring mangroves.
• Suggestions: Integration of Mangroves into the national REDD+ programs need of the hour

2) UNESCO WORLD HERITAGE FORESTS: INDIA’S SUNDARBANS AMONG 5 SITES WITH HIGHEST ‘BLUE CARBON’ GLOBALLY

• Researchers at UNESCO, the World Resource Institute and the IUCN estimated the gross and net carbon absorbed and emitted by the UNESCO World Heritage Forests between 2001 and 2020
• Key highlights of the study:
  • UNESCO World Heritage Forests in 257 sites absorbed approx. 190 million tonnes of CO2 from the atmosphere each year. This is roughly equal to half of UK’s annual CO2 emissions from fossil fuels.
  • They also store a substantial amount of carbon in addition to absorbing CO2 from the atmosphere. The total carbon stored by these forests is approx. 13 billion tonnes.
• UNESCO lists 50 sites across the globe for their unique marine values. This represents just 1% of the global ocean area. But they comprise at least 15% of the global carbon assets.
  • The top five sites include Great Barrier Reefs (502 million tonnes of Carbon), Everglades  National  Park  in  USA  (400 Mt C), Banc d’Arguin National Park in Mauritania (110 Mt C), Bangladeshi Portion of Sundarbans (110 Mt C) and Sundarban National Park in India (60 Mt C).
• Worrying trend:
  • 10 of the 257 forests emitted more carbon than they captured between 2001 and 2020 due to different anthropogenic disturbance and pressures.

3. GRASSLANDS

• Grasslands are types of vegetation mainly comprised of grasses belonging to the families Poaceae that include plants like millets, rice, wheat, bluegrass, ryegrass, bamboos, sugarcane and many more.
  • In India various famous grasses are doab (durva), lemongrass, kans, sewan, congress grass etc.
• Global Distribution of Grasslands:
  • Grasslands go by different names in different parts of the world.

Region	Name
US Midwest	Prairies
South America	Pampas, Ilanos, and cerrados
Central Eurasia	Steppes
West African	Savannas
Australia	Rangelands

• • Climatic Conditions:
    • Grasslandswouldbe found in places where there is not enough regular rainfall to support the growth of forest, but not so little that deserts form.
• Types of Grasslands: Tropical and Temperat
  • Tropical Grasslands  are  also  called Savannahs. They are found in warm and hot climates where the annual rainfall is between 50.8 to 127 cms per year.
    • They have scattered trees and some shrubs.
    • Distribution:
      • The largest savannahs are found in Africa  (Savanna).  It covers  more  than  50%  of the entire continent.
      • They are also found in Australia, South America (campos in Brazil, Llanos in Venezuela) and India.
  • Temperature grasslands include the Eurasian steppes (in Ukraine and Russia), North American Prairies, Argentine Pampas, Down in Australia, and Veld in South Afria.
    • They are found in wide plains which are drier than Savannahs withbut much colder.
    • They are flat, treeless, covered with grass, and have rich soil.
• What they have in common is that grasses are their naturally dominant vegetation.
• Depending on how they are defined, they account for 20-40% of the global land area.
• They are generally  open  and  fairly  flat.  Also, grasslands are  generally  very  fertile  as there is no heavy rain to wash away the nutrients.
  • This makes them vulnerable to human encroachment. For e.g., the much of the prairies have been encroached upon for agriculture purpose. This threatens biodiversity which depends on the grassland ecosystem.
• Key threats: Farming, overgrazing, invasive species, illegal hunting, climate change etc.
• Grasslands and Biodiversity:
  • Grasslandsupport variety of species. Vegetations on the African Savannah, for example, feeds animals including zebras, wildebeest, gazelles, and giraffes.  Similarly, temperature grasslands support prairies dog, badgers, coyotes and a variety or birds.

4. FAMOUS GRASSES IN INDIA

Doab Grass or Durba grass (Cynodon dactylon):

These are common type of grass seen across India. They also have cultural  significance  and  is  used  in deity worship. They are also used in Ayurveda system of India and in ancient medicines.

 

Lemon Grass:

Cymbopogon genus, also known as lemongrass, barbed wire grass, silky heads, Malabar grass.

• • Some species, particularly Cymbopogon citratus are commonly cultivated as culinary and medicinal herbs because of their scents, resembling that of lemon.
  • Lemongrassandits oil is also believed to produce therapeutic properties.
  • They may be used for producing citronella oil, which is used in soaps, as an insect  repellant (especially mosquitoes and houseflies)

Kans Grass is a grass native to Indian subcontinent. It is a perennial grass, growing upto three meters in height, with spreading rhizomatous roots.

They form important habitat for the Indian Rhino in Assam.

Revenna Grass (elephant grass): It is a big, tall and large kind of grass that grows in moist and wet habitat types in India.

Other important grasses are Sewan grass, Carpet grass, Manila Grass  (Korean grass), Napier Grass, Desho Grass, Foxtail Bristle grass, Big Leaf Grass, Congress grass,

5. BAMBOOS

• Introduction:
  • Bamboos, the most  diverse  groups  of  plants  in  the  grass  family  belong   to subfamily  Bambusoidae of the family Poaceae (Gramineae).
  • They are fast growing perennial plants and are found in tropical, sub-tropical  and  mild  temperature regions of the world.
  • Factors for geographical distribution: Precipitation, temperature, altitude, and soil conditions.
    • As per FAO, globally there are 1,200 species of Bamboo in 90 genera across the world.
    • Large tracts of natural bambooforests are found in tropical Asian countries between 15 degree N – 25 degree N latitudes.
• In India, bamboo is found naturally almost throughout the country except in Kashmir region.
  • There are 125 indigenous and 11 exotic species of bamboo from 23 genera.
  • Bamboos are found in abundance in the deciduous and semi-evergreen forests of the NE India and tropical moist deciduous forests of Northern and Southern India.
    • NE states and WB account for more than 50% of the bamboo resource of the country.
    • Other Bamboo rich areas are A&N, Chhattisgarh, MP, and the Western Ghats.
  • Major bamboo genera of India are Arundinaria, Bambusa, Chimonobambusa, Dendrocalamus, Dinochola, Gigantochloa etc. Different climatic conditions have different species in abundance.
• Various properties of Bamboo:
  • The various properties of bamboos are availability in different sizes, light weight yet strong, hard, flexible, straight, fast growing, abundant, and hence having many uses.
• Significance of Bamboo:
  • Economic Significance: Bamboo contributes to subsistence needs of about 2.5 billion people around the world, a majority of whom are tribal, forest dwellers, or communities dependent on forest resources.
  • Other uses of bamboo include making normal and final quality paper, fishing poles, furniture, flooring, handicrafts, walking sticks etc.
  • Environmental benefits: Bamboo plays a very important role in bio-diversity conservation, carbon sequestration and soil moisture conservation.
  • Food: Young Bamboo shoots are used as food in some cuisines.
• Protection Status in India:
  • Indian Forest Act was amended in 2017 to exempt Bamboo grown in non-forest areas from definition of tree. This did away with the requirement of felling/ transit permit of its transport and economic use.
• Total Bamboo bearing area of the country has been estimated to be 15.0 million ha.
  • Madhya Pradesh (1.84 million ha) has the largest area followed by Arunachal Pradesh (1.57 million ha), Maharashtra (1.35 million ha) and Odisha (1.12 ha).

6. SEAGRASSES

• Why in news?
  • In Baltic Sea, citizen drivers restore seagrass to fight climate change (July 2023)
    • This is part of a new project that trains local citizens to restore seagrass meadows in the Baltic Sea. The hope is that this painstaking work can help tackle climate change. Seastore Seagrass Restoration Project , run by the GEOMAR Helmholtz Centre for Ocean Research in Keil, Germany, is one of the first that aims to enable citizens to restore seagrass autonomously.
• Introduction:
  • Seagrasses are marine flowering plants that thrive fully submerged in shallow oceanic and estuarine habitats. They are one of the most important coastal habitat.
  • Global coverage of seagrass is estimated to be 3.45 X 10^5 km2, which represent about 0.1% –0.2% of the ocean floor.
  • In India,total seagrass cover is estimated to be 517 km2 with 14 reported species and six genera.
    • Halophila beccarii (IUCN: VU), is the most commonly distributed species reported from all the coastal states except islands, acts as a pioneer species in the succession process of mangrove formation.
  • Distribution of seagrasses in India:

The overall distribution of seagrass meadows in India occurs from  the intertidal zone to a maximum depth of 15 m with varying species diversity.

The Major seagrass ecosystem along the coast of India are found in:

• • • • • Gulf of Mannar and Palk Bay regions on the east coast comprise the largest seagrass meadows in India, covering 80 and 320 km2respectively.
        • The Ramasar site of Chilika Lagoon in Odisha state also has seagrass meadows that have expanded from 20 km2 to 80 km2 after the opening of the new bar mouth.
        • Gulf of Kuchchh on the west coast;
        • The lagoons of islands in the Lakshadweep in the Arabian Sea and;
        • Andaman and Nicobar Islands in Bay of Bengal.
• Significance of Seagrasses Ecosystem:

Provisioning Services:

• • Medicine (treatment of heart conditions, sea sickness etc.)
  • Food (Nutritious seeds)
    • Recently, a study has shown the presence of various biological metabolites in some India seagrass that can be used effectively in the food and pharmacological industries.
  • Fertilizer (Nutrient rich biomass)
  • Livestock feed (food for goats’ sheep etc.)
  • Building Material (Such as roofing for houses)

Supporting Services:

• • Key Fishing Grounds as they offer a complex habitat for a variety of fish and other marine organisms like Dugongs.
  • Seagrass based    fisheries    are    globally important and are present wherever seagrass exists, supporting subsistence, commercial and recreational activities.
  • Their high rates of primary production result in well-oxygenated waters that support complex food webs.

Regulating Services:

• • Coastal Protection: Seagrass reduce the energy of waves and thus protect the seashore.
  • Carbon Sequestration: Seagrass store more than twice as much carbon from planet warming CO2 per square mile than forests do on land, according to a 2012 study. They accumulate CO2 from both in-situ production     and sedimentation of particulate carbon from the water column.
  • Water Purification: They trap fine sediments and suspended particles in the water column and increase water clarity.
• Threats to Seagrass Ecosystems: Globally, seagrass habitations have declined in area and several species are threatened due to several natural and anthropogenic stressors:
  • Natural Stressor: Cyclones, heavy rainfall, coastal uplift and subsidence, grazing herbivores, and diseases
  • Anthropogenic Stressors:
    • Commercial Fishing and trawling activities: this is the most important threat to seagrass in India.
    • Boat activities for recreational purposes
    • Runoff (Pollution) from coastal aquaculture and agriculture
    • Shell Harvesting and Seaweed cultivation
    • Accidents like Oil Spills.
• Key Steps which protect Seagrasses:
  • CRZ Notification 2011, issued under Environmental (Protection) Act, 1986, has classified seagrass meadows as CRZ1-A (Ecologically sensitive area). It prohibits developmental activities in its vicinity.

7. RECENT INITIATIVES TOWARDS ENHANCING GREEN COVER: MIYAKI FORESTS

• These forests are developed using Miyawaki method to create urban forests. Dr Akira Miyawaki, botanist and professor, is the inventor of the technic since 1980. He is a recipient of the 2006 Blue Planet Prize, which is the equivalent of a Nobel prize in ecology.
• Using the method, native urban forest ecosystems can be created much quicker.
  • The method take its inspiration directly from process and diversity in nature: 15 to 30 different species of trees and shrubs are planted together. This plant community works very well together and is perfectly adapted to local weather conditions.
  • The habitat thus created get more complex over time and attract much more biodiversity. Vegetation becomes much denser than conventional plantations, and it has the structure of a mature natural forest.
  • It is a multistorey structure, where different levels of vegetation appear. The forest thus structured delivers many benefits in the form of ecosystem services.
  • Faster Recovery: It would take 200 years to let a forest recover on its own. But with the Miyawaki method a similar result is achieved in 20 years.

• The technique works worldwide irrespective of soil and climatic conditions.
• Miyawaki Forest at Ektanagar Gujarat:
  • At Ektanagar, the Miyawaki Forest will include following divisions: A native Floral Garden, a timber garden, a fruit garden, a medicinal garden, a Miyawaki section of mixed species and a Digital Orientation Centre.

8. ORCHIDS IN INDIA

• What are orchids?
  • They are a diverse and widespread group of flowering plants, with blooms that are often colorful and often fragrant commonly known as the Orchid family. They belong to the family Orchidaceae, which is one of the largest family of flowering plants with possibly over 27,000 species and more than 800 genera.
  • Habitats: Orchids can be found in nearly every habitat, but most orchid species are tropical.
• As per Botanical Survey of India, there are 1256 species of Orchids in India.
  • Orchids can be classified in three types:
    • Epiphytic: (Plants growing on another plants including those growing on rock boulders and often termed lithophyte).
    • Terrestrial: (Plants growing on land and climbers)Mycoheterotrophy: (Plants that derive nutrients from mycorrhizal fungi that are attached to the roots of a vascular plants.
    • In India, of all orchids 757 are epiphytic, 447 are terrestrial, and 43 are mycoheterotrophy.
  • State wise distribution:
    • Arunachal Pradesh (612 species); Sikkim (560 species) and West Bengal (with Darjeeling Himalayas having high species concentration) with 479 species.
• Orchids of North Bengal are facing threats (June 2023)

The wild orchids of Darjeeling Hills and Dooars are facing threats due to habitat loss (mostly due to deforestation).

The most endangered are the epiphytic orchids – the type that grows on another plant/tree merely for physical support. Orchids are also natural gauges of air quality because they don’t grow in polluted air

Applications:

• • The Oroan and Kharia tribal communities use wild orchids to treat range of diseases – cut and fractures, skin diseases, aches and pains.
• Some Important species of Orchids: 

The Dendrobium aphyllum carries pinkish violet, fragrant flowers;	The Bulbohyllum leopardinum, with its pale green and spotted red flowers simulate a leopard's spots;
Dendrobium transparens	Aerides Maculosa - Foxrush Orchid
Vanda Tessellate is greenish with a striking blue purple lip

9. EXOTIC ALIEN PLANT SPECIES

1) EXOTIC ALIEN PLANT SPECIES

• A study published in Biological Invasions in 2018 showed that as many as 471 plant species that are alien or exotic – not native to India – are ‘naturalized‘ for they can thrive in the country’s wilderness by forming stable populations.
• Naturalized species reproduce naturally in the environments they colonize.
• Invasive species are naturalized species which reproduce naturally but so prolifically that they alter the workings of the natural ecosystem they colonize and invade.
• The list of 471 Exotic – Naturalized Plant Species include:
  • Common Guava (Psidium guajava)
    • Not invasive
    • Exotic species in India. Native to Mexico and Central Asia.
  • Lantana Camara
    • Invasive
    • It replaces undergrowth and prevents native undershrub and plants from surviving.
  • Siam Weed (Chromolaena odorata) (native to South America and central America)
    • Invasive
  • Tridax daisy
    • Invasive
  • Mimosa Pudica
    • Invasive
  • Proposis Juliflora
    • Invasive
  • Parthenium Hysterophorus (Carrot grass, Gajar Ghans)
    • Invasive
• Tamil Nadu (331) leads the states having highest number of naturalized plants, followed by Kerala (290).
• Lakshadweep (17) has the least number of exotic naturalized plant species.
• 110 alien plants now occur in more than 31 states in India.
• Cause of Worry?
  • We have to worry about invasive species among these. The government needs to strengthen quarantine measures adopted before a plant is brought to the country.
  • In 2017, a study identified India as one of the ‘hot-spots’ of naturalized plant species and among the seven regions in the world that have the highest number of invasive species.

2) INVASIVE PLANT SPECIES IN INDIA

• Invasive Plant Species threaten 66% of India’s natural systems: report published in the Journal of Applied Ecology.
  • The finding is based on National level survey conducted in India.
  • The 11 high concern invasive plant species that showed presence in 20 states of the country included Lantana Camara, Prosopis juliflora and Chromolaena odorata.
  • Economicloss: The study estimates that loss due to these biological invasions will cost the Indian economy upto $182.6 billion

A) PROSOPIS JULIFLORA / MESQUITE (ANGREJI BABOOL OR VILAYATI BABOOL IN HINDI) (SEEMAI KARUVELAM IN TAMIL)

• It is a shrub of small tree in the family Fabaceae.
• It is native to Mexico, South America and the Caribbean.
• It has become an invasive weed in Africa, Asia and Australia.
• Distribution in India
  • They are distributed throughout the country and are aggressive colonizer.
  • They are common weed of waste lands, scrub lands and degraded lands.
• Considered a threat to biodiversity
  • It has survived where other tree species have failed, and in many cases, becomes a major nuisance.
  • It is a water-greedy plant that depletes ground water and nullifies the growth of native trees.
  • In 2004, it was rated one of the world’s top 100 least wanted species (Invasive species specialist group of the IUCN, 2004)
• Was considered a boon in 1960s
  • In the light of severe firewood shortage
    • In 1960s, TN government had made provisions for aerial seeding of the plant from helicopter
  • The tree was also used to erect fences, making it difficult for animals to invade agriculture fields.
• Other news about it
  • It is affecting the wild ass population in Kutch Gujarat.

B) PROPOSIS CHILENSIS

• Why in news?
  • An invasive plant from South America (Prosopis Chilensis) is threatening to pulverise indigenous plants across the 21 islands where 96 species of birds have been recorded. (April 2023: Source – TH)
• About Prosopis Chilensis
  • It is a drought resistant plant native to arid regions of four South American countries – Argentina, Bolivia, Chile, Peru.
  • Invasive in India:
    • It has become a cause of trouble in Gulf of Mannar Biosphere Reserve.
  • There is vary less or no study on the invasiveness of this species on how it came to India unlike the equally invasive Prosopis juliflora.

C) BLACK MIMOSA (MIMOSA PIGRA)

Genus Mimosa contains 400-500 species, which are mostly native to South America.

It is a woody invasive shrub that originates from tropical America and has now become widespread throughout the tropics.

• • It has been listed as one of the world’s 100 worst invasive species and forms dense, thorny, impenetrable thickets in wet areas.

Distribution in India

• Throughout
• Abundant in still or slow floating waters. Nuisance for aquatic ecosystem.

D) PARTHENIUM HYSTEROPHORUS (CARROT GRASS)

• It is an annual herb which is native to the American Tropics.
• It is an invasive species in India and several other countries. In India it is also known as Carrot grass, Congress grass or Gajar Ghans.
• It invades disturbed land, including roadsides, infests pastures and farmlands, leading to disastrous loss of yield.
• The plant produces allelopathic chemicals that suppress crop and pasture plants, and allergens that affect humans and livestock. It also frequently cause pollen allergies.
  • All four of Assam’s Rhino reserves – The national park of Kaziranga, Orang, Pobitaro and Manas – are currently reeling under the attack of these invasive plants.

E) LANTANA CAMARA

It is also known as big-sage, wild sage, red sage and tickberry. It is a species of flowering plant within the verbena family, Verbenaceae, that is native to American tropics.

How was it introduced in India?

Lantana arrived in India as a decorative shrub in the British colonial period but quickly took over several ecosystems as an invasive species.

Current Spread: The plant currently covers 40-50% of India’s area and have also invaded national parks and pasture lands.

It has spread from its native Central and South America to 50 different countries, where it has become invasive species.

• • Reduces biodiversity: It often outcompetes more desirable species, leading to reduction in biodiversity.
  • Impacts Agriculture: It can also cause problems if it invades agricultural areas as a result of its toxicity to livestock as well as ability to form dense thickets which if left unchecked can greatly reduce the productivity of farm land.

Recent Updates: A decade long initiative in MP to reclaim land overrun by Lantana helps residents restart agriculture and restore natural biodiversity. (Dec 2023: Source: DTE)

F) SIAM WEED (COMMUNIST PACHA)

• It is a common invasive species of Kerala, and is locally known as Communist Pacha (green) as it spread all over the state within a short span of time just like Communism did during the same time in 1950s.
• Siam weed is native to South America. Researchers have regularly pointed out this plant being responsible for harming many native plant species.
• Why in news?
  • After flood, there were reports of Siam weed becoming more common in Kerala.

G) SENNA SPECTABILIS (CALCEOLARIA SHOWER)

• Details about Senna Spectabilis
  • It is a plant species of the legume family and is native to South and Central America.
    • Here, they are often grown as an ornamental in front yards, parks, gardens, buildings, etc. due to their bright yellow flowers that bloom during the summer months.

• • The species has become an invasive alien species in Africa and South-India, after it was introduced for resources such as firewood as well as to fight deforestation and desertification.
  • Along with Lantana Camara and Wattle, it is among five major invasive weeds that had taken over vast swathes of the Nilgiris.
  • InMadumalai Tiger Reserve, policy level decisions are being considered that will allow Tamil Nadu Newsprint and Papers Limited (TNPL) to remove the species from the landscape for paper making.

H) WATER HYACINTH

• Why in news?
  • MP’s newest Ramsar wetland covered in invasive water hyacinth which is threatening biodiversity (2023)
• About Water Hyacinth (Pontederia crassipes)
  • It is an aquatic plant native to South America. It is naturalized throughout the world and often invasive outside the native range.
  • It is also known as “Terror of Bengal“ as it competes strongly with native species. They have caused shortage of fish in Bengal.
    • It flourishes in Bengal’s hot and humid climate and can live well and kill nearby plankton and water-borne species.
    • They double their biomass in six days and is one of the fastest growing plant known.
    • They take over local aquatic species. Additionally, these plants can produce thousands of seeds every year and these seeds can remain viable for over 28 years.
  • It reduces the dissolved oxygen in the water and increases the biochemical oxygen demand causing the death of aquatic species.
• Other problems causedbyHyacinth:Economicloss,negativelyimpact hydel powerproject, pisciculture etc.
• Note: In small quantities water hyacinth can be good for ecosystem as they can remove heavy metal from water and can thus act as a water purifier.
• News: Sankhya Sagar in Madhya Pradesh (which was declared a Ramsar site) has virtually disappeared under a thick layer of water hyacinth.

I) CANOCARPUS TREES

• Concerns over the management of invasive Conocarpus species of trees have recently led to Gujarat (2023) and Telangana (2022) banning their use. Several other states may follow suit – which is likely to discourage horticulturalists and nurseries from multiplying the species and using lakhs of its saplings in afforestation and landscaping projects across the country over the next year.
• About Canocarpus Trees:
  • There are two species of Canocarpus (buttonwood) trees, with several varieties of hybrids –Canocarpus erectus, which is widely used in India (and is native to South America) and Canocarpus lacifolius is native to East Africa.
  • They are easily propagated and multiplied in nurseries through stem cuttings.
  • They have also been known to cause pollen allergies and respiratory problems in the vicinity of plantation.
• Why do urban green initiatives end up deploying them in the first place?
  • Since they are non-native species – they face very few or no pests or pathogens in new habitats, which makes their proliferation easy. They often require very little aftercare.
  • Somespecies like Canocarpus are not browsed by livestock and are thus favored for horticultural and landscaping projects.

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