The Sapotaceae of Indonesia and the Potential Role of Botanic Gardens in their Conservation

Indonesia holds a large percentage of Malesian Sapotaceae taxa with an estimated 15 genera and 158 species. Bogor Botanic Gardens currently hold 12 genera and 41 species of which 29 are native to Indonesia. This represents just under 20% of Sapotaceae species currently recorded from Indonesia. The utility of these collections is dependent on the type of data associated with them and on the quality of identification of the material. Of the 29 native species only three have had a global threat assessment made and, of these, one, Madhuca boerlageana (Burck) Baehni, is considered Critically Endangered. The regional botanic gardens initiative of the Indonesian government is establishing botanic gardens in each of the 47 ecoregions of Indonesia. This new initiative is potentially very important for in situ and ex situ conservation of the Indonesian flora. So far it has brought into cultivation 39 threatened species, however none of these are Sapotaceae. The lack of global IUCN threat data is a major impediment to the prioritisation of collection, cultivation and conservation of Sapotaceae species

Extension of Earth-Moon libration point orbits with solar sail propulsion

This paper presents families of libration point orbits in the Earth-Moon system that originate from complementing the classical circular restricted three-body problem with a solar sail. Through the use of a differential correction scheme in combination with a continuation on the solar sail induced acceleration, families of Lyapunov, halo, vertical Lyapunov, Earth-centred, and distant retrograde orbits are created. As the solar sail circular restricted three-body problem is non-autonomous, a constraint defined within the differential correction scheme ensures that all orbits are periodic with the Sun’s motion around the Earth-Moon system. The continuation method then starts from a classical libration point orbit with a suitable period and increases the solar sail acceleration magnitude to obtain families of orbits that are parametrised by this acceleration. Furthermore, different solar sail steering laws are considered (both in-plane and out-of-plane, and either fixed in the synodic frame or fixed with respect to the direction of sunlight), adding to the wealth of families of solar sail enabled libration point orbits presented. Finally, the linear stability properties of the generated orbits are investigated to assess the need for active orbital control. It is shown that the solar sail induced acceleration can have a positive effect on the stability of some orbit families, especially those at the L2 point, but that it most often (further) destabilises the orbit. Active control will therefore be needed to ensure long-term survivability of these orbits