by
Gren Lucas
Secretary
Threatened Plants Committee of IUCN
c/o The Herbarium
Royal Botanic Gardens
Kew, England
Foresters have rightly been concerned with the depletion and decline in the diversity of wild populations of important tree crops, but less activity and concern has been concentrated on trees as species whose continued existence is in danger and whose potential benefits have been little utilized or even studied. One of the aims of the IUCN Threatened Plants Committee, set up in 1974, was to correct this imbalance, so that data could be made available to help ensure the survival of as many species as possible, preferably in their original habitats where natural evolution may continue and natural diversity can be maintained, but also in seed banks, botanic gardens and other forms of ex situ preservation. Each species is by its very nature a unique expression of genetic resources and potential that cannot normally be recreated by man from related taxa, and that is worthy therefore of protection and conservation wherever possible. Certainly data should be available so that land managers can make fully evaluated decisions in land management and so on.
To complement the lists of threatened species being produced for various parts of the world, and to help highlight the potential species losses that could occur, the Threatened Plants Committee has recently completed the first part of The IUCN Plant Red Data Book 1. This gives detailed case histories (Red Data sheets) on 250 rare and threatened plants from all parts of the world, the species being carefully selected to show the range of threats to plants and the various groups and areas most affected, as well as to highlight threatened species of particular botanical or horticultural interest or of special economic importance and potential. For each species, data are given on conservation status, threats to survival, distribution and habitat together with a short description and an evaluation of its interest or potential value to man. Of particular importance are sections on those conservation measures already taken to help ensure survival and proposals on what needs to be done. The aim is not only to draw attention to these 250 species alone and to provide a basis for their conservation, but by means of examples to demonstrate the growing and continuing threats to the world's natural ecosystems and the diversity of plants they contain. As time progresses and more information becomes available, further volumes of the Plant Red Data Book will be issued, giving sheets on additional threatened species as well as updated versions of previous sheets wherever major changes in status and conservation have occurred. As a stimulus, the introductory chapters include a revised version of the famous IUCN ‘Action Treatment’, originally produced by Sir Peter Scott's Survival Service Commission as a guide to what everyone and anyone, professional or amateur, voter or decision-maker, can do to promote the survival of species.
Most of the 250 plants included (1% of the estimated threatened plant species) are herbs and shrubs, but there is a considerable proportion of forest trees, despite the great difficulties in identifying threatened species among whole forest ecosystems that are in danger such as in most rain forests. For some of these trees, the sheets have been compiled from the draft accounts put together by experts on the IUFRO Working Party on Conservation of Gene Resources; the TPC is most grateful to these workers, and in particular to their Chairman, Professor Larry Roche of Bangor University, for permission to make use of this most valuable data where it concerns threatened species. Their work also covers important forestry species such as Pinus caribaea and Nesogordonia papavifera which are not endangered at species level but which are declining and a number of whose provenances are threatened. It is greatly to be hoped that the full results of their activity will soon be published under the aegis of FAO, and the TPC team stand ready to help in any way they can.
Typical of the tree species included and of particular interest to foresters in East Africa will be Vepris glandulosa (formerly in the monotypic genus Tecleopsis), of the Rutaceae. In the past it appears to have been used for making walking sticks and other wooden objects, possibly even spears, bows and arrows. However it is now too rare to be used even in this limited way, being reduced as far as is known to eight trees and a number of seedlings in a single site near Muguga, Kenya. Fortunately the locality is within the 15.5 hectare reserve on the estate of the Agriculture and Forestry Research Organization, Muguga (AFRO), who are attempting to propagate the species from seed. Other endangered trees are less fortunate in their localities: for example, Zanthoxylum paniculatum, a deciduous aromatic tree also in the Rutaceae, is only known from two individuals on the island of Rodrigues (Indian Ocean), where the endemic forest has been devastated by cultivation and by introduced plants and animals to an extent that 32 out of the 34 recorded endemics are now either Extinct or Endangered. Perhaps the most extreme example uncovered so far is of a new species of Diospyros (true ebony), as yet undescribed, which is only known from a single elderly and endangered tree on Mauritius. Tragically the species is dioecious (i.e. having male and female flowers on separate trees) and so unless a male is found to complement the existing female, this species, unless vegetatively reproduced, is certain to become extinct in due course. Even if a male be found, great efforts would be needed to ensure effective cross-pollination, collect the seed at the appropriate time, grow on the seedlings and rehabilitate them into a suitable locality where they can be protected from the exotic, introduced plants and animals that have played such havoc with the majority of the island's endemic forest vegetation. This tree could be of great value to man, with potential as a source of ebony in its own right and hence of valuable income to Mauritius, being relatively larger and more robust than the other species of Diospyros in the Mascarenes. In addition, as the Red Data Sheet concludes: “With a group of such great economic importance it is especially vital that gene-pools of all its members are conserved so that they will be available for future use and breeding work”.
With the great ravages of Dutch Elm Disease in England, much attention has been concentrated on relatives of the English elms that may have some resistance to the disease. It is not without significance that one of the relatives showing some resistance, Ulmus wallichiana from the Himalayas, is an Endangered species, being under threat by lopping for cattle fodder throughout its range. On a recent visit to the Himalayas, the Dutch botanist and elm specialist H.M. Heybroek found only three flowering specimens of this tree other than those in a game reserve at Dachigam, Kashmir, despite the fact that the species is recorded as formerly frequent from central Nuristan in Afghanistan, through Pakistan and Kashmir to Nepal. This example shows all too well the interdependence of all peoples on all floras.
Other trees in the Red Data Book that are rare and threatened and will be of interest to foresters included Cupressus dupreziana from Algeria, C. macrocarpa from two groves on the Pacific coast of California, Juniperus bermudiana, Betula uber (a rare birch recently rediscovered in the southern Appalachians), Vateria seychellarum (an endangered dipterocarp with a disjunct distribution from the Seychelles), Drypetes caustica from Mauritius and Reunion, Neowawraea phyllanthoides from the Hawaiian Islands, Cladrastis lutea in the USA, Serianthes nelsonii from Guam, Sophora toromiro (the only tree on Easter Island) and a range of Australian eucalyptus. Among crucial relatives of tree crops are Punica protopunica, the only wild relative of pomegranate and when last seen in 1967 reduced to 4 ageing trees on the island of Socotra, Olea laperrinei from the mountains of the Sahel and Sahara, and a new species of Ceratonia (Carob) from a few localities in Oman. One extraordinary example is Persea theobromifolia, reduced to about 12 individuals, all to be found in the exceptionally rich reserve of Río Palenque in Ecuador; not only is it a near relative of avocado, and one that could be of great breeding value in future, but it is also a timber tree that was clearly of major economic importance in the past. In this minute reserve of 0.8 sq km are found almost 50 species not known from anywhere else in the world; the site has one of the highest known figures for plant diversities at around 600 species per sq km. This incredible plant and locality illustrates both the desperate need for conservation and the importance to man's future welfare of ensuring these species are not lost.
But these species are only a small percentage of threatened trees. The Threatened Plants Committee estimate that on a world scale at least 25,000 species of flowering plants are dangerously rare or under severe threat, and so the 250 species covered in The IUCN Plant Red Data Book are but the tip of an iceberg. Saving these plants, many of which could be of crucial value to the future, is of the greatest importance to us all and should be a major component of the programmes of all organizations that deal with land and natural resources.
