Global acceptance – that conservation of Biodiversity is essential; so, many countries and world organizations are active with definite agenda for conservation
What is conservation?
“Conservation is the management of human use of the biosphere to yield greatest sustainable benefit to current generations, while maintaining its potential to meet the needs & aspirations of future generations”
Types of Conservation – (1) in-situ, (2) ex-situ
What is in-situ conservation?
‘conserve biodiversity within evolutionary dynamic ecosystems of original habitat or natural environment’
e.g., conserving any species of mangrove forest within mangrove forest itself.
example: Sundri (Heritiera fomes) of Sundarbans
Merits of in-situ conservation:
- ensures conservation of single sp. as well as other dependent spp. on same plant in the habitat; e.g. pollinators, insects, nest builders, herbivores. etc.
- some plant requires mycorrhizal association, so ensures it
- niche characteristics can be preserved
- ‘struggle for existence’ & ‘survival of the fittest’ capacity develops; dynamism with ecosystem evolution takes place
- easier to conserve, any species may have 500-5000 viable population, conservation of such a high number is difficult via other methods (ex situ).
Regions of in-situ Conservation
- undisturbed ecosystem rich in biological reserve
- sometimes disturbed ecosystem (from where bio-resources are regularly collected & exploited) can also be selected for in-situ conservation. Because disturbance may sometime also cause increase in biodiversity
- Primary & Secondary forest’s biodiversity may be same
- application of ‘ecopark’ concept & sometimes in co-operation of ethnic tribes
e.g., Brazil, uses of resources is allowed in some reserves forest,, except cutting large trees for wood, tribal people collect nuts, rubber juice, resin, fruits, etc. keeping species survival at tolerable scale
It is important for conservation of spp. Size of the reserves is indirectly proportional to the loss of biodiversity. So, reserve size should be relatively large to sustain biological interaction containing sufficient population
Consideration for Reserve Selection
- spp. list should be complete with information on population dynamics
- higher number spp. with endemism
- of crop plants (Vavilov centres)
What is Ex-situ conservation?
‘keeping components of biodiversity alive outside of their original habitats or natural environment’
e.g., Aquilaria agallocha from Sylhet & Heritiera fomes from Sundarbans conserved in Botanical Gardens of Dhaka University
(1) Botanical Gardens –1,600 botanical gardens present globally
- rare, taxonomically, economically, important plants are cultured
- ¼th of total angiosperms of world planted in botanical gardens.
- 23 spp. now extinct are planted in Kew Botanical Garden, England
- attempts are made to rehabilitate those plants to their original habitats
- in Kew ~2000 spp. are present which are endangered in their country of origin
- carry out common program to cultivate the endangered spp.
- BGCI (Botanic Garden Conservation International) & CPC (Centre for Plant Conservation) extend helps
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|Species||Collection number||Country of origin|
|Calandrinia feltonii||3||Falkland Is.|
|Erica verticillata||10||S Africa|
|Sophora toromiro||3||Easter Is.|
Plants cultivated ex-situ in British Botanic Gardens. All are extinct in their natural habitats.
(2) Seed Bank – having history of 25 yrs, done in small places, Kew Gardens seed bank preserved seeds of British flora; seeds of many Extinct plants preserved in seed banks
Two Ex plants-
- Bromus interruptus (Kackel) Druce
- Schoenoplectus triqueter (L.) Palla preserved in seed bank
Two kinds of seeds
- orthodox: viability increases with decrease in temperature & losing water content; they can be dried & preserved at -20°C; ~70% of phanerogams are of this type; rest 30% are recalcitrant type
- recalcitrant: viability loses via decrease water content, e.g., mango, rubber etc., can be preserved via cryogenic preservation technique of embryo tissue
- Field gene bank – good for recalcitrant seeds, conserves live plants out side their original and native habitats e.g. Casava (from Africa) conserved in Columbia (S America). may result hybridization and spreading diseases; rubber, mango, sweet potato, etc.
- In-vitro – by liquid culture or tissue culture of callus from recalcitrants;
- DNA-preservation – DNA & essential genes can be protected
- Pollen conservation – pollen grains can be preserved which could be later on fertilized with live plants to get viable seeds; only male plants can be preserved
Which spp. Should get the priority of Conservation?
- Rare, Endangered; having higher risks of extinction
- Related plants for crop plants, to conserve genetic materials, disease resistant characters, etc.
- Key stone spp. (whose extinction brings also the extinction of others)
- Closely related spp. from the evolutionary standpoint
Syed Nasif Elias Faruqui, B.S. (Hons), Department of Botany, University of Dhaka