To conserve the Plant Biodiversity is really a daunting task and we can not jump over to conclude to say about specific strategy .It basically depend upon your objective like crop/species which you want to conserve and which mode or form you want to conserve either it will be short term.medium term or long term basis.Moreover either the plant or spp you are going to conserve either you are interested in In-Situ conservation or Ex-situ conservation.
The germ plasm conservation of plants is very much essential because it preserves the provides information about the genetic stability well as in vitro multiplication is one of the important mass cloning method to protect endangered medicinal plants. Conservation through micro propagation technique also allows the user to conserve the plant well as the phyto-therapeutic value of the plants.
In general - always include society and socio-economics of the region you are working in. It is becoming more and more obvious that "strict" conservation plans which do not take the social level into account will most certainly not work!
Yes Andre...you are right....for sustainable and meaningful conservation of germplasm you must include the local community into account..I mean they can conserve ..not nay planned in situ or ex situ plan. They must be motivated to manage and use biodiversity as a part of their socio-economic activities...livelihood...economic development...recent efforts are there see IUCN's recent moves, Resilient Center (Sweden) IIED (UK) and BGCI...all human development efforts must include this as an integral part....the only way..please think....